INFLUENCE OF RATION GRAIN CONTENT ON FEEDLOT PERFORMANCE AND CARCASS CHARACTERISTICS By Harold Dee Woody. A DISSERTATION Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Animal Husbandry l978 ABSTRACT INFLUENCE OF RATION GRAIN CONTENT ON FEEDLOT PERFORMANCE AND CARCASS CHARACTERISTICS By Harold Dee Woody Corn Plot Studies Two trials were conducted to determine the effect of ration grain content on feedlot performance and carcass characteristics of growing and finishing beef cattle. The percent grain in the corn silage dry matter was varied by planting corn at different plant populations. In trial 1, corn silage was harvested from plant populations of 24,709, 49,419 and 74,128 plants/hectare or from high oil or brown midrib corn. Grain percent was highest at the 24,709 plant population (48.9%) and was reduced to 27.4% when the population was increased to 74,128. The percent grain in the high oil and brown midrib plants were 8.7% and 15.0% lower than the normal population. Dry matter yield increased 11.3% between the 24,709 and 49,419 populations; no further increases were found at the 74,128 p0pulation. In the second trial, corn silage was harvested from plant populations of 24,709, 49,419 or 123,548 plants/hectare. Grain percent was highest for the 24,709 (53.8%) and was reduced to 36.9% when the populations were increased to 123,548. Dry matter yield fell 5.3% between the 24,709 and 49,419 population; there was a 37.8% increase between 49,419 and 123,548 population. Harold Dee Woody Feeding Studies The effect of ration grain content on feedlot performance was studied when 160 steers were fed in a two-year feeding trial. Average daily gains increased and feed required per unit gain decreased as the percentage of grain in the ration increased (P<:.01). Steers fed all silage rations increased in gain by 17.4% (.99 !§_.82 kg) and feed efficiency was improved 12.3% (8.38 vs 9.55) as silage grain content was increased from 30% to 50%. Steers fed a high concentrate ration with 90% grain gained 6.6% faster (1.24 v§_1.16 kg) and required 16% less feed per unit gain (6.05 v§_7.22) than those fed 70% grain. Ration grain content influenced DE, NEm and NEg values (P<:.05). Net energy for gain was 8.9% lower than predicted when the ration contained 70% grain. Carcass characteristics were adjusted to an equal carcass weight and the percentage of grain in the ration influenced carcass fat, fat thickness and dressing percent (P< .05). Maturity, marbling, quality grade, yield grade, ribeye area and kidney, heart and pelvic fat were not influenced by ration grain content. Steers fed on a two—phase system had similar gains (1.09 vs 1.10 kg) but improved in feed efficiency by 6.5% (6.80 v§_7.27) when compared to those receiving a constant percent grain ration. Steers fed on the two-phase system had a larger ribeye area and a lower yield grade (P<:.0005). Harold Dee Woody Economic Analysis As the ration grain content was increased from 30% to 100%, cost of feeding, manure handling and storage were reduced by 5.9¢ per day (22.l¢ vs‘16.2¢) but the manure credit increased by l.19¢ per day (4.06¢ !§_2.87¢). The resultant net cost per day was 4.7l¢ higher (18.09¢ g§_l3.38¢) for the cattle receiving all silage. Corn silage was priced such that it yields the same net return per acre as corn grain. At $2.00 per bushel corn, prices are $15.52 and $14.90 per ton for silage containing 47% and 30% grain, respectively. Steers fed on the high concentrate system had a clear advantage at $2.00 per bushel corn over the all silage ration containing 50% grain. But, at $2.75 per bushel corn the all silage ration with 50% grain had an advantage. The two-phase system was competitive with the high concentrate ration at $2.00 corn and is competitive with the all silage system at $3.50 corn. ACKNOWLEDGMENTS The author wishes to express his deepest appreciation and gratitude to Dr. D. G. Fox for his advice and guidance throughout the graduate program. Appreciation is also expressed to Dr. J. R. Black for his valuable counsel and statistical advice throughout the program of study. In addition, the author is deeply grateful to Dr. H. D. Ritchie, Dr. J. T. Huber and Dr. N. G. Bergen for their advice and review of this manuscript. Thanks are extended to Dr. E. C. Rossman for his valuable counsel. Appreciation is expressed to Dr. R. H. Nelson and the Animal Husbandry Department for the use of facilities, research animals and financial assistance throughout the author's graduate program. Acknowledgment is extended to Dr. D. R. Hawkins and Dr. H. A. Henneman for the opportunity to develop skills in the teaching area. Special thanks are extended to the graduate students for aid in collection and analysis of the data. Appreciation is expressed to Elaine Fink, Phyllis Whetter and P. K. Ku for laboratory assistance and to Ron Cook, Lawrence Cramer and other personnel involved in the research project. Sincere thanks are expressed to Betty Talcott for secretarial assistance and to Mrs. Grace Rutherford for her careful typing of this manuscript. ii TABLE OF CONTENTS LIST OF TABLES ......................... LIST OF FIGURES ........................ INTRODUCTION .......................... LITERATURE REVIEW ....................... The Influence of Plant Population on Corn Plant Composition ...................... The Feeding Value of Brown Midrib and High Oil Corn Silage ...................... Prediction of Feedlot Performance from Laboratory Analysis of Feedstuffs ................. Influence of Ration Grain Content on Feedlot Performance and Carcass Characteristics .............. Effect of Feeding System on Efficiency of Roughage and Grain Utilization ................. OBJECTIVES ........................... MATERIALS AND METHODS ..................... Corn Silage Harvested From Three Plant Populations . . . . Experimental Design ................. Laboratory Analysis and Plant Component Determinations ................... Feedlot Study ...................... Experimental Design and Rations ........... Feeding, Weighing and Management Practices ...... Slaughter, Carcass Evaluation and Collection of Data for Estimation of Carcass Composition ..... Procedures for Estimation of Carcass Composition . . . . Metabolism Study ..................... Experimental Design ................. Sample Collection .................. Chemical Analysis .................. Statistical Analysis ................... Page v ix Page RESULTS AND DISCUSSION ...................... 66 Corn Plot Study--Trial l .................. 66 Dry Matter Distribution of Corn Silage Harvested From Varying Plant Populations .............. 66 Dry Matter Distribution of High Oil and Brown Midrib Corn Silage ..................... 68 Corn Plot Study--Trial 2 .................. 70 Dry Matter Distribution of Corn Silage Harvested From Varying Plant Populations .............. 70 Comparison of the Two-Year Study of Corn Silage Grown in Different Plant Populations ............ 72 Feeding Studies ...................... 82 Description of Initial Slaughter Cattle ........ 82 Feedlot Performance .................. 83 Carcass Characteristics ................ 91 Net Energy Value of Rations Varying in Grain Content . . 98 Two-Phase System Versus Constant Added Grain ...... 103 Performance of Steers Fed High Oil or Brown Midrib Corn Silage .................. 107 Predicting Feedlot Performance from Acid Detergent Fiber and Ration Grain Content ................. 111 Feedlot Performance .................. 111 Predicting Net Energy Values .............. 117 Application to Other Corn Varieties .......... 119 Influence of Ration Grain Content on Cost of Feeding, Manure Handling and Storage, and Manure Credit ...... 120 Pricing Corn Silage .................... 128 Economic Analysis ..................... 136 CONCLUSIONS ........................... 141 APPENDIX ............................. 143 LITERATURE CITED ......................... 160 iv Table LDCDNOS 10. ll. l2. l3. 14. 15. 16. LIST OF TABLES Composition of Corn Silage Components .......... Relative Distribution of Total Dry Matter in the Corn Plant ........................ Ig_Vitro Dry Matter Disappearance of Various Plant Components ........................ Mean Heat Increments of Individual Volatile Fatty Acids and a Mixture of Acetate, Propionate and Butyrate Infused into the Rumen of Fasted Mature Cattle ...... Two-Year Summary of Performance Data of Finishing Steers Fed Rations Containing Corn Silage in Four Different Feeding Programs ..................... Experimental Design (Trial 1) .............. Experimental Design (Trial 2) .............. Nutrient Composition of Ration Ingredients (Trial 1) . . . Nutrient Composition of Ration Ingredients (Trial 2) . . . Composition of the Protein Supplements .......... Determination of Net Energy Value of Rations ....... Dry Matter Distribution in Corn Plants (Trial 1) ..... Characteristics of Corn Silage Harvested From Three Plant Populations (Trial 1) ............... Dry Matter Distribution in High Oil and Brown Midrib Corn Plants ....................... Characteristics of Corn Silage Harvested From Normal Plant Populations, High Oil and Brown Midrib Corn Dry Matter Distribution in Corn Plants (Trial 2) ..... 34 42 49 50 51 52 53 58 57 67 69 69 71 Table 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. Characteristics of Corn Silage Harvested From Three Plant Populations (Trial 2) .............. Regression Equations Developed for the Prediction of Relative Dry Matter Distribution in Corn Silage From Silage Grain Content .................. Relative Dry Matter Distribution of Corn Silage Varying in Grain Content ................ Shrunk Weight, Carcass Weight and Carcass Composition of Initia1 Slaughter Cattle .............. Effect of Silage and Total Ration Grain Content on Performance of Steer Calves (Trial 1) ......... Effect of Silage and Total Ration Grain Content on Performance of Steer Calves (Trial 2) ......... Significance of Pooled Results on the Influence of Ration Grain Content on Feedlot Performance and Carcass Characteristics ................ Influence of Total Ration Grain Content on Carcass Characteristics (Trial 1) ............... Influence of Total Ration Grain Content on Carcass Characteristics (Trial 2) ............... Regression Equations Developed for the Prediction of Carcass Traits ................... Influence of Ration Grain Content on Net Energy Values (Trial 1) ....................... Influence of Ration Grain Content on Net Energy Values (Trial 2) ....................... Comparison of Steers Fed on Two-Phase System v§_ Constant Added Grain Rations .............. Carcass Characteristics of Steer Fed on Two-Phase System v§_Constant Added Grain Rations ......... Feedlot Performance of Steer Calves Fed High Oil and Brown Midrib v§_Norma1 Corn Silage (Trial 1) . . . . vi Page 76 76 82 84 85 88 92 93 97 105 108 Table 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. A.1 A.2 A.3 Carcass Characteristics of Steers Fed High Oil and Brown Midrib !§_Normal Corn Silage (Trial 1) ....... Net Energy of High Oil, Brown Midrib v§_Norma1 Corn Silage (Trial 1) ..................... Relationship Between Acid Detergent Fiber, Ration Grain Content and Feedlot Performance (Trial 1) ..... Relationship Between Acid Detergent Fiber, Ration Grain Content and Feedlot Performance (Trial 2) ..... Effect of Ration Grain Content on Manure Volume and Nutrient Composition ................... Manure Handling and Feeding Costs as Influenced by Total Ration Grain Content ................ Nutrients Available and Fertilizer Value of Manure as Influenced by Ration Grain Content .......... Net Cost of Feeding, Manure Handling and Storage and Manure Credit .................... Cost of Corn and Corn Silage Production ......... Price of Corn Silage Per Ton as Influenced by Corn Price ........................ Feed Disappearance .................... Cost Summary ($/ch Gain) ................ Cost Summary of Various Feeding Systems ......... Acid Detergent Fiber Determinations of Plant Components of Silages Varying in Grain Content in Trial 1 ........................ Crude Protein Determinations of Plant Components of Silages Varying in Grain Content in Trial 1 ...... Acid Detergent Fiber Determinations of Plant Components of High Oil, Brown Midrib and Normal Corn Silage in Trial 1 .................. vii Page 109 110 122 125 143 144 Table A.4 A.1O Crude Protein Determinations of Plant Components of High Oil, Brown Midrib and Normal Corn Silage in Trial 1 ......................... Acid Detergent Fiber Determinations of Plant Components of Silages Varying in Grain Content in Trial 2 ...... Crude Protein Determinations of Plant Components of Silages Varying in Grain Content in Trial 2 ....... Fermentation Values for Silage Varying in Grain Content, High Oil and Brown Midrib Corn .............. Individual Performance and Carcass Data (Trial 1) Individual Performance and Carcass Data (Trial 2) Scanoprobe Estimates of Fat Thickness Over the Twelfth Rib (Trial 1) .................. Scanoprobe Estimates of Fat Thickness Over the Twelfth Rib (Trial 2) .................. Effect of Ration Grain Content on Nitrogen Retention (Trial 1) ........................ Effect of Ration Grain Content on Nitrogen Retention (Trial 2) ........................ Nitrogen Retention of High Oil and Brown Midrib Xi. Normal Corn Silage (Trial 1) ............... Calculation of Net Energy Value of Rations Varying in Grain Content (Trial 1) ................ Calculation of Net Energy Value of Rations Varying in Grain Content (Trial 2) ................ viii Page 144 145 145 146 147 149 157 158 159 Figure 10. 11. 12. 13. LIST OF FIGURES Scheme of energy metabolism with expected losses . . . . Influence of ration grain content on dry matter digestibility and digestible and metabolizable energy ......................... Net energy for maintenance and gain in relation to total gain in the ration .............. Relationship between corn plant population and percent grain and stalk in the ration ......... Relationship between corn plant population and percent leaf and cob-husk in the ration ........ Relationship between corn plant population and dry matter yield and ration protein content ...... Relationship between corn plant population and ration ADF (%) level .................. Acid detergent fiber of the whole plant y§_the non-grain portion at various corn silage grain levels ......................... Acid detergent fiber of the whole plant v§_the non-grain portion at varying stages of maturity of the corn plant ................... Effect of ration grain content on average daily gain and feed efficiency .................. Effect of ration grain content on dry matter intake Influence of ration grain content on fat thickness and carcass fat .................... Influence of ration grain content on yield grade and dressing percent .................. ix Page 32 36 38 73 74 77 80 81 81 86 87 95 96 Figure Page 14. Effect of ration grain content on metabolizable energy and net energy for maintenance and gain ........ 101 15. Relationship between acid detergent fiber and average daily gain and feed efficiency ............. 114 16. Relationship between ration grain content and average daily gain and feed efficiency ............. 116 17. Relationship between ration grain content and dry matter intake and net energy for gain ......... 118 18. Price of silage relative to grain price ........ 134 INTRODUCTION Corn silage is the principal source of forage in beef cattle rations in the midwest. Thirty-five to 40% more energy can be grown/ acre when corn is harvested as silage than as grain. Corn varieties and plant population have a strong influence on the ear-stover ratio and energy production. Corn variety alone may alter the ear-stover ratio from 25% to 64% (Rossman §£_gl,, 1975). Further, weather and plant population influence the ear to stover ratio. Currently only one energy value is listed in the NRC "Nutrient Requirements of Beef Cattle" (NRC, 1976). Studies are needed to identify the net energy value of corn silage as influenced by the ear-stover ratio. Net energy value of a feed may vary due to the percent grain in the ration and the associative effects present in mixed rations. The associative effect of feedstuffs occur due to a change in digestion and metabolism of nutrients as a result of the incorporation of a feed ingredient into a ration containing one or more other ingredients. This effect occurs particularly when grains and roughages are mixed together in an animal's diet. Thus, the net energy value of an indi- vidual feedstuff is variable depending upon the ingredient proportion in the ration. Studies are needed to determine the net energy of rations with varying increments of corn grain added to beef cattle diets. LITERATURE REVIEW The Influence of Plant Population on Corn Plant Composition Wurster (1972) reported that the approximate dry matter distribution of various components of the corn plant are grain, 46%; stalk, 23%; leaves, 11%; cob, 11% and husk, 9%. Average composition of the corn silage components were reported by Vetter (1973) and is described in Table l. Alterations in the ear-stover ratio by plant population or harvesting at various stages of maturity levels will influence the crude protein, acid-detergent fiber, dry matter digest- ibility and subsequent net energy value of corn silage rations. The relative dry matter distribution of various plant components when harvested at various stages of maturity was reported by Ayres and Buchele (1971) and is summarized in Table 2. When corn silage was harvested at various stages of maturity or when stressed by increased plant p0pu1ations, there is an alteration in the dry matter distribution of the various plant components. As the corn population increases per hectare, the average grain yield of the individual plant significantly decreases (Duncan, 1958; Colville _t._l., 1966; Lutz gt _l,, 1971; Stivers gt 11., 1971). An increase in corn plant population from 9,884 to 59,303 plants/ha resulted in a reduction of ear weight from .32 to .13 kg. The average ear weight of .24 kg was secured at 29,652 plants/ha which corresponded Table 1. Composition of Corn Silage Components (Vetter, 1973)a % % In vitro Crude Acid-detergent digestible Plant components protein fiber dry matter Grain 10.2 -- 91 Leaf 7.0 37.0 58 Husk 2.8 41.6 68 Cob 2.8 42.8 60 Stalk 3.7 48.2 51 aAverage percentage composition. Table 2. Relative Distribution of Total Dry Matter in the Corn Planta (Ayres and Buchele, 1971) Kernel moisture % Plant part 40 35 30 25 20 Grain 38.4 42.4 46.4 50.5 54.5 Stalk 27.7 25.1 22.5 19.9 g 17.2 Leaf ' 15.1 13.2 11.3 9.4 7.5 Cob 11.0 11.1 11.3 11.5 11.7 Husk 7.8 8.1 8.5 8.5 9.1 aPredicted values by linear regression analysis. to the highest dry matter yield (Lang gt 21,, 1956; Lutz gt_gl,, 1971). Stivers gt_gl, (1971) reported that average grain yields at 69,000 plants/hectare were 2.3% lower than that with 54,000 population. The amount of dry grain produced per plant and the ratio of dried shelled grain to total dry matter decreased as the plant population increased (Fairbourn g§_al,, 1970 and Lutz 23.21;: 1971). In a number of studies, however, increases in corn plant population consistently increased dry matter production per hectare (Wasko and Kjelgaard, 1966; Rutger and Crowder, 1967; Lutz and Jones, 1969; Robinson and Murphy, 1972). In these studies corn silage dry matter yields increased linearly with increased population up to 98,839 plants/hectare. Alexander gt_al, (1963) found that increasing the plant population from 16,679 to 33,358 plants/ha increased yield of dry matter by 47.9%. Fairbourn et_gl, (1970) found similar increases in dry matter yield when corn plant populations were increased from 21,000 to 44,970 plants/hectare. Rutger and Crowder (1967) and Stivers g__a1, (1971) reported a 4.0% to 6.0% increase in total dry matter yield when plant populations increased from 49,419 to 86,485 plants/hectare. Most studies have shown however that the percent grain in the dry matter is reduced when the plant population is increased. The energy value of corn silage likely varies due to varying grain content and ear-stover ratio. Duncan (1958), Rutger and Crowder (1967) and Fairbourn gt_gl, (1970) reported a reduction in the amount of grain per-plant as corn plant populations increased. As plant populations increased from 49,000 to 86,000 plants/ha ear content was reduced by 10% (Cummins and Dobson, 1973). In this study, there was also a 5% increase in stalk content. Bryant and Blaser (1968) however, noted only a slightly altered ratio of ear, stalk and leaves to whole plant weight when plant populations were increased from 39,000 to 98,000 plants/hectare. Similar results were reported by Robinson and Murphy (1972), who found no significant change in the ratio of forage to grain yield in populations ranging from 29,500 to 98,800 plants/ha. Increasing plant populations and thus reducing the grain content results in lowering of the percentage of proximate con- stituents in corn silage. Lang gt_al, (1956) reported a significant decline in protein content of corn grain from 11.8% to 9.8% when plants/ha were increased from 9,880 to 59,300. Alexander gt_al, (1963) compared 41,215 to 82,430 plants/ha and found a reduction in protein content in the whole corn plant from 7.2% to 6.0%. Holter and Reid (1959) and Huber gt 21, (1965) reported that higher plant populations resulted in decreased protein digestibility, but results were not significant. High plant populations, however, increased levels of digestible energy, total digestible nutrients and crude protein by 40%, 42% and 27%, respectively. Lodging and stalk barrenness also contributes to altered ear-stover ratios when plant populations were increased. There were also increases shown in plant height and stalk breakage with increases in plant population. Lang gt_al, (1956) reported a 2 to 3% stalk barrenness at 29,650 and up to 15% at 59,000 plants/hectare. Giesbrecht (1969) found that 3% of the stalks were barren at 29,650 plants and increased to 15% at 75,000 plants/hectare. The Feeding Value of Brown Midrib and High Oil Corn Silage The grain and the soluble non-cell wall fraction of the plant (Van Soest and Wine, 1967) is nearly 98% digestible. However, the lignin content within the plant cell walls inhibits the digesti- bility and utilization of cellulose and hemicellulose in microbial fermentation. Thus, the amount of lignin content of a feedstuff has a direct effect upon its digestibility, intake and energy utilization in the ruminant animal. Investigations in the production of low lignin corn plant were first conducted by Kuc and Nelson (1964) and Gee e§_§1, (1968). In these studies it was discovered that brown midrib mutant genotypes produced corn plants with lowered lignin content in the vegetative portion of the plant. Brown midrib mutants are identified by the brown pigment in the midrib of the leaf blade, stem tissue and cob. Muller §£_g13 (1971, 1972) found a 40% reduction in lignin content in brown midrib corn plants as compared to normal inbred lines. Studies have shown that low lignin corn has a 7% to 9% increase in jg_yjtrg dry matter disappearance (Barnes gt al,, 