EFFECT OF ORGAMC AC“) TREATMENT ON PRESERVATION, FERM£NTATSON AND NUTRITIVE VALUE OF UNPROTECTED FORAGES AND HIGH MOISTURE EAR CORN Thesis far the Degree of Ph. D. wcmem STATE UNWERSHY FAWWAK TURN SLElMAN 1922 ' This is to certify that the __ thesis entitled Effect of Organic Acid Treatment on Preservation, Fermentation and Nutritive Value of Unprotected Forages and High Moisture Ear Corn presented by Fawwak Turki Sleiman has been accepted towards fulfillment of the requirements for Ph.D. degree inDairy Science ( [1/ 1/ Major professor MW 2.. / 0-7639 ABSTRACT EFFECT OF ORGANIC ACID TREATMENT ON PRESERVATION, FERHENTATION AND NUTRITIVE VALUE OF UNPROTECTED FORAGES AND HIGH MOISTURE EAR CORN By Fawwak Turki Sleiman Experiments were conducted to determine the preservative effect of organic acids on forages left under minimal protection conditions. The acids were: formic, pr0pionic and acetic. Acids were used at different levels and combinations. Part I consisted of 4 trials and was designed to determine which acid level or combination of acids is most effective in re- tarding spoilage of rye forage. Also, the influence of acid treat- ment on fermentation characteristics and acceptability of treated forages by the animals was examined. In trial I, three treatments were used: control, 1% formic and 1% AP (60 Acetic: 40 Propionic). The temperature of the control was higher 4 hours after treatment 28.3 C, compared to 2l.9 and 25.5 C on the AP and formic acid treatments, respectively. The control temperature peaked by the third week (54 C) and corresponded to a peak in the pH on this treatment. At 3, 9, and T4 days after storage, mold was detected Fawwak Turki Sleiman on control, AP and formic treatments, respectively. The DM recovery was higher on the acid treatments than the control. Temperature changes were highly correlated +0.98 with amount of molded 0M. Formic acid treatment had the lowest pH values and control the highest. Changes in pH were directly correlated with temperature (+0.98) and with the amount of molded DM (+0.92). Organic acid production was lower on formic than AP. The control treatment had the highest concentration of butyric acid. After removal of molded layer, lactic acid levels were comparable to that of good silages. Temperature and VFA concentrations were negatively correlated -0.46. Also, VFA concentrations were negatively correlated with molded DM, -0.6l. Changes in protein content were not different (P > .05). Also, differences in NPN content after the first week of storage were not significant (P > .05). Cows consumed 7.9, 7.4 and 9.6 kg of DM/day on control, formic and AP, respectively. In trial II, spoilage was first detected on the control followed by the low levels of acids (0.25%). However, a mixture of l:l of F:AP at 1.0 and 1.5% resulted in highest recovery of UN. The changes in pH were directly related to those of temperature +0.76. Temperature was negatively correlated with the time of mold detection, -0.93. Animals consumed forage treated at the high acid level (l.5%). In trial III, the effect of moderate compaction on acid treatment was tested. A delay Fawwak Turki Sleiman in temperature rises was observed for all acid treatments compared to control which spoiled first. Temperature, pH and VFA relation- ships were similar to those observed with previous studies. Pro- pionic acid treatment resulted in the least Spoilage followed by the l% mixture of P+F. Changes in ADF (Acid Detergent Fiber) and ADF-N were not different among treatments (P > .05). In trial 4, rye was treated with 0.4% formic acid and ensiled in conventional upright silos. Milk production and persistency and milk composition were not different (P > .05) on formic rye, control rye and alfalfa haylage. Although forage intakes were not significantly different (P > .05) slightly higher consumption was observed on the formic treated rye compared to control (8.3 vs 7.6 kg of 0M daily). In part II corn forage (38% DM) was treated with different acid treatments and left uncompacted. In trial I, the control molded first and had the highest temperatures. The second treatment to spoil was acetic acid. The pr0pionic acid treatment maintained the lowest temperature throughout the 6 weeks of storage and the AP and pr0pionic acid forages had the least amount of molded 0M. Tem- perature was negatively correlated (-0.8l) with the time of mold detection and positively related +0.40 to amount of molded EM. Formic acid treatment had the lowest pH value. The pH was negatively correlated (-0.6l) to time of mold detection. Total organic acid Fawwak Turki Sleiman production of unspoiled silage was higher on control, formic and pr0pionic than other treatments. Crude protein and NPN contents were not different among treatments (P > .05). AP and pr0pionic acid treatments had the lowest temperatures during the short acceptability trial suggesting that propionic acid depressed after- fermentation. In trial II, 5l different acid levels and combina- tions were used. The first treatment to Spoil was the control and the last to Spoil were those to which l.5, l.0 and 1.25% pr0pionic acid were added. Formic plus pr0pionic was more effective in delay- ing spoilage than formic alone or formic plus acetic. Earlier detec- tion of mold occurred as the pr0portion of acetic acid added to forages increased. Temperature and time of mold detection were negatively correlated (-0.54). Part III was conducted to study the effectiveness of organic acids as peripheral preservatives. In trial I, more 0M molded on the control (64%) and least on the AP treatment, 23.8%. Addition of pr0pionic to formic decreased the amount of molded DM by 38% compared to formic alone. Preserved material was fed to lactating cows and intakes of 9.5, 9.4, 8.3, and 9.0 kg of 0M were observed for AP+F, AP, formic, and control, respectively. When high 0M (50%) corn silage was used, the highest amount of Spoilage (90%) was on the control and the least on propionic acid, 9.7%. Formic acid was a Fawwak Turki Sleiman better preservative than AP or acetic acid on high DM material. In trial II, acids were sprinkled on t0p of horizontal silos and more DM molded on the control (34 kg/sq m) while pr0pionic acid treatment had the least amount (22.4 kg/sq m). AP treatment delayed further spoilage when applied on material that had been placed in the silo several days earlier and was partially spoiled. Acid treatments had lower pH values than controls. Changes in pH were directly related to the amount of molded DM (+0.66). Lactic acid concentrations were higher in the upper layers while acetic acid levels were higher in the lower levels. Crude protein and NPN content were not affected by the different acid treatments. Part IV was conducted to determine the effect of organic acid treatment on urea-treated HMEC (High Moisture Ear Corn). In trial I, formic acid alone depressed lactic acid production. However, lactic acid concentrations were not affected by acid treatment in presence of urea. Pro-Sil and control treatments had higher pH than acid treatments. Highest intake were observed on urea-formic acid treated HMEC but differences among treatments were not significant (P > .05). Also, milk production and persistency and milk composition did not differ (P > .05) between treatments. In trial II, pH values were lower on treatments without NPN addition. Formic acid depressed lactic acid production. Milk production and persistency and HMEC Fawwak Turki Sleiman intake was higher on the acetic than other acid treatment even though differences were not significant (P > .05). Untreated and Pro-Sil treated HMEC had the highest temperatures during the study. EFFECT OF ORGANIC ACID TREATMENT ON PRESERVATION, FERMENTATION AND NUTRITIVE VALUE OF UNPROTECTED FORAGES AND HIGH MOISTURE EAR CORN By Fawwak Turki Sleiman A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Dairy Science 1972 7 q t/ f) ACKNOWLEDGEMENTS The author's sincere appreciation to his major professor, Dr. John T. Huber, for his able guidance and advice. His support and patience throughout the study is greatly acknowledged. The author is further indebted to the other members of his graduate committee, Dr. Hugh H. Henderson, Dr. Harold D. Hafs, Dr. Robert M. Cook, and Werner G. Bergen for their advice and participation in the writer's graduate program. The author also wishes to thank Dr. C. A. Lassiter and Dr. J. A. Hoefer for making the facilities of Michigan State Uni— versity and the Michigan Agricultural Experiment Station available for this research. Appreciation is also extended to my friends, Dr. R. E. Lichtenwalner, Danny Britt, Alfred Dutrow, and Lars Vikmo for their help during this research. The statistical advice of Dr. Roger Neitzel and the photographic help of Ted Ferris are appreciated. The generous supply of acids by Celanese Chemical Company, Corpus Christi, Texas, is greatly appreciated. Last but not least the author would like to extend his deep appreciation to the Lebanese National Council For Scientific Research for the financial support throughout the three years of study. ii TABLE OF CONTENTS Page LIST OF TABLES ......................... viii LIST OF FIGURES ......................... xii INTRODUCTION .......................... l REVIEW OF LITERATURE ...................... 3 Stage of Maturity and Moisture Level of the Plant at Ensiling Time ....................... 3 Corn Silage ....................... 3 Sorghum Silage ..................... 6 Rye Silage ....................... 7 Barley Silage ...................... 8 Wheat Silage ...................... 8 Oat Silage ....................... 9 Alfalfa Silage ..................... 9 The Effect of Temperature and Oxidation on Silage Quality. . 11 Silage Additives ...................... 14 Addition of Acids to Ruminants ............. l4 VFA and Lactic Acid Addition to Rations ......... 17 Formic Acid Treatment of Silages ............ 18 iii TABLE OF CONTENTS (cont.) Page High Moisture Corn ..................... 24 Feeding Value of HMC .................. 24 Chemical Changes in HMC ................. 25 Non-Protein Nitrogen and HMC .............. 26 Acid Treated Grains ..................... 27 PART 1. EFFECT OF ORGANIC ACID TREATMENT 0N UNPROTECTED RYE FORAGE INTRODUCTION .......................... 31 MATERIALS AND METHODS ...................... 32 Trial I ........................... 32 Trial II .......................... 34 Trial III .......................... 34 Trial IV .......................... 35 RESULTS AND DISCUSSION ..................... 37 Trial I ........................... 37 Forage Temperatures and DM Preservation ......... 37 Characteristics of Fermentation on Acid Treatment. . . . 40 Changes in pH .................... 40 Organic Acids .................... 41 Correlations .................... 44 Influence of Acid Treatment on Nitrogen Content of Forages ...................... 45 iv TABLE OF CONTENTS (cont.) Page Acceptability of Acid Treated Rye Forage ........ 46 Trial 11 ................. ' ......... 47 Effect of Acid Treatment on Forage Temperature and Time of Spoilage ................... 47 Characteristics of Fermentation on Acid Treatment. . . . 49 Changes in pH .................... 49 Volatile Fatty Acid Concentrations ......... 50 Lactic Acid ..................... 51 Formic Acid ................... . . 51 Effect of Acid Treatment on Nitrogen Content ...... 52 Acceptance of Acid Treated Rye Forages ......... 53 Trial III .......................... 53 Changes in Temperature, 0M Recovery and Spoilage . . . . 54 Fermentation Characteristics .............. 56 Changes in pH .................... 56 Organic Acids .................... 58 Nitrogen, ADF and ADF-N ................. 60 ADF ......................... 61 ADF-N ........................ 62 Trial IV .......................... 