1971; Muller gt_al,, 1972). Lechtenberg gt_al, (1972; 1974) reported an increase in in vitrg_dry matter disappearance in the stem, leaf blade, leaf sheath, husk, tassel and cob of 10.4, 11.0, 7.0, 15,0, 17.7 and 12.7 percent, respectively, for brown midrib corn plants over normal corn (Table 3). There was also a 35 to 60% increase in the rate of cell wall and cellulose disappearance. Table 3. In Vitro Dry Matter Disappearance of Various Plant Components (Lechtenberg gt_al,, 1972) Leaf Leaf Genotype Stem blade sheath Husk Tassel Cob Grain BM], % 46.4 58.2 55.5 72.6 45.4 55.6 90.2 8M2, % 52.1 60.4 53.9 73.2 48.5 55.1 91.5 8M3, % 60.8 69.0 62.9 80.7 62.0 63.5 92.5 Normal, % 50.4 58.0 55.9 68.6 44.3 50.8 90.5 Muller —£-§ln (1972) and Colenbrander gt_al, (1977) evaluated the digestibility, intake and feeding value of brown midrib corn silage. Lowered lignin content accounted for an increase of 15% digestibility of dry matter, total fiber, cellulose and hemicellulose. Similar results were shown in a feeding trial with cattle when Colenbrander gt_al, (1973, 1975) obtained significant improvement in average daily gains, feed efficiency and dry matter intake for brown midrib corn stover silage when compared to normal corn stover silage. The increase in performance appeared to be due to increased levels of energy through higher levels of intake and digestibility. These results are supported by the work of Stallings §t_gl, (1977) who found an increase in dry matter digestibility of 9.1% (61.5 y§_56.5%) and 9.3% (70.9 y§_64.3%) in sheep digestion trials. In another study, Colenbrander _t_§l, (1977) fed 48 Hereford steers the following rations: (A) normal corn silage; (B) brown midrib corn silage; (C) normal silage plus 30% added corn; and (D) brown midrib silage plus 30% added corn. For the steers fed the all silage rations, those fed brown midrib gained 8.2% faster (.98 1g .90 kg) and required 12.7% less feed per unit of gain (5.36 y§_6.14) than those fed normal silage. Steers fed brown midrib plus added corn had similar gains and feed efficiency when compared to those fed normal silage plus corn. Thus, when brown midrib silage is fed without addi- tional grain, performance is increased due to increased digestibility. When grain is added, the effect of the lower lignin content in brown midrib silage is reduced. In another attempt to improve the nutritive value of corn silage, crop geneticists developed a high oil corn variety. The high oil corn improves the energy content by increasing the oil content in the grain portion of the plant. Several investigators have reported an increase of oil content in the kernel (Brunson gt_gl,, 1948; Leng. 1967). The oil content of 4.7% in normal corn may be increased to 7 to 13% by the result of selection (Schneider gt_al,, 1952; Welch, 1969). Selection for high oil content also increased the proportion of germ in the kernel by 61%. Geneticists have shown improvements of oil content in the corn grain by increasing the ratio of germ weight to endosperm weight. Lang gt a1 (1956) also reported that the percent oil in the grain increases as the corn plant population decreases. The grain in the normal corn variety contained 4.23% oil when corn popula- tion was 59,280 plants/hectare but increased to 4.58% at 9,9880 plants/hectare. McCollough gt_al, (1972) fed steers in a 126 day feeding trial to determine the feedlot performance of different sorghum and corn varieties. Average daily gain and feed efficiency for the steers were: high oil corn (.78, 8.96) and regular corn (.95, 7.75). The steers fed the high oil corn had reduced gains (17.9%), poorer feed efficiency (13.5%) and reduced dry matter intake (2.1%). High oil fed steers had less fat thickness, reduced marbling and lower quality grades but had a more desirable yeild grade. Cost/cwt. gain was 13.5% higher for the high oil fed steers. Prediction of Feedlot Performance from Laboratory Analysis of Feedstuffs Accurate prediction of the energy value of feedstuffs is necessary for accurate formulation of feedlot rations. Studies have indicated that a decline in digestibility of fiberous components in feedstuffs is directly related to changes in cell wall digestibility. The cell wall includes cellulose, hemicellulose and lignin. The lignin within the cell wall is indigestible and protects the cellulose from digestion. It appears to be a major factor in reducing intake and digestibility of high forage rations. 10 As cell wall constitutents or crude fiber increases, the ratio of net energy to total digestible nutrients declines (Van Soest, 1973). "Associative effects" pose a problem in the estimation of net energy values through chemical analysis of feedstuffs. When various levels of concentrate are added to a forage ration there tends to be a decline in cell wall digestibility and net energy value. Van Soest (1971) formulated a system for estimating the net energy value of a ration by determination of the digestible dry matter (DDM) and total digestible nutrients (TDN) from chemical analysis of feedstuffs, as follows: TDN (%) = DDM=Total Ash+Silica+ 1.25 Ether Extract+l.9 NEm (Mcal/Kg) .029 TDN (%)- 0.29 NEg (Mcal/Kg) .029 TDN (%)- 1.01 This system more adequately estimates the net energy value of high roughage rations than does the TDN system. It was concluded, however, that a constant value of 70% TDN should be used for all corn silages. In contrast, Schmid gt_al, (1975) reported that the digest- ibility of corn silage varied from 56 to 70% and sorghum silage from 45.1 to 65.8% when 23 various silages were fed to sheep. Regression equations were developed for predicting average daily gains from digestible dry matter intake (DDMI): AUG (9) - 38.44+-.209 DDMI (kg). 11 Agronomic characteristics of the corn silages were also correlated with quality measurements. The percent leaves were highly correlated with ADF (0.90) and average daily gain (-O.68). The percent ears were also correlated with ADF (-O.87) and gain (0.68). Dry matter yield had a relatively low correlation with dry matter intake (-0.15) and average daily gain (-0.26). Taller and higher yielding corn silage had a higher percent of leaf and stalk while early maturing, shorter corn had a higher percentage of ears and improved animal performance. Marten et 31, (1975) measured the quality of 25 corn and 26 sorghum silages in a sheep feeding trial. Correlations of chemical analysis of the silage indicate that ADF was highly correlated with crude fiber (r==0.94) and cellulose digestion (r==0.97). Due to the high correlation between fiber measurements, both ADF and crude fiber were useful in estimating similar parameters. However, ADF values were higher and more accurate measurements than those for crude fiber. Regression equations were formulated for the prediction of dry matter intake when sheep were fed corn silage or sorghum silage rations: 0.61 Corn Silage: DM Intake (g/Wt '75) 85.49- .75 ADF (%) R2 k9 Sorghum Silage: DM Intake (g/Wt '75) 82.87-.78 ADF (%) R2 kg 0.81 It was concluded in this study that the low cost and predictability of ADF determination makes it a useful procedure for predicting silage energy value. 12 In a later study, Marten gt_gl, (1976) measured the digestibility of 23 corn and 26 sorghum silage varieties when fed to sheep. Correlations of acid detergent fiber with dry matter intake were 0.53 for corn silage and 0.77 for sorghum silage. Across all sorghum silages: on Intake (g/Wtkg'75) = 83.79-101 ADF (%) R2 = 0.50. Dry matter intake was correlated (r==0.66) with the jn_yjyg_digestible dry matter of sorghum silage while intake and digestibility correlation was considerably lower for corn silage (r==0.40). ADF was the most accurate predictor of digestibility as compared to alternative analysis (crude fiber, cellulose) and accounted for 80 percent of the variation, while crude fiber was the best predictor of intake, accounting for 72% of the variation. Chandler and Walker (1972) developed a linear program for computerized ration formulation. The relationship between crude fiber and net energy for lactating cows was observed for 45 feedstuffs com- monly used in dairy rations and varying from corn grain to alfalfa hay. When a number of feed ingredients were formulated into a ration, crude fiber was a good predictor of ration energy content. Regression equa- tions were developed for predicting net energy value of feedstuffs from crude fiber analysis as follows: Net Energy (Mcal/Kg DM) = 2.38- 0.034 Crude Fiber (%) 13 There was a strong negative correlation between ration fiber level and ration energy level (r2 = 0.79). Thus, the use of chemical analysis of feedstuffs in determining ration energy level is a useful method for predicting performance in cattle. Galyean gt_a1, (1978) studied the feasibility of predicting feedlot performance from laboratory analysis of grain. Data from 14 cattle feeding trials involving the evaluation of processed grain were utilized to study the relationship between laboratory analysis of grains and feed intake, average daily gain and feed efficiency. Laboratory analysis of the grains in the study included jg_vjtrg_dry matter disappearance (IVDMD), jg_yjtrg_gas production and degree of gelatinization. Correlations of intake with the various laboratory analysis were small (-0.22 to —0.36) and did not indicate a strong association. In contrast to these data, Albin et_al, (1966) reported correlation values of 0.88 and 0.99 between IVDMD and feedlot gain and efficiency, respectively. Brown and Radcliffe (1971) concluded that because of the loss of volatiles in oven drying of silage, in vitro DDM of silage was not satisfactory in predicting jg_ijg_DDM in cattle. A correlation of 0.70 was found between in vivg_00M and jg_yjtrg_DDM, in oven dried samples. When corrected for volatile losses, a correlation of 0.88 was obtained. Van Soest (1965) studied the correlation of chemical analysis of forages and animal performance. Correlations between chemical analysis and performance varied and was reduced when several species 14 were analyzed. Lignin, acid detergent fiber and cell wall digestibility were better predictors of digestibility than dry matter intake. Correlations were reported between digestible dry matter (00M) and ADF (-0.86), 00M and cell wall constituents (-0.86), 00M and lignin (-0.79). Digestibility and intake were not related in forages that contained low cell wall contents. When cell wall contents were increased in forages, intake was highly correlated with chemical and digestible dry matter. It was concluded in this study that the relationship between digestible dry matter and dry matter intake was dependent on the proportion of digestible energy from cell wall constituents. Ademosum gt_al, (1968) evaluated sorghum-sudan grass harvested at various stages of maturity on the basis of intake, digestibility and chemical composition. ADF was an adequate predictor of digestible dry matter (-0.90), digestible energy (-0.88) and dry matter intake (-0.86). The formulated regression equation for prediction of digest- ible energy (DE) from ADF and lignin analysis is as follows: DE (Kcal/Wtkg‘75) = 66.09+ .65 ADF (%)- 9.33 Lignin (%) R = 0.99 In this study, ig_yjtrg.DDM had no advantage over ADF, lignin and protein analysis as a predictor of the nutritive value of feeds. The effect of fiber level on performance in young calves was reported by Jahn gt_al, (1970). Body weight gain declined as the fiber level in the ration increased. Dry matter intake was increased as fiber level increased in low fiber diets but intake was reduced in high fiber 15 diets. Increased fiber levels increased the amount of content in the alimentary tract and can influence weight gain. Regression equations were developed relating fill, as a percentage of liveweight at slaughter and acid detergent fiber, as follows: Fill = 8.33 + 0.41 ADF (%). Increased fiber decreased soluble carbohydrates in the ration, reduced dry matter digestibility and increased crude fiber digestibility. Due to the variation in digestibility of feedstuffs and subsequent alteration in performance, many studies have been completed in an attempt to more accurately predict performance (Van Soest, 1971; Chandler and Walker, 1972; Marten gt al,, 1975; Schmid gt_al,, 1976). Many improvements have been shown in the evaluation of feedstuffs through chemical determination. But, further research is needed to accurately predict performance and net energy values for feedlot rations that vary in grain content and digestibility. Influence of Ration Grain Content on Feedlot'Performance and Carcass Characteristics Research has shown that as ration grain level is increased, feedlot performance is improved (Pinney gt_gl,, 1966; Jesse gt_gl,, 1976a, 1976b; Hammes gt_al,, 1964). When cattle are fed high silage y§_high grain rations, average daily gain and feed efficiency is reduced, days on feed and non-feed costs are increased. Also, studies have reported a less desirable quality grade and eating quality of 16 steers when fed high forage diets when compared to those fed grain (Black gt_al,, 1940; Meyer gt_§1,, 1960). But most of these com- parisons were made when cattle were slaughtered at different weights and thus resulting in a different carcass composition. In examining the effect of ration energy level on feedlot performance and carcass characteristics, numerous_studies have been conducted. In early studies, Richardson gt_gl, (1961) fed heifers rations with a roughage-to-concentrate ratio of: (A) 1:1; (8) 1:3; and (C) 1:5. Heifers fed the 1:5 rations gained 13.6% faster (1.03 y§_0.89 kg) than those fed the 1:1 ration (P<:.05). Carcass grade and marbling score was higher for the steers fed rations B and C, but the results were not significant. Lofgreen and Adams (1976) fed 80 Hereford crossbred yearling steers various alfalfa-to-concentrate ratios of 100:0; 70:30; 40:60; or 10:90. The steers fed the rations containing the all alfalfa ration had reduced gains (0.98 vs 1.17, 1.22, 1.14 kg) and were less efficient (11.50 1; 9.12, 8.17, 8.00) than those fed the added concen- trate rations. Steers fed the 60% concentrate ration had the highest rate of gain (1.22) but no significant difference was shown in effi- ciency when the concentrate level was increased to 90% of the ration. There was no difference in carcass characteristics among steers fed the concentrate rations. Steers fed the alfalfa ration had a lower percentage carcass fat and quality grade, but were slaughtered at lighter weights. The 30% and 60% concentrate rations were utilized 5% better than the 90% ration. These findings conflict with earlier 17 studies that describe the presence of associative effects and a reduction in energy utilization when concentrate comprises 50 to 80% of the ration (Byers gt_al,, 1975a, 1975b; Kromann, 1967). Lancaster gt a1, (1972) compared the performance of 91 Angus steer calves fed a high concentrate finishing ration (78% milo) with steers fed a high roughage, growing ration (84% hay) prior to being fed a high concentrate ration. Steers were fed for 76 days on the growing ration and finished for 118 days on the finishing ration. For the first 76 days, steers fed the high concentrate ration gained 21.7% faster (1.29 v§_l.01 kg) and required 6.5% less feed per unit of gain (6.30 y§_6.74) when compared to those fed a high roughage ration. For the finishing ration, the steers started on the high roughage ration and switched to a high concentrate ration had 12.3% higher gains (1.46 vs 1.28 kg) but were similar in feed efficiency (6.49 y§_6.30). Steers started on the high roughage ration expressed compensatory gain when switched to the high concentrate ration. When the 194 day trial was summarized, average daily gains were the same, but the steers fed the high concentrate for the entire trial had an 8.7% improvement in feed efficiency (6.00 y§_6.57). There were no differences in carcass traits or body composition but steers fed high concentrate had more fat covering and a higher degree of marbling. Theuninck (1977) studied the effects of a growing ration on the performance during the finishing period when 56 Angus crossbred steers were fed. During the 61 day growing period the rations fed included: (A) corn silage full fed, or (B) 1.36 kg of high moisture l8 corn plus a full feed of corn silage. The rations fed during the 98 day finishing period included: (A) corn silage full fed, or (B) 3.6 kg of corn silage plus a full feed of corn. During the growing period, steers fed rations A and 8 had similar gains (0.96 y§_0.98 kg) and feed required per unit of gain (6.05 v§_5.90). During the finishing phase, steers fed ration B gained 12.1% faster (1.32 v§_l.16 kg) and improved in feed efficiency by 10.5% (6.11 vs 6.83) as compared to those fed ration A. The nutritional level fed during the growing phase did not affect total feedlot performance. Carcass characteristics were not influenced by energy level. Pinney gt_gl, (1966) fed 50 yearling Angus steers for 125 days on rations varying in proportions of ground corn and corn silage. The rations were: (A) corn silage plus ground shelled corn at 1.5% of body weight, (8) corn silage plus ground shelled corn at 1.0% of body weight, and (C) corn silage plus ground shelled corn at 0.5% of body weight. Average daily gain (kg) and feed efficiency for the rations were: (A) 1.06, 7.74; (B) 0.98, 8.93; and (C) 0.92, 9.83. The higher grain fed steers had slightly higher gains and were more efficient than those fed the higher roughage rations. Carcass grade was not influenced by ration energy level. Cost of gain was in favor of the steers fed high silage rations. Perry and Beeson (1976) conducted five experiments with calves and yearling steers to study the extent corn silage energy could be substituted for shelled corn in finishing rations. The amount of corn added to corn silage ranged from 0.9 kg per head daily to 85.65% of the 19 ration. In four of the five trials, steers fed the highest level of corn grain gained faster (P< .01) and were more efficient (air-dry basis) than those fed the high silage diets. Steer calves gained gained 16.7% faster (1.20 y§_1.00 kg) and were 19.8% more efficient (7.40 y§_9.00) when fed the high corn rations. Similarly, yearlings had a 12.0% improvement (1.42 vs 1.25 kg) in gains and 16.3% improvement in feed required per unit of gain (9.20 y§_7.70) when fed high grain rations. Calves or yearlings fed high silage rations had similar quality grades as those fed high corn rations. Jesse gt_§l, (1976a) studied the effects of feeding various corn-corn silage combinations on feedlot performance. The rations were fed in cornzcorn silage combinations of: (A) 30:70; (8) 50:50; (C) 70:30; and (D) 80:20. Steers were slaughtered at 314, 454 and 545 kg. Steers fed the high silage ration (A) gained slower (0.90) than steers fed rations B (1.06), C (1.13) or D (1.11 kg). Dry matter intake, expressed as a percentage of empty body weight, was 2.25, 2.40, 2.52 and 2.37% for rations A, B, C and D. Carcass characteristics were similar; however, the steers fed the high concentrate rations were fatter and had a higher quality grade. The comparative slaughter technique was used to determine the net energy value of the various corn-corn silage rations (Jesse gt_al,, 1976b). Regression analysis was used to estimate corn and corn silage net energy values for the rations. Net energy values were not affected by ration combination (P< .05). Net energy for gain for corn and corn silage were 1.17 and 1.05 Mcal/kg, respectively. 20 Peterson gt_gl, (1973) fed rations with corn silage-to-high moisture corn at ratios of: (A) 100:0; (B) 67:33; (C) 33:67; and (D) 0:100, to 160 Angus crossbred steer calves. Average daily gain and feed required per unit of gain for steers fed the various rations were: (A) 1.18, 7.45; (B) 1.25, 7.11; (C) 1.39, 5.50; and (D) 1.48, 5.04. Average daily gain and feed efficiency improved linearly as the level of grain in the ration increased (P<:.Ol). Energy level did not influence marbling, kidney, heart and pelvic fat or quality grade. Miller gt_al, (1970) compared levels of forage and concentrate for growing and finishing Holstein steers. Ratios of corn silage-to- concentrate for the various rations were: (A) 3:1 from 181.4 kg to market; (8) 3:1 from 181.4 to 340.1 kg. followed by 1:1 to market weight; (C) 3:1 from 181.4 to 340.1 kg, followed by 1:2 to market; and (0) 1:1 from 181.4 kg to market. Average daily gains were: 1.10, 1.20, 1.24, and 1.20 kg and feed requirement per unit of gain was 6.49, 5.96, 5.81 and 6.00 for steers fed rations A, B, C and D. The steers fed ration D had the most rapid gains and were the most efficient. Carcass characteristics did not differ among treatments except the steers fed ration A had less marbling and a lower quality grade. Feed cost was highest for steers fed equal amounts of corn silage and con- centrate (D), but, non-feed cost was highest for steers fed the high silage ration (A) for the entire trial due to lower gains and a longer time on feed. The value of high silage rations for fattening beef cattle was studied by Hammes g__al, (1964). During the two-year study, several 21 combinations of silage and concentrate were fed, including: (A) 20% hay or haylage plus 80% corn silage plus 0.79 kg cottonseed meal, (8) corn silage plus 0.91 kg cottonseed meal, and (C) high concentrate ration. Steers fed ration A had lower gains as compared to those fed the high concentrate, fattening ration. But, feed efficiency, whether expressed as dry matter or TDN required per unit of gain, was in favor of the high silage fed steers when compared to those fed high concen- trate. Ration energy level had no effect on carcass characteristics. Workers from the Iowa station have reported on the influence of ration energy level on feedlot performance and carcass characteris- tics (Burroughs and Topel, 1969; Topel _tnal., 1973; Self and Hoffman, 1977). In a two-year feeding trial, Burroughs and Topel (1969) fed rations consisting of all silage or silage plus 38% grain to steers. For the first trial, steers fed the all silage ration gained 26.2% slower (1.10 y§_l.49), were on feed 47 days longer, and required 19.4% more feed per unit of gain (8.82 vs 7.11) than those fed added grain rations. In the second year, steers fed corn silage had 23.5% slower gains (1.08 y§_l.41 kg) and were 11.5% less efficient (7.91 y§_7.00) than those fed silage plus grain. In the two-year study, carcass characteristics were not affected by ration energy level. Net energy for maintenance and gain (Mcal/kg) were 0.79 and 1.29 for corn silage and 1.41 and 1.14 for silage plus added grain rations. Topel gt al. (1973) studied the influence of energy consumption during growth on carcass composition of 20 crossbred steers. The steers were slaughtered at 362.8 and 498.9 kg and were fed ad libitum 22 or restricted energy intake. During the growing phase, the steers fed the restricted energy intake gained slower (0.78 v§_l.22), were less efficient (7.13 v§_5.69) and required 71 more days on feed to reach 362.8 kg. When slaughtered at 498.9 kg, the full fed steers had 33.0% faster gains (0.77 y§_1.15), were 10.1% more efficient (7.37 y§_8.20), and required 132 fewer days on feed. The steers fed to the heavier weights required more feed per unit of gain than the lighter steers due to increased maintenance requirements. Carcass composition and characteristics were similar for the steers fed the two energy levels. Self and Hoffman (1977) reported on the effect of silage level on feedlot performance of yearling steers. Steers were fed rations with various ratios of silage-to concentrate, as follows: (A) 25:75; (8) 45:55; and (C) 15:85. Steers fed the high silage ration had the lowest average daily gain (0.99) as compared to those fed rations B (1.13) and C (1.16). TDN required per unit of gain was lower for the high concentrate ration (5.87) than for the ration A (6.80) or B (6.17). Steers fed the high silage ration had similar dry matter intake (8.98 and 8.75 kg) but was reduced for the high concentrate (7.98). Preston gt_al, (1975) studied the role of roughage in high concentrate rations for finishing steer calves. One hundred and twenty steer calves of various breed types were fed high concentrate rations containing various sources and levels of roughage. Rations containing low levels of pelleted cob, dried brewers grains and lime- stone treated corn silage were compared to all concentrate rations. 23 Feedlot performance was not affected by any of the roughage sources or levels, but feed efficiency was slightly reduced when roughage was added. Steers fed 2.27 or 6.80 kg of corn silage plus concentrate had 8.3% reduced gains (1.34, 1.32 !§_1.45 kg) and 14.0% poorer feed efficiency (5.17, 5.66 y§_4.66) as compared to the all concentrate ration. Carcass characteristics were not influenced by ration energy level. Klosterman gt_al, (1965) conducted three experiments to determine the effect of corn silage or ground ear corn fed at various stages of growth and fattening upon carcass composition of beef cattle. In trial one, periods were on a time constant basis while a constant amount of gain was the basis used in the second trial. A third trial was conducted using the same rations for two time constant periods. Cattle fed the ear corn ration gained faster than those fed all silage, regardless if the ear corn was fed during the first, middle or last part of the feeding period (P<:.05). Dressing percentage was increased when the ear corn was fed in the finishing stage. Ration energy level had no significant influence on carcass characteristics. Newland (1976) finished 40 Angus and 40 Angus heifers on all corn silage or all concentrate rations. When fed corn silage, steers required 56 days longer (210 y§.154) and heifers 29 days (183 y§_154) longer to reach low choice as compared to those fed all concentrate. When fed all concentrate, steers gained 21.5% (1.30 v§_1.02 kg) and heifers 21.1% faster (1.09 vs 0.86) than those fed all silage. Those fed all concentrate required 28.5% less feed per unit of gain 24 (5.40 ii 7.55). Ration energy level did not influence carcass characteristics. Cost per cwt. gain was reduced for the steers fed the all silage rations. Gill _tnal. (1976) reported on the effect of feedlot rations containing various corn silage levels. The rations contained (A) 14%, (B) 30%, or (C) 75% of the ration dry matter from corn silage, the remainder from high-moisture corn. Average daily gain and feed efficiency for the steers fed the various rations were: (A) 1.41, 5.49; (B) 1.50, 5.69; and (C) 1.15, 7.40. Steers fed the high grain ration (A) had higher gains (18.4%) and improved feed efficiency (25.8%) than those fed the high silage ration (C). Steers fed the 75% silage ration had lighter carcass weights than those fed 14% silage (310 y§_324 kg). The 75% silage fed steers had a lower dressing per- centage, marbling score and kidney, heart and pelvic fat but had more backfat thickness (P<:.01). The high silage fed cattle were fed 28 days longer but had a much lower quality grade. If steers had been fed to a similar weight, smaller differences would be expected in carcass characteristics between the high silage v§_high concentrate fed steers. Utley §t_gl, (1975) studied the feedlot performance and carcass characteristics when 68 crossbred steer calves and yearlings were fed all forage gs high concentrate rations. Steers fed the high concentrate ration gained 21.5% faster (1.35 v; 1.06 kg) than those fed the all forage ration (P<:.05). Steer calves and yearlings had similar gains when fed the all forage rations. However, yearlings 25 gained 7.9% faster (1.40 y§_l.29 kg) than calves when fed the high concentrate diet. When slaughtered at a similar weight, steers fed the high concentrate ration had more marbling, higher yield grade and more fat over the ribeye than steers fed the all forage rations (P< .05). Oltjen §t_gl, (1971) fed all forage diets to finishing beef cattle. Forty-eight Hereford steer calves were fed the following rations: (A) all concentrate; (B) pelleted, all-forage ration; (C) all concentrate followed by all forage, and (0) all forage followed by all concentrate. Average daily gains and feed efficiency for steers fed the various rations were: (A) 1.27, 5.71; (B) 1.05, 10.06; (C) 1.09, 7.98; and (D) 1.11, 8.14. Steers fed the all con- centrate ration had 17.3% higher gains and 43.2% improvement in feed efficiency. Steers fed all forage during the growing phase and switched to all concentrate for the finishing phase had similar gains and feed efficiency as those fed all forage and switched to all forage. Carcass grade was higher for the steers fed all concentrate. Embry and Fredrikson (1968) fed 100 steer calves various combinations of silage, ear corn and shelled corn. Rations fed were: (A) corn silage, 6.8 kg plus high moisture ear corn, full fed; and (8) corn silage full fed the entire trial. Steers fed ration A gained 28.2% faster (1.10 v§_0.79 kg) than those fed ration B. Steers fed the all silage ration had a lower marbling score and quality grade. But, the all silage steers were fed to a lighter weight (475 v§_523 kg); if these steers were fed to the same weight as the silage plus grain fed steers, differences in carcass parameters would likely be reduced. 26 Garrett (1971) determined the influence of rations varying in level of roughage and concentrate on feedlot performance and body composition when fed to yearling Hereford heifers. The roughage-to- concentrate ratios were: (A) 15:85; (8) 50:50; and (C) 85:15. The heifers were slaughtered following 70, 140 and 230 days of feeding the different rations. Gains were similar for rations A and B but gains were reduced for the steers fed the high roughage ration (C). Quality grade was increased by one-third of a grade for the steers fed the high concentrate ration when compared to those fed the high roughage rations. When fed to an equal body weight, final body composition was not greatly affected by the ratio of roughage-to— concentrate. The net energy value of the roughage or grain was constant and did not vary when fed at varous proportions in the ration. Recently Michigan workers have studied the effect of ration energy level on feedlot performance (Newland and Henderson, 1965; Minish gt al,, 1966, 1967; Hawkins gt_al, 1967; Henderson and Britt, 1974; Danner and Fox, 1977; Crickenberger g__§l,, 1977). Newland and Henderson (1965) fed steers rations varying in levels of concentrate- to-hay, including: (A) 50:50; (8) 61:39; (C) 71:29; and (D) 82:18. Average daily gain (kg) and feed efficiency (85% dry matter basis) for the rations were (A) 0.94, 10.89; (B) 1.00, 9.90; (C) 1.44, 7.34; and (D) 1.49, 6.51. Steers fed the high concentrate ration gained 36.9% faster and required 40.2% less feed per unit of gain. Carcass traits were not influenced by ration energy level. 27 Minish gt_al, (1966, 1967) conducted two feeding trials and reported on the effect of concentrate level on feedlot performance and carcass characteristics. Steers were fed rations containing: (A) all silage, or (B) 60% concentrate-40% silage. In trial 1 steers fed the high concentrate ration (B) gained 36.6% faster (1.09 vs 1.72 kg) than those fed all silage (P<:.05). Steers fed the high concentrate ration had improved quality grades but no other carcass traits were influenced by ration energy level. In the second trial, steers fed the high con- centrate ration gained 20.7% faster (0.92 y§_1.16) than those fed high silage (P<:.05). Steers fed the high concentrate ration had improved quality grades. Hawkins §t_al, (1967) fed 64 steers and heifers either all silage or silage plus a 1% added grain ration. Steers fed the added grain ration gained 7.7% faster (1.08 vs 1.17 kg) but were similar in feed efficiency when compared to steers fed all silage rations. The heifers fed all silage had 7.9% lower gains and required 8.2% more feed per unit of gain than those fed added grain rations. There was little difference in carcass grade due to ration energy level; but, those fed the high silage ration had lighter carcasses as compared to those fed rations containing various rations. Henderson gt a1, (1974) fed rations containing various ratios of shelled corn-to-corn silage, including: (A) 40:60; (8) 60:40; and (C) 80:20. In conflict with previous studies, as grain level in the ration was increased, there were little change in gain or feed effi- ciency. Cattle were fed to a similar final weight and no difference was found in carcass characteristics. 28 In a more recent study, Danner and Fox (1977) conducted two trials to compare the influence of different feeding systems on effi- ciency of energy utilization and carcass characteristics when calves and yearlings were fed. The feeding programs included: (A) 85% concentrate-15% silage; (B) 40% concentrate-60% silage; (C) all silage, switched to 85% concentrate-15% silage one-half the way through the feeding period; (0) all silage, switched to 85% concentrate-15% silage two-thirds the way through the feeding period; and (E) all silage fed continuously. Yearling steers fed ration A had 35.7% faster gains and were more efficient than those fed all silage (E). When adjusted to an equal carcass weight, there were no differences in marbling or quality grade but steers fed all silage had a more desirable yield grade than steers fed the 85% concentrate ration. Little difference was found in metabolizable energy required per lb of retail beef, but those fed on the two-phase system and switched early were the most efficient. Calves fed ration A gained 22.8% faster and were more efficient than those fed all silage. Calves fed all silage had lower quality grade than those on the other systems, but no difference was found in yield grade. Steers switched earlier on the two-phase system (C) gained 8.6% faster than those fed ration 0. Two feeding trials involving 189 steer calves were conducted to compare performance and carcass traits when fed either corn silage or 60% corn-40% silage rations (Crickenberger ;t_;l., 1976). In both trials, ration energy level influenced average daily gain (P<:.05). In trial 1, steers fed added grain rations gained 46% faster than those fed 29 all silage. High grain fed steers had more external fat, kidney, heart and pelvic fat, higher quality grade but reduced yield grade. In trial 2, the high grain fed steers gained 27% more rapidly when compared to those fed all silage; but ration energy level did not influence carcass characteristics when adjusted to the same final carcass weight. Goodrich gt_al, (1974) analyzed 17 university experiments that involved 878 steer calves to determine the influence of corn silage on performance. Average daily gain declined 23.7% (1.14 y§_0.87 kg) as corn silage level was increased from 10% to 80% of the ration. Exam- ination of the data revealed that a 10 percentage unit increase in corn silage decreased gain to a greater extent when 70 to 80% corn silage was fed (0.063 kg) than when the ration contained 10 to 20% corn silage (0.014 kg). Feed required per unit gain increased linearly as corn silage level was increased. Maximum dry matter intake occurred when the ration contained 40 to 50% corn silage. The impact of corn silage on gain and feed efficiency when fed at various levels is useful for accurate prediction of feedlot performance. To accurately compare the influence of ration grain content on feedlot performance and carcass characteristics, there are three adjustments that should be taken into consideration. First, perfor- mance data should be adjusted to an equal dressing percentage. Cattle fed a high roughage ration will typically have more fill than high concentrate fed cattle and thus, will influence the rate of gain (Burroughs gt_gl,, 1965; Utley §t_al,, 1975; Peterson gt_al,, 1973). 30 Second, adjustments should be made to correct for errors in dry matter determination. Due to the loss of energy containing volatiles, dry matter intake may be underestimated by 7% when determined by oven drying (Brown and Radcliffe, 1971; Jones and Larsen, 1974; Fox and Fenderson, 1976). Third, cattle should be slaughtered at the same final weight for accurate comparison of diet on performance and carcass characteristics. When slaughtered at various final weights, performance and carcass composition may be greatly influenced by differences in physiological maturity. Most studies reviewed have not taken these factors into consideration in measuring the effect on ration energy content on feedlot performance. Numerous studies have been reported on the influence of ration energy level on feedlot performance and carcass characteristics. As ration grain content is increased, gain is increased but composition of gain was not influenced (Hammes gt_al,, 1964; Minish gt_§l,, 1966; Pinney gt_gl,, 1966; Riley, 1969). In contrast, other workers have concluded that ration energy level may influence carcass composition (Oltjen gt_al,, 1971; Utley gt_al,, 1975; Jesse gt_§l,, 1976). In the review of literature, the effect of ration grain content on carcass composition is still in question. More research is needed to accu- rately assess the impact of high roughage vs high concentrate rations on body composition. 31 Effect of Feeding System on Efficiency of Roughage and—Grain Utilization The interactions of dietary ingredients was first reported by Armsby in 1917; digestibility was reduced 12% when feedstuffs containing carbohydrates were added to hay rations. Later, Forbes (1931) concluded that the energy value of feedstuffs cannot be evaluated individually in mixed rations. Kriss (1943) reported that the nutritive value of indi- vidual feeds depends on the combination with other ingredients when mixed rations containing alfalfa hay and corn were fed. Hamilton (1942) reported on the effect of corn sugar upon digestibility of the nutrients of a ration. As the level of corn sugar was increased in the ration, digestibility of crude fiber decreased. Swift and French (1954) reported a reduction in fiber digestibility when starch or other soluble carbohydrates were added to rations. The conventional scheme of energy metabolism and variation in energy losses is shown in Figure 1 (NRC, 1966; Reid, 1962). From the gross energy ingested, 20 to 60% of the energy is lost as fecal energy which contains undigested feed, bacterial cell residue and digestible fluids. A portion of the digestible (0E) is excreted as urinary energy (3 to 5%) or lost as gas production (5 to 12%). From the metabolizable energy (ME), considerable energy is lost as heat increment (10 to 40%). The remaining energy is divided into net energy for maintenance (NEm) and gain or production (NEg), as described by Lofgreen and Garrett (1968). Alteration in digestion and metabolism of feedstuffs influence the net energy value of a diet. 32 GROSS ENERGY OF FEED --.FECAL ENERGY (20-60%) 1. FEED ORIGIN 2. METABOLIC ORIGIN DIGESTIBLE ENERGY (DE) A. GAs PRODUCTION (5—12%) B. URINARY ENERGY (3-5%) 1. FEED ORIGIN 2. ENDOGENous ORIGIN METABOLIZABLE ENERGY (ME) IIIIIID’ II. HEAT INCREMENT (IO-40%) 1. HEAT OF FERMENTATION 2. HEAT OF NUTRIENT NET ENERGY (NEM+P) METABOLISM /\ MAINTENANCE ENERGY (HEM) pRODUCTION ENERGY (NEP) l. BASAL METABOLISM l. GRowTH 2. VOLUNTARY ACTIVITY 2. FATTENING 3. HEATING AND COOLING 3. MILK OF THE BODY 4. WOOL 5. REPRODUCTION 6. WORK Figure 1. Scheme of energy metabolism (NRC, 1966) with expected losses (Reid, 1962). 33 Classical papers by Armstrong and Blaxter (1957a, 1957b), Armstrong gt_al, (1957) and Armstrong gt 11. (1958) have studied the effect of heat increment on nutrient metabolism in the ruminant. Heat increment (HI) represents the energy expended by the animal during the ingesting and fermentation of feedstuffs. Energy lost as heat is divided into heat of fermentation and heat of nutrient metabolism, but due to difficulty of calculation, these processes are summarized as heat increment. This loss Of energy is Considerable and influences the utilization of metabolizable energy and the net energy evaluation of feedstuffs. Armstrong and Blaxter (1957a) concluded that the heat increment Of mixed rations were variable and were not the sum of the individual feeds or volatile fatty acids (VFA) of the ration. Following the infusion of VFA's into the rumen, heat increment was measured in sheep. Heat increment for the VFA's were, acetic acid, 40.8; propionic acid, 13.5; and butyric acid, 15.9 Kcal/100 Kcal of metabolizable energy. A mixture of VFA's of 5:3:2 of acetic, propionic and butyric acid was projected to yield a heat increment of 27.0 Kcal/Kcal of ME, but only 17.0 was observed. The heat increment of VFA's was determined when infused separately or in a mixture into fasting dairy cows (Holter e__al,. 1970, Table 4). Measured heat increments were, acetic acid, 40; propionic acid, 18.0; and butyric acid, 18.0 Kcal/100 Kcal Of metab- olizable energy. Mixed VFA's yielded a heat increment Of 32.0, while 29.5 Kcal/100 Kcal of ME was projected. As a sole source of energy, 34 acetic acid was considerably less efficient than propionic acid or butyric acid. The increase of observed heat increment when compared to projected losses suggest the presence of associative effects in mixed rations. Table 4. Mean Heat Increments of Individual Volatile Fatty Acids and a Mixture of Acetate, Propionate and Butyrate Infused into the Rumen of Fasted Mature Cattle (Holter, Heald and Colovos, 1970) HI, Kcal/100 Kcal ME Observed Calculated Acetate 40 -- Propionate 18 -- Butyrate l8 -- Mixture, 52:31:17a 32 29.5 aMolar ratio of acetate, propionate and butyrate. Blaxter and Wainman (1964) fed varying levels of hay and corn grain to sheep and cattle in a metabolism study. As the percentage grain in the ration increased from 0 to 100%, fecal energy losses increased linearly. Methane losses increased linearly with increased levels of corn until the ration contained 60 to 80% grain, then declined markedly. There was a small effect of diet on urinary loss. Nitrogen digestibility increased with increasing levels Of grain in the ration, but the increase was most marked when grain levels were greater than 35 60%. Metabolizable energy was linearly related to the grain level in the diet. When the percentage of grain in the ration was increased from 0 to 100%, efficiency of utilization of metabolizable energy for maintenance increased from 71 to 79% and from 29 to 61% for fattening. Results of this study suggests that high increments of heat and low efficiency of utilization with high roughage rations are due to the nature Of the end products of fermentation and digestion process. There was an inverse relationship between ration fiber content and the efficiency of utilization for fattening. Asplund and Harris (1971) studied the digestibility of energy and utilization of nitrogen in sheep fed varying proportions of alfalfa hay and beet pulp. Mixed rations containing alfalfa hay and dried molasses beet pulp in equal amounts had an increase in ether extract and nitrogen free extract digestibility and a decrease in biological value of nitrogen in comparison to the digestibility when feed ingre- dients were fed independently. The digestibility was significantly higher for gross energy, dry matter and nitrogen when the lowest level of energy was fed. It was concluded in this study that associative effects were present but at a lesser magnitude than previously predicted. Byers, Matsushima and Johnson (1975a) used an indirect respiration calorimeter in determining the net energy value of corn silage with various increments of added grain. When corn grain was added at levels of 34 and 67% of the ration, the NEm values decreased 4.7 and 14.8% below the predicted values (Figure 2). The NEg values 60‘ Dry Matter Digestibility, % 65- - 36 ,gar . a"' OBSERVED 3AM ELSO‘ 3.20 d 3010 "‘ 3.00 1 ZLQO‘ Digestible Energy (Kcal/g) I OBSERVED 3.20 « 3.10 - 2.90 < 2.80 - 2.fl3‘ 24m - 2.50 - Metabolizable Energy (Kcal/g) r’ ’,t' OBSERVED Figure 2. T I 34 67 100 Percent Total Grain in Ration Influence of ration grain content on dry matter digestibility and digestible and metabolizable energy (Byers, Matsushima and Johnson, 1975a). 37 expressed a similar decrease of 10.4 and 12.3%. The metabolic interactions due to varying grain levels influenced dry matter digestibility, digestible energy and metabolizable energy of the ration, as shown in Figure 3. When corn grain was added at 34% of the ration, dry matter digestibility, DE and ME were depressed by 4.8%, 4.8% and 7.4% and at the 67% added grain 6.2%, 7.4% and 12.1%, respectively. Observation of these parameters indicate that the net energy value for maintenance or gain for feedstuffs in a diet by assuming additive energy values is not an accurate procedure. The greatest Changes in digestion and metabolism of corn silage appears when corn grain is added at levels of 50 to 90% of the ration as shown in Figure 3 (Byers, Matsushima and Johnson, 1975b). The energy value of corn grain is considerably less when added to high silage rations as compared to its value in high grain rations. The NEg value of corn grain was 1.34 Kcal/g in a ration consisting of 10% grain-90% corn silage as compared to 2.09 Kcal/g in an all corn diet. Net energy values for maintenance for corn grain were 2.36 and 1.72 Kcal/g when added to all corn silage or all corn grain rations. The net energy values for corn silage were significantly lower when corn grain was added at various increments than when fed alone. The greatest changes in corn silage energy value occurred when the silage was less than 50% of the ration while corn grain NE Changed the most rapidly when included at levels between 20 and 60% of the ration. In a similar study, Preston (1975) summarized three trials and reported the net energy values for corn grain and corn silage when the 38 .AnmNOP .comczoO use mswgmzmumz .mcoamv copumg mzu cw :wmm Page“ op coFumpog cw :wmm new mucmcmgcwms so; xmcmcm umz .m mL:O_O 20_H(6.25) for each plant component was determined from a dry sample using the Technicon Auto-Kjeldahl system. Acid detergent fiber of the dried feed samples were determined by the standard Van Soest procedure (Van Soest, 1963; Van Soest and Wine, 1967). 