63 Milk Production, Persistency and Milk Composition as Affected by Formic Acid Treatment of Rye Silage. . . . 63 Effect of Formic Acid Treatment on Nitrogen Content of the Silages .................... 65 TABLE OF CONTENTS (cont.) Page PART 2. EFFECT OF ACID TREATMENT ON THE PRESERVATION 0F UNPROTECTED CORN FORAGE INTRODUCTION .......................... 97 MATERIALS AND METHODS ...................... 98 Trial I ........................... 98 Trial II .......................... 99 RESULTS AND DISCUSSION ..................... 100 Trial I ........................... 100 Temperature and Amount of Spoilage ........... 100 Fermentation Characteristics .............. 102 Organic Acids .................... 103 Protein and NPN Content of Corn Forages ......... 105 Acceptability of Corn Forage .............. 106 Trial II .......................... 107 Temperature and Amount of Spoilage ........... 107 PART 3. PERIPHERAL PRESERVATION 0F SILAGES INTRODUCTION .......................... 120 MATERIALS AND METHODS ...................... 121 Trial I ........................... 121 Trial II .......................... 121 TABLE OF CONTENTS (cont.) Page RESULTS AND DISCUSSION ..................... 123 Trial I ........................... 123 Trial 11 .......................... 126 PART 4. EFFECT OF ORGANIC ACID TREATMENT 0N HMEC WITH AND WITHOUT UREA INTRODUCTION .......................... 131 MATERIALS AND METHODS ...................... 132 Trial I ........................... 132 Trial 11 .......................... 133 RESULTS AND DISCUSSION ..................... 134 Trial I ....................... . . . . 134 Trial II .......................... 136 SUMMARY AND CONCLUSIONS ..................... 143 BIBLIOGRAPHY .......................... 149 APPENDIX ............................ 157 vii Table 10. 11. 12. LIST OF TABLES EXPERIMENTAL TREATMENTS FOR RYE FORAGE. PART 1, TRIAL II ........................ EXPERIMENTAL TREATMENTS FOR RYE FORAGE. PART I, TRIAL III ....................... EFFECT OF ACID TREATMENT ON RYE FORAGE TEMPERATURES (PART 1, TRIAL I) ................... EFFECT OF ACID TREATMENT ON RYE FORAGE PH (PART 1, TRIAL I) ........................ EFFECT OF ACID TREATMENT ON VFA AND FORMIC ACID CONTENT OF RYE FORAGE (PART 1, TRIAL I) ........ EFFECT OF ACID TREATMENT ON LACTIC ACID CONTENT OF RYE FORAGE (PART 1, TRIAL I) .............. EFFECT OF ACID TREATMENT ON CRUDE PROTEIN CONTENT OF RYE FORAGE (PART 1, TRIAL I) .............. EFFECT OF ACID TREATMENT ON NPN CONTENT OF RYE FORAGE (PART 1, TRIAL I) ................... EFFECT OF ACID TREATMENT ON ON OF RYE FORAGE (PART 1, TRIAL I) ........................ EFFECT OF ACID TREATMENT 0N FORAGE TEMPERATURE AND TIME OF SPOILAGE (PART 1, TRIAL II) .......... EFFECT OF ACID TREATMENT ON pH OF FORAGES (PART 1, TRIAL II) ....................... EFFECT OF ACID TREATMENT ON ACETIC ACID CONCENTRATIONS (PART 1, TRIAL II) ................... viii Page 67 68 69 69 7O 70 71 71 72 73 73 74 1a LIST OF TABLES (cont.) Table 13. EFFECT OF ACID TREATMENT ON PROPIONIC ACID CONCENTRATIONS (PART 1, TRIAL II) ........... 14. EFFECT OF ACID TREATMENT ON BUTYRIC ACID CONCENTRATIONS (PART 1, TRIAL II) ........... 15. EFFECT OF ACID TREATMENT ON LACTIC ACID CONCENTRATIONS (PART 1, TRIAL II) ................... 16. FORMIC ACID CONTENT AND RECOVERY (PART 1, TRIAL II) . . . 17. EFFECT OF ACID TREATMENT ON DM CONTENT OF THE FORAGES (PART 1, TRIAL II) ................... 18. EFFECT OF ACID TREATMENT ON CRUDE PROTEIN (PART 1, TRIAL II) ....................... 19. EFFECT OF ACID TREATMENT ON NPN CONTENT (PART 1, TRIAL II) ....................... 20. DRY MATTER CONTENT OF RYE FORAGES (PART 1, TRIAL III) . . 21. EFFECT OF ACID TREATMENT AND PACKING ON TEMPERATURE AND TIME OF SPOILAGE (PART 1, TRIAL III) ........ 22. EFFECT OF ACID TREATMENT AND PACKING ON ON RECOVERY AND INVISIBLE LOSSES OF RYE FORAGES (PART 1, TRIAL III) . . 23. EFFECT OF ACID TREATMENT AND PACKING ON pH OF RYE FORAGE (PART 1, TRIAL III) ............... 24. EFFECT OF ACID TREATMENT AND PACKING ON ACETIC ACID CONCENTRATIONS OF RYE FORAGE (PART 1, TRIAL III). . . . 25. EFFECT OF ACID TREATMENT AND PACKING ON PROPIONIC ACID CONCENTRATIONS OF RYE FORAGE (PART 1, TRIAL III). . . . 26. EFFECT OF ACID TREATMENT AND PACKING ON BUTYRIC ACID CONCENTRATIONS OF RYE FORAGE (PART 1, TRIAL III). . . . 27. EFFECT OF ACID TREATMENT AND PACKING ON LACTIC ACID CONCENTRATIONS OF RYE FORAGE (PART 1, TRIAL III). . . . ix Page 74 75 75 76 76 77 77 78 79 80 80 81 81 82 82 LIST OF TABLES (cont.) Table 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. EFFECT OF ACID TREATMENT AND PACKING ON FORMIC ACID CONTENT AND RECOVERY IN RYE FORAGE (PART I, TRIAL III). EFFECT OF ACID TREATMENT AND PACKING ON TOTAL NITROGEN CONTENT OF RYE FORAGE (PART 1, TRIAL III) ....... EFFECT OF ACID TREATMENT AND PACKING ON NPN CONTENT OF RYE FORAGE (PART 1, TRIAL III) ........... EFFECT OF ACID TREATMENT AND PACKING ON ADF CONTENT OF RYE FORAGE (PART 1, TRIAL III) ........... EFFECT OF ACID TREATMENT AND PACKING ON ADF-N OF RYE FORAGE (PART 1, TRIAL III) ............... MILK PRODUCTION PERSISTENCY AND MILK COMPOSITION ON THE DIFFERENT SILAGES (PART 1, TRIAL IV) .......... DRY MATTER CONTENT AND CONSUMPTION OF SILAGES AND CONCENTRATE (PART 1, TRIAL IV) ............. AVERAGE NITROGEN AND NPN CONTENT OF THE SILAGES (PART 1, TRIAL IV) ................... EXPERIMENTAL TREATMENTS FOR CORN FORAGE (PART 2, TRIAL II) ....................... DRY MATTER, TEMPERATURE CHANGES, TIME AND AMOUNT OF SPOILAGE OF UNPROTECTED CORN FORAGE AS AFFECTED BY ACID TREATMENT (PART 2, TRIAL I) ............ EFFECT OF ACID TREATMENT ON CORN FORAGE pH, VFA AND LACTIC ACID CONCENTRATIONS (PART 2, TRIAL I) ...... ORGANIC ACID RECOVERY ON THE UNPROTECTED CORN FORAGE TREATMENTS SIX WEEKS AFTER TREATMENT (PART 2, TRIAL I). EFFECT OF ACID TREATMENT OF CORN FORAGE ON CRUDE PROTEIN AND NPN CONTENTS (PART 2, TRIAL I) ....... EFFECT OF ACID TREATMENT ON ON INTAKE AND TEMPERATURE DURING THE ACCEPTABILITY TRIAL (PART 2, TRIAL I). . . . X Page 83 83 84 85 86 87 87 88 110 112 113 114 114 115 LIST OF TABLES (cont.) Table Page 42. EFFECT OF DIFFERENT ACID TREATMENTS 0N TEMPERATURE CHANGES AND TIME OF SPOILAGE (PART 2, TRIAL II) . . . . 116 43. EFFECT OF ACID TREATMENT 0N AMOUNT OF SPOILAGE (PART 3, TRIAL I) ................... 129 44. PERIPHERAL TREATMENT OF SILAGES (PART 3, TRIAL I) . . . . 129 45. PERIPHERAL TREATMENT OF BUNKER SILOS WITH ORGANIC ACIDS (PART 3, TRIAL II) ................... 130 46. DRY MATTER, NITROGEN, NPN, pH AND LACTIC ACID CONCENTRATIONS OF HMEC AS INFLUENCED BY ACID OR NPN TREATMENT (PART 4, TRIAL I) .............. 139 47. MILK PRODUCTION, PERSISTENCY, BUTTERFAT AND FEED INTAKE 0F COWS FED VARIOUS HMEC TREATMENTS (PART 4, TRIAL I) . 139 48. CHEMICAL COMPOSITION OF HMEC TREATED WITH NPN AND ORGANIC ACIDS (PART 4, TRIAL II) ............ 140 49. MILK PRODUCTION AND PERSISTENCY, MILK COMPOSITION AND FEED INTAKE 0F COWS FED VARIOUS HMEC TREATMENTS (PART 4, TRIAL II) ................... 141 50. TEMPERATURES OF HMEC TREATED WITH NPN AND ORGANIC ACIDS (PART 4, TRIAL II) ................... 142 xi LIST OF FIGURES Figure Page 1. The Effect of Acid Treatment on Rye Forage Temperature (Part 1, Trial I) ............. 89 2. The Effect of Acid Treatment on Rye Forage pH (Part 1, Trial 1) ................... 91 3. Temperatures of Packed Rye Forages Treated With Varying Levels of Formic (F) or Propionic (P) Acids (Part 1, Trial III) .................. 93 4. Changes in pH of Packed Rye Forages Treated With Varying Levels of Formic (F) or Propionic (P) Acids (Part 1, Trial III) .................. 95 5. Relationship of Acid Level and Type to Days After Harvest Spoilage Was First Detected .......... 118 xii PM of CES onl Sc. INTRODUCTION Roughages play a predominant role in dairy cattle rations, primarily because they are recognized as the most economical sources of energy. In areas where hay curing is difficult and losses are high, silage offers a method to overcome these problems. The pro- cesses which convert fresh forages to silage can, at best, preserve only what is already there. The voluntary intake and the nutritive contribution a forage makes towards meeting the animal needs is related to certain factors of management, composition of the forage, the efficiency with which the animal uses the ingested nutrients and the environment. The farmer must consider the various aspects of production, harvesting, storage and feeding which may influence the value of his silage. In developing countries the farmers usually Operate on small scale and therefore good storage facilities are not used in order to reduce the cost of Operation thus resulting in more feed loss. While in the developed countries, where farming is a large scale business, the farmer uses the best available storage facilities but still has Peripheral losses in upright and bunker silos. In addition, some farTners desire to make more silage than their facilities hold. This 1 material is often left under minimally protected conditions resulting in tremendous spoilage. The objectives of these studies were to examine the possibil- ities of preserving silages with organic acids with minimal storage protection and to determine which level and combination of these acids are most effective; also, to determine the acceptability of such silages by the ruminant animal. I! 'C_’_ (I) REVIEW OF LITERATURE Many factors influence the nutritive value and the degree of preservation of stored forages and grains. Some of the factors that are of great importance in making good quality silages are: l. The state of maturity and moisture level of the plant at ensiling time. 2. The effect of oxidation and temperature on silage preserva- tion. 3. Silage additives. In this review, information and publications related to these factors will be discussed. Stage of Maturity and Moisture Level Of The Plant At Ensiling Time Egrn Silage The maturity of the plant at harvesting is one of the major factors that influences the production of good quality silages. 3 Noller gt_gl, (1963) found that milk stage had a slightly higher dry matter (DM) digestibility (72%) compared to the very early dent (70%) and late dent (69%) stages. They also observed that the voluntary intake by heifers was 20-30% higher for the two more mature stages. Byers and Ormiston (1964) found that the DM yields of silage/acre was 6.97 tons for the control (31.5% ON) and 6.21 tons for the mature (54.9% ON). The DM consumption and digestibility were 16.1 vs 16.6 kg and 62.7 vs 56.7% for the control and mature silages, re- Spectively. Similar results were obtained by Bryant gt_gl, (1965) who found that milk production and persistency, DM digestibility and consumption were higher for the mature corn harvested at the hard dough stage (31.8% ON) than for the corn harvested at milk stage (21.7% DM). Results obtained by Huber gt_al, (1965) indicated no signifi- cant differences in milk composition, body weight gains, efficiency of milk production or total digestible nutrient (TDN) content of silages harvested at soft (25.4% ON), medium (30.3% ON), and hard dough stages (33.3% ON); while milk yields and DM intakes increased significantly with DM content of the silage. When corn was harvested at late stage (58-63% DM), Gordon gt_gl, (1968) found that the DM yields were 19-27% less than that harvested at early stage (26-30% DM), and that the digestibility of DM and acid detergent fiber (ADF) were lower in the mature silage. In addition, they observed that early silage had more VFA and lactic acid and that the late silage had a tendency to heat when fed in hot weather. In contrast to most of the previous reports, Perry et_gl: (1968) said that the corn plant if stored in gas-tight silos, may be harvested at a much later stage than at hard dough which has been recommended by other workers. They also reported that the digesti- bility of