48 Feedlot Study Experimental Design and Rations In trial 1, 80 Charolais crossbred steers weighing 226.8 kg were fed to determine the net energy value of rations containing corn silage varying in grain content and the impact of added grain on corn silage net energy value. The calves were purchased in November at a feeder calf sale at Gaylord, Michigan, and were transported by truck 402 km to the MSU Beef Cattle Research Center. Upon arrival the steer calves were fed an experimental starting on feed ration for a period of 28 days prior to the beginning of the experiment. As shown in the following experimental design, the steers were randomly allotted by weight groups to their respective treatment (Table 6). Each of the three silages grown at different plant popu- 1ations with varying grain content (27% to 49%) were fed to two pens Of eight steers each with one of the two pens receiving the respective silage plus added grain in the ration. In addition, one pen of steers each were fed a 91% or 96% concentrate ration. Brown midrib and high oil silage were each fed to one pen of eight steers. Ingredients fed in trial 1 and the nutrient composition of each ingredient is described in Table 8. In trial 2, 80 Hereford steers weighing 272.1 kg were fed. The calves were purchased in October from the Arthur King Ranches in Channing, Texas, and were transported 1,931 km by truck to the MSU Beef Cattle Research Center. Upon arrival the steers were fed an experimen- tal starting on feed ration for a period of 28 days prior to the beginning of the experiment. 49 Table 6. Experimental Design (Trial l)a High Corn Silage plus concen-. Brown High silage added grain trate midrib oil No. steers/ treatment 8 8 8 8 8 8 8 8 8 8 % grain in silage 27 43 49 27 43 49 43 -- 36 39 % added grainb 4 4 4 39 39 39 86 96 4 4 Total grain in ration 29 40 50 55 64 68 91 96 38 41 aAverage initial shrunk weight of 226.8 kg. bIncludes corn in supplement. As described in the following experimental design, the steers were randomly allotted by weight groups to their respective treatments (Table 7). Each of three corn silages grown at different plant popu- lations and with varying grain content (36% to 53%) were fed to two pens of eight steers each with one of the two pens of eight steers receiving the respective silage plus added corn grain. One pen of steers was fed a 90% or 96% concentrate ration. In addition, two pens of steers were fed on a two-phase system in which they received all silage rations containing low (36%) or high (53%) grain content silage. Steers on the two-phase system were switched from their respective silage ration to all concentrate at 415 kg. At this time it was predicted that they would consume approximately the same amount of 50 Table 7. Experimental Design (Trial 2)a Two-phase systemb High Corn Silage plus concen- Low grain High grain silage added grain trate silage silage NO. steers/ treatment 8 8 8 8 8 8 8 8 8 8 % grain in silage 36 50 53 36 50 53 50 -- 36 53 % added grainC 5 5 5 48 51 53 59 95 31 31 total grain in ration 38 51 54 59 67 69 90 96 57 68 aAverage initial shrunk weight of 272.1 kg. bSteers were switched from all silage to all concentrate at 415 kg. CIncludes grain in supplement. total grain throughout the feeding period as the respective silage plus added grain group. The ration ingredients fed in trial 2 and the nutrient composition of each ingredient is shown in Table 9. Composition of the urea-mineral protein supplements fed in the two-year feeding study is described in Table 10. At the beginning of the experiments, rations were supplemented to a 13% crude protein level. When the steers reached 408 kg, the protein level in the ration was reduced to 12.0%. 51 Table 8. Nutrient Composition of Ration Ingredients (Trial 1) Nutrient content, % of dry matter . Int. Dry' a Crude a Ingredient ref. no. matter protein Ca. P Corn, aerial pt, w-ears, w-husks, ensiled 27% grain -- 27.70 8.65 0.28 0.21 0.95 43% grain -- 30.60 8.66 0.28 0.21 0.95 49% grain -- 32.90 9.74 0.28 0.21 0.95 High oil -- 27.90 9.47 0.28 0.21 0.95 Brown midrib -- 30.40 7.90 0.28 0.21 0.95 Corn, dent, yellow, grain gr. 2 US 4-02-931 70.000 10.50 0.03 0.35 0.46 Urea, 45% N 100.00 281.00 -- -- -- Limestone, grnd. 6-02-632 100.00 -7 33.80 -- -- Phosphate, def. grnd. 6-01-780 100.00 -- 33.10 18.00 -- Calcium sulfate -- 100.00 -- 20.30 -- -- Potassium Chloride -- 100.00 -- -- -- 52.30 Trace mineral salt -- 100.00 -- -- -- -- Vitamin Ab -- Vitamin Dc -- aDetermined by actual laboratory analysis. bVitamin A, 30,000 IU per g. cVitamin 03, 3,000 IU per g. 52 Table 9. Nutrient Composition of Ration Ingredients (Trial 2) Nutrient content, % of dry matter Int. Dry a Crude a Ingredient ref. no. matter protein Ca P Corn, aerial pt, w-ears, w-husks, ensiled 36% grain -- 37.20 8.10 0.28 0.21 0.95 50% grain -- 42.80 8.40 0.28 0.21 0.95 53% grain -- 41.40 8.70 0.28 0.21 0.95 Corn, dent, yellow, grain gr 2 US 4-02-931 70.00 10.50 0.03 0.35 0.46 Urea, 45% N -- 100.00 281.00 -- -- -- Limestone, grnd. 6-02-632 100.00 -- 33.80 -- -- Phosphate, def. grnd 6-01-780 100.00 -- 33.10 18.00 -- Calcium sulfate -- 100.00 -- 20.30 -- -- Potassium Chloride -- 100.00 -- -- -- 52.30 Trace mineral salt -- 100.00 -- -- -- -- Vitamin Ab Vitamin Dc aDetermined by actual laboratory analysis. bVitamin A, 30,000 IU per g. CVitamin 03, 3,000 IU per g. 53 Table 10. Composition of the Protein Supplements Ingredienta Ration Low High Corn grain grain silage High corn corn +40% corn concentrate silage silage grain rations Gd. sh. corn, dent yellow, gr. 2 US Urea (45% N) Trace mineral salt Vitamin Ab Vitamin Dc Calcium sulfate Defluorinated phosphate Limestone, grnd. Potassium chloride -------- (% content of supplement)--------- 53.78 55.55 55.32 55.24 19.77 15.33 15.25 13.50 3.19 3.32 3.32 2.80 0.13 0.13 0.13 0.13 0.13 0.13 0.13 0.13 3.95 4.13 4.11 4.05 9.05 10.27 5.50 -- -- -- 4.24 13.27 -- -- -- 9.90 aAverage nutrient composition (NRC, 1976). bVitamin A, 30,000 IU per g. cVitamin 03, 3,000 IU per g. 54 Feeding, Weighingyand Management Practices The corn silage fed in this experiment was stored in upright concrete silo while the high moisture corn was stored in a Harvestore silo. Immediately prior to feeding, corn silage, high-moisture corn and the urea-mineral supplement were mixed in a horizontal batch feed mixer. The complete rations were fed once daily. Feed intake was recorded daily and the unconsumed feed removed and weighed periodically. Protein content (N x 6.25) and dry matter of the corn silage, high- moisture corn and urea-supplement was determined bi-weekly. Crude protein of the ration ingredients was determined from a wet sample using the Technicon Auto-Kjeldahl system. Moisture was determined from drying for 24 hours in a forced air oven at 60°C. Corn and corn silage intakes were adjusted for errors in dry matter determination by factors of 1.03 and 1.068, respectively (Fox and Fenderson, 1977). Initial and final shrunk weights for all cattle were obtained after a 16 hour shrink without feed and water. Intermediate weights were obtained every 28 days following a 16 hour shrink without water. Within 12 hours of arrival, steers were vaccinated for pasteurella and a 3-way vaccine containing infectious bovine rhino- tracheitis (IBR), bovine virus diarrhea (BVD) and parainfluenza (P13). Steers were injected with 2 million international units of vitamin A and a pour-on for grubs and lice was administered. A pasteurella booster was given at two to four weeks following the initial injection. In trial 1, all steers were implanted initially and every 112 days with Synovex S. In trial 2, steers were implanted initially and at 112 intervals with Ralgro. 55 All steers (8/pen) were housed in concrete, fully covered, straw bedded pens. Slaughter, Carcass Evaluation and Collection of Data for Estimation Of Carcass Composition In trial 1, steers fed high grain rations were slaughtered when 80% were estimated to grade low choice; the remaining pens were slaughtered when they reached approximately the same shrunk weight (512.5 kg). When steers were removed from the experiment they were held off feed and water for 16 hours, the twelfth rib fat was estimated by an Ithaco Ultrasonic Scanoprobe and individual shrunk weights were taken. Cattle were then transported by truck 105 km to Walter Packing Plant in Coldwater, Michigan, where they were slaughtered. Warm car- cass weights were obtained and the carcasses chilled for 24 hours prior to evaluation by a federal USDA grader. Following carcass evaluation, the 9-10—11 rib cut was removed from one side of each carcass according to procedures described by Hankins and Howe (1946). Rib samples were transported to the MSU meats laboratory for further processing. In trial 2, cattle were removed from the experiment with an average shrunk weight of 497.5 kg and were processed in a similar procedure as in trial 1. Cattle were transported 177 km to the Dinner Bell Packing Plant in Archbold, Ohio, where they were slaughtered. Warm carcass weights were obtained and the carcasses were Chilled for 24 hours prior to evaluation by a federal USDA grader. Following carcass evaluation, the carcass composition was determined by the specific 56 gravity technique (Kraybill, 1952). In this procedure the left side of each carcass was split between the 12th and 13th rib and each quarter was weighed in air and then submerged under water into a stainless steel tank (238.9 cm wide by 464.5 cm in height) and weighed under water with a 5 kg Toledo Pan Balance scale (Toledo Scale Company, Toledo, Ohio). Carcass and water temperature (centigrade) were meas- ured periodically. Carcass composition was estimated from specific gravity using previously developed equations, as described in Table 11. Procedures for Estimation of Carcass Composition In trial 1, six Charolais crossbred steers (226.8 kg) were selected at random by weight groups and slaughtered to determine initial body composition. Steers fed high grain rations were slaugh- tered when 80% were estimated to grade low Choice and then the remaining pens were slaughtered when they reached approximately the same shrunk weight (512.5 kg). At the time of slaughter, the 9-10-11 rib section was removed for Chemical analysis. The rib cut samples were separated into soft tissue and bone. The soft tissue was ground and mixed five times with a Hobart meat grinder using a 0.47 cm plate. Approximately 500 g of sample was frozen for storage. Prior to analysis, samples were thawed for 24 hours. Chemical analysis of each rib sample included crude protein (N x 6.25), ether extract, ash and moisture content. Protein content was analyzed using wet samples by the Technicon Auto- Kjeldahl system. Ether extraction was determined from dried samples using the Goldfisch procedure. Moisture was determined from drying 57 in a forced air oven at 100°C for 24 hours. Fat and protein determination of the 9-10-11 rib section from chemical analysis was used to estimate initial and final body composition (Hankins and Howe, 1946). Empty body composition was estimated from carcass composition using the equations developed by Garrett and Hinman (1969). In trial 2, four Hereford steers (274.4 kg) were selected at random by weight groups and were slaughtered to determine the initial body composition. The procedure for removing the steers for slaughter was the same as trial 1. To estimate initial body composition, the 9—10—11 rib section was removed for Chemical analysis (Hankins and Howe, 1946). Chemical analysis included crude protein, ether extract, ash and moisture determination, as described in the first trial. At the termination of the feeding trial, final body composition was determined by the specific gravity technique (Kraybill _t_al,, 1952). Empty body composition was estimated from carcass composition using the equations developed by Garrett and Hinman (1969). The determi- nation of net energy values of the rations from previously established equations is described in Table 11. 58 Table 11. Determination of Net Energy Value of Rations Net energy value of each of the rations were determined from previously established equations, as follows: 1. Total carcass composition is determined by: a. Analysis of the 9-10-11 rib section (Hankins and Howe, 1946). Carcass protein, % = .66X + 5.98 where X = 9-10-11 rib cut protein, %. Carcass fat, % = .77X + 2.82 where X = 9-10-11 rib cut fat, %. b. Specific gravity technique (Kraybill, 1952). $0 = (carcass wt. in air)/(carcass wt. in air minus carcass wt. in water) (correction for water and carcass temperature). Carcass fat, % = 587.86 - 530.45X where X = carcass specific gravit (Garrett and Hinman, 1969). Carcass protein, % = (20.0X - 18.57 times 6.25 where X = carcass specific gravity (Garrett and Hinman, 1969). 2. Empty body weight is calculated from the regression equation of Garrett gt_al, (1978) Y = 1.316X + 32.29 where Y X empty body weight; and Chilled carcass weight. 3. Empty body composition is calculated from carcass composition (Garrett and Hinman, 1969). Empty body protein, % = .7772X + 4.456 where X = carcass protein, %. Empty body fat, % = .9246X - .647 where X = carcass fat, %. 4. Energy retained is determined from the difference in body protein and fat between initial and final slaughter groups of cattle. Energy retained (Kcal) = FG x 9367 + PG x 5686 where FG = kg fat gain (Blaxter and Rook, 1953); and PG = kg protein gain (Garrett gt_al,, 1958). 5. Metabolizable energy (ME) value of the rations is determined in a metabolic trial. 59 Table 11--Continued Relationship between heat production (HP) and metabolizable energy intake (ME) is used to determine the feed needed for maintenance (Lofgreen and Garrett, 1968). a. HP = ME intake - energy retained. b. A regression of heat production (log HP) on metabolizable energy intake is established between total heat produced for the ration at gg_libitum intake and basal heat production. c. NEm = 77 Kcal . DM intake/wt°75 where ME==HP NE = Energy retained g Total DM intake - 0M needed for maintenance' 6O Metabolism Study Experimental Design The rations previously described were fed in metabolic trials to determine the metabolizable energy value of the various rations. In trial 1, 10 Charolais crossbred steer calves weighing 284.1 kg were utilized. The study consisted of 10 treatments fed to 10 steers for four periods. Each steer was fed for 15 days for adaptation to the respective ration, followed by a 5 day collection period. At the end of each period, each steer was randomly reassigned to a different treatment, with the restriction of never receiving the same ration twice. In trial 1, rations fed were the same as those in the feedlot study (Table 8). Each of three silages with varying grain content (27% to 49%) were fed to two steers each with one of the steers receiving the respective silage plus added grain in the ration. In addition, one steer was fed a 91% or 96% concentrate ration. Brown midrib and high oil silage was also fed to one steer. In trial 2, 8 Hereford steer calves weighing 209.5 kg were utilized. The second study consisted of 8 treatments fed to 8 steers over four periods. As in trial 1, each steer was fed for 14 days for adjustment to the ration and was followed by a 5 day collection period. Rations corresponded with those fed in the feedlot study (Table 9). Each of three silages with varying grain content (36% to 53%) were fed to two steers each with one of the steers receiving the respective silage plus added grain in the ration. One steer each was fed a 90% or 96% concentrate ration. 61 In both years, ration crude protein was supplemented to 12.5%. Calcium, phosphorous, trace mineral salt and Vitamins A and D were supplemented according to NRC (1976) recommendations. Rations were mixed and fed ag_1ibitum once daily. The unconsumed feed was weighed and recorded daily. All animals were housed in an environmentally controlled room and were maintained in 91 cm x 244 cm individual collection stalls. All steers had free access to water. Sample Collection Ration samples were obtained daily for each steer during the collection period. A sample of mixed ration for each steer was frozen for the duration of the collection period.- At the end Of each period the composite samples were thawed, finely Chopped in a Hobart food Chopper, mixed and 1 kg was refrozen for further determinations. In each period, total feces excreted for each steer was collected in a steel trough lined with plastic bags. At least every two days, the feces was collected, weighed, thoroughly mixed and a 10% subsample retained and frozen. At the end of the period, com- posited feces samples for each steer were thawed, mixed and approx- imately 1 kg was retained and frozen for dry matter, nitrogen and fecal energy determinations. The total urine excreted during each period was collected for each steer. A plastic carboy, placed under each collection stall which contained 200 m1 Of 18 N sulfuric acid to prevent ammonia loss, was used 62 for collection. At least every two days, urine was collected, measured and diluted to 10 liters of water. Approximately 10% or 1 liter of urine subsample was placed in plastic bottles and stored in a cooler during the collection period. At the end of the collection period, approximately 500 ml of sample was retained and frozen for nitrogen determination. Chemical Analysis Dry matter determination. Moisture was determined on the feed and feces samples. Feed samples were dried for a period of 24 hours in a forced air oven at 60°C. Approximately 200 g of feces was acidified with 25 ml of 4 N sulfuric acid and then dried similarly. Acid-detergent fiber determination. Feed samples collected during the metabolism studies were dried and used to determine the acid detergent fiber level by using the standard Van Soest procedure (Van Soest, 1963; Van Soest and Wine, 1967). Energy determination. Gross energy (Mcal/g) of the feed samples were determined by the Parr Adiabatic Oxygen Bomb Caliori- meter System. Bomb caliorimetry was performed on fecal samples. Metabolizable energy was estimated from digestible energy using a correction factor of .82 (NRC, 1976). Nitrogen determination. Total nitrogen of the feed, urine and feces collected during the metabolism study was determined by the Technicon Auto Kjeldahl System. 63 Statistical Analysis Statistical tests were designed to analyze the effect of ration grain content on feedlot performance and carcass Characteristics. In both trials, least square regression analysis was applied to estimate parameters (Searle, 1971; Rao and Miller, 1971; Seber, 1977). Addi- tional details in describing the analytical procedure may be found in Black and Harpster (1978). Parameter estimations were based upon least square procedures, as follows: y. l = ZBk xik T ”° 1 where: y is the dependent variable (e.g., average daily gain, carcass Characteristics), Xi are the independent variables (e.g., ration grain content, carcass weight) and "i is the error term. Feedlotyperformance. As previously reviewed, steers were fed corn silages varying in grain content, silage plus added grain or high concentrate rations in a two-year study. The impact Of ration grain level in the diet on feedlot performance was analyzed. Dependent variables included average daily gain, feed efficiency, NEm, NEg and dry matter intake. Independent variables included percentage of grain in the ration, source of grain and year. The following test was typical: Hypothesis: H : Feedlot performance is not influenced by increasing the percentage of grain in the ration. N : Steers receiving high grain rations had superior feedlot performance. 64 Model: Feedlot performance = BO+B1 %Grain+-B2 year where: year = {;} Test: B]=0 _v_s_ 8 >0. 1 Carcass Characteristics. The impact of ration grain level in the ration on carcass Characteristics was analyzed. Among the dependent variables estimated were marbling, maturity, quality grade, fat thick- ness, ribeye area, kidney, heart and pelvic fat, yield grade, carcass fat and dressing percent. The independent variables were percentage of grain in the ration, carcass weight and year. The test, for example, was: Hypothesis: H : Carcass Characteristics are not influenced by increasing the percentage of grain in the ration. y; Na: Steers receiving high grain rations are fatter than those fed all silage. Model: Carcass = BO+B1 %Grain + 82 Year + 83 carcass weight where: year = { ;} Test: 8 = O y§_ 8 :>0. 65 Model comparisons. Carcass data were analyzed in two steps. First, the hypothesis that hot carcass weight should be included as an independent variable was tested against the hypothesis that it should not. The following test was employed: LRSSE'URSSE)/# of restrictions ~ . . ' SSE/(I-K) Fa. # of restr1ct1ons, I-K where: RSSE is the error mean sum of squares when the restriction is imposed while URSSE is the error sum of squares when there is no restriction. Second, the hypothesis was tested for all parameters described in the previous section. Significance levels. Values at the P< .20 level were presented to allow for pooling similar data in later trials (Black and Harpster, 1978). For example, when the results of four trials are pooled with each a significance value of .10, they would have a significance value of .03 when combined. RESULTS AND DISCUSSION Corn Plot Study--Trial 1 Dry Matter Distribution of Corn Silage Harvested From Varying Plant Populations The plant dry matter distribution for the different plant populations in the first trial is reported in Table 12. Grain percent was highest for the 24,709 plant population (48.9%) and reduced to 42.6% and 27.4% when plant populations were increased to 49,419 and 74.128 plants/hectare, respectively. With increased plant density, percent stalk in the corn plant increased from 20.1% to 36.9%. Also, leaf content was increased from 16.9% to 28.1% with an increase in plant population. As grain content decreases with increasing popu- lation, a decrease in cob (31.3%) and husks (65.5%) were observed. Total dry matter yields were increased by 11.3% when plant populations were increased to 49,419, but no further increase was found at 74,128 plants/hectare, as shown in Table 13. With increased plant density, grain yield/hectare was reduced by 38.3%. There was a drastic increase in barren stalks from 6.6% to 47.5% when plant p0pu1ations were increased. The lack of increase in dry matter yield at the high popula- tion was most likely due to a large reduction in grain content and a high degree of barren stalks. Increasing plant populations and thus reducing the grain content resulted in lower protein in the corn silage. 