the product (75-73%) remained quite constant regardless of the harvest date, even though the stalks and leaves had been exposed to a relatively long period of weathering following maturity. The acceptability of the silage remained about the same in one experiment but declined in the second. In comparison, Coppock (1969) reported that corn harvested for silage over a broad range in maturity exhibited little change in DM digestibility but an increase in DM intake occurred through the range of 25-35% DM. McCullough (1971) found that corn crop was least affected by maturity and grasses and legumes the most affected because in corn 50% or more of the total nutrients in the silage were in the ear. The date of harvest had no significant effect on the percent crude protein or ether extract according to Caldwell and Perry (1971) but found that these were positively correlated with crude fiber, nitrogen free extract (NFE) and ash. They also observed that a maximum yield/hectare occurred at the time when plant con- tained 33% DM. [m LDpez gt_al, (1970) reported greater pH values for corn silages with low (25%) or high (52%) 0M than with medium (30%) DM when the corn was harvested at the different stages of maturity and treated with urea or soybean meal and ensiled in small plastic silos stored under controlled temperatures. A significant decline in lactic acid concentration was observed with advance in maturity and that total organic acid concentration declined from 11.94% of ON in low DM samples to 3.14% of BM in high DM silage. They also observed a higher VFA concentration with lower nitrogen supplementation. Sorghum Silage Nehring and Laube (1958) found little effect of maturity at harvest on digestibility or sorghum harvested between flower and milk stage. A decline in the digestibility of crude fiber, NFE, and pro- tein with maturation of Tracy sorghum from the milk to the mature stages was reported by Helm and Leighton (1960) who found that the highest TDN (65%) was at the soft dough stage. Mississippi studies (Browning and Lusk, 1965) revealed no significant differences in DM or energy digestibility for Tracy sorghum harvested from the late flowering to the ripe seed stage. The deterioration in quality of forage sorghums with advanc- ing maturity may be explained, in part, by results of Thurman et_gl, (1960), who found that increased yields with advancing maturity were man so? (28 foul Cl'ei di‘ 851a of | her it manifested mainly in higher yields of stalks. They also observed that the percent of heads, blades and sheaths decreased with yield. When Atlas sorghum silages were harvested at milk (21% DM), soft dough (24% 0M), hard dough (26.5% ON) and mature stages (28.2% ON) and compared as roughages for lactating cows, Owen (1962) found that consumption of 0M increased and FCM/lb. of DM intake de- creased with advancing maturity. He also observed that the consump- tion of silage (as fed), milk fat percent and body weight changes were not significantly affected by maturity at harvest. Because the differences found in quality of the silage OM favoring early-cut silage appear insufficient to compensate for the usual yield advantage of harvesting sorghum after reaching maturity, he recommended to harvest sorghum when acreage yields are near maximum. This is usually at the hard seed stage. Rye Silage When Italian rye grass was wilted and ensiled at 34 and 47% DM or ensiled as fresh grass 15.9% ON, McDonald gt_91: (1968) found that the DM losses from wilted silages were low and ranged from 6.7-10.4%. The researchers observed that the residual amounts of sugars in the wilted silages were directly related to the degree of wilting and that little fermentation occurred in material of 47% DM. Barley Silage Polan gt_§l, (1968) harvested barley at three stages of ma- turity (bloom, milk and dough) and found that DM content increased (P < .05) with stages of growth, but DM yields increased signifi- cantly between bloom and milk stage only. The dough stage was lower in crude fiber and higher in NFE than milk or bloom, but there was little change in protein content. The barley ensiled at these 3 stages was fed as the sole source of roughage to lactating cows. Milk production was similar for the 3 treatments. Silage 0M intake was least (P < .01) for bloom silage and resulted in lowest (P < .05) body weight gains. In digestibility trials DM and NFE were least (P < .05) digestible for the dough silage. Crude fiber digestibility was highest (P < .01) at bloom. Cows fed milk stage silages exhibited lowest rumen acetate and highest propionate. Wheat Silage McCullough and Sisk (1967) fed wheat silages harvested at early heading, milk and dough stages to dairy heifers as the only feed and found that intake of the early cut silage was superior to the late cut. Crude protein was highest and crude fiber, cellulose and NFE were lowest for the early cut silage. They added that the superiority of early cut silage was retained when 20, 35, and 50% of the silage DM was replaced with a grain mixture. Oat Silage Martz gt_al, (1959) compared oat silages harvested at boot (21% DM), early milk (23.5% ON) and soft dough (29.9% ON) as a source of roughage for lactating cows to supply about 86-88% of the total forage DM intake. Dry matter intake of the soft dough was highest but the TDN intake was highest at boot. Milk production was corre- lated with TDN intake of the silages. The authors concluded that the Optimum stage to ensile oats was at the boot stage or soon thereafter. Alfalfa Silage When the moisture level of alfalfa haylage was reduced from 53 to 35% Owen and Senel (1963) observed a decrease in pr0pionic and butyric acids from 1.7 and 1.3%, respectively, to unmeasurably small amounts. Acetic acid levels averaged about the same (1.6%) while lactic acid was reduced to 1.8% or just one half the level in the hay- lage of higher moisture content. They concluded that the lower acid content and higher pH of low moisture haylage was an indication of a decrease in the amount of fermentation. 10 Gordon gt_al, (1965) ensiled alfalfa from 39 to 65% DM and found that high 0M levels resulted in less fermentation. They also observed higher DM intakes with increasing levels of DM but this re- sponse was less consistent above 50%. They did not find marked dif- ferences in milk production or DM digestibility and concluded that for storage in conventional silos, more than 50% DM was neither de- sirable nor harmful. Gordon (1968) showed that protein digestibilities were sub- stantially reduced in haylages ensiled at high DM levels (55%) re- gardless of the type of storage used. Roffler g__gl, (1967) reported that Alfalfa-Brome forage preserved as hay was lower in protein, ether extract, and ash than that preserved as low moisture silage or wilted silage. Ammoniacal nitrogen constituted a greater proportion of the total nitrogen in wilted than in low-moisture silage. Sutton and Vetter (1968) found that the OM and nitrogen digestibilities of Alfalfa hay (92% 0M) were significantly higher than that of alfalfa haylage (60% DM) and silage (28% DM) and that the digestibility of silage nitrogen was significantly higher than that of haylage. 11 The Effect of Temperature and Oxidation 0n Silage Quality Oxidation occurs for a short period just after ensiling in well packed or gas-tight silos. Temperatures rise slowly to a peak, are constant for some time and then drop to a level corresponding to ambient temperatures. The degree of oxidation and the amount of heat produced are closely correlated. Thus, temperature rises are often a good indication of the degree of spoilage that occurred in the silage. According to Barnett and Duncan (1954) poor quality silages are high in VFA content and low in lactic acid. To prevent the forma- tion of butyric acid they recommended compressing the mass to make it more air-tight. Wieringa gt_gl, (1961) reported that temperature was of great importance in influencing the different kinds of microaorganisms which dominate the fermentation and is associated with the amount of proteolysis and subsequent ammonia production. They also stated that the presence of oxygen resulted in a faster loss of soluble sugars because respiration in silages continues for a longer time. They added that at temperatures above 40 C, oxygen was reSponsible for the fixation of protein into undigestible compounds and that under farm conditions the highest percent of butyric acid and NH3 were found in silages with a maximum temperature of 40-50 C. Their recommendation was that temperature of the silages must be kept 12 below 30 C to prevent putrefaction and/or fixation of indigestible protein. Langston gt_gl, (1962) showed that aerated silages had high temperatures and pH values with increased butyric acid and NH -N; 3 whereas, lactic acid concentrations were depressed. They also ob- served that total acids were higher in sealed than aerated silages which suggested to them that some of the substrate initially present was destroyed as a result of aeration. Therefore, high levels of sugars did not insure silage of superior quality unless the forage was properly packed to exclude air. Zimmer and Gordon (1964) used laboratory silos (jars) which were sealed continuously for 38 days or sealed with the exception of aeration on the first, second, third, and sixth day. They reported that oxygen consumption was greatest for unwilted-chopped silage during the first and second days of aeration. Grinding the material improved total preservation and reduced CO and DM losses. Improve- 2 ment of fermentation was indicated by lesser amounts of NH3 and butyric acid and greater amounts of lactic acid. A correlation co- efficient of +0.71 was observed between CO2 production and DM losses, so they concluded that aeration resulted in poor preservation of the silage. Honig (1969) conducted gas balance tests with silages. He found that DM losses increased linearly with the amount of added air, l3 and observed losses as high as 2% of DM per month of storage. He also reported that the digestibility of nutrients as well as the quality and stability of silages decreased with increased air. He recommended air tightness of silos because of its economical impor- tance in preventing 0M losses. With insulated silos Federson (1971) found that oxidation was accompanied by a large rise in temperature and high DM losses in high moisture silages. Temperature increases in the silos without oxygen present were negligible. He observed that the pH closely paralleled the added oxygen supply. These data agree with those of Honig (1969); that the loss in DM rose almost linearly with an increased oxygen supply. Pierson gt El: (1971) reported that digestible protein was lost when haylage heated during the ensiling process. They reasoned that heating caused the protein to react with other materials in the plant to make part of the protein indigestible by animals. Van Soest (1965) showed that exposing feed samples to high temperatures caused an increase in the apparent lignin content when analyzed by the sulfuric acid method. The analysis of this artifact lignin fraction showed that it contained a high percent of nitrogen. He suggested that the nitrogen content of the ligno-cellulose frac- tion might estimate the amount of compositional change due to heat damage. dul C61 th; grl 83 LT (u 0|” 14 Thomas and Hillman (1972) reported that excessive heating during the curing process of haylage, baled hay or stacked hay caused carmelization to occur between plant proteins, sugar and water result- ing in product which was insoluble and indigestible. They concluded that the carmelization effect was small but measurable at 46 C, greater at 51.7 C, and protein digestibility was markedly reduced at 57 C. Silage Additives At the present time there are many additives that could be