66 Table 12. Dry Matter Distribution in Corn Plants (Trial 1) 67 Plants/hectare 24,709 49,419 74,128 Plant component: Grain Stalk Leaves Cob Husks ---% in plant dry matter --- 49.0 20.1 16.9 8.0 6.1 42.6 24.6 21.9 7.1 3.8 27.4 36.9 28.1 5.5 2.1 Table 13. Characteristics of Corn Silage Harvested From Three Plant Populations (Trial 1) Plants/hectare 24,709 49,419 74.128 Dry matter yield (ton/hectare) 11.22 12.65 12.35 Grain yield (bu/hectare) 230.3 225.8 142.1 Barren stalks, % 6.6 21.8 47.5 Protein, % 9.74 8.66 8.65 Acid detergent fiber, % 22.8 24.7 26.7 68 Increasing plant populations from 24,709 to 74,128 plants/hectare reduced the silage protein content from 9.74% to 8.65%. Acid detergent fiber was 15.0% higher for the silage containing 27.0% grain. Dry Matter Distribution of High Oil and Brown Midrib Corn Silage The plant dry matter distribution for the high oil and brown midrib corn silage as compared to the normal variety of similar plant population of 49,419 plants/hectare is reported in Table 14. Percent grain in the high Oil and brown midrib plants were 8.7% and 15.0% lower in the normal 49,419 population, respectively. High oil corn was sim- ilar in stalk content but the brown midrib variety had 13.4% more stalk. Also, brown midrib corn had a 4.8% increase in leaf content but no increase was found for the high oil variety, as compared to the normal population. High oil and brown midrib varieties were 29.7% and 12.1% higher in cob and husk content, respectively. Dry matter yields of high oil and brown midrib corn silage as compared to a normal variety of similar plant population of 49,419 plants/hectare are reported in Table 15. The high oil variety was similar but the brown midrib variety had a 9.0% lower dry matter yield than the 49,419 population. Grain yields were reduced by 19.2% and 22.6% for the high oil and brown midrib corn, respectively. The high ‘oil variety had a protein content of 9.74% while the brown midrib silage was the lowest of those studied. Acid detergent fiber content was similar to normal for the high oil but was reduced by 8.9% for brown midrib. 69 Table 14. Dry Matter Distribution in High Oil and Brown Midrib Corn Plants (Trial 1) a High Brown- Normal oil midrib ---% in plant dry matter-mm Plant component: Grain 42.6 38.9 36.2 Stalk 24.5 24.5 28.4 Leaves 21.9 21.1 23.0 Cob 7.1 9.4 8.4 Husks 3.8 6.1 4.0 aPopulation—-49,4l9 plants/hectare. Table 15. Characteristics of Corn Silage Harvested From Normal Plant Populations, High Oil and Brown Midrib Corn (Trial 1) a High Brown a Normal oila midrib Dry matter yield (ton/hectare) 12.65 12.63 11.51 Grain yield (bu/hectare) 225.8 206.6 174.7 Barren stalks, % 21.8 14.1 5.7 Protein, % 8.66 9.74 7.90 Acid detergent fiber, % 24.7 24.3 22.5 aPopulation--49,4l9 plants/hectare. 70 Corn Plot Study--Trial 2 Dry_Matter Distribution of Corn Silage Harvested From Varying Plant Populations The plant dry matter distribution for plants grown at 24,709, 49,419 and 123,548 plants/hectare is reported in Table 16. Grain percent was highest for the 24,709 plant population (53.8%) and was reduced to 50.7% and 36.9% when plants/hectare were increased to 49,419 and 123,548, respectively. As plant density was increased, stalk and leaf content was increased by 38.9% and 42.9%, respectively. With increasing plant population and a reduction in grain content, there was a decrease in cob (20.7%) and husk (22.6%). Yields of corn silage harvested from varying plant populations in trial 2 are reported in Table 17. Total dry matter yields were reduced by 5.2% when plant populations were increased to 49,419 but an increase in yield of 34.6% was found at 123,548 plants/hectare. When plant density was increased to 49,419 plants/hectare grain yield was reduced by 10.7%. As population was further increased, there was a 4.8% increase in bushels/hectare. There was an increase in barren stalks to 23.6% with the highest population. Increasing plant popu- lations from 24,709 to 123,548 plants/hectare reduced the protein content from 8.7% to 8.1%. Acid detergent fiber was 21.1% lower for the silage containing 53.8% grain compared to silage harvested from the high population with 36.0% grain. 71 Table 16. Dry Matter Distribution in Corn Plants (Trial 2) Plants/hectare 24,709 49,419 123,548 ---% in plant dry matter --- Plant component: Grain 53.8 50.7 36.9 Stalk 15.1 18.3 24.7 Leaves 14.5 16.6 25.4 Cob 8.2 7.3 6.5 Husk 8.4 7.1 6.5 Table 17. Characteristics of Corn Silage Harvested From Three Plant Populations (Trial 2) Plants/hectare 24,709 49,419 123,548 Dry matter yield (ton/hectare) 10.40 9.86 15.91 Grain yield (bu/hectare) 235.2 210.0 247.1 Barren stalks, % -- 4.1 23.6 Protein, % 8.7 8.4 8.1 Acid detergent fiber, % 19.5 21.7 24.7 72 Comparison of the Two-Year Study of Corn Silage Grown in Different Plant Populations The effect of corn plant population on dry matter distribution of plant components is plotted in Figures 4 and 5. As corn plant populations increased, there was a dramatic reduction in percent grain in the ration dry matter. Percent grain was lower at the lower plant population in trial 1 than in trial 2 due to an increase in stalk barrenness. These data are in agreement with most studies; the percent grain in the dry matter is reduced when the plant population is increased. Duncan (1958), Rutger and Crowder (1967) and Fairburn gt_al, (1970) reported a reduction in the amount of grain per plant as corn plant populations increased. As plant population increased from 48,999 to 86,000 plants/hectare, ear content was reduced by 10% (Cummins and Dobson, 1973). An increase in corn plant population from 9,884 to 59,303 plants/hectare resulted in a reduction of ear weight from .32 to .13 kg. The amount of dry grain produced/plant and the ratio of dried shell grain to total dry matter decreased as the plant population increased (Fairbourn gt 11., 1970 and Lutz _t_al,, 1971). In View of these studies, the energy value of corn silage would be expected to vary due to varying grain content and the ear to stover ratio. The percent stalk and leaf in the corn plant dry matter increased with increased plant density. Percent stalk increased at a greater rate in trial 1 due to a dramatic decline in the grain content of the corn plant. Cummins and Dobson (1973) reported a 5.0% reduction in stalk content as plant population was increased from 73 60080 "" .E 42020 "' 16 S. (D +3 ‘1' C Q) U ‘5; 33.80 4 o. " Trial 1 25.00 4 i i i ,, : 20000 50000 80000 110000 . Plants/hectare Trial 1 36080 "’ ff. 27.20 1- f6 +9 cf) 4.: J. 5 Trial 2 2 m 56.60 1" O. 10.00 i #4— 4 i : t 4 20000 40000 75000 104000 132000 Plants/hectare Figure 4. Relationship between corn plant population and percent grain and stalk in the ration. 74 35060 ”' 1r Tria1 1 14- 8 240‘0 "' _l +, Trial 2 c I. I (D U . S. Q) Q 17020 1’ 1D 10.00 i a: 4 3 3 e: 4 20000 40000 76000 104000 132000 Plants/hectare 2 x 1' \ T . 1 2 m A r1a :g ——x A O U 107' 4..) g . U Tr1a1 l S. (I) a A 20000 771 48000 ' 75000 ' 104000 11 132000 Plants/hectare Figure 5. Relationship between corn plant population and percent leaf and cob-husk in the ration. 75 48,999 to 86,000 plants/hectare. Bryant and Blaser (1968), however, noted only a slight altered ration of ear, stalk and leaf to whole plant weight when plant population was increased from 38,999 to 98,799 plants/hectare. Similar results were reported by Robinson and Murphy (1972), who found no significant change in the ratio of forage to grain yield in populations of 29,503 to 98,802 plants/hectare. Regression equations were developed from mean values of 240 samples for the two-year study for the prediction of relative dry matter distribution of corn silage with varying levels of grain content (Tables 18 and 19). As the grain content in the corn silage dry matter increased from 30% to 55%, percent leaf and stalk decreased by 48.6% and 56.2%, respectively, while cob and husk content increased. The grain content in the silage was highly correlated with the leaf (R2= .97), stalk (R2= .94), cob (R2= .92) and husk (R2= .68) content Of the corn silage dry matter. These results are in agreement with Ayres and Buchele (1971) who reported a similar decrease in stalk and leaf content as grain increased in the corn plant when harvested at varying maturity levels. Increased corn plant population resulted in increased dry matter yield (Figure 6). As reported in trial 1, total dry matter yields were increased by 11.3% when plant populations were increased to 49,419, but no further increase was found at 74,128 plants/hectare. The reduction in dry matter yield at the high population was due to a dramatic reduction in grain content. In trial 2, dry matter yields were reduced by 5.2% when plant populations were increased to 49,419 76 Table 18. Regression Equations Developed for the Prediction of Relative Dry Matter Distribution in Corn Silage From Silage Grain Contenta Plant component Regression equation by R2 Leaf Y = 44.01- .54 grain (%) 1.05 .97 (11.41) Stalk Y = 55.72-.75 grain (%) 2.03 .94 (8.16) Cob Y = 2.91+ .10 grain (%) 0.32 .92 (45.44) Husk Y = -2.67i .19 grain (%) 1.45 .68 (2.93) aRegression equations developed from mean values of 240 samples over 2-years. "T" values in parentheses. Table 19. Relative Dry Matter Distribution of Corn Silage Varying in Grain Content Percent grain in silage Plant component 30 35 40 45 50 55 Leaf 27.8 25.1 22.4 19.7 17.0 14.3 Stalk 33.3 29.6 25.8 22.1 18.4 14.6 Cob 5.8 6.3 6.8 7.2 7.7 8.2 Husk 3.0 4.0 4.9 5.9 6.8 7.8 aPredicted values by linear regression analysis of mean values over 2-years. 77 ” 0| 0 O O A U 'U E -.— 13.00 .. >- :3 +9 ‘r 4.3 (U 2 11 DO .. s>3 o D 9.00 4 4 4 44 4 4 § 20000 40000 76000 104000 132000 Plants/hectare 9.30.. 1’ F L a; 9020‘ 4..» O S. a. q, .4.) 5 40 'Trial 1 8 8060 ‘P Q) 0. 4* Trial 2 8.00 4 4 . 4 . 4 4~ 20000 45000 76000 104000 132000 Plants/hectare Figure 6. Relationship between corn plant population and dry matter yield and ration protein content. 78 plants/hectare but dry matter yields were increased by 34.6% at the higher populations. In numerous studies, increased corn plant popu- lation consistently increased dry matter production per hectare (Washko and Kjelgaard, 1966; Rutger and Crowder, 1967; Lutz and Jones, 1969; Robinson and Murphy, 1972). In these studies corn silage dry matter yields increased linearly with increased population up to 98,839 plants/hectare. Alexander gt_31, (1963) found that increasing the plant population from 16,679 to 33,358 plants/hectare increased yield of dry matter by 47.9%. Fairbourn gt_al, (1970) reported similar increases in dry matter yields when corn plant populations were increased from 21,000 to 44,972 plants/hectare. Rutger and Crowder (1967) and Stivers et_al, (1971) reported a 4.0% to 6.0% increase in total dry matter yield when plant populations increased from 49,419 to 86,484 plants/hectare. The effect of corn plant populations on the protein content of the whole corn plant is shown in Figure 6. In trial 1 protein was reduced from 9.74% to 8.65% with increased plant populations. There was also a decline of protein content from 8.7% to 8.1% in the second study. Alexander gt 31. (1963) compared 41,216 to 82,431 plants/ hectare and found a reduction in protein content in the whole corn plant from 7.2% to 6.0%. Lang gt_al, (1956) reported a significant decline in protein content of corn grain from 11.8% to 9.8% when corn was harvested from 9,884 to 59,303 plants/hectare. Holter and Reid (1959) and Huber gt_al, (1965) reported that higher plant populations resulted in decreased protein digestibility, but results were not significant. 79 The effect of corn silage harvested from different plant p0pu1ations and with varying grain content on acid detergent fiber is shown in Figure 7. In trial 1, acid detergent fiber was lower for the corn silage harvested from the low population and containing 49.0% grain compared to the silage harvested from the high population with 27.0% grain. In trial 2, acid detergent fiber was 21.1% lower for the silage containing 53.8% grain compared to silage with 36.0% grain har- vested from the highest population. The relationship between acid detergent fiber of the whole plant and the non-grain portion at various corn silage grain levels is shown in Figure 8. As the percent grain in the silage was increased, percent ADF of the whole corn plant was reduced but the percent of ADF in the non-grain portion increased. Johnson §t_al, (1978) reported the results of 50 corn silages that were harvested at different stages of maturity (Figure 9). There were small differences in digestibility and the increased grain levels were offset by increased levels of ADF in the non-grain portion. Our results are in agreement with those of Johnson et_gl, (1978), as percent grain in the silage was increased, ADF of the whole corn plant was reduced while ADF in the non-grain portion increased. As corn plant population increased, grain proportion is reduced and the percent leaf, stalk, cob and husk in the dry matter increased. The non-grain portion is high in fiber and is increased considerably when the grain portion is reduced. Studies have indicated that a decline in digestibility of fibrous components in feedstuffs directly 80 ._m>mp “av uo< cowpmg use :owumpzaoa acmpg :Lou cmmzumn awcmcowpmpma .N mczmwu mcopums\mucm_a ooowm— oooeoa ooomh ooooe oooow " v 4 v 4 +1 w 4* H:0.0« ,O 0¢;_HN 4 4 oméu 4. N 3.7:. L owéu P _eeee .4 . .om.hu 30v 1U33Jad 81 45.. ‘1' % ADF of Non-Grain .. “ Portion 32 . sf 0 :0 36. I: 4..) C 0.1 01 S... d) 4..) 0) C3 20. 12 Q < 0 % ADF of Whole Plant 20' zof 303 403 503 1 Percent Grain in Silage (% of DM) Figure 8. Acid detergent fiber of the whole plant y§_the 115» 40. Acid Detergent Fiber (% Of DM) 25) Figure 9. non-grain portion at various corn silage grain levels. % ADF of Non-Grain Portion % ADF of Whole Plant 20 $0 40 50 7“ Corn Grain (% of DM) Acid detergent fiber of the whole plant y§_the non-grain portion at varying stages of maturity of the corn plant (Johnson gt_gl,, 1978). 82 accounts for changes in cell wall digestibility (Van Soest, 1971). Cell wall is the most important component in feedstuffs of plant origin and includes cellulose, hemicellulose and lignin. The lignin within the cell wall is indigestible and appears to be the major factor in reducing the digestibility of high forage rations. The acid deter- gent fiber procedure determines the lignocellulose constituent of feedstuffs. Feeding Studies Description of Initial Slaughter Cattle The composition of steers selected at random by weight groups and slaughtered to estimate initial carcass composition is reported in Table 20. The mean dressing percentage and carcass composition was used to estimate initial weight and composition of the cattle placed on experiment. Table 20. Shrunk Weight, Carcass Weight and Carcass Composition of Initial Slaughter Cattle Carcass Carcass No. Shrunk Carcass Dressing protein fat Cattle type head wt., kg wt., kg (%) (%) (%) Charolais cross 6 232.7 131.1 56.4 18.3 14.7 Hereford 4 272.4 153.3 55.9 17.8 18.1 83 Feedlot Performance The effect of ration grain content on feedlot performance in Trial 1 is reported in Table 21. Performance data were adjusted to a constant dressing percentage of 62.2%. Steers fed the all-silage rations with 50% grain gained faster and were more efficient than those fed 29% grain. As grain was increased from 55% to 96%, steers had higher average daily gains and improved feed efficiency. The effect of ration grain content on feedlot performance in Trial 2 is reported in Table 22. Performance data were calculated on a constant dressing percentage of 61.7%. When the percent grain in the all-silage rations was increased from 38% to 54%, gains and feed effi- ciency were improved. As ration grain level was increased to 96%, steers gained faster and required less feed per unit gain. The pooled data for the two-year trial is shown in Figures 10 and 11 and reported in Table 23. Average daily gains increased and feed required per unit gain was improved as the percentage of grain in the ration increased (P<:.0005). Steers fed all silage rations increased in gain by 17% (.81 V; .98 kg) and feed efficiency improved by 12.3% (8.38 y§_9.55) as silage grain content was increased from 30% to 50%. Steers fed 69% grain gained 14.0% faster (1.16 y§_.98 kg) and were 13.4% more efficient (7.22 y§_8.38) than those fed all silage with 50% grain. Steers fed a high concentrate ration with 90% grain gained 6.6% faster (1.24 1; 1.16 kg) and required 16% less feed per unit gain (6.05 ys 7.22) than those fed 70% grain. However the data was not consistent across years. 84 .mwmzpese Ow; Fpiopim ma umswssmumu new mmeuseuu .sowues muesusmosou Fpe op so_uepseue xmmziozu e mswssu um» we: emeFPm sgouu .»_m>wuuesmms .OOO._ use mO._ we msouuem On sowpeswELepmu segues xsu s? mgossm so» musezsa ueumswue use; mxepsw mmepwm ssou use ssouu .emeppm s_ swesm use swesm umuue mmuzpusm .NN.NO .mmeusmusms Oswmmmsu usepmsou e op umumsnue age: eueO .me>_eo smmpm uessmmosu mweposeso O umuzpusw usesueesu sueme O.mm e.mN 0.0m u.Nm 0.0m _._O N.ON u.mN uN .pe» mmeoseu OP.O O0.0 _m.m FF.O O0.0 mm.O em.O em.m sPeO\umwm me.O N0.0 P0.0 N0.0 e0.0 N0.0 N0.0 O0.0 “swam—seem O0.0 ON.O O0.0 OO.m O0.0 -1 -1 -1 ssou z: ou_.O UFO._ Oe.m OF.O mm.O OO.N NN.O _O.N mmepwm ssoO Ne.m ON.O mo.m ON.O N0.0 O0.0 e0.0 m_.O aux .exeusw 2O apweO NN._ Ne.P ON._ OO._ OO.P NO.F _O.F O0.0 Ox .swem OFWeO oeN OOF OON OON ouN NON OON OON ummm so man OmO FOO emO ONO Ome NNO F—O NOe Ox ..p3 _eswm OmN OON OmN OmN NON OON oeN NON ox ..gz Fewuwsm OO _O OO uO Om Om Ow ON 2O sowpes s? ssoo Peuop useusms usmempsssm NO usesmpssam NO psmsm_ss:m NO “sweepsssm NO essmemz ssou gem mme~_m ON, eme_wm NOO woe—mm Nmm ssou ONO ssou Omm Amwmee ZOO sowpwmossoo sowuem : :2: mm>—eu mepm mo moseEsoesms so usmusou swesO sowuem Fegoh use mmepwmemo uomywm .FN mpneh 85 .msowues muesusmosou "Ne OsN>Neoms mppueo on sowgepseue xmmziozp e Oswsou umm we; OOeNNm ssoO .oscwssomu Nuw>esO ONNNoesm No ueswssmumu New mmeoseOm u .AONON .nwm.mw gmumssexv ONO>Nuomomws .OOO._ use mO._ No msouoem On sowuesNEsmumu segues xsu s? mgosse so» musezso umumowue msmz mmxeusm eOeNNm ssoo use ssoOU N—e use up usmusoo swesO ANOOO sONs use ANOOV sop Oswsmepsoo OOeNNm ssou Eosw uosouwzm msmwpm .Ox ONO we sowpes muespsmusoo .mOeNNm s? swesO use sNesO umuue wouONOsH .mm>peo sooam usowwsm: usONm umuoposN psmEoemsp soeNe useumsou e so umumswue mgm: eueO O .NNN._OV mOeusmosmO Oswmmmsu O.Nm 0.0m m.em O.em O.Nm m.Om O._m O.Nm 0.0m e.ON mN .ueO mmeogeu Oe.O NO.N O0.0 N0.0 mO.N NO.N Oe.N ON.N Om.O em.O sNeONummu O0.0 N0.0 Ne.O O¢.O O0.0 _N.O ON.O O0.0 O0.0 O0.0 usmEmposom ON.N ON.N O0.0 Oe.O OO.N OO.N OO.N 1- 1- -1 ssoo z: NO.¢ O0.0 uON.O uN0.0 ON.e ON.O eO.e NN.N e0.0 ON.N mOeNNm ssoO OO.N mO.N Oe.O N0.0 NO.N OO.N NO.N OO.N eO.N OO.N OOx .zO O’NeO N_.N NO.F ON.N NN._ NN._ OO.N OO.N NO.N O0.0 e0.0 Ox .sNeO NNNeO OON OON NON NON NON NON OON OmN OON OmN uOON so mer OOO OOe NNO NNO OOO OOe OOe NOO ONO OOO Ox ..p3 Neswm ONN mNN mNN eNN mNN ONN mNN eNN mNN ONN Ox ..u3 NewuNsH OO NO OO OO OO NO OO em NO Om 2O soNNes sN ssoo Peace psoosms mOe—Nm mOeNPm .Ooom NO .sssm NO usosopaaom NO usmEOFOOOm NO mesmemz swesO sNesO ssou NNO mOeNNm NNN OOeNNm NOO mOeNNm NNO sON: 3o; ssoo NOO ssoo NNN OmmessiozN Amwmeo ZOV sowuwmoseoo sompem AN NeNsNO mm>NeO smmum No moseEsowses so «sousou swesO sowuem NeuoN use mOeNNm No NOONNO .NN eNOeN 86 106071. , Trial 1 ((9) (D 3 Trial 2 (X) 5 1.40-- 0: g a CD :2 1.20- E Q d.) 3’ “L, 1000" > < -80 20 Percent Grain in Ration (% of 0M) 9.004- >, U C .2 N .U I: 4.. Lu '0 7000 1" CD 12 ~ Trial 1 (Q)) Trial 2 (X) 5.00 4 4 4 4 4 4 4a 4 20. 40. . 60. 80. 100. Percent Grain in Ration (% of 0M) Figure 10. Effect of ration grain content on average daily gain and feed efficiency. 87 .mxeusw segues Ngu so psmusou swesO soNpes Oo OUONNO .PN msOONN sowuem s? swegO Osmosms 00— cm or Nm 0* en ON P r 4 d d. D d Ana _ _eNsN L 64 00 d O) rac— (91.53‘°1M/Sw9J6) aiBiUI W0 88 Table 23. Significance of Pooled Results on the Influence of Ration Grain Content on Feedlot Performance and Carcass Characteristics Significance Carcass characteristics level Average daily gain (kg) .......... <.0005 Feed efficiency .............. <.0005 Maturity .................. NSa Marbling .................. NS Quality grade ............... NS Fat thickness (cm.) ............ .04 Ribeye area (sq. cm.) ........... NS Kidney, heart, pelvic fat (%) ....... NS Yield grade ................ .16 Carcass fat (%) .............. .02 Dressing (%) ................ .01 NE (Mcal/kg) ............... <.0005 9 aNS = not significantly different: P >.20. 89 An examination of Figure 10 reveals that gains were increased by .009 kg per 1% unit increase in ration grain content up to 70%. Feed efficiency was improved by .058 per 1% unit increase in grain. The source of grain, whether added grain or grain in silage, does not appear to be an important factor. The feed efficiency for the steers fed the low grain silage plus 35% added grain was equal to the weighted average of those fed high grain silage (7.98 y§_7.94). Steers fed 91% grain in trial 1 performed better than expected, based on previous studies. The results in trial 2 were consistent with previous studies. Dry matter intake (g/wt '75) remained constant as percent k9 grain in the ration increased, but was dramatically reduced for steers fed the high concentrate rations (Figure 11). It is concluded from the results of this study that an alteration in the ear-stover ratio of corn silage influences feedlot performance. As silage grain content is increased from 30% to 50%, average daily gain is increased (17%) and feed efficiency is improved (12%). This is in contrast with NRC (1976) that lists only one energy value for corn silage. The impact of added grain on feedlot performance was examined in View of various studies. As the percent grain in the ration was increased by 1%, gains were increased and feed efficiency improved. The results of the literature reviewed were as follows: 90 Gain (kg) Feed/Gain Woody (1978) .009 -.058 Peterson gt_al, (1973) .006 -.052 Gill _e_t__a_]_. (1975) .005 -.052 Newland $3.21: (1976) .005 -.039 Danner (1978) .007 -.050 Goodrich §t_al, (1974) .007 -.O47 The results of this study were consistent with the other studies reviewed. In this study, percent grain in the ration had a greater impact on performance. This is due to adjusting gains to a constant dressing percent and correcting for errors in dry matter determination for calculating feed/gain. The impact of grain in the ration on performance may vary due to the level fed. Goodrich gt_al, (1974) reported a greater decline in gain when corn was reduced in high roughage than in high concentrate rations. In this study, as ration grain content was increased up to 80%, gains were improved. At this point, gains leveled off and were reduced for the steers fed 96% grain due to a dramatic reduction in dry matter intake. These results were supported by Fox (1977), Jesse _t_g1, (1976a) and Prior g; El: (1977) who reported that average daily gain increased as the energy density in the ration increased up to 70% to 80% corn in corn-corn silage rations. The comparison in feedlot performance for steers fed high silage y§_high concentrate rations are in agreement with previous studies (Pinney §t_§l,, 1973; Minish §t_al,, 1967; Riley, 1969; Peterson gt Q1, 1973; Gill gt_§l,, 1976). These studies conclude 91 that as ration grain content increased, gains were improved and days on feed and non-feed costs were reduced. Utley gt al. (1975) fed crossbred steer calves and yearlings all forage or high concentrate rations. Steers fed the high concentrate ration gained 21.5% faster than those fed all forage (P<:.05). Minish gt g1. (1966) reported a 36.6% increase in gain when steers were fed a 60% concentrate-40% silage y§_all silage rations. In the second trial, Minish gt 31. (1967) reported that steers gained 20.7% faster when fed the 60% concentrate ration over the all-silage fed steers. Peterson gt_al, (1973) found a linear response in gain and feed efficiency (P<:.Ol) when the level of grain was increased in the ration when steers were fed corn silage:corn ratios of 100:0 to 0:100. Gill §t_§l, (1976) reported that steers had higher gains (18.4%) and improved feed efficiency (25.8%) when the corn:corn silage ratio was increased from 25:75 to 76:24. Carcass Characteristics The influence of percent gain in the ration on carcass Characteristics in trial 1 is reported in Table 24. All measurements were adjusted to a final empty body weight of 469.9 kg. As the percent grain in the ration increased, steers had a higher degree of carcass fat and a more desirable quality grade. The influence of percent grain in the ration on carcass composition in trial 2 is reported in Table 25. All parameters were adjusted to an equal final empty body weight of 448 kg. Steers fed the high grain rations were fatter and had poorer yield grades. 