used on silages in order to increase their protein content or to change the pattern of fermentation. This review will cover the in— fluence of organic acids, and their effect on the fermentation pattern, preservation of silage and the performance of the animal. Addition of Acids to Ruminants When 400 Cal. of acetic acid, pr0pionic or n-butyric or 800 Cal. as n-butyric were administered to sheep with positive energy balance, Armstrong and Blaxter (1957) found that the acid administra- tion did not interfere with the normal process of rumen fermentation or impose non-physiological conditions upon the animals. They added de 15 that the energy retained when the acids were given was partly stored as protein, but mainly as fat. After the administration of 0.5-1.5 kg sodium acetate per day to cows on fat depressing diets an appreciable improvement in milk fat percentage was reported by Balch and Rowland (1959) while the administration of 414 g sodium propionate under the same condi- tions did not restore the fat percent. They also observed that on normal diets the administration of 500 g sodium acetate did not af- fect the milk fat content. With continuous infusion techniques Rook and Balch (1961) found that acetic acid caused an increase in milk yield, and yields of fat, lactose and protein and a specific increase in fat percentage. The infusion of propionic acid and butyric acid had no effect on yield of milk, but propionic acid specifically de- creased the yield and percentage of fat and increased the yields and percent of protein, SNF; as where butyric acid infusion increased the yield and percent of fat. In addition to the previous study Rook 33 al. (1965) reported similar findings with other infusions, but when acids were given in combination, effects on fat content were additive. They also observed that formic acid infusions were without significant effect on milk yield and composition. Montgomery and Baumgardt (1963) reported that lactic acid was converted to butyric acid in the rumen when 700 kg cows on an all-hay diet were infused over a 4 hour period with 340 g lactic acid which 16 had been diluted to four liters with water. In another study, Montgomery gt El: (1963) found a significant decrease in hay con- sumption with acetic acid infusion while the infusion of pr0pionic, butyric and lactic acids caused a moderate decrease in voluntary hay intake. Because no change in cellulose digestion occurred they concluded that the acids had little effect on rumen micro-organisms. Ulyatt (1965) found that feed intake decreased significantly in sheep given acetic acid at a dose rate of 200 Cal. on low and high planes of nutrition, but the decrease was more pronounced on the low plane. An increase in intake was observed with 200 Cal. of propionic acid on both planes of nutrition but 300 Cal. pr0pionic depressed intake at the low level of nutrition. Vercoe and Blaxter (1965) infused formic acid into sheep on dried grass diets at a constant rate for 17 days and found that methane (CH4) and CO production increased but there was no signifi- 2 cant change in 0 consumption. Rapid infusions of sodium formate 2 resulted in smaller increases in CH4 production with a depression in 0 consumption and CO production. They concluded that rapid infus- 2 2 ion of formic acid depressed overall metabolism, probably by inter- ference with micro-organisms other than those concerned with methanogenesis. Simkins gt_gl, (1965) reported that when VFA mixtures (60 acetic, 20 pr0pionic, 20 butyric) were infused into cows on pelleted pr l 3:- I ‘1‘ 17 alfalfa hay diet to meet 15% of the estimated digestible energy requirement, consumption of pelleted ration decreased significantly. A significant decrease in hay consumption was also observed when pr0pionic and butyric acids were infused. They concluded that VFA's can act as satiety signal compounds in affecting food intake. McCullough (1971) reported an improvement in milk production and butterfat percent when acetic acid was infused into the rumen. This finding led him to conclude that rumen fermentation may be a limiting factor for milk production in certain cows. VFA and Lactic Acid Addition to Rations Bentley gt_gl, (1956) reported that the addition of sodium salts of acetic, pr0pionic and lactic acids to corn-cerelose-urea-hay or corn-hay rations produced significant increases in gains of lambs fed to about 45 kg body weight. The apparent feed replacement values were calculated at 1 kg of the acid salt for 3-10 kg of feed. In their first study Senel and Owen (1966) reported a signif- icant increase in DM intake when lactate and acetate were added to a basal ration in a 3 to 1 ratio at 11.8% of the ON. The basal ration consisted of 67% sorghum silage, with the remaining 33% a mixture of beet pulp and soybean oil meal. In a second study (1967), no change 18 in voluntary intake was observed with 2% acetic or 1% butyric acids added singly or in combination; but intake was reduced when the acid levels were doubled. They concluded that depression in DM consump- tion and lower rates of gain which often result from feeding silage rations compared to hay are due to a factor(s) other than the acetate and lactate contributed by the silages. Formic Acid Treatment of Silages Waldo gt_gl: (1966) reported that when unwilted orchard—grass silage preserved with 0.5% formic acid was fed to heifers as the sole ration, daily gains were higher (851 vs 744 9) than on hay. Heifers on hay ate more dry matter, but digestibility of the silage was higher at either restricted or ad libitum feeding. A 17% improvement in the apparent digestible energy resulted from formic acid treatment. When unwilted alfalfa was treated with 0.5% formic acid significantly higher daily gains were observed by Waldo §t_gl, (1968) in heifers fed acid treated silage compared to controls. In another study Waldo gt 31, (1966) found that animals fed unwilted silages treated with formic acid consumed more digestible energy, gained more weight and used the digestible energy more efficiently on a net or gross basis. The formic acid silages were lower in pH, butyric and acetic acids, ammoniacal nitrogen, and higher in lactic acid. In a study 19 using sorghum and alfalfa silages Waldo gt_gl, (1969) recovered less DM for the untreated silage compared to the formic acid silage. They also observed that the treated silage contained less cellulose than the untreated silage and that the animals consuming control alfalfa silage required 1.4 times as much digestible energy/unit gain as those fed the acid treated silage. In another study compar- ing formic to control silages, Waldo gt_gl, (1971) reported that digestible energy intake above maintenance per unit gain was less and that gain per metric ton of OM was higher for treated silages (122 vs 80 kg). A better recovery of energy from the silo was also observed for treated compared to control silages (91.9 vs 85.6%). Derbyshire and Gordon (1969, 1970) and Derbyshire gt_gl, (1971) found that alfalfa orchardgrass wilted and treated with 1.17% formic acid, or orchardgrass silages treated with 1.1% formic acid on a 0M basis had significantly lower ADF, lignin, cellulose, pH values, NH3-N as percent of total nitrogen. Also the treated silages had lower acetic and lactic acids than untreated silages. They sug- gested that direct acidification by the formic acid inhibited many of the biochemical changes noted in untreated silages. Silage treatment had no significant effect on average milk production, per- cent butterfat and percent SNF even though milk yields for cows receiving treated silages were slightly higher. Heifers gained more lveight on the formic acid treated silages. In another experiment 61 Or am 20 wilted silage was treated with 0.8% formic acid and direct cut silage with 0.5% resulting in a marked improvement in DM recovery of the wilted forage and increased OM digestibility of both silages treated with acid. A slight depression in percent of butterfat was observed for the formic treatment. Addition of formic acid to wilted forage improved feed efficiencies 34% in growing heifers. Because of the compounding effect of concentrate feeding and body energy changes a similar increase in efficiency was not demonstrated with milking cows. In fermentation studies with lucerne, Carpintero gt_gl, (1969) used formic acid at 0.85% and found that this level was sufficient to achieve an immediate pH fall to 4.2. The formic acid inhibited both lactic acid and clostridial activities. They also observed that water soluble carbohydrates (WSC) were preserved and suggested a beneficial effect on ruminants. Wilkins and Wilson (1969) added formic acid at the rate of one half gallon per ton to grass silage and found that the pH dropped immediately to about 4.4 with little change during the first 6-12 days in the silo. Lactic acid in the treated silage was low; but for crops high in WSC, such as rye grass, these workers suggested that the lactic acid content would be comparable to untreated silages. However, Huber (1970) showed a greater depression in lactic acid content of corn silage, which is usually high in WSC, due to formic acid treatment than has usually been reported for other crops. No 21 change in the digestibility of the silage was observed but mean intakes were higher for the fonnic silages (Wilkins and Wilson, 1969). Castle and Watson (1970) harvested Timothy and perennial rye grasses at about 17-20% OM for treatment with 1/2 gallon/ton of formic acid. The silages were vacuum packed and temperatures were recorded. They found that formic acid treatments had about 7-15 C lower temperature rises than the control and that the max- imum temperature recorded occurred about one week after the silos had been filled. Lactic acid was higher and butyric lower in treated silages indicating that formic acid improved the type of silage fermentation. Acid treatment increased digestibility and OM intakes (ll-12%). In another study (Castle and Watson, 1970), unwilted or wilted herbage was treated with formic acid. Digesti- bility and total soluble sugar content of the wilted herbage which was treated were lower than for the unwilted-treated or the unwilted- control silages. Treatment resulted in increased OM intakes and decreased milk production. The significant increases observed in the SNF and protein contents of milk were related to higher energy intakes on treated silages. The authors concluded that wilting of silages did not have the same beneficial effects as did formic acid treatment. 