92 .mwmxpese ON; NpiopiO Na umswsgeumu we» mmeoseum .ON n muwoso 3o; ”O n uooO sON: "O u uooO eOesm>< "muegO auvpeoou .ON 0 i—NeEm ”NF u oppmsm mN— +NNOEO ”OF M upmmuoz .m n +< mN n < mp n 1< “zuwssaez ase_eeese O .mOeNNm sw swesO use swesO umuue mmuoposH .Ox ONO mo psONoz xssssm NesNN e on musosmmssou Hes» Ox OOO No NsONmz xuoa Nessa pseumsou e on umumowu O.NN N.O 0.0_ 0.0N 0.0 N.ON 0.0 0.0 umuesO anpeoc O.e_ N.O O.NN O.N_ 0.0N O.NN N.NN O.NN OOswposez O.N m.~ O.N N.m _.N e.~ O.N N.~ N .eeO Neseeg N.ON 0.00 e.ON 0.00 N.OO O.NO N.OO O.NN so .Om .eese mxmowm OO._ NN.O —0.0 P0.0 «N.O ON.O ON.O N0.0 Eu .mmmsxuwsp peg N.N O.N O.N F.N O.N O.N O.N N.N ONuNsouez O.NO N.NO O.NO O.NO O.NO O.NO N.NO N.NO N OstmogO OO NO OO eO Om Om OO ON 2O sopues sN ssoo Feuou uswogms “swampsoom NO useemNsoom NO usoemposzm NO psmsmNsssm NN mgsmemz seed Nee emes_m NN_ ame_em Nam emepem Nee ssoo NNO ssoo NOO Newmeo zOO sowuwmoosou somuem eNN NeNLNV moNpmNsepoesesO mmeoseu so psegsoo seesO sowpem NeuoN No mosmspmsH .eN mpoeN 93 ”O n oem_Nm mm .ON 0 +psmepm mop n - P_e5m m_P appeEm ”NP .oocwsgooa Oup>egO ONNNomsm No umsNEsmpwu we» mmeuseu eomoso 3o; ”O n uooO sON: "O n uooO eOegO>< ”eueLO zuwpesom m .N u upsONNO +NNeEm mm— u lumwuoz "OsNNOsezu .m u +< "N u < up n 1< "Nuwgsuezu .Ox ONO we sowues opegpsmosoo NNe ms» ow pseusoo swesO ANmOv sONs use ANOOV zop Oswsweusou mOeNNm sgou Eosw umsuuwzm mgmmumo usONwz xssssm Neswe ou .mOe—mm sw sNeLO use swesO uwuue wouONOsH .Ox O.NOO we musosmessoo Hes» Ox Owe No usONmz Nuoo ONOEO psepmsoo e on umumonu O.N 0.0 e.O 0.0 0.0 0.0 0.0 0.0F 0.0 0.0 mwuesO ONNNeOO O.N N.O e.O N.O e.O 0.0 N.O O.NN 0.0 0.0 uOsNNOLez N.O O.N O.N N.O N.O O.N N.O N.O N.O O.N N .peN zmsuwx O.NN O.NO N.ON O.¢N N.ON N.ON O ON N.ON O.NN O.NO .Eo .Om .emse wxmowm NN._ Om.N OO._ Oe.~ om._ N_._ OO.F «O.N e_.p e0.0 .su .mmmsonsu we; O.N O.N N.N N.N N.N O.N O.N N.N O.N O.N uxuwssuez N.NO O.NO O.NO O.NO O.NO O.NO N.NO N.NO 0.00 0.00 N OswmmmsO OO NO OO OO OO NO OO eO NO ON 2O sowues s? ssoo Nepop “smegma OOeNNm eOeNNm .ossm NO .ssom NO pseEo—saam NO usmEmNosom NO mssmemz svesO swesO ssou NNO wOeNNm NN— wOeNNm NOO OOeNNm NNO sON: 3o; ssou NOO ssoolmrm ammegsiozN Amwmen ZOO soNmeosEoo sowuem eAN NeNst muwummgeuoegecu mmeoseu sO usmpsou swesO soNpeO NepoN No wusmspwsn .ON opaeN 94 The analysis of the pooled data on the effect of ration grain content on carcass characteristics for the two-year study is reported in Table 23. The percent grain in the ration influenced carcass fat, fat thickness and dressing percent (P<:.05) when adjusted to an equal carcass weight, as shown in Figures 12 and 13. Maturity, marbling, quality grade, ribeye area and kidney, heart and pelvic fat were not influenced by ration grain content. The impact of grain was the same irrespective of whether the source was from silage or added grain. The developed regression equations for the prediction Of carcass Characteristics is reported in Table 26. Numerous studies have been reported on the influence of ration energy level on carcass composition. The results of this study are consistent with other studies that conclude that ration energy level influences carcass composition (Guenther gt_al,, 1965; Oltjen gt_al,, 1971; Utley gt_gl,, 1975). Guenther et_al, (1965) reported increased carcass fat when cattle were fed on a higher plane of nutrition. Utley et_al, (1975) concluded that steers fed high concentrate rations had more marbling, poorer yield grade and more fat thickness than steers fed all forage rations when adjusted to a constant weight (P<:.05). Oltjen gt_al, (1971) reported that carcass grade was higher for steers finished on all concentrate is those finished on all forage (P< .05). In contrast, other workers have concluded that composition of gain is not influenced by ration energy level (Pinney gt_al,, 1966; Garrett, 1971; Preston gt_al,, 1975; Perry and Beeson, 1976; Jesse 95 .. x 1.464- x ,y ‘x E ii x m ID 3 x _5 .x U E 1005 " 0 .— 15’ U- _ Trial 1 (O) o 0 Trial 2 (x) c) (D 01 .55 4 4 4 4 4 4 4 4 20.0 40.0 50.0. 00.0 100.0 Percent Total Grain in Ration .. x x 330‘0 ‘L 1 0 ‘1. x A 32020 {P ES 4J db (6 1.1. (ll 31 000 "F m Trial 1 (0) f6 4: ‘- . {3 Tr1a1 2 (X) 29.503- ' (D .L x 0 l l 1 1 25.50 4 4 0 _ 4 4 . . . . 20.0 40.0 50.0 50.0 100.0 Percent Total Grain in Ration Figure 12. Influence of ration grain content on fat thickness and carcass fat. 96 3060 1" x x x: :x 3020 "' Q) «1- ‘U 2 CD 2080 1"" '0 F5 .. >' ’< Trial 1 (O) 2040 "' 0 0 , 0) Trial 2 (X) 0 2.00 44 .4 4 4 4 4 4 4 20.0 40.0. 60.0 50.0 100.0 Percent Total Grain Ration 53.50 «- 0 52.5034 3Q 1- Cl .5 U) 61060 1" U) (D s- 11- C’ x X' Trial 1 (O) 50'5” " Trial 2 (x) «F :x 59.50' 44 .4 4 44 4 44 4 4 20.0 40.0 50.0 50.0 100.0 Percent Total Grain in Ration Figure 13. Influence of ration grain content on yield grade and dressing percent. 97 .mommspsmses sm mmope> e»: .Newsp OswummN semxiN EosO umsopm>mu msowpeocm sommmmsOmme N_e.ev No_.v Nee.~v ON. N0.0 so: NOOO..+sem> NOOO...NsNesO NOOO..+NOO. n NNO OswmmesO Aeo.ev Ame.mv Ame.mv ON. Ne.m 30; ONO..+gem> NNO..+NsNesO OOO..+N0.0N n NNO new mmeoseu NNe.mv Amm.ev Ape..v Fm. O0.0 3o: eOO..+see> Fem..+NsNeLO eOOO..+NNN. n eueeO upmw> ANe.~O Nee.ev Ame.v OF. O0.0 3o: NOO..+sem> OON..+NsNegO NOO...ON._ n NNO ION A_m.ev ANN.PO AeN.O _m. O0.0 30: NO..+sem> NON. -NsmesO NOO...NN.em n N.su .Omv emse exmowm Nem.ev Aom.NO Neo.ev OO. «N.O 3o: NOO..+seo> OOO..+NsNeLO POO..+OO.N- n momsxowsp Hem ANO.FO ANN.MV Neo.v mp. Oe._ mo: eOO..+sem> FO.e..NsNeLO NOOO. -O0.0 n eueLO xpmpeoo Nee.mv A_P.mv Ame.v ON. mp.m OO: ONO..+see> ONO._.NsNesO NNO. -mem. n OsNNOLez Ame.v ANm.ev Nom._v Om. Ne.O 30: OOOO..+sem> NON..+NsNesO ONOO..+NN._ n Newsopez NO me sowaesce sowmmosOmm mesmemz emaNesN mmeoseu No sowuowumss msu sow umsope>mO msowueocm sommmmgOeO .ON mNoeN 98 ._t._l., 1976a). When steers were fed to an equal weight, Garrett (1971) found little difference in body composition when fed varying roughage-to-concentrate ratios. Perry and Beeson (1976) fed steers high silage or high concentrate rations and reported no difference in quality grade. Preston gt 51, (1975) reported that carcass character- istics were not influenced by ration energy level when steers were fed various roughage—to-concentrate levels. Also, Jesse gt_§l, (1976a) fed steers various proportions of corn:corn silage of 30:70 to 80:20 and concluded that composition of carcass gain for a given weight was not affected by ration (P< .05). Net Energy Value of Rations Varying in Grain Content Net energy values determined for each of the rations fed in the two-year feeding trial are reported in Tables 27 and 28. Ration grain content influenced ME (P= .02), NEm and NEg (P<:.0005). When the developed regression equations were applied, ME, NEm and NEg were non-additive as ration grain content increased from 30% to 70%, but increased sharply when grain level was further increased to 100%, as shown in Figure 14. When energy values were determined by analysis of silage and silage plus grain (30% to 70%) y§_high concentrate rations (70% to 96%) as compared to analyzing across all diets (30% to 96%), ME, NEm and NEg were 2.9%, 4.3% and 8.9% lower than predicted, respectively, at the 70% grain level. Energy values for the 69% grain ration in trial 2 were omitted from the analysis due to the inconsistency with the other data. 99 .AONON .Omzv NO. x Omsmsw mpnwummmwu On umuepzopeu a .Nsueewgopeu neon an uesNELONOOe me\Neezv eez OO.N NN.N ON.N NN.N O0.0 OO.N O0.0 OO.N s NO.N OO.N OO.N OO.N OO.N OO.N NO.N OO.N NONNNeuzv Nz ON.N NO.N OO.N ON.N NO.N OO.N OO.N ON.N NONNNeuzv ONOsmsm epneNNNooeNOz OO.N OO.N OO.N NN.N NO.N NO.N NO.N NO.N NONNNeuzw xOsesw mpnwpmm NO ep.e NN.e om.e e~.e mN.e em.e Ne.e m~.e eam¥\FeezV Noumea meets OO NO OO eO OO OO Os ON 2O sowues s? ssou Neuou usmuges “swampsssm NO NsmEONOOOO NO psoEmNssom NO uswEszssm NN mssmemz ssoo NOO mOeNNw NNN mOeNNm NOO mOeNNm NmO ssou NNO ssoo NOO Amwmeo ZOO sowpwmosEoo soNpeN AN NeNLNv mmope> OOLmsO pmz so usmusou swesO sowpem mo mosmspNsN .NN mpnep 100 .NeNm_ .oszv NO. x Negese apesemeeeu Ne emeepsepeo O .Nguoswgopeu neon ma uosPELmumOe Nex\seesv as: ON.N NO.N OO.N O_._ OO.N OO.N OO.N O0.0 E mo.~ eo.~ om.~ me.s «O.N mm._ me._ oe.~ Nm¥\Peezv ez NO.N me.~ Ne.e om.~ NO.N NO.N _m.~ e~.~ NOONFeesO oxOsesm epaeNNFonepmz OO.N OO.N NO.N NO.N OO.N OO.N NO.N ON.N NONNNeuzO xOswsm mPoNNOOONO NN.N ON.N O0.0 NO.e ON.N NN.e mp.e OO.N ONONNNeon xOsoso mmoLO OO OO OO NO OO eO NO Om 2O sowpes sw ssoo Nepow usmusws psmEmNsoom NO usmEmpasom NO usmemposom NO usmEeNsssm NO mesmew: ssoo NNO mOeNNm NNN eOeNNm NOO mOerm NNO sgoo NOO ssoo NNO NmNmeo zOV sowummoasoo sowuem AN NeNLNV mmope> OOLmsN umz so “smusou sNeLO sowuem mo musmzpmsm .ON mpaeh 101 1 x >10 2080 1" ’5. .x \ '5 9 I Z 2.404 v 0 £5 x Trial 1 (0) ‘9 Trial 2 (X) 2.00 ‘r t J. 4 4 1 4. 20.0 40.0 80.0 80.0 100.0 Percent Total Grain in Ration x X 2.00 r E \ 4L '5 U 5 E‘L6044 Trial 1 (0) $2 Trial 2 (X) 1.20 4 4 + 4 4 4 a 20.0 40.0 60.0 80.0 100.0. Percent Total Grain in Ration x X ’5 1.68 «- .y. \ 73 U db 5 ND) 2 1.200 0 ° Trial 1 (O) x Trial 2 (X) .04 4 4O 4 4 4 4 4 20.0 40.0 50.0 50.0 100.0 ' Percent Total Grain in Ration Figure 14. Effect of ration grain content on metabolizable energy and net energy for maintenance and gain. 102 The impact of silage grain content on net energy value of the ration was lower than predicted. Net energy for gain for all silage rations increased from .94 to 1.04 Meal/kg as silage grain content increased from 30% to 50%. This is an increase Of .05 Mca1/kg with each 10% increase in silage grain level. A similar trend was found as added grain in the ration was increased to 70%. Grain content had a greater impact on the enrgy value of the ration when increased from 70% to 100%; NEg was increased .14 Mcal/kg for each 10% increase in grain level. Thus, the impact of grain on the energy value of the ration was lower than predicted up to 70% grain, then had a greater impact. The depression in NEg at the 70% grain level accounts for the improvement in efficiency when steers are fed on the two-phase system y§_constant added grain rations. In agreement with previous studies, the greatest change in digestibility was found between 50% and 80% grain in the ration. Vance gt_gl, (19715) reported a curvilinear relationship for NE 9 as percent grain in the ration was increased from 36% to 97%. NEg of the corn grain increased while that of corn silage decreased as varying increments of corn grain was added to the ration. Byers, Matsushima and Johnson (19755, 19750) reported a depression in dry matter digestibility, ME, NEm and NE by 6.2%, 12.1%, 14.8% and 12.2% 9 when the total ration contained 67% grain, respectively. As grain content was increased from 70% to 100%, NEg increased more dramatically. 103 Two-Phase System Versus Constant Added Grain Performance data were pooled for the steers fed on the two-phase and compared to those fed silage plus a constant amount of added grain. Due to a high value for the silage plus added grain fed steers, NEg was calculated using developed regression equations and compared to actual values for those fed on the two-phase system. For the two-phase system, steers fed all corn silage during the growing phase and switched to an all concentrate ration at 415 kg had similar gains (1.09 y§_l.10 kg) but improved in feed efficiency by 6.5% and net energy for gain by 5.1% (1.11 1; 1.17 Mcal/kg) when com- pared to steers fed silage plus a constant amount of added grain throughout the entire feeding period (Table 29). The steers fed on the two-phase system had a larger ribeye and an improved yield grade (P<:.05); no differences were found for the other carcass Characteristics (Table 30). These results agree with Dexheimer §t_al, (1971) where gains were equal but feed efficiency was improved when steers were fed on the two-phase system in comparison to silage plus added grain fed simultaneously. Fox and Black (1975) suggested three factors that lead to improved efficiency when cattle are fed on a two-phase system (high roughage ration fed during the growing phase followed by a high concentrate ration fed during the finishing phase) in comparison to steers fed a constant amount of added grain throughout the entire feeding period. First, associative effects are present in feedlot rations when grain comprises 50% to 80% of the ration. Due to an 104 Table 29. Comparison of Steers Fed on Two-Phase System y§_Constant Added Grain Rationsa Silage plus Two-phaseb Significance added grain system level Daily gain, lb. 1.09 1.10 NS Daily DM intake (g/WTkg.75) 91.3 85.3 .13 Feed/gain 7.27 6.80 .10 Carcass fat, % 32.2 31.3 NS NEg, Mcal/kg 1.11 1.17 Not tested aData calculated on a constant dressing percentage (61.7%). bSteers switched from corn silage to all concentrate ration at 415 kg. 105 Table 30. Carcass Characteristics Of Steer Fed on Two-Phase System ii Constant Added Grain Rationsa Silage plus Two-phase Significance added grain system level Dressing % 62.1 61.9 NS Maturityb 2.5 2.5 NS Fat thickness, cm 1.47 1.47 NS Ribeye area, sq. cm. 76.8 80.0 .05 Kidney fat, % 3.3 3.1 NS Marblingc 8.9 8.1 NS Quality graded 8.8 7.9 NS Yield grade 3.4 3.0 .0005 Carcass fate 32.2 31.2 .15 aAdjusted to a constant carcass weight of 343.5 kg. bMaturity: A- = 1; A = 2; A+ = 3. cMarbling: Small+ = 12; Small° = 11. dQuality grade: Average good = 8; High good = 9. eCarcass fat determined by specific gravity technique. 106 interaction of the fiber and grain portion in the ration there is an alteration in digestion and metabolism of nutrients and a depression of dry matter digestibility and metabolizable energy; thus, resulting in a reduction in efficiency of energy utilization (Byers gt 31., 1975a). The 5.1% improvement of NEg for the two-phase system gs constant added grain rations support the results Obtained when grain content was increased from 30% to 100% in the ration. When NEg was determined by analysis of grain from 30% to 70% and from 70% to 100%, as compared to analyzing across all diets with grain from 30% to 96%, NEg was depressed by 8.9%. Byers gt 11. (1975b) also reported a 12.2% depression in NEg when the ration contained 67% grain. Secondly, when cattle are switched from a high roughage ration fed during the growing phase to a high concentrate ration, there is compensatory performance, resulting in a more efficient use of dietary energy during the finishing t_;l., 1970). Thirdly, cattle are fed for slower rates of phase (Fox gain during the growing phase when they are of lighter weight and their maintenance requirements are lower. During the finishing phase the cattle are heavier which results in higher maintenance requirements. When fed a high grain ration during this period they have a higher rate of gain and spend less time in this phase. Thus, a lower percent of feed is used for maintenance requirements and more is available for gain under the two-phase system. 107 Performance of Steers Fed High Oil or Brown Midrib Corn Silage Feedlot performance for steer calves fed high oil or brown midrib y§_normal corn silage is reported in Table 31. Steers fed brown midrib gained 5.6% faster and required 6.4% less feed per unit of gain than those fed normal silage. These results are in agreement A with Colenbrander g__al, (1977) who reported that steers fed brown midrib gained 8.2% faster and required 12.7% less feed per unit of gain as compared to those fed normal silage. Similar results were shown by Colenbrander gt 51, (1973, 1975) who reported improvements in average daily gain and feed efficiency for steers fed brown midrib corn silage. Dry matter intake was similar for steers fed brown midrib and normal silage. This is in conflict with Muller gt_§l, (1972) and Colenbrander gt_al, (1972) who reported that steers fed brown midrib silage had increased dry matter intake. The increased intake was related to a 15% increase in dry matter digestibility when the low lignin silage was fed. Steers fed high Oil silage had reduced gains (13.9%) and poorer feed efficiency (7.0%) than those fed normal silage. These results are in agreement with McCollough gt_al, (1972) who reported that steers fed high oil silage had 17.9% reduced gains and a 17.9% poorer feed efficiency. Carcass characteristics for steers fed high oil, brown midrib and normal silage are reported in Table 32. Steers fed brown midrib silage had a higher degree of fat thickness, kidney fat and carcass fat but a poorer yield grade than those fed normal silage. Steers fed 108 .OOO.— No souoew e No somueswssmamu segues Nsu s? msossm sow musezos umpmowue mew: mxeusw mOeNNm ssoOo .NN.NO .mOeusmosms Oswmmmsu useumsou e o» uepmowue «so: eueO .mm>Neu Loeum uesommoso mNeNosesO asONm umuspusw usmeuemsu sone eeumee oez N_.e Ne.m 4N.e eweONeeeN Ne.o mm.o Nm.o psesepsssm N_.N ee.N NN.N eme_em seoo eaomee “oz ON.N oN.N eN.e ONONO exeese smpyee Ngu NFNeO mo. moo.v moo. NO.N Ne.o _o.P Ox .seee Npees NeN NNN NeN ease so mNeo NNO ewe _Fm ex ..53 Peeps NNN NNN oeN as ..e: _eeeNsN Nessos NeELos Numwmm amsuwz szosO NNo sON: NeELoz wgsmew: m> m> swez owsuws szosO Nwo sON: xumwse> ssoO .1. N_ _eweev eee_em ssou Pessoz m> owsuwz szosO use NNO sON: um; mm>NeO smmum mo mumesgomsms popummu .NO ONOeN 109 .op u .o_ mavosu so; no u uoom saw: u uFPmEm ”Pp .mwmapmcm aw; n opmem "NF ppuopum an umcwsgwpmu any mmmugmum "w u uoom mmmgm>< "mumgm apwpmaoc .m +P_mem mm_ u -ummuoz "mcwpngmzo -< “xuwgzpmzn .mx mpm yo pgmwmz xcagsm Fee?» a op mucoammggou was» ax mow mo uzmwoz auon xuaEm ucmpmcou m op umumanu .. .. mz o.o_ m.m o.m umumgm apwpmso -- -- mz ~._. m.op ~.P_ um=__agmz who. mooo.v mooo.v P.m m.P m.~ & .pmy amzumx mmo. mz mmo. _.wn o.ow ~.mw Eu .cm .mmgm mamamm co. cgou .u. A— pawgpv mumpwm cgou Posse: m> nwgcwz :zogm wen ”we saw: um; mgmwum mo mumumwmmaumgmsu mmmogmo .Nm mpnmp 110 high oil had a lower degree of fat thickness, kidney fat and carcass fat but a more desirable yield grade than those fed normal silage. Net energy values of high oil, brown midrib !§_normal silage are reported in Table 33. NEg was similar for brown midrib and normal silage but was reduced 7.0% for the high oil silage ration. Table 33. Net Energy of High Oil, Brown Midrib gs Normal Corn Silage (Trial 1) Corn variety Measure Normal High oil Brown midrib Gross energy (Mean/kg)a 4.32 4.19 4.12 Digestible energy (Mcal/kg) 2.87 2.94 2.99 Metabolizable energy (Mcal/kg) 2.36 2.41 2.45 NEm (Meal/kg) 1.46 1.49 1.55 NEg (Mcal/kg) l.0l 0.93 1.03 aDetermined by bomb calorimetry. bCalculated by digestible energy x .82 (NRC, l976). lll Predicting Feedlot Performance from Acid Detergent Fiber and Ration Grain Content Feedlot Performance The relationship between acid detergent fiber, ration grain content and feedlot performance for trial l is reported in Table 34. When the developed regression equations for the rations increasing in grain from 30% to 80% were applied, a reduction in ADF from 26.7% to 5.7% resulted in increased gains from .80 to 1.35 kg/day and improved feed efficiency from 9.55 to 5.97. Increased grain in the ration resulted in increased gains from .80 to l.32 kg/day and improved feed efficiency from 9.74 to 5.96. In trial 2, as ADF was reduced from Zl.l% to 5.2%, gains were increased from 8.58 to 5.89 (Table 35). Increased grain level in the ration resulted in increased gains from .88 to l.32 kg/day and improved feed efficiency from 9.l8 to 5.96. When the results were plotted, ration ADF levels were closely related to feedlot performance (Figure l5). Ration fiber level was inversely related to feedlot performance, in agreement with Chandler and Walker (l972) and Jahn gt_al, (l970, l976). Acid detergent fiber was an adequate predictor of feedlot performance; it accounted for 78%, 89% and 9l% of the variation in gain, dry matter intake and feed efficiency, respectively. Regression equations for gains and dry matter intake did not include the high grain rations due to a sharp decline in performance. Regression equations 112 .ucmeummgu\mo>pmo cmopm vogammocu mwm_ogm;u pgmvm mam: wgmghm mm.~ n.¢w op.c NN.P o.m mm mm.— n.¢m mo.m m¢.~ n.m Pm oF.F NP.P mm.o n.mop m.pop e.no~ Fm.m -.w om.w mm.p wo.p mo.~ N.op m.o_ o.w~ mo cm mm mo.p ew.o mo.p ~.mm m.eo~ o.po_ mm.w ¢N.w en.m No.p o~._ mw.o w.- n.em n.mm om ow mm mx\_~uz .mmz oz\mv memos” 2o cmmm\vmmu ox .cwmm xpvmo x .Lmawm acmmgmawc ku< mumpwm cw ccou acmusFucw scrum; cw cgou ucmogma ax Am“. acmEmpnaam go :Loo xcm ucmsmpaaam fie mmmpwm amp :Loo xmm “cosmpaazm fie mumpwm xmm cgoo xmm acmempaasm Nu mmmpmm amm Amwmmn zov cowummoaeoo cowpmm mgammmz m AF mechv mocmsgomgoa poFumwu use “coucou cwmcw comumm .cmnwm pcwmcmpmo u_o< cmmzpmm Qwsmcowumpom .vm «yank 113 .ucwEammLu\mm>_mo gmmum ucommgm: ugmwm «gm: «Lochm «N._ .m.P mo.. cP.F mm.F oo._ mo.. om.o m¥\_auz .mmz m.N~ m.- P._m e.Pm ¢.Fm ¢.om ~.mm m.mm Am~.mxpz\mv agapcm 2o om.m No.m «O.N um.“ we.“ mu.“ mm.w am.m evam\uaaa m_.F NN.F NP._ eo.F mo.p .o.. om.o em.o ax .cmmm >Pwao m.m N.m m.mp «.m. P.mp o.mp N.w_ F.FN N .amnvc pcamaapau cwa< mm om me so am am Pm mm mmaFPm cw cgoo mcmuapucw cowpmg cw cgou acmogma gcmampanzm mm “cosmpaazm xm pcmeopaaam am acmEmpaasm aw mgammm: ecou awn mma_.m amp ama_wm Rom mmmp_m Rmm coco Rom coco Rpm Amwmmn zcv cowummoasoo compmm MAN pmwchv mocmsgomcma popummm ucm pampcou :wmgw cowumm .Lmnvm ucmmgmumo uvo< cmmzumm avgmcowumpmm .mm m—nm» 114 '1 g 1 115 W 0 AUG (KG)=1.50-.026 ADF(Z)-.083 YEAR 2 ° R2=0.78 fig Trial l (0) >_ Trial 2 (X) : 1.22< (I D DJ 3 a: 1.00 DJ > a: .. x o .77 3 : 49 : :15 i: :21 : 2427 RCID 'DETERGENT FIBER (z) F/G (KG)=S.01+.169 ADF(%) ,_ 9,00 .. R2=o.91 U 2 E U LI. IL U o 7.00 ‘- 3: Trial 1 (0) IL ~ Trial 2 (x) 5.020.; : : : 15% 215 . 27' RCID DETERGENT FIBER(1) Figure l5. Relationship between acid detergent fiber and average daily gain and feed efficiency. 115 developed for the prediction of feedlot performance from ADF determination are as follows: . Across all rations: F/G (kg) = 5.o1+-.169 ADF (%) 33 = .41 R2 = 0.91 (11.93) y . 30% to 80% grain: ADG (kg) = l.50-.0260 ADF (%)-.083 year AA = .06 R2 = 0.78 (4.97) (4.01) Y 2.40 R2 DM intake = 98.15+ .05 ADF (%)-6.05 year A? 0.89 (9/wtkg-75) (.27) (7.35) The level of grain in the ration had a definite effect on feedlot performance (Figure l6). As the percent grain in the ration increased, steers gained faster and had improved feed efficiency. Total ration grain content accounted for 87%, 89% and 93% of the vari- ation in gain, dry matter intake and feed efficiency, respectively. Regression equations for the prediction of feedlot performance from ration gain content are as follows: . Across all rations: F/G (kg) = ll.54-.062 grain (%) AA = .35 R2 = 0.93 (13.49) y . 