22 Fisher gt_gl, (1971) found that milk yields were signifi- cantly higher on silages made from direct cut sorghum-sudangrass treated with 0.5% formic acid as compared to wilted silages without formic acid. The acid-treated silage had lower fiber and energy digestibility but efficiency of energy utilization for milk produc- tion plus body gain was greater (P < .05). Henderson and McDonald (1971) studied the effect of formic acid on the fermentation of grass of low OM content (11.8-17.3% 0M) and found that the acid prevented oxidation of WSC in a short period (4 hrs), thereby preserving more sugar for fermentation. Formic treatment also had an inhibitory effect on proteolytic clostridia; therefore less proteolysis occurred. They concluded that formic acid treatment of low OM silages decreased the formation of lactic acid and volatile nitrogen when used at high levels (0.34% and higher), but increased the production of ethanol and restricted the breakdown of lactic acid to butyric acid. Taylor and Philips (1970) reported that total aerobic counts in silage treated with formic acid (1/2 gallon/ton) were lower than those in the untreated silages and a similar trend was observed with lactobacillus counts. They also found that the anaerobic proteolytic count was depressed markedly by the addition of formic acid, but the anaerobic lactate fermenters and the thermophilic counts were higher in the acid treated than in the control silage. They concluded that 23 the addition of formic acid to silages provided suitable conditions for the growth of desirable organisms and the suppressed undesirable ones which resulted in an improvement in the silage quality. Saue and Breirem (1969) reported an 80-90% OM recovery in grass treated with formic acid (0.33 liters/100 kg). At 30 hours after ensiling higher temperatures (64 vs 30 C) and sugar losses (68 vs 13%) were observed on the control silage compared to formic acid silage. They also observed that formic treatment limited respiration (3.2 vs 6.4 g of C02/100 9 ON), decreased undesirable fermentation caused by Coli-Aerogenes, and depressed breakdown of protein as suggested by low NH3 levels. They concluded that the preservative effect of formic acid was directly related to its hydrogen ion concentration, and that it is less bactericidal for lactic acid fermenters than for undesirable organisms. In another study the same two authors found that feeding formic acid silage increased milk yields above those in cows fed hay as the only rough- age. Because no differences in efficiency of energy utilization were observed when comparing hay and silage in the rations they reasoned that milk stimulation was due to a chemical rather than an energy effect. 24 High Moisture Corn Under current conditions feeding high moisture corn (HMC) is probably one of the most economical and efficient ways of using grain in cattle rations. High moisture corn can be harvested as soon as the kernel reaches physiological maturity. Therefore harvesting can commence 2-3 weeks earlier than usual without the expense of artifi- cially drying. In addition, early harvest may permit greater utili- zation of corn stalks. Another major benefit of HMC is a reduction in harvesting losses. Handling Operations are also decreased; since once the product is in storage, no further processing is needed before feeding. Feeding_Value of HMC The results of two trials by Beeson and Perry (1958) indi- cated that fattening beef cattle utilized high moisture ground ear corn (32% moisture) from 10-15% more efficiently than regular ground ear corn when grains were adjusted to the same moisture. Iowa researchers (Burroughs, 1971) also found that when corn was harvested and stored at 24-30% moisture, the feeding value of the grain OM was increased by 4-9% above that of artificially dried corn. No differences were observed in OM intake between steers on HMC and those on grain ration. Zogg §t_gl, (1961) examined the 25 nutritive value of HMC fed with various silages and found that the efficiency of utilization of the OM Of the HMC increased as the mois- ture content of the corn increased from 22 to 32%. In contrast, Bridson (1972) compared dry corn with HMC in rations with low rough- age levels (10% Or less of diet OM) and found that dry grain was better for rate of gain. However, HMC resulted in superior animal performance when fed with high roughage levels (20% or more of diet OM). In trials to evaluate HMC as the primary source of concen- trate energy for dairy cows, McCaffree and Merril (1968) found that high moisture (HM) shelled corn resulted in significantly lower forage OM intake, milk fat percent and total OM intake and signifi- cantly higher milk production than HM ear corn. No differences were observed in TON or grain OM intakes. Barrington and Jorgenson (1971) found that milk production and feed efficiency were similar for HMC and dry corn, but milk fat tests were lowest in the group fed HMC. In contrast, Johnson and Otterby (1971) reported that milk fat de- pression was not a problem in rations containing 33% HMC and that rations containing corn silage and HMC appeared to support lactation. Chemical Changes in HMC Schmutz et_gl, (1962) related nutritive value of HMC ensiled at: 24, 32 and 45% moisture to chemical and bacteriological changes. 26 Lactobacilli and Anaerobes were lOg/ml after 10 days and yeast were ten times higher for the drier corn at 60 days. Acetic acid was highest at 45% moisture. Weight gains increased with lactic acid concentration of HMC which was directly related to moisture content. When dry cracked corn was reconstituted to 20, 25 and 30% moisture and ensiled in quart jars, Sprague and Breniman (1969) ob- served little fermentation at 20% moisture. There were high pH values and low concentrations Of lactic acid and soluble protein. At moisture contents of 25 and 30% the pH was lower than at 20% with more lactic acid and soluble proteins present. They concluded that the minimum moisture content to prevent mold in HMC was 30-35%. Non-Protein Nitrogen and HMC Schmutz et_gl, (1962) found that 50% of the urea added to HMC was degraded to ammonia by 20 days and 80% within 60 days. Outton and Otterby (1971) found that HMC which was supple- mented with urea or diammonium phOSphate and placed in sealed evacu- ated bags for 45-60 days had higher pH values, higher NH3 levels and greater nitrogen losses than control or soybean meal-treated HMC. The HMC treated with urea was highest in acetic and lowest in pro- pionic acid, with low concentrations of lactic acid and ethanol. 27 Acid Treated Grains Grains absorb liquids as a natural phenomenon necessary be- fore germination can take place. Acid is absorbed in a similar way by combining with the grain embryo to prevent growth. Orysdale (1970) estimated losses (not Spoilage) caused by the production of C0 during fermentation in sealed storage to be 2 as high as 5% and found that the loss in value of the feed was almost equivalent to the cost of adding pr0pionic acid to grain which would incur essentially no C02 loss. In addition, the acid-preserved grain was found to keep for a year or more under Open storage conditions. Jones (1970) did not detect heating or mold growth at seven days in samples treated with mixtures of VFA's (14:83:01, 40:40:20; 70 acetic:20 pr0pionic:10 butyric) and placed in unsealed plastic bags, while the controls molded (185,000-62,000 colonies/g) and had an off-odor. A pH of 4.4 or less was found effective in inhibiting mold formation. For 72% OM ear corn this required a 1% level of acid addition. When HMC (66.7% ON) preserved with 1.5% propionic acid was fed to dairy cows and heifers at 4.5 kg/animal daily, Jones et 31. (1970) found that FCM, persistency Of milk production, milk fat and protein percent and rate of gain were not significantly dif- ferent than for animals fed untreated HMC. Slightly higher gains were noted for treated corn even though maximum daily intake of the 28 acid approximated only 68 g/day. In another report Jones (1971) found that either pr0pionic acid or mixtures Of acetic and pr0pionic acid effectively preserved corn grain ranging in moisture content from 28 to 33%. But, HM ground ear corn, at moisture levels within this range heated within several weeks and molded even though it was treated with 1.2% pr0pionic acid. Marion et_gl, (1972) found that steers fed HM grain treated with O, 4, and 6% acetic or pr0pionic acid gained well at the lower levels of acid addition. Gains were higher than controls (P < .05) at 4% and lower (P < .05) at 6% added acid. In another study, pro- pionic acid was added at 2% to dry grain or to grain reconstituted to 30% moisture and stored for 14 days in Open barrels and compared in feeding trials with same untreated grain kept in air tight plastic bags. No significant differences in daily gain, feed intake or feed/kg gain were observed. Treated grain did not heat or mold while the untreated grain did. Bridson (1972) reported that Purdue University researchers found 6% more rapid gains in steers full fed HMC treated with acetic and pr0pionic acids (60:40 ratio) at the 1.5% level compared to dry corn. Feed efficiencies favored the acid treated corn. In compar- ison, Wilson and Long (1972) found a 5% increase in feed efficiency of steers fed HMC treated with 1.6% acetic and pr0pionic acids (60:40) compared to steers fed dry untreated corn. They did not Observe 29 significant differences in the digestibility of the corn but reported that more protein was digested and retained by lambs fed the acid treated corn. The amount of pr0pionic acid required for preservation was found by Miller (1971) to be directly prOportional to the moisture content of the grain. When pr0pionic acid treated grain was fed to yearling steers there was no evidence of lower palatability and no adjustment period was required for feeding the treated corn. For HMC with 25% moisture, Miller (1971) suggested adding 1% pr0pionic acid but 1.25% was needed for material with 30% moisture. When pigs were fed HMC (76% OM) treated with 1.5% propionic acid which was stored in bins Open to air, Young et_gl, (1970) found that the animals gained at a similar rate and had a feed efficiency equal or better than pigs fed dry corn (90% OM). No problems of mold or heating were reported for the acid treated grain. Otterby and Murphy (1971) studied the effectiveness of dif- ferent acids in preventing hydrolysis of urea (at 1%) added to HMC (68% OM) placed in polyethylene bags which were then evacuated and sealed. They found that OM and nitrogen losses were minimal during fermentation. The lactic acid concentrations were lowest on treat- ments made with 1% urea plus 1% acetic acid, 1% acetic acid, and 1% propionic acid. Largest amounts of lactic acid were reported for the control and the 1% urea treatment. 30 It seems that after reviewing most of the available litera- ture on organic acid treatment of silages little is known at the present time about the relative effects of the different acids (formic, acetic and pr0pionic) as silage preservatives. The liter- ature on these acids deals mainly with their influence on feed intake and animal performance with minor information relating their effects on silage recovery. Therefore, a main Objective of this thesis was to supply information on the preservative role of these organic acids under different conditions and at different levels and combi- nations. PART I EFFECT OF ORGANIC ACID TREATMENT ON UNPROTECTED RYE FORAGE INTRODUCTION Better animal performance as measured by intake, feed effi- ciency, and gain in body weight has resulted from feeding formic acid treated silages (Waldo et_§l,, 1966, 1968; Derbyshire and Gordon, 1971; Castle and Watson, 1970). However, little is known at the present time about the relative effectiveness of different organic acids (formic, acetic, and pr0pionic) as silage preserva- tives. Also, no data are available on the effects of these acids as silage preservatives under minimally protected conditions. The objectives Of Part I were to determine which acid or combination of acids was the most effective preservative of material stored under complete aerobic conditions with minimal protection. Also, changes in fermentation and animal performance due to acid treatment were determined. 