30% to 80% grain: ADG (kg) = .557+-.0085 grain (%)- .042 year A§==.05 R2 0.87 (6.86) (3.00) 116 E 1.60-‘1 ADG (KG)=.557+.009 GRAIN(Z)-.092 YEAR (9 E J R2=0.87 ' £3 1.40» )- d CI: (9 ‘3 1.20 o “J ' . x :0 CE 5 E; .1.00u Trial 1 (0) Trial 2 (x) .80‘ . i : 2. i. __q 40 60 80 100 PERCENT GRRIN IN RRTION (1 OF DH) . F/6(KG)=11.SA-.062 GRAIN (Z) >- 9.00- % R2=o.93 m Trial 1 (0) (J .. Trial 2 (X) E: )< u. LIJ c: 7.00 a m LLJ LL. 5.00. : : : : : : ‘ 20. 40. 60,- 00. 100. PERCENT GRRIN IN RRTION (2 OF on) Figure 16. Relationship between ration grain content and average daily gain and feed efficiency. 117 DM intake = 96.54+ .01 grain (%) - 5.94 year 39= 2.4l R2 = 0.89 (9/wtkg-75) (.19) (1.45) Predicting Net Energy Values As grain level in the ration was increased from 30% to 70%, ADF and ration grain level accounted for 33% and 23% of the variation in NEg, respectively. In comparison, ADF and grain level accounted for 62% and 63% of the variation of NEg when ration grain level was increased from 70% to l00%. Due to the presence of associative effects, ADF and ration grain level accounted for a lower percent of the vari- ation in NEg as the ration grain level was increased to 70%. As grain level in the ration was increased to l00%, ADF and ration grain content were more useful predictors of NEg due to the greater impact of added grain (Figure l7). Regression equations developed for the prediction of NEg of rations varying in grain content are as follows: . 30% to 70% grain: NEg (Mca1/kg) = 1.405-.O179 ADF (%) AA = .11 R2 = .33 Y (2.12) NEg (Mcal/kg) = 0.785+-.005 grain (%) AA = .l2 R2 = .23 Y (1.66) . 70% to 100% grain: NEg (Mca1/kg) = 1.662- .0377 ADF (%) 0A = .18 R2 = .62 y (2.60) NEg (Mca1/kg) = 0.077i'.015 grain (%) by = .18 R2 = .63 (2.63) NEG (MCAL/KG) 118 r X X 1.58 I" 1020 "’ ‘3 Trial 1 (0) Trial 2 (X) - X .84 i 4* 4. ‘r i i i ‘. 20.0 40.0 60.0 00.0 100.0 PERCENT TOTAL GRAIN IN RATION 0 13 102" 0 mA 0 1.1.10.0 X 35:: 9. x lEE; x 5:3 5 82'1" TY‘Ta] 1 (0) Trial 2 (X) 72 f : : : 2_§ x~4 20 34 48 62 76 90 100 PERCENT GRAIN IN RATION Figure 17. Relationship between ration grain content and dry matter intake and net energy for gain. 119 Application to Other Corn Varieties The equations relating performance to ADF were used to predict the performance of steers fed brown midrib and high oil corn silage. The predicted gains were 3.5% higher and feed/gain was 3.2% lower for steers fed high oil than actual performance. Predicted gains for steers fed brown midrib were l2.7% lower than actual but feed efficiency was 7.2% higher. Nhen regression equations relating ration grain content and performance were applied, the predicted feed/gain was 3.2% lower and gains were 4.0% higher than actual for steers fed high oil silage. Predicted gains for steers fed brown midrib silage were 17.3% lower and feed/gain was l2.l% higher than actual values. In comparison, ration grain content and ADF analysis were useful predictors of performance for steers fed high oil silage but was not accurate for steers fed brown midrib. In conclusion, determination of ration grain content is an alternative method to chemical analysis of feedstuffs for predicting feedlot performance. From a farmer's viewpoint, determination of corn silage grain content from forage yields and bushels of grain produced per acre is a practical method of predicting performance of feedlot rations. ADF was an accurate predictor of feedlot performance; it accounted for 78% and 91% of the variation in gain and feed efficiency, respectively. In comparison, ration grain content accounted for 87% and 93% of the variation in gain and feed efficiency, respectively. When regression equations were applied to high oil and brown midrib corn varieties, ration grain content and ADF analysis were useful 120 predictors of feedlot performance for steers fed high oil but was not accurate for those fed brown midrib silage. With the exception of high grain rations, dry matter intake was not influenced by ADF or ration grain content. Dry matter digestibility was increased as ration grain content increased and ADF was reduced. When steers were fed rations with 30% to 70% grain, ADF and ration grain content accounted for a low degree of the variation in NEg but increased to 62% and 63% as ration grain content increased to l00%. Associative effects pose a problem in accurate estimation of net energy value of feedstuffs, particularly when the ration contains between 60% to 70% grain. Influence of Ration Grain Content on Cost of Feeding, Manure Handling and'Storage, and Manure Credit Economic analysis of the impact of the level of corn in corn- corn silage rations requires an analysis of nonfeed as well as feed costs (Black and Fox, l977). Total cost per unit gain is: (———> .W. (W Increasing the level of corn silage in the ration influences nonfeed costs per day in three ways. First, the amount of feed that must be handled per day is more than three times larger for an all-corn silage ration than an all-concentrate ration. Second, daily manure production goes up as the percent corn silage in the ration increases since corn silage is lower in digestibility than corn grain. More manure requires more storage space and more handling cost. Third. 121 the value of the manure "credit" per day is influenced by the percentage of corn silage in the ration, both in terms of volume and nutrient (N, P205, and K20) density. All of these factors must be considered in the determination of the most profitable feeding program. The influence of ration grain content on manure storage and nutrient composition was analyzed from data obtained in the two-year feedlot trial (Table 36). A slatted floor housing area is assumed; input-output coefficients and costs are based on a 600 to 800 head one-time capacity. The cost factors for alternative grain levels are partitioned into annual use cost for building and pit, feeding, labor, manure handling, veterinary and cattle processing expenses. The facility cost was based upon the cost of the building plus pit for manure storage of a six-month period. Pit investment cost per head capacity is given by: Investment cost = $94 + 5 x pit depth (ft.) The investment cost is based upon discussions with builders and data from Petritz (1977). Daily use cost was estimated as investment cost times 17% depreciation and interest, repairs, and property tax (given annual use cost per year) divided by 340 days (effective capacity). Cost of the building structure with slatted floor was figured at $5.40 per sq. foot; 20 sq. feet was allotted per steer (Petritz, 1977). Daily building cost was: Building cost = [(cost per sq ft x 20 sq ft/steer) x l7%] % 340 days 122 .xvzum Emwpoamums cmmx-ozy m socw cmuumppou spoon m.~_ eo.m e~m.o ~¢.~ mm.o~ o.m o.m mm o.¢_ Nm.~ “mm.o ON.N me.- o.w m.m om mbmcbcmucou saw: ~.w_ em.~ mo._ me.m “a.- ~.m_ m.m mo m=_a mmmpwm m.¢P m~.~ _mm.o mo.e mm.- N.~_ m.m No m.m_ mm.N ~_._ mo.m ON.NN N.op _.0 mm :wmcm umuu< o.m_ ~_.~ Po._ _m.m mo.m~ m.¢_ m.m em m.P_ mo.~ ep._ mm.m _o._m «.mp _.o _m m.m_ mm._ No.P ~_.¢ No.PN o.m_ «.0 mm mmmpwm _P< “N _awce m.m_ m~.~ om~.o mm. _m.mm m.m m.o om m.e_ mm.N oeo.o mm.m ~m.m~ N.NF 0.“ Fa mbmcbemucoo saw: 0.0. w_.N mm~.o mo.o mm._~ m.om m.o we m=_a mmmpwm m.o_ mp.~ mem.o an.“ _~.¢~ m.om N.@ we ..~_ mm._ umm.o om.o em.~m ~.mm N.w mm =_mcm umuuq m.m_ mm.~ ofio.o NN.o mm.m_ m.pm “.0 om N.m_ mm.. ¢o~.o mm.c o_._N o.om N.N oe 0.5. mm._ “a“.o .m.m Ne.m_ o.mm “.0 mm mma__m __< up Patch mxape_ z a z a Aapv 2a Asa av Anpv A_v corona e? corona cmuums mmumm mews: mmumm mmumu mmumw were: cwmcm & ago “a: cowuwmoaeou ucmwguaz ucm manpo> mgacmz :o ucwacoo :wmgw cowpmm we Hummwm .om m—amh w 123 The manure handling costs reflect labor and machinery expense (Hughes, 1973). Labor charge was calculated at .0004l hours required per gallon times the total gallons of manure per day at an hourly wage rate ($5.00): Labor cost = (hrs/gal x total gal/day) x hourly wage rate Pump and spreader use cost was .49¢ per gallon times the number of hours required for handling the manure (.0004l hours per gallon times gallons per day). Feeding cost was divided into labor and machinery components (Hughes, l973). Time was estimated at .000l hours per pound of feed times the number of pounds fed per steer (as-fed basis). The labor cost for feeding was calculated at an hourly wage rate ($5.00). The machinery cost consisted of wagon plus tractor expenses. A cost of 62¢ was charged per hour of feeding time. Tractor cost for feeding was calculated as previously for manure ($6.00 per hour times hours required per day). Labor cost for handling and processing cattle was estimated at .6¢ per day. The nutrients available were developed from metabolic trial data and their economic value given ration grain content were deter- mined. A 40% storage loss and a 5% application loss of N was assumed (Beef Housing and Equipment Handbook, 1976). Phosphorous availability was determined by conversion of elemental P to P205 by division of .44; 75% of P205 is available to the plant. Available potassium was deter- mined by conversion of elemental K to K20 by a division factor of .83, 124 90% of which is available. Nutrient availability from manure was in agreement with Peverly (1966) who reported values for nitrogen (51%) and phosphorous (8l%). Fertilizer value (¢ per day) was determined using values of ll.5¢ N; l6$ P205; and 8¢ per pound for K20. The impact of ration grain content (corn in silage plus added corn) is reported in Table 36. Urine production is independent of ration grain content. Feces, in contrast, is a linear function of ration grain content. Wells gt_al, (1972) reported a manure volume of 2.3 pounds (DM) for steers receiving an all-concentrate ration and 5.0 lbs/day for those receiving a high roughage ration. Snapp and Neuman (1960) reported a yield of 63 pounds of wet manure for steers fed high roughage rations compared to 36 pounds for high grain. Nutrient density is influenced by ration grain content. Nitrogen excretion per day is constant except for the high concentrate diets, which are l5% lower. Thus, the nitrogen per pound of manure is lower for a high silage than a high concentrate diet. The daily excretion of phosphorous tends to fall as the percent concentrate increases; potassium shows a similar but more pronounced pattern. Manure handling costs and feeding costs y§_ration grain content are reported in Table 37. As total grain (corn in silage plus added corn) in the ration increases from 30% to l00%, there is a decrease in the manure storage (.72 cu. ft. vs .37 cu. ft.), reduced pit depth (8.58 ft. g§_4.90 ft. per head capacity) and a lower manure handling cost per day (6.87¢ !§_5.95¢). 125 .mmmz Apgaog x nap\c: pooo.v mcwuwmm so» umcwacmg mcaoz "mcwummw com Lonmbu .mmmz ngzo; x mast Lma _mm Page» x A_¢ooo.v Pam can mcaozg "pmou Lonmgu .mamu o¢M\A&~_ x pmou “Lav nomad am=n .gw mcmscm mo Lassa: mos?» m + mm.emw uu_a mo «moon m~.op mm.o_ mo.up om.m_ eo.m_ _o.FN ~e..~ m_.- Asv swU\bmoo Pouch m. o. m. o. m. m. m. m. Aev m:w_u=m; m=_a .pa> Lac Lona; 50., mm.~ ¢_.N mm.~ mm.~ mm.m mo.e o~.¢ Peach m~.o mm.o om.o oo.~ mP.p 0N.P om._ ~¢.F xgmcwgumz .m.o “m.o mp._ NN.F ~m.. m~.N mu.~ m~.N atone; ”Axdu\ug “moo mcwvmmm mo.~ mm.~ mm.m wo.m mo.¢ mm.e m~.¢ mo.m _m30h oo.~ mm.~ oo.~ mm.~ m_.m me.m mm.m um.m scaewzumz hm.o mo.o m~.o om.o mm.o ma.o o_._ F_._ Tomanms ”Axmu\ev umou mcwpucm; mczcmz mm.__ m¢.F_ .o.__ mN._P mm._~ o¢.~F ¢_.~_ NN.~_ _abo» oe.m o¢.m oe.m o¢.m oe.m o¢.m oe.m oe.m smU\bmou am: me_u_wsm m¢.m mo.m P~.m mm.o m¢.m eo.m e~.m em.w asan\pmou am: up; mo.m_F mm.~Np w~.¢~_ ma.mm_ mm.¢mp mp.~m_ mm.¢mp m¢.~mp am .pmou be; om.¢ N¢.m m¢.m we.m OO.N mm.“ mo.w mm.m Au;\pc .cm omv spawn be; um.o ~¢.c ~¢.o ~m.o Rm.o No.o no.o N~.o sac\u;\umcw=cmc “we to ¢wL.=Q "ANdn\ev “moo xpwpwuau u--------------..cmuume xgu cowumc cw c_mcm acmucmm ............... oop om ow on on om. ow om mgammmz mumcucoucoo cvmcm wanna mng mmm__m mmm_wm F_< now: ucmucoo :wmgu cowumm Peach xn umucmzpmcH mo mpmou mcwummu new mcwpucm: mezzo: .Nm mpnm» 126 Building cost, including building structure plus slatted floor, is constant. Total facility cost is reduced from l2.27¢ per day to ll.35¢ per day as the ration grain level is increased. Manure handling cost is divided into labor and machinery components. The labor cost required for manure handling is l.ll¢ per day for the all-silage ration v§_.57¢ per day for the all-concentrate ration. Machinery cost, including pump and spreader, is reduced from 3.97¢ per day to 2.06¢ per day. Total cost for manure handling is 2.35¢ per day less for the steers fed the high concentrate ration. Feeding cost for the rations varying in grain content was divided into labor and machinery components. The labor cost is reduced from 2.73¢ to .92¢ per day as ration grain level increases. Machinery cost falls from l.47¢ to .76¢ per day. Total feeding cost per day is lower for the high grain ration (4.20¢ to l.67¢ per day). Manure handling plus feeding cost is 5.90¢ lower per day for the high grain ration. When comparisons are made for the total feeding period, steers fed all concentrate rations for 2l7 days had a facility, manure handling and feeding cost of $35.26 per steer as compared to $65.79 for the steers receiving the high silage ration for 297 days. The influence of ration grain content on total nutrients available from manure and corresponding fertilizer values is reported in Table 38. Nitrogen availability (pounds per day) was constant as grain level was increased, but decreased slightly for the high con- centrate diets. Phosphorous decreased from .10 to .07 pounds per day and potassium was reduced from .12 to .06 pounds per day. These values 127 .00 omx ”00, 00mm “00.__ z “0P\00000 .Rom ONv— .Nmm mONQ .fimm z uucmpa CLOU OH mpnmpmm>m mucwwLHq—c we Hcmuopwmw nw.m mm.~ w_.m N¢.m om.m en.m om.m 00.0 Ammu\ev mezcme Eocw cgaumg _0poh 00. 00. 00. 00. NR. 00. 00. 00. A0000 230000000 Np.— Np.p Np._ mm.~ mm.” ¢¢._ o0.~ o0._ Amomav mzcozamoca N~._ N~.p om._ om._ om.F om.P om.P om.F sz cmmocu_z nA>0c\ev m:_0> LmNpppugmm we. no. so. mo. mo. OF. op. NF. on Nxv Ezpmmmuoa mo. no. so. mo. mo. mo. op. OF. A momav macogamocm FF. FF. mp. mp. mg. mp. mp. mp. sz cmmocpwz 0A000\npv mpnm_00>0 mpcmwcuzz om.~ up. m em.m ~m.m mm.e 00.0 No.0 em.m Apmmv waspo> .0900 m.m m. up m.mp ¢.mp ¢._N 0.0N «.NN m.om anpv 00000 0.0 0. 0 0.0 0.0 0.0 0.0 0.0 0.0 A_0 wept: -n-------------ugmuums xgu c0090; :0 cpmgm ucmugma ............ cop om om ox am On ow om mczmmmz mumgucmucoo cmmcm nmuum mzpa mmmp_m mmmp_m FP< ;m_= pcmpcou apnea :owumm >5 nmucma_»cH 00 mcacmz $0 m3P0> cmepwpcmu 0:0 mpnm_00>< 0pcwwcuaz .mm m—amh 128 are similar to estimated fertilizer nutrient in liquid beef waste, as reported by Pherson (l973). Fertilizer value from the manure was calculated from the nutrient availability for the various grain rations. Nitrogen value was l.50¢ per day for the silage rations but was slightly reduced to l.27¢ per day for the high concentrate rations. Phosphorous (P205) and potassium (K20) were reduced by .48¢ per day as grain level was increased. Total returns (credits) from manure (¢ per day) are 4.06¢ for the steers fed the low grain gs 2.87¢ for the steers fed the all con- centrate ration (Table 39). When comparisons are made for the total feeding period, steers fed all concentrate for 2l7 days had a lower return for manure ($6.23/steer) as compared to steers fed all-silage ($l2.06/steer) for 297 days. Pricing Corn Silage Economic analysis of feedlot trials, particularly those involving alternative levels of corn in the diet, requires prices for shelled corn and corn silage. A whole farm budgeting approach (Connor gt 31., 1976) is required to accurately assess the roles of corn silage and shelled corn in farmer-feeder operations including factors such as labor and machinery scheduling and machinery inventory. A good approximation can be developed based upon the fact that pro- ducers have the option of selling corn as cash grain as well as harvesting it as silage. Thus, the "cost" of producing corn silage is influenced by the market value of corn grain through the opportunity 129 Table 39. Net Coat of Feeding, Manure Handling and Storage and Manure Credit Percent gain in ration dry matter 30 40 50 60 70 80 90 100 Feeding, manure storage and handling cost (¢/day) 22.15 21.62 21.01 19.04 18.36 17.68 16.89 16.25 Manure credit (¢/day) 4.06 3.90 3.74 3.50 3.42 3.18 2.95 2.87 Net cost/day (¢) 18.09 17.72 17.27 15.54 14.94 14.50 13.95 13.38 cost of 1and--the net earning capacity of land if it were used to grow corn. Other costs indlude fertilizer, seed, herbicides and insecti- cides, field operations, storage and interest on operating capital. When corn is harvested as silage, the corn stalks are not returned to the soil; the dollar values for nitrogen, phosphorous and potassium must be adjusted accordingly. Too, adjustments must be made for handling and storage losses between the field and at the feedbunk. The cost of growing, harvesting and storing corn g§_corn silage for different plant populations is reported in Table 40. Total nonland costs are partitioned into seed, fertilizer, herbicide and insecticide, field operations, management and supervisory labor, and interest on operating capital. A seed cost of $45 per unit (80,000 seeds per unit) was budgeted; a 10% loss during germination was assumed. 130 Table 40. Cost of Corn and Corn Silage Production C000 Corn silage (plants/acre) rain 20,000 10,000 20,000 30,000 50,000 Price/unit 100 bu 14 T 16 T 18 T 20 T Item ($) ($) ($) ($) ($) ($) Seeda b 45/80,000 12.50 6.24 12.50 18.75 31.25 Fertilizer N .115/lb 12.65 20.13 21.85 23.58 25.30 P205 .16/1b 8.00 9.12 10.40 11.68 12.96 0 .08/1b 4.80 21.00 24.00 27.00 30.00 Lim 11.00/T 0.80 0.90 1.10 1.30 1.50 Herbicides and insecticidesc d 16.00/A 16.00 16.00 16.00 16.00 16.00 Field operations Plowing 8.50 8.50 8.50 8.50 8.50 Disking 4.40 4.40 4.40 4.40 4.40 Planting 6.00 6.00 6.00 6.00 6.00 NH application 3.00 3.00 3.00 3.00 3.00 Cu1tivating 3.20 3.20 3.20 3.20 3.20 Spraying 2.50 2.50 2.50 2 50 2.50 Combining 17.00 -- -- -- -- Grain hauling .07/bu 7.00 -- -- -- -- Chopping, hauling & silo filling -— 27.00 30.00 33.00 36.00 Drying .023/point 23.00 -- -- -- -- Grain storage .15/bu 15.00 -- -- -- -- Silage storage 1.75/T -- 24.50 28.00 31.50 35.00 Management and supervising labor 6.00 8.00 8.00 8.00 8.00 Interest on operating Avg. 7 mo. capital 10%/yr 5.42 6.31 7.19 8.07 9.31 Total nonland cost Per acre 155.77 166.80 186.64 206.48 232.92 Per bushel 1.56 -— -- —- -- Per ton -- 11.91 11.67 11.47 11.65 a$45/unit (80,000 seeds per unit), 90% germination. b Warncke gt_gl,, 1976. CNott gt_gl . 1977. d Schwab and Gruenewald, 1978 (costs include fuel plus labor). eHoglund, 1977 (calculated as bunker cost x 17% for property tax, depreciation and interest. 131 Fertilizer cost was determined by accounting for the removal of nutrients from the soil when corn is harvested as silage as compared to harvesting as grain. Corn yielding 100 bushels of grain per acre when harvested as shelled corn is estimated to remove 110 pounds of nitrogen, 50 pounds of P205 and 60 pounds of K20 per acre (Warncke gt_gl,, 1976). It is estimated that 16 tons of corn silage removes 175 pounds of nitrogen, 57 pounds of P205 and 262 pounds of K20 per acre. Prices used were: 11.5¢, N; 16¢, P205; and 8¢ per pound for K20. Lime was budgeted at $11 per ton. Herbicides and insecticides were budgeted at $16 per acre (Nott gt_al,, 1977). Field operations were priced at custom rates (Schwab and Gruenwald, 1978). They were adjusted upward if it appeared they were inadequate to yield an adequate return on machinery investment as well as covering depreciation, labor and cash costs such as fuel and repairs (Black, 1978). Silage costs were increased as yield per acre was increased. Silage storage costs are based upon a moderately large bunker; a 12 year life and 10% opportunity cost on capital were used in pricing. The nonland costs reflect the differences in the cost of growing and harvesting corn as silage v§_grain. The total "cost" of corn silage based upon yielding the same net per acre to land as corn grain is derived as follows: Step 1. Sum of nonland costs of = growing, harvesting and storing corn as grain "Imputed" rental = Gross return if on land sold as grain 132 Step 2. Calculate the cost Sum of nonland costs of of silage ($/acre) Step 1 + growing, harvesting and storing corn as corn silage Step 3. Calculate the cost = [Cost of silage of silage ($/ton) per acre é Yield:] 1 Net retention where net retention is the ratio of corn plant forage dry matter into the silo compared to the corn silage dry matter that is removed. A 7% loss was assumed (Prigge and Owens, 1976). This is a low estimate compared to many literature values; however, part of the losses reported in the literature reflect errors in dry matter determination for corn silage that run between 6% and 13% (Fox and Fenderson, 1977). The total nonland cost for corn grain and for corn silage grown at different plant populations is reported in Table 40. Seed cost increased from $6.24 to $31.25 per acre as plant population was increased. The silage yield increased from 14 to 20 tons per acre. There was an increase in the nitrogen cost from $20.13 to $25.30, P205 from $9.12 to $12.96 and K20 from $21 to $30. Fertilizer costs increase considerably when corn is harvested as silage as compared to grain due to the removal of stalks and leaves from the field during harvest (Warncke gt_gl,, 1976). Field operations, including the cost of plowing, disking, planting, nitrogen application, cultivating and spraying, were the same for corn grain and for corn silage harvested for all plant populations. Grain hauling was estimated at 7¢ per bushel and drying 133 at 2.3¢ per point of moisture removed. Cost for chopping and silo filling increased from $27 to $36 per acre as yields increased. Interest on operating capital was based upon 10% per year. As corn silage yields per acre increased, interest on operating capital increased from $6.31 to $9.31. Total nonland costs per acre increased from $166.80 to $232.92 as silage yield increased from 14 to 20 tons/acre. However, on a dollars per ton basis, cost was reduced from $11.91 to $11.65. The price of corn silage per ton required to give the same net return as when crop is harvested as grain, is shown in Figure 18. This relationship was obtained by first determining the "imputed rental charge" on 1and--the net return to land if the corn had been sold as cash grain. As the price of shelled corn increased from $2.00 to $3.50/bushel, the "imputed" land rental increased from $44.23 to $194.23. Second, silage cost per acre considers the land rental charge plus the sum of nonland costs for corn grown, harvested and stored as silage. With a $2.00/bushel shelled corn price, silage costs per acre were $211.00, $230.90, $250.70 and $277.15 per acre as yields increased from 14 to 20 tons per acre, respectively. With a $3.50/bushel corn price silage costs were $361.00, $400.70 and $427.15 per acre as yields increased from 14 to 20 tons per acre. As reported in Table‘41,total costs of silage/ton at $2.00/bushel shelled corn price are $16.20, $15.52, $14.98 and $14.90 for yields of l4, l6, l8 and 20 tons, respectively; at $3.50/bushel they increased to $27.73, $25.60, $23.94 and $22.97 per ton. 134 .ouwcq cwocm o“ m>wucpmg ommpwm we move; .m_ mgsmwm A:m\av :Lou mo wows; om.m oo.m Rim OO.N r1 _ _ _ 18.3 18.0: 184: 18.8 uoo.mm cok om 5: M: uooim =8 0_ 180m :2 2 53m uol/g) 369113 uuog go aotud ( 135 Table 41. Price of Corn Silage Per Ton as Influenced by Corn Price Corn silage yield/ton Corn price ($/bu) 14 ton 16 ton 18 ton 20 ton 2.00 16.20 15.52 14.98 14.90 2.50 20.05 18.88 17.96 17.59 3.00 23.89 22.24 20.95 20.28 3.50 27.73 25.60 23.94 22.97 The following equations describe the relationship between the season average price of shelled corn and the price of corn silage: Silage yield of 14 ton per acre (10,000 population) Price of corn silage = $0.82+-7.69 - price of corn Silage yield of 16 ton per acre (20,000 population) Price of corn silage = $2.08+-6.72 - price of corn Silage yield of 18 ton per acre (30,000 population) Price of corn silage = $3.044-5.97 - price of corn Silage yield of 20 ton per acre (50,000 population) Price of corn silage = $4.14+-5.38 - price of corn. 136 In summary, the costs of growing corn silage, dollars per ton, is developed for alternative prices of shelled corn. Silage is priced such that it yields equivalent net returns to land as could be achieved growing shelled corn. The standard price is based upon a loamy clay soil capable of producing 100 bushels of shelled corn or 16 tons of corn silage per acre. The "out of the silo" price is $15.50, $18.00, and $22.25 at $2.00, $2.50, and $3.00 per bushel, season average shelled corn prices, respectively. Additionally, corn silage prices were developed for alternative plant populations, hence different yields and grainzforage ratios were considered. Economic Analysis The economic impact of the level of grain in the ration is evaluated from a total cost/cwt gain perspective; namely, — = < 22:: > we... + The framework is described in Black and Fox (1977). Nonfeed costs included labor and machinery for feeding, labor for observing cattle, housing and machinery for manure storage and handling. The costs are adjusted for manure credit. The costs of manure storage and handling and the manure credit adjustment are reported in Table 39. As the ration grain content was increased from 30% to 100%, costs were reduced by 5.9¢ per day (22.1¢ !