31 MATERIALS AND METHODS Trial I Four trials were conducted to evaluate the preservative effect of organic acids on unprotected rye forage. In trial I, chopped rye forage harvested at the boot stage was wilted to about 27% OM then transferred into temporary silos (3x1.5m). The silos used were snow fences lined with polyethylene. They held about 3 ton portions of fresh rye forage. The treatments were control; 1% acetic and pro- pionic acids (AP) (60:40 ratio), and 1% formic (F) acid. The acids were diluted 1:1 with water and added at a constant rate to the forage as it went up the hay elevator into the silos. Forage samples were taken immediately before and after treat- ment and then 3 times weekly. The samples were kept frozen at -5 C until analyzed for OM, total nitrogen and NPN according to AOAC (1960). Silage extracts were prepared by homogenizing a 25 gram aliquot of the sample in a Servall Omni-Mixer with 100 ml of dis- tilled water for 1 minute and straining through two layers of cheesecloth. About 20 ml aliquot of the extract was used for deter- mining pH by using a Beckman pH-meter. The remainder of the extract 32 33 was deproteinized using 1 ml of 50% sulfosalicylic acid (SSA) and 9 ml of extract. The sample was then centrifuged at 18,000 rpm for 10 minutes and stored in a refrigerator for later analysis. The VFA content of the silage was determined by injecting samples of the deproteinized silage fluid described above into a Packard gas chromatograph. Formic acid was determined by following same procedure used for VFA but with some modifications made through the use of Packard Detector Power Supply. Colorimetric procedures of Barker and Summerson (1941) were used to determine lactic acid con- tent of the deproteinized sample. Temperature of forages was recorded twice daily by using five thermometers located at different positions in the silos. In addition, Spoilage was recorded when first observed. At the end of 4 weeks, all spoiled material was removed, weighed and sampled for OM determination. The preserved forage was fed in a short accepta- bility trial to four lactating cows per treatment. Cows used, averaged 18 kg of milk/day and weighed about 550 Kg. The trial was for 1 week during which rye forage served as the only roughage. A concentrate mixture was fed at 1 Kg to 3 Kg milk daily. Forage was sampled for analysis three times during the feeding trial. Feed intakes were recorded daily for each animal. 34 Trial II In trial II, rye from the same harvest used in trial I was placed loose in Open 220 liter drums. Portions of about 35 Kg were treated with varying amounts of the acids (Table 1) diluted in water (1:5). Acid was sprinkled on the rye forage which was mixed by roll- ing on polyethylene plastic sheets. The treated material was then transferred into the drums and left unpacked. Forages were sampled as in the previous trial. Also, temperature was recorded twice daily and spoilage was monitored. After 3 weeks the drums were emptied and the unspoiled material was sampled. In two treatments (4 and 7) rye was well-preserved so it was fed to young calves to test accepta- bility. Trial III In trial III, rye forage was cut at late boot and wilted in the field to about 35% OM. It was then chOpped and ensiled in 220 liter drums as described above. The acids used were pr0pionic (P), formic (F), and a mixture of 1:1 (P:F) (Table 2). The acids were diluted 1:1 with water, sprinkled on the rye and mixed as in the previous trial. Two drums were used per treatment. For each acid 35 treatment silage in 2 drums was left loose and two others were packed. In the unpacked drums, 18 Kg occupied the same volume as 36 Kg in packed drums. At the end of every week the packed drums were emptied, aerated and repacked. Samples were taken before and after treatment and at weekly intervals for analysis as described in the two previous trials. In addition, the samples were analyzed for ADF and ADF-N after the method of Van Soest (1967). Tempera- tures were recorded for the first 3 days after ensiling and then every other day thereafter for the first 2 weeks. Days after harvest when mold first appeared was also recorded. Trial IV In trial IV, 21 lactating cows, averaging more than 18 Kg of milk/day were assigned in a randomized block design to three silage treatments. The treatments were control rye silage, rye silage treated with 0.4% formic acid, and alfalfa haylage. Rye silages were of the same cut as used in trials I and II, but ensiled in conventional upright silos. In addition to silages, which were fed ad libitum as the only forages, a concentrate mixture was fed at 1 Kg per 3 Kg milk. The feeding trial was for 7 weeks, the first 2 36 weeks were used as a standardization period. During the experi- mental period, silages were sampled 3 times weekly, composited and frozen for later analysis. Daily silage intake, milk production and persistency, and biweekly milk composition were determined. RESULTS AND DISCUSSION Trial I Forage Temperatures and OM Preservation Temperatures of the untreated forage were higher a few hours after filling than those treated with the AP or formic acid (Table 3 and Figure 1). The control rye increased in temperature until the third week and peaked at 53.9 C; while a peak of less than 40 C was observed during the second week for the acid treated forages. The temperature of the acid treated rye plateaued between the second and third week. Spoilage was first observed on the control treatment at 3 days. This corresponded to an average temperature of about 50 C. The time when spoilage was first observed on the control forage agrees with the findings of Zimmer and Gordon (1964) who reported that 02 consumption was highest during the first and second days of aeration. Also, this finding is in agreement with the observa- tions of Honig (1969) and Federson (1971) who reported that oxida- tion was accompanied by a large rise in temperature and high OM losses. 37 38 The temperatures of the formic acid treatment were slightly higher than the AP for the first 10 days; after which they were slightly lower. Spoilage was Observed on the AP before the formic acid treated forages (9 vs 14 days) which corresponded to tempera- tures of 37.5 C and 39 C, respectively. These observations indicate that acid treatment (1% on a wet basis) delayed oxidation or limited respiration even under completely aerobic conditions. This decrease in respiration could be attributed to the inhibition of the aerobic micro-organisms by the acids. Weiss and Daniel (1970), reported that formic and pr0pionic acids had strong bacteriocidal effects. Thus, the delay in spoilage, the lower heat production and decrease in ON losses could have been due to a decreased number of aerobic organisms resulting from acid treatment. The amount of CO2 produced was not measured but it was probably higher for the control than the acid treatments. Zimmer and Gordon (1964) reported a correlation coeffi- cient Of +0.71 between amounts of OM loss and C02 produced. More OM was preserved on the AP than the formic acid treatment (83 vs 78%), and both acids resulted in higher OM recoveries than the control (57%); which might be related to the higher temperatures ob- served on control silage in the early stages of storage and to the earlier detection of Spoilage. When the average 4 week temperature was correlated with amount of OM Spoiled at the end of the study a correlation coefficient of +0.98 was obtained. This correlation is 39 higher than that obtained by Zimmer and Gordon (1964) for OM and C02 produced. The higher OM recoveries on acid treated forage are in agreement with Waldo et_gl, (1969) who added formic acid to con- ventional silos. However, the amount recovered was somewhat lower than the 80-90% reported by Saue and Breirem (1969). This could be due to the lower OM content and anaerobic storage conditions of their silages; while our forages were unprotected. Also, these findings are in agreement with those of Gordon and Goering (1972) who Observed less mold on 55% OM chopped forage ensiled in snow fences and treated with AP (2.1%) than on untreated forage. Lower counts and less activity of micro-organisms on acid treatment probably resulted in more fermentable carbohydrates which escaped fermentation. This is in general agreement with Taylor and Philips (1970) who found lower aerobic counts after formic acid treatment compared to control treatments; and with Saue and Breirem (1969) who observed higher sugar losses on the control than formic acid treated silages; and to Henderson and McDonald (1971) who found that formic acid prevented the oxidation of WSC for four hours after ensiling, thus preserving sugar for subsequent fermentation. 4O Characteristics Of Fermentation on Acid Treatment Changes in pH The change in pH values during the experimental period are given in Table 4 and Figure 2. The control treatment had a pH of 6.4 at the beginning of the study which then increased to 6.5 by the end of the first week. The pH of the control reached its peak ( 7) by the third week. This peak in pH was parallel to the peak in temperature Observed on this treatment during the same period. The pH values for the acid-treated rye were lower than the control. The lowest pH values were obtained by formic acid treatment due to a stronger acid effect of formic compared to pr0pionic or acetic acids (AP treatment). The pH values were positively correlated (+0.98) to the temperatures observed for the different treatments. Also, a high correlation coefficient (+0.92) was Obtained between pH and degree of spoilage. These findings agree with those of Waldo et_gl, (1968), Derbyshire and Gordon (1969) and Carpintero et_gl, (1969). The pH values Observed on the formic acid treatment during the first two weeks agree well with those reported by Wilkins and Wilson (1969) who found little change in pH during the first 6-12 days after ensil- ing. Our data shows that unprotected forage treated with formic acid maintains a low, stable pH for 1-2 weeks. Decreases in pH were also 41 Obtained for the AP treatment but changes between the first two weeks were larger than for formic acid treatment (0.15 vs 0.02). The low pH values on the acid treatments suggest that fermentation was de- layed due to a decrease in viable micro-organisms. Organic Acids The VFA concentrations for the different treatments are given in Table 5. Acetic acid in control forage increased during the first week to about 0.55% on a OM basis, and continued to increase by the second week. However, this increase was lower than that observed on the AP treatment even after correcting for the amount of acetic acid added. This indicates that the AP treatment influenced fermentation by Offering a more apprOpriate medium for acetic acid-forming bac- teria. The acetic acid production on the formic acid treatment was lower than that of the control for the first week but then increased over the control and remained lower than that of the AP treatment. The low acetic acid concentrations on the formic acid treatment might be explained by the inhibitory effect of the formic acid on the bac- teria during the first week of storage. A trend similar to that shown for acetic was Observed for the Drwapionic acid concentrations; which increased during the first week Or; control forage to about 0.35% and then decreased until the end of FATE? study. The AP treatment had more pr0pionic acid than the control 42 and that observed at 1 week was approximately double the original level. This apparent increase may have been due to distribution or sampling error. Even though some production of propionic acid occurs, it is doubtful that this would be sufficient to account for the large change observed in the forage. However, pr0pionic acid addition (from AP) may have stimulated bacteria to produce more pro- pionate. The amount of pr0pionate detected decreased with time and at the end of the 4-week period only 63% of the initial level was present. Since the rye forages were stored under aerobic conditions, considerable production of butyric acid was expected, particularly in untreated forages. In general, the control forage exhibited higher concentrations of butyric acid than acid treatments, which was in agreement with the observation of Irvin et_al, (1956) who reported that in poor quality silages, butyric acid was present after 5-8 days. The AP treatment had the lowest concentrations of butyric acid. In other studies formic acid has decreased butyric and acetic acid levels in regular silage (Waldo et_g1,, 1968; Derbyshire and Gordon, 1970; Castle and Watson, 1970). Lactic acid was not detected during the first week after harvest (Table 6). Irvin et_gl, (1956) found that in silages of poor quality the lactic acid increased in the first 5 days and then 43 decreased but in good quality silages lactic acid concentrations in- creased during the first 8-12 days. After 10 days, lactic acid was detected in the control and in the formic treatments (0.75 vs 0.50%) but not on the AP treatment. By the third week less than 1% (on a OM basis) lactic acid was pres- ent in all treatments. The low amount of lactic acid detected after 2-3 weeks could be related to the difficulty in getting a represen- tative sample because of mold in the tOp layers. After the removal of Spoiled layers, higher concentrations of lactic acid were present in the well-fermented material. The data suggests that lactic acid was either not produced or disappeared in forage sampled near the periphery of the mass; whereas much higher concentrations of lactic acid were detected in material after Spoilage was removed. In con- trast, the place and time of sampling the forage seemed to have less effect on concentrations of the other acids present. These results are somewhat different from those reported by Emery et_gl, (1965) who Observed that lactic acid concentrations achieved a maximum within 5 days after ensiling; and to those Of Allen et 31, (1937) who found that lactic acid concentrations in grass silages were highest during the fifth to eighth day of fermen- tation. Barnett (1954) stated that lactic acid peaks by the third day and Langston et 31, (1958) reported a peak within 5-8 days after ensiling direct-cut alfalfa and orchard grass silages. The 44 contradicting Observations in this study are probably because these forages were stored under aerobic conditions. However, these find- ings are in agreement with those reported by Wilkins and Wilson (1969) who observed low lactic acid concentrations on formic acid treated silages but were comparable to those of untreated silages after fermentation was complete. For corn silage, Huber (1970) and Huber et_al, (1972) found a large decrease in lactic acid concentra- tions (20% of control) resulted from formic acid treatment of corn silage which was in agreement with the finding of Henderson and McDonald (1971). Correlations Total VFA was negatively correlated with pH values, -0.29. This indicates that as the amount of VFA increases the pH values de- crease. A negative correlation was also Obtained between temperature and total VFA levels (-0.46); indicating that high temperatures de- press VFA production and general fermentation. Also a negative correlation was obtained between VFAs and amount of OM loss (-O.6l) suggesting that high concentrations of VFA are associated with higher recoveries. 45 Influence of Acid Treatment on Nitrogen Content of Forages The crude protein of forages is given in Table 7 and ON in Table 9. A slightly lower value was observed on the AP treatment at the beginning of the experiment which might be attributed to sampling error. However, differences in crude protein were not statistically significant (P > .05). A correlation Of -0.62 was obtained for average temperature and percent crude protein content in the final sample suggesting that as the temperature increases less protein is preserved. In addition to the effect of temperature, the acidity seems to play a role in saving the protein. Henderson and McDonald (1971) suggested that formic acid treatment inhibited proteolytic clostridia and therefore less proteolysis occurred. A similar finding was re- ported by Saue and Breirem (1969). The percent NPN expressed on OM basis is shown in Table 8. At the beginning of the experiment all treatments had a similar NPN content; however, this increased (P < .05) by the first week with the greatest rise occurring on the control treatment. At the end of four weeks and after removal of Spoiled forage the NPN was higher on the formic acid than the AP treatment but highest values were still noted for the control even though differences were not significant (P > .05). 46 The lower NPN on the formic acid treatment compared to AP during the first few weeks was probably due to a greater inhibition of proteolysis by formic because of its stronger acidity. A corre- lation coefficient of +0.82 was obtained between the percent of NPN on the 4th week samples and the four weeks average temperature. The decrease in proteolysis and aerobic counts reported by Taylor and Philips (1970) indicated an advantage of acid treatments for pre- serving the protein of ensiled material, especially when left under aerobic conditions. Acceptability of Acid Treated Rye Forage The preserved material was fed in a Short acceptability trial to 12 lactating cows (4 cows/treatment). The feeding trial lasted 1 week during which the rye served as the only forage. Daily forage OM intakes on the control, formic acid and AP treatments averaged 7.9, 7.4 and 9.6 Kg, respectively. The experimental period was too short and the number Of cows too few to attach any significance to treatment differences. However, cows accepted the treated rye with no problems and milk production and composition were normal. The fermentation patterns described in the previous sections are in agreement with those reported in literature for acid-treated Silages. Even though insufficient silage was available for a large 47 enough study to detect real differences in animal performance, in- creased DM intake (Castle and Watson, 1970), better gains in heifers, more digestible energy and improved feed efficiencies (Waldo et 21,, I 1968; Derbyshire and Gordon, 1970) have resulted from acid treatment of silages. Trial II The results of this trial are shown in Tables 10 through 19. Results are summarized and presented in a manner similar to those for Trial I. Effect of Acid Treatment on Forage Temperature and Time of Spoilage 0n the day Of harvest the control treatment (1), had the highest temperature (30 C), and lowest temperatures (15 C) were observed for the 1.5% (trt 7) and 1.0% (trt 4) acid treatments (Table 10). The average temperatures for the first 4 days after treatment were highest on the control (37.1 C) followed by 0.25% formic acid (37 C) and then 0.25% AP (36.4 C). Treatments 7 and 4 had the lowest temperatures at this time. 48 Two days after harvest spoilage was noted on the control treatment and at 3 days on 0.25% acid (Table 10). The higher the acid level, the longer Spoilage was delayed. 0n the fourth day after harvest Spoilage was detected on the 0.5% AP treatment. Three treatments, 2 (0.5% F), 5 (1% (1F+3AP) and 11 (0.75% AP) Spoiled by the fifth day; treatment 10 (0.75% F) on the sixth day, and treat- ment 6 (1% (3F+1AP) on the ninth day. Some spoilage was detected on treatments 4 and 7 on the 15th and the 18th days, reSpectively. The last two treatments to Spoil maintained the lowest temperatures to the end of second week of storage, but detection of spoilage corre- sponded to temperature rises similar to those when other treatments Spoiled. The correlation coefficient for the average temperature recorded during this study and the days after harvest that spoilage was detected was -0.93. These observations are in general agreement with those of the first trial and show that acid treatment lowers temperature rises and delays Spoilage. Acid treatment may have delayed oxidation by lowering the acrobic bacteria counts in forages (Taylor and Phillips, 1970; Henderson and McDonald, 1971). When the experimental Silos were emptied by the end of the 3rd week all treatments were totally spoiled except 4 and 7 which showed 65 and 90% recoveries, respectively. The data suggest that 49 high levels of acids will preserve unprotected as well as those stored in conventional silos for at least 3 weeks. Characteristics of Fermentation on Acid Treatment Changes inng The changes in pH due to the different treatments are given in Table 11. At the beginning of the experiment the pH of the con- trol was the highest (6.2) and it increased during the first week and reached a peak Of 8.3 by the third week. This observation was similar to that obtained in the previous trial. The pH values of acid-treated drums were lower than the control. In initial samples formic acid treatments resulted in a lower pH value than acetic and pr0pionic. After 3 weeks treatments 4 and 7 had the lowest pH values. The average temperatures were positively correlated to the pH values (+0.76). This correlation is similar to our observations in the pre- vious trial. A negative correlation Of (-0.75) was obtained between pH and days until spoilage was Observed. Thus, higher pH values were associated with earlier spoilage. 50 Volatile Fatty Acid Concentrations Acetic, pr0pionic, and butyric concentrations for the dif- ferent treatments are given in Tables 12, 13, and 14, respectively. A general increase in acetic acid was shown for all treatments until the end of the sampling period at 3 weeks. Formic acid-treated forages were lower in acetate than those treated with AP during the early period, but little difference due to treatment was noted at 2 or 3 weeks. Little change in acetic acid of forages occurred after 2 weeks even though they were stored unprotected. The higher value on treatment 3 could be due to sampling error. Little or no pr0pionic acid was Observed in the control and formic acid treated forages. Usually some propionic acid has been reported in silages, but its absence in these samples may reflect the aerobic nature of the fermentation. 0n AP treatments there was a net loss of pr0pionic acid after the initial samplings were corrected for added acid. All rye forages used in this study had some butyric acid at 0 days. This level ranged from 0.11-0.56% on OM basis. A decrease in butyrate concentrations were noted thereafter. This decline usually corresponded with spoiling of the forages and highest levels were detected at 3 weeks in samples where least spoilage occurred. 51 Lactic Acid Similar to what was observed in the previous trial, lactic acid was not detected before the 10th day after treatment (Table 15). Initially highest concentrations (3.99% on OM basis) were observed in forage treated with 0.25% AP and the control was second. The AP treatments had highest concentrations of lactic acid at 10 days. The low levels in formic treated forages was probably due to a greater inhibition of fermentation than in the control or AP treatments. By the second week the lactic concentrations drOpped drastically on the control (0.41%) and were not detected by the third week probably due to the early spoilage observed on this treatment. In general, formic acid addition seemed to have an inhibitory effect on lactic acid concentrations, but this was not true for treatment 10 (0.75% formic). Similar Observations were reported by Huber, 1970; Huber_et_gl,, 1972; and Carpintero t 1., 1969. Formic Acid The formic acid recovery rates were determined for forages treated with this acid (Table 16). Recoveries were highest for treat- ments 7, 6, and 4 indicating that as the amount Of formic increased its recovery also increases. This could be explained by the acid inhibiting micro-organisms which would metabolize it. Lower microbial 52 counts have been shown for formic acid treated silages than for con- trols. Effect of Acid Treatment on Nitrogen Content The DH content of the different treatments is given in Table 17 and the crude protein in Table 18. Formic acid treatment usually re- sulted in greater decreases in OM content than AP. This increase in moisture might be due to greater condensation on formic acid, but this was not suggested by higher temperature rises. The eleven treatments had similar crude protein content at the beginning of the study. The differences in crude protein could be related to heat production and time of Spoilage. High heat resulted in earlier spoilage and higher OM losses. Hence, nitrogen made a larger percent of OM. Again, there was a trend towards formic and AP treatments to react quite differently with greater increases in crude protein occurring in forages to which formic had been added. A sim- ilar pattern was seen for the control treatment which spoiled most rapidly. With respect to NPN (Table 19), all treatments started with a similar level, but the NPN increased faster on treatments that spoiled during the first week. This increase in NPN could be the result of proteolysis. It was observed that the acids dapressed 53 proteolysis when compared to the control. The NPN levels were lower on formic than AP treatments (trt 10 vs 11 and 8 vs 9) which might be due to stronger inhibition of proteolysis by formic acid as sug- gested by Taylor and Phillips, 1970. However, other comparisons between these acids (2 vs 3) showed the Opposite trend. Treatments 4 and 7 maintained a lower percent of NPN due to the inhibition of proteolysis and therefore protein was saved and made available to animals. Acceptance of Acid Treated Rye Forages Only two treatments (4 and 7) were preserved in this study. The preserved material was fed to young animals (4 months old) for 2 days. The animals consumed an average of 4.14 kg and 1.8 kg (as fed) on treatments 7 and 4, reSpectively. Of course, it is dangerous to generalize from very short trials but the animals did accept the 1.5% acid level as long as the material was not Spoiled. Trial III Results are summarized in Tables 20-32. No acceptability trials were conducted in this study. 