§_16.2¢) but the manure credit increased by 1.l9¢ per day (4.06¢ y§.2.87¢ per 137 day). The resultant net cost per day was 4.71¢ higher (18.09¢ vs 13.38¢) for the cattle receiving all silage with 30% grain than those receiving the 100% concentrate ration. As reported in Table 42, feed disappearance for rations varying in grain content from 30% to 100% was determined from developed equations, as previously discussed. The cost of producing corn silage from different plant populations is reported in Table 41. Corn silage is priced such that it yields the same net return per acre as corn grain. The additional costs for fertilizer and handling are reflected in the silage price. At $2.00 per bushel corn, the prices are $15.52 and $14.90 per ton for silage containing 47% and 30% grain, respectively. At $3.50 per bushel corn, the prices are $25.60 and $22.97, respectively. The prices of urea and minerals were held constant for all corn prices, as was the interest charge per head per day. The cost summary, based upon the feed disappearance summary in Table 42, is given in Table 43. A basic question is: "How high does the price of corn have to get before the relatively higher non- feed costs per cwt gain, associated with the high silage system, are more than offset by the widening feed cost differential following from the fact that corn prices rise faster than silage prices?" The high concentrate system has a clear advantage at $2.00 per bushel corn over the all-silage ration containing 50% grain. But, at $2.75 per bushel corn, the all-silage ration with 50% grain has an advantage. The 30% grain, all-silage ration is never competitive. 138 Table 42. Feed Disappearance Percent grain in ration dry matter Measure 303 sob 70C 903“ Performancee Daily gain, kg 0.82 0.99 1.16 1.24 Feed/gain 9.55 8.38 7.22 6.05 Days on feed to gain 600 lbs 333 275 234 219 Feed disappearance/cwt gain Corn silage (T, 32% ON) 1.37 1.22 0.56 0.12 Corn (bu, 85% 0M) -- -- 6.52 10.25 Supplement (lbs, 90% 0M)f 84.9 74.5 57.1 47.0 aLow grain corn silage (27% grain in silage DM), 92%; supplement, 8%. bHigh grain corn silage (47% grain in silage DM), 92%; supplement, 8%. cHigh grain corn silage, 50%; corn grain, 43%; supplement, 7%. dHigh grain corn silage, 12.3%; corn grain, 80.7%; supplement, 7%. eDeveloped from regressions on pooled data. The 80% added corn rations were excluded due to the "erratic" values in Trial 1 relative to Tril 2 and previous experimental work. fCorn-urea-mineral supplements are described in Table 10. 139 Table 43. Cost Summary ($/ch Gain)a Percent grain in ration dry matter 30 50 70 90 Measure ($) ($) ($) ($) Nonfeed costs: Yardage, net manureb 10.05 8.13 5.84 5.09 Interest on feederc 4.50 3.72 3.15 2.96 Tota1 14.55 11.85 9.00 8.05 Feed costs: $2.00/bu corn 24.41 22.39 24.28 24.30 $2.75/bu corn 30.66 29.21 32.50 33.06 $3.50/bu corn 36.92 36.06 40.70 41.71 Total costs: $2.00/bu corn 38.96 34.24 33.28 32.35 $2.75/bu corn 45.21 41.06 41.50 41.11 $3.50/bu corn 51.47 47.87 49.70 49.75 aSee Table 42 for performance data. Costs reflect experimental condition; they are not adjusted for death loss, very poor doers, or time to get on feed. bSee Table 39. Excludes veterinary and marketing costs since they are similar across feeding systems. cThe interest charge budgeted is 8.1¢/head/day irrespective of corn price. In fact higher corn prices reduce feeder prices and resultant interest cost. However, in the long run, high corn prices reduce beef supplies which raises fed beef prices; resultant increase in feeder prices will raise the interest charge although not the previous levels. 140 As reported in Table 44, the two-phase system is competitive with the high concentrate system at $2.00 corn and is competitive with the all silage system at $3.50 corn. Table 44. Cost Summary of Various Feeding Systems Feeding systems Total costs 100% Two- 50%a 90% concentrate, ($/bu corn) corn silage phase corn silage 12% silage 2.00 34.24 31.70 33.28 32.35 2.75 41.06 39.39 41.50 41.11 3.50 47.87 47.05 49.70 49.75 aApproximately 50% grain in silage. CONCLUSIONS Corn silage grain content increased from 27% to 53% as plant population was decreased. Average daily gain and feed efficiency was influenced by ration grain content (P <.01). Ration grain content influenced carcass fat, fat thickness and dressing percentage (P <.05). Steers fed all silage increased in gain 17% and feed efficiency improved 12.3% as silage grain content increased from 30% to 50%. NEg of corn silage increased from .94 to 1.04 Mcal/kg as grain content increased from 30% to 50%. NEg was 8.9% lower than predicted when the ration contained 70% grain. NEg sharply increased from 1.14 to 1.28 Mcal/kg as ration grain content was increased from 70% to 96%. Steers fed on the two-phase system had similar gains but improved in feed efficiency by 6.5% over those fed constant added grain. Acid detergent fiber or ration grain content were equally useful for predicting performance and NEg. 141 10. 11. 12. 142 Relative to corn price, silage costs were $15.50, $18.90 and $22.25/ton at $2.00, $2.50 and $3.00/bushel. Non-feed cost minus manure credit was 4.71¢ higher per day for steers fed silage y§_those fed high concentrate rations. At $2.00 per bushel the high concentrate system is more economical, but at $2.75 per bushel all silage (50% grain) has an advantage. The two-phase system was competitive at $2.00 and $3.50 per bushel corn. APPENDIX 143 Table A.l Acid Detergent Fiber Determinations of Plant Components of Silages Varying in Grain Content in Trial 1 Percent grain in silage dry matter Plant component 27 43 49 ------------ (% ADF)------------- Leaf 35.1 35.1 37.7 Stalk 38.1 42.7 44.0 Husk 35.6 37.8 38.1 Cob 42.0 43.9 45.2 Grain 3.8 3.6 4.0 Table A.2 Crude Protein Determinations of Plant Components of Silages Varying in Grain Content in Trial 1 Percent grain in silage dry matter Plant component 27 43 49 ----------- (% protein) ----------- Leaf 11.5 9.5 11.1 Stalk 5.7 5.7 6.0 Husk 4.4 4.8 5.1 Cob 4.0 3.8 3.2 Grain 11.0 11.1 12.4 144 Table A.3 Acid Detergent Fiber Determinations of Plant Components of High 0i1, Brown Midrib and Normal Corn Silage in Trial 1 Plant component Normal High oil Brown midrib ---------------- (% ADF) ---------------- Leaf 35.1 34.3 35.4 Stalk 42.7 40.0 33.6 Husk 37.8 37.7 35.5 Cob 43.9 45.4 37.4 Grain 3.6 4.9 4.2 Table A.4 Crude Protein Determinations of Plant Components of High Oil, Brown Midrib and Normal Corn Silage in Trial 1 Plant component Normal High oil Brown midrib -------------- (% protein) -------------- Leaf 9.5 14.3 8.5 Stalk 5.7 6.8 6.3 Husk 4.8 5.1 5.0 Cob 3.8 3.0 3.4 Grain 11.1 10.8 10.1 145 Table A.5 Acid Detergent Fiber Determinations of Plant Components of Silages Varying in Grain Content in Trial 2 Percent grain in silage dry matter Plant component 36 50 53 ------------- (% ADF) ------------- Leaf 38.0 34.4 33.4 Stalk 48.4 42.7 36.0 Husk 3916 38.6 37.9 Grain 3.3 3.3 4.3 Table A.6 Crude Protein Determinations of Plant Components of Silages Varying in Grain Content in Trial 2 Percent grain in silage dry matter Plant component 36 50 53 ----------- (% protein) ----------- Leaf 8.3 9.2 12.2 Stalk 6.3 4.1 6.5 Husk 3.8 3.9 4.0 Grain 9.7 10.1 11.7 146 Table A.7 Fermentation Values for Silage Varying in Grain Content, High Oil and Brown Midrib Corn Plant population Corn variety Brown 10,000 20,000 30,000 50,000 High oil midrib Trial 1: Lactic acid, % 4.28 3.89 5.49 -- 6.36 4.50 Soluble N, % 43.71 56.9 57.69 -- 54.23 42.18 pH 3.83 3.72 3.88 -- 3.73 3.97 1%: Lactic acid, % 3.55 3.62 -- 3.24 Soluble N, % 48.70 49.63 -- 44.88 pH 3.93 3.90 -- 3.92 147 a..Non n.««N oNNn.c O.N..o NN.NN .«.o. m.N n..m N.N «N.O a a .o.o N.oom ..Nm. moN m .NN oN o.o«NN «.ono NoNN.o ..«..o no.NN NN.N. m.N ..o. o.N «N.O N N mo.o N.N.n N.o«. moN m «mo oN N.ONoN o..oo oNNN.c ch..c .o.om .o.m. ..N o.am c.n No.. 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N.55 «o:e..eee--N.< «.... 151 Tab1e A.10 Scanoprobe Estimates of Fat Thickness Over the Twe1fth Rib (Tria1 1)a Estimated Actua1 Estimated Actua1 Pen Steer fat fat Pen Steer fat fat no. no. cm cm no. no. cm cm 24 626 0.25 0.76 20 614 0.76 0.76 639 0.51 0.51 616 0.25 0.76 657 0.76 1.14 631 0.64 0.76 671 0.25 0.13 642 0.51 0.38 677 0.25 0.89 650 0.38 0.51 680 0.51 0.76 669 0.76 1.02 681 0.64 1.02 684 0.51 0.64 695 0.76 1.02 737 0.64 0.89 23 629 0.76 0.64 19 647 0.76 0.51 630 0.76 0.89 654 0.76 0.76 634 0.64 0.64 670 0.51 0.51 651 0.51 0.76 673 0.64 0.76 655 0.25 0.76 676 0.76 1.02 662 0.76 1.14 691 0.25 0.25 690 1.02 1.27 692 0.76 0.89 736 0.76 1.02 734 0.76 0.64 22 623 0.76 0.76 18 622 1.02 1.14 637 1.02 1.14 635 0.51 0.76 659 0.51 0.89 665 0.64 0.38 664 0.76 0.76 666 0.51 0.38 674 0.64 0.38 667 0.51 0.51 683 0.51 0.76 675 0.64 1.14 697 0.25 0.89 689 1.02 1.40 735 0.51 0.64 700 0.38 0.38 21 624 0.76 1.02 17 613 0.76 0.51 627 0.51 0.89 633 1.52 2.16 632 0.64 0.51 649 0.76 1.27 648 0.76 0.89 652 1.02 1.52 656 0.76 1.02 653 1.02 0.89 672 1.02 1.14 663 1.02 1.02 679 1.27 2.03 668 0.76 1.02 693 0.76 0.76 687 0.51 0.38 aITHAco ultrasonic SCANOPROBE, Ithaca, New York. 152 Tab1e A.10--Continued Estimated Actua1 Pen Steer fat fat no. no. cm cm 16 615 0.25 0.64 617 0.51 0.64 640 0.25 0.38 641 0.25 0.64 685 0.25 0.51 686 0.25 0.76 688 0.25 0.51 696 0.51 0.25 15 619 0.64 1.02 621 0.76 1.02 625 1.02 2.29 628 0.76 0.51 644 0.25 0.64 660 1.27 1.02 698 0.51 0.89 699 0.76 0.76 aITHAco u1trasonic SCANOPROBE, Ithaca, New York. 153 Tab1e A.11 ScanOprobe Estimates of Fat Thickness Over the Twe1fth Rib (Tria1 2)a Estimated Actua1 Estimated Actua1 Pen Steer fat fat Pen Steer fat fat no. no. cm cm no. no. cm cm 24 220 0.76 1.02 20 204 0.89 0.76 227 0.64 0.89 221 0.64 0.38 338 0.64 0.76 242 0.51 0.76 252 0.89 1.14 300 0.51 0.51 260 1.14 1.02 304 0.89 0.89 265 1.02 1.02 318 0.76 0.76 296 0.64 1.40 335 1.02 1.52 345 1.02 1.40 340 1.02 1.14 23 212 1.27 1.27 19 199 1.14 1.65 223 1.14 1.27 256 1.14 1.65 233 0.89 1.02 263 1.52 2.03 272 1.02 0.89 264 1.27 1.91 275 1.14 1.27 321 0.89 1.27 316 1.52 1.91 343 1.02 1.02 327 1.14 1.65 348 1.14 1.52 351 1.02 1.27 358 1.52 1.91 22 238 0.64 0.89 18 207 1.14 1.52 253 1.02 1.27 215 1.14 1.27 270 0.89 1.27 216 1.02 1.52 292 0.76 0.76 217 1.14 1.40 303 0.76 1.40 228 1.14 1.91 305 0.76 1.14 261 1.65 1.91 307 0.64 0.51 322 1.02 1.52 313 0.76 1.27 349 1.02 1.27 21 205 0.64 1.02 17 214 1.14 2.29 206 0.89 1.78 224 1.27 2.21 210 0.89 1.27 244 0.51 1.60 312 0.76 0.76 246 1.02 1.14 329 1.02 1.27 273 0.76 1.27 336 1.02 0.89 306 1.14 2.03 337 1.40 1.02 314 1.02 1.14 363 1.14 1.02 331 1.02 1.27 a1THAco ultrasonic SCAOPROBE, Ithaca, New York. 154 Tab1e A.11--Continued Estimated Actua1 Pen Steer fat fat no. no. cm cm 16 235 1.02 1.40 239 1.02 0.89 262 1.02 1.40 271 1.02 1.02 297 1.65 1.65 311 1.02 1.14 341 1.02 1.78 344 1.14 0.76 15 202 1.02 1.27 229 1.14 1.40 267 0.51 0.89 269 1.78 2.51 302 1.02 1.02 332 0.76 1.14 339 0.51 1.14 362 1.27 1.27 aITHAco u1trasonic SCANOPROBE, Ithaca, New York. 155 0.0m N.ON N..O N.OO N.N. N.OO O.NO O.m¢ ...O 0.0N 0.0N ..ON N.ON «..N o.mN. O.NO m.om O.NO N.OO N.ON O.NO N.OO 0.0m N.OO O.NO O.NO. N..O. N.OO. O.NO. m.O¢. N.N 0.0 O.N O.N N.N ON .N OO OO Om O.N. m.ON O.NO m.mm 0.0m O.mm O.NO m.ON N.OO. N.OO ..ON N.OO 0.0¢ N.OO O.NO N.NN. ..Nm. N.NO. N.O ..N o.O om ON ON .N.Ouc. .0 NV um:.mum. :mNo.p.z .NaUNNV Omc.m.m. OmNogu.z .NOONNV OO..N.uxm OONOLN.O .ONON .NaONNO cmNosp.c .Oumu .OOONNV :mNogp.c N.OO.NO .NaUNNO N.OOO. OONONN.2 .Nau\m.v N.ONO. smegma N.O .zO. =o..ac c. cgou .N.O» Ocmogmm OOOEO.OOOO NO cgou NNN OOOEN.OOOO NO ONO..O NN. Ocmsm.OO=m NO om“..m NNO cgoo NOO pcmso.OO=m NN NNO..O NNN .N.OOO 2O. OO.N.NOOEOO OO.NON N.NONN: .. .a.c.v =o..:o.om coNo...z co .co.cou =.a.O =o..am No .oo... N..< o.na. 156 N..~ O.N. N.ON ..ON N.ON N.ON N.ON N.OO O.Nm O.NN N.NN N.NO. 0.0N. ..ON. ..ON. O.Nm N.OO N.NO O.NO N.Nm ..OO O.NO N.OO O.NO N.NO O.N.. O.NO. O.NN. O.NO. O.NO. O.N N.O N.O. O.N N.O ON ON NO NO NO NO N.m.. N.O .m O.NO. N.N Om . ON: ON: .NaU\ :m m N.O N.N.O. No NV .N.O. ONNocp.z .NaONNV .N.N. cmNogp.z NV OO.chuxm OONOLN.: .OOON .NaONNO OONOLO.O .OumN .NaONNO NON..O N.OO..O .NaUNNV .N.O. cmNogu.z ..au\m.v .O. .mpums NOO Azov OO.NON :. Ogoo .Opou pcmugma OOOEN.OOOO NO NOOEO.OOON NO NOOEO.OOON NN OOOEO.OO=m NO mgzmmmz cgou NNN ONO..O NN. ONO..O NOO NNO..O NNN ccou NOO Ocou N.O .N.OOO 2O. OO.N.OOOEOO OO.NON .N .N.NN. OO..:muw. ONNONO.O co ucmpcoo O.OON OO..N. No OONNNO m..< N.OON 157 Tab1e A.14 Nitrogen Retention of High Oi1 and Brown Midrib y§_Norma1 Corn Si1age (Tria1 1) Corn variety High Brown Measure Norma1 oi1 midrib Dry matter intake (kg/day 7.1 7.9 7.3 Nitrogen intake (g/day) 137.1 137.8 153.4 Urinary nitrogen (g/day) 50.2 45.0 52.2 Feca1 nitrogen (g/day) 48.1 53.2 43.4 Tota1 nitrogen excretion (g/day) 98.3 98.2 95.6 Nitrogen retained (g/day) 38.8 39.6 57.8 Nitrogen retained (% of intake) 28.3 28.7 37.7 158 “N..O N.N.O NON.O NNN.O N.O.O NO..N OOO.O NN..O NO..N ON..O .O....oz. =..N co. m: "OO.N NNO.. ONN.O ”NN.O .N0.0 ON0.0 NN0.0 ONO.O ..O.. .NO.O .O....ox. aocaaaua..a co. m: ON..... NNO..N. N.N.OO. NOO.O.. N.O..O. OON..N. NOO..N. ONN.N.. NNO..N. ONN.N.. ...o.. 55......aaa c.a.acN-O: ON..OO. NNO..ON noo.om. O.N.OO. NNN..O. ON..NN. «NN.O.N N....O. N.O.ONN NO..NO. .3: ..uas ca N.NNO. .uaca ..o: .ON.O.N .Nn.n.n NNO.ONN OOO.NNN .oo.NN. ..O.O~N O.N...N NN..NNN OO..... OO..NNN .N.. a: .as ..==\a...=. Oz N...o .O..N. «N..ON .ON.N. ....N. N.O.m. O.N.O. ONO..N O...N. NON.NN O...N. ..aoOO a.a.¢. O: ...ao .Nm.o .NN.O OOO.O N.O.O OOO.O ONO.O N.O.o OO..N OOO.O . .Nm.o .a.\.ao=. an... O: ca..~¢ OO..N. ON.... .ON... NNN... .NO.O. O.N.N .OO.°. N.N.O. can... OO..N. ..aoOO c..m...a.as-ms N..uu .a>< .N..O .N..O N.N.O ..N.O .N..O .NN.O ON°.O NNO.O ....O .N..O ..aoz. oo=.=ooc.as-wz N..«u .a>< NOO...O . Nom.ONO ..N.OON OOO.NOO.. NON..OO .NO.OOO NN..»ON NO..NON OOO.OON ONO..NO ..aoOO 3a. =.aa Nucaaa .a>< .NN.ON. NNO.OON ONN.NNN N.O.ONN N.N.ON. ONO..O. O.N.OO. ONN.OO. N.N...N NOO..ON .... .aa.m\=.am ..N om..a>< OO...O. ”NN.NN. NNO.NO. O.N.Nm. NNN..O. NNO.NO. OOO..O. .O..NO. ONO.OO. OO..NO. ..aozv =.o.aca =.~N .Ncoao .o>< O.N.NO NN..OO NOO..O NNN..O .ONN.NO O...N. O....O ONN.NO ONO..O NNO..O .O.. coo.a\=.am =.~.o.a aaaca>O NON..NO «ON.NNO N.N.ONO ONO.NNO ONO..NO ONN.NNO ONO..NO .NN.NNO .O~.NNO ONO.NNO .....e. ..o: Nae. ..an NON.O. N.N.O. .ONN... NOO... N.0.0. OO..N. OO..O. OO..N. N.O.O. N.N.O. a.a.=. 2a N..au aNaga>< ooo.ao~ coo.NON OOO.NON OOO.NON OOO.NON OO0.0NN OOO.NON OOO.ONN OOO.NON OOO.ONN woo. ea .N.O O.N..ON OOO.OOO.. ON....O.. ONO.N.O.. .N...ON N.N.ONN NON.OON N.O.NON ooo.~NN on..moo.. .O.. ..a.. ..o: Nae. ..an OOO..N .OO.ON N....N ON..." «NN.NN ONO.ON OOn.NN ONO.NN .ON.NN ..O.ON .ae.. ..a. .ao. ..aea a OO..O. OO..O. oo..o. OO..O. OO..O. oo..o. OO..O. oo..o. oo..o. OO..O. .....=. ..a. Nae. ..aea a N.N.O. .Oo.O. NOO... N.O... NN..O. O.N.O. O.N.O. ONN.O. NOO... N.N.O. ..=.. .=.a.aca Nae. ..aea . ONN.O. ONN.O. ONN.O. ONN.O. ONN.O. ONN.O. ONN.O. ONM.O. NON.O. aNm.O.. .....a. .=.a.aca Ova. ..aea . ONO..OO ONO.OOO .N...OO OOO..OO OOO.NOO ON..OOO ONO.OOO ONO.OOO ONO.OOO OOO..OO .O.. .3: .....c. aoaca,< O. N O N O m N N. N . .35.. 22...... OO NO ON ON NO ON NO NO NO NO owmma-ozp.aili sou».- NNO OO..-g :. :.O.N “gouge; .N .~.th u:ua:ou.:.~sm c. NO.NLO> OOO.NO¢ NO O:.O> Nugocu as: No Oo.uO.:u.ou O..< «.O.» 1559 .538. N..... .332 O. O...N .58.... OO..N NO..N ONO.O «NO.N OO..N OO..N OOO.O NON.O ON..O ON..O .a.\..ox. =..N so. .2 NON.O .NO.O ONO.O ONO.O NNO.O NO0.0 NN0.0 N.0.0 NNN.O «ON.O ...N..ox. oo=.=o.=..s La. .2 NON.ON. NOO.O~. .ON.N.. ONO.O.. N.N.N.. NON.N.. NO..O.. .N..NN. NNN.N.. ”ON.N.. ...o.. 55......aaa =.o.acg-ux OOO.ON. NNN.NN. ONN.NO. NON.¢.N OOO.ON. .NN.NN. «OO.NN. NOO..ON N.N.ON. NON..O. ..z aouas ca N.N.O. .uaca .aaz O.N.NON ..N.N¢N ONO..ON OO..NON O.N.OON N.O.NNN NNN.NNN OO..N.N ma..OON N.N.NNN .N.. .3 .ae ..==Na.o.c. u: N..ao co. ON ONO.O. ”ON.N. NO..NN «.N.N. NO..O. NOO.O. NO..N. NNN.ON O...N. ...az. a...=. Ox N..co OO..N N.N.O ONN.O ONO.O NO..N NNm.o Nom.c N.N.O .OO.O .NO.O .a.\.ao:O as... O: ea...“ «ON.O. ONN.N NOO... NNN.N. N.N.O. N.O.N OOO.O. .om.N .ON... m.m.o. ..aozv =.oo...=.~e-uz N..au .o>< NO..O .NN.O NN..O NNN.O NNN.O ..O.m OO..O N.N.O NN..O NO..O ..aoOO ooeaaa.c.ae-mx ...au .a>< O.N..ON mNo.N.N N.O..OO.. N.N.OON NNN..OO O.N.ONO O.N.ONO.. ONO..OO NOO.OOO.. .Oo..oo.. ..aozv ..O =..N .Ncoaa .a>< OOO..NN NON..O. NN..OON ONO.ONN. N.N.OON OON..N. ONN.O.N ONO.NON N.N.ONN .OO.ONN .O.. .aoo..c.am ..N om.co,< NON.NNN O.N.OON .OO.N.N OO..ONN ONN.NON OOO.NO. OmO.O.N OOO.OO O...NMN ..O.NNN ..aon =.aoa.a c..o Nagoaa .a>< NOO.OO NO..N. m...mO .emn.NN NN..OO O...NN ONN.NO NNN..N ..O.ON NON.OO .O.. Loo.o\=..o =.a.aca ou..a>< n~O...v .NN.OO. .NN..O. o...mN. NOO.MN. NOO..O. .NN.NO. ”NN.NN. NOO.OO. OOO.OO. .....=. ..o: Neon Nags. N.N.O. ONO... .N...O. ON..N. ONN.O. N.N.O. OO..N. N.N.O. ONN.O. ONO... a...=. ta N...u amaca>< OOO.OON ooo.~m~ ONN.¢NN OOO.ON. OOO.O.N OOO.OON OOO.OON OOO.OON OOO.ONN OOO.NON woo. co .N.O evo.O.O.. ONO.N.N ONO.O.O.. .NO.ONO.. ONO.NNN N.O.NON OOO..OO.. O.N.NNO.. OON.Ooo.. O.N..mo.. .O.. ..c.. ..u: Ova. ..asu ON..NN .N...N . N.O.NN ONO..N .NO.NN OOO.ON ONN.NN .ON.ON NON.NN «N..ON ..a.. ..a. Nvo. ..aea . .OQN.N. O.N.N. O.N.N. O.N.N. O.N.N. O.N.N. O.N.N. O.N.N. O«N.N. O...N. .....=. .O.. Nee. ..NEa . NNO.O. ovc.N. «ON.O. NNO.O. NON.O. ONO.O. OON.O. OOO.O. NOO.O. ..N.O. ..=.O .=.a.aca N.O. N.aeo u N.O.O. N.O.O. ONO.O. O«O.O. O.O.O. O.O.O. ONO.O. OOO.O. N.O.O. O...N. .....=. .=.u.aca Nae. Noaea . OO..N”. OO..NNO OO..N.O OON..NO OO..N“. OO..NNO O.N.ONO O...NNO ooo.m~m ONO.ONO ...O ..x .a...=. amoeo>< a. N O N O m c m N . .35.. 2952:. on on O. .. a. .N .o a. on o. O..N.; ..o .N.O $6.5 .. .....O acoueou =.acO =. NO..... ago..~. No ma... NNgocm “a: No =o....=o.~o N..O o.na. LITERATURE CITED LITERATURE CITED Ademosum, A. A., B. R. Baumgardt and J. M. Scho11. 1968. Eva1uation of a sorghum-sudangrass hybrid at varying stages of maturity on the basis of intake, digestibi1ity and chemica1 composition. J. Anim. Sci. 27:818. A1bin, R. C., A. Simnacher and R. M. Durham. 1966. In vitro digestion of a11-concentrate ration. Rep. on Texas Tech._Eo||ege Research 55. A1exander, R. A., J. F. Hentges, Jr., W. K. Robertson, G. A. Barden and J. T. McCa11. 1963. Composition and digestibi1ity of corn si1age as affected by ferti1izer rate and p1ant popu1ation. J. Anim. Sci. 22:5. A11ison, D. N.. and D. F. Osbourn. 1970. The ce11u1ose-1ignin comp1ex in forages and its re1ationship to forage nutritive va1ue. J. Agr. Sci. Camb. 74:23. Armsby, H. P. 1917. The Nutrition of Farm Anima1s. New York: MacMi11an. Armstrong, D. 6., and K. L. B1axter. 1957a. The heat increment of steam-vo1ati1e fatty acids in fasting sheep. Brit. J. Nutr. 11:247. Armstrong, 0. 6., and K. L. B1axter. 1957b. The uti1ization of acetic. propionic and butyric acids by fattening sheep. Brit. J. Nutr. 11:413. Armstrong, D. 6., K. L. B1axter and N. McC. Graham. 1957. The heat increments of mixtures of steam-vo1ati1e fatty acids in fasting sheep. Brit. J. Nutr. 11:392. Armstrong, 0. 6., K. L. B1axter, N. McC. Graham and F. N. Wainman. 1958. The uti1ization of the energy of two mixtures of steam- vo1ati1e fatty acids by fattening sheep. Brit. J. Nutr. 12:177. Asp1und, J. M., and L. E. Harris. 1971. Associative effects on the digestibi1ities of energy and the uti1ization of nitrogen in sheep fed simp1ified rations. J. Anim. Sci. 32:152. Ayres, G. E., and W. F. Buche1e. 1971. Harvesting and storing corn p1ant forage. Am. Soc. Agr. Engr. 71:665. 160 161 Badway, A. M., R. M. Campbe11, D. P. Cuthbertson, D. F. Fe11 and N. S. Mackie. 1958. Further studies on the changing composition of the digesta a1ong the a1imentary trait of sheep. 2. Vo1ati1e fatty acids and energy re1ative to 1ignin. But. J. Nutr. 12:384. Barnes, R. F., L. D. Mu11er, L. F. Bauman and V. F. Co1enbrander. 1971. "In Vitro" dry matter disappearance of brown midrib mutants of maize. (Zea. Mays L.) J. Anim. Sci. 33:881. Beef Housing and Equipment Handbook. 1976. Midwest P1anning Service #6. B1ack, J. R. 1978. Cost of producing corn. Ag. Econ. 78:18. B1ack, J. R., and D. G. Fox. 1977. Interpretation and use of research resu1ts. Mich. Agr. Exp. Sta. Res. Rpt. 328. B1ack, J. R., and H. Harpster. 1978. Standard, but se1dom used statistica1 techniques. Mich. Agr. Exp. Sta. Res. Rpt. B1ack, w. H., R. L. Hiner, L. B. Burk, L. M. A1exander and C. V. Ni1son. 1940. Beef production and qua1ity as affected by method of feed- ing supp1ements to steers on grass in the Appa1achian region. USDA Tech. Bu11. 717. B1axter, K. L., and F. M. Wainman. 1961. The uti1ization of food by sheep. J. Agr. Sci. 57:419. B1axter, K. L., and F. N. Wainman. 1964. The uti1ization of the energy of different rations by sheep and catt1e for maintenance and for fattening. J. Agr. Sci. 63:113. B1axter, K. L., and J. A. F. Rook. 1953. 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