54 Changes in Temperature, OM Recovery and Spoilgge The OM content of the different treatments is given in Table 20. The difference in initial OM can be attributed to very high temperatures during harvest which dried the forage while pre- paring treatments. The general trend of a lowering of OM Observed for most forages might be due to heating and condensation. The initial temperatures taken 4 hours after placement of forages in drums were higher for packed than unpacked treatments. During the first week this trend was reversed with packed treatments lower than those Of the unpacked except for propionic acid additions (Table 21 and Figure 3). The higher initial temperatures on packed treatments suggests the beginning of normal fermentation which never occurred in the unpacked drums exposed to more air. The delay in temperature rises for all acids compared to the controls indicates some inhibition of spoilage for both acids even at 0.5% application, but the marked superiority of pr0pionic over formic in preventing high temperatures was shown during subsequent weeks. The first treatment to spoil was the unpacked controls (4 days). Also, mold spots were detected on the 4th day on the packed controls and 0.5% formic with and without packing. However, the mold observed on these treatments was not as extensive as that observed on the unpacked controls. This indicates that 0.5% formic acid may have 55 extended some protection, but it was not enough for good preservation under the conditions Of this study. Two weeks after the initiation of this study several unpacked treatments were completely spoiled (Table 22). Those unpacked treatments that were not totally spoiled at this time were 1% pr0pionic, 1% mix and 0.5% propionic acid. For those 16.6, 56.3, and 58.8% respectively, of their initial OM was Spoiled. Spoilage was only 3.7% on the 1% packed propionic acid treat- ment by the end of two weeks and 8.1% after 3 weeks. Forage losses increased probably because of the weekly aerations. High invisible losses of OM (35-39%) were Observed on the packed, 0.5% mix, 0.5% formic and the control forages indicating that these low concentra- tions of acid did not prevent oxidation or gas production. Based on the total OM recovery packed forages were superior to the unpacked. For acid comparisons on packed treatments 1% propionic acid ranked first, followed by the 1% mix, and then 0.5% pr0pionic. A Similar relationship to that Obtained in the first two trials was observed between temperature and amount of Spoilage. A correlation coefficient of +0.53 was obtained in this trial for these two factors; and higher correlation was obtained between temperature and total OM loss (+0.69). The values obtained in both cases showed that as the temperature of the ensiled material increased, total losses were greater. These observations are in agreement with those 56 of Daniel et.gl, (1970) who found that pr0pionic acid reduced the frequency and intensity of secondary fermentation and prevented heating and growth of yeast. These researchers agreed with findings of Zimmer and Gordon (1964) who reported a +0.71 correlation between C02 production and OM loss and found that about 18 g COZ/kg OM were produced on the control treatment after five aerations compared to 10 and 4 g on the 0.3 and 1.0% pr0pionic acid. Weise (1970) Showed that the presence of air even at the beginning of fermentation had a damaging effect on fermentation and Silage quality. The results of this trial, with respect to the factors dis- cussed, indicate the superiority of pr0pionic acid over formic acid as a preservative for forages stored under aerobic or partially com- pacted conditions. This observation also applies to mixed treatments which showed that replacement Of formic acid with some propionic acid resulted in higher OM recoveries. Moreover, partial compaction also decreased OM losses. Fermentation Characteristics Changes in pH The changes in pH are Shown in Table 23 and Figure 4. The pH of the controls were higher than those of acid treatments, as was noted in the first two trials. Lower pH values were again observed 57 on the formic acid treatments compared to pr0pionic. Also, mix treatments had lower pH values than the pr0pionic alone due to the action of formic acid. The pH values of the acid treatments at the beginning of this study were slightly higher than those of similar treatments in Trial II; probably because the higher OM content of forage in this trial. After 1 week of storage the pH of the packed control was Similar to that of the 1% prOprionic or formic acid suggesting that a somewhat normal fermentation occurred on the packed control. These observations are different from those of Trial II, due to the packing effect which reduced air exposure. The pH values for the two unpacked treatments which were best preserved (1% pro- pionic and 1% mix) did not change after initial readings. The pH of the packed treatments generally decreased by the second week indi- cating that fermentation and acid production were progressing. AS the amount of Spoilage started to increase the pH values increased. Between 0 and 3 weeks pH values for formic treatments increased while those for pr0pionic and mix decreased. At the end Of 3 weeks a correlation coefficient of +0.13 was obtained between pH and percent spoilage and a higher coefficient +0.29 between pH and percent invisible OM loss whereas a coefficient of +0.42 was shown between pH and total OM losses. This correlation is lower than the ones in previous trials probably due to decrease in losses due to packing. Also, a correlation of +0.37 was observed 58 for average temperatures and pH values recorded during the three weeks experimental period. These observations indicate that lower pH values and temperature increases are associated with higher OM recovery of exposed forages. Organic Acids Little or no acetic acid was noted in the initial samples, but levels in all packed forages increased during treatment with highest values generally after 3 weeks (Table 24). Acetate production was greater on fonnic--than pr0pionic-treated forages. The data sug- gests that formic acid treatment did not completely inhibit fermenta- tion, but delayed it for at least one week. This could be attributed to lower microbial counts (Taylor and Phillips, 1970). Little or no pr0pionic acid (Table 25) was detected on control and formic treatments. PrOpionate levels of forages treated with this acid remained quite constant during the entire period. Recoveries at 21 days ranged from 56 to 84% and were directly related to the amount of acid added. When pr0pionic acid was mixed with formic acid the recoveries of pr0pionic were decreased (56-57%). This might mean that formic acid addition favored certain micro-organisms which metabolized pr0pionic acid (Taylor and Phillips, 1970; Saue and Breirem, 1969). 59 Butyric acid concentrations were higher than those observed in the first two trials (Table 26). However, these fluctuated from week to week and were lowest at end of the study. It was expected that some butyric acid would be detected because of the aerobic con- ditions (Henderson and McDonald, 1971; Taylor and Phillips, 1970; and Saue and Breirem, 1969). Lactic acid concentrations are given in Table 27. Lactic acid was not detected on the initial samples. However, contrary to what was Observed in the first two trials substantial lactic acid was detected at one week. This finding could be related to packing which was absent in the first two trials. These observations are in agreement with those of Emery et_gl, (1965), Allen et_gl, (1937) and Langston et_gl, (1958) who observed a peak in lactic acid in the first 5 to 8 days after ensiling. The first week lactic acid concentrations were highest on control and low acid treatments. This means that low levels of acids combined added to packed silage resulted in some fer- mentation (Taylor and Phillips, 1970). By two weeks, lactic acid appeared on the unpacked pr0pionic and mix treatments. Only two packed treatments, 0.5% pr0pionic acid and 1% mix, decreased in lactic acid concentration by the second week. These treatments might have been affected more by the first aeration than other treatments. This response to aeration could be explained by the inhibition of the lactic acid forming bacteria. The third week lactic acid concentrations 60 were low on the control, 0.5% formic and 0.5% mix, but remained more than 4% on OM basis. The increase in lactic acid on the 0.5% propi- onic by the third week could be due to less influence of the second aeration on the lactic acid bacteria compared to the first. However, Daniel et 21, (1970) reported that propionic acid lowered to about 50% the lactic acid concentrations of grass Silage when compared to con- trols. In general, the lactic acid concentrations of packed acid treatments are in agreement with those reported for well preserved silages. These findings suggest that acid treatments used in this study resulted in a cool fermentation, the type which is needed to obtain good quality silages. Initial levels of formic acid very closely approximated those added to forages. At 0.5% formic recoveries were negligible for the second and third weeks, but when 1% formic or mix acids were used 41-95% of the added formic was recovered (Table 28). PrOpionic acid apparently inhibited the metabolism of formic, especially under com- plete aerobic conditions, perhaps by its influence on microbial action. Nitrogen, ADF and ADF-N The nitrogen contents of the different treatments are given in Table 29. Initial nitrogen content was similar on all treatments and averaged 1.5% on OM basis. Little change in total nitrogen was Observed indicating little effect of heat in this study. 61 The percent NPN (Table 30) averaged 0.56% on OM basis at the beginning of the study. An increase in NPN was observed on all treatments by the first week. The highest increase was on the con- trol and 0.5% packed propionic acid treatment. This increase in NPN suggests that proteolysis occurred. Acid treatments inhibited pro- teolysis when compared to the control. The least proteolysis occurred on the 1% pr0pionic acid as indicated by the lower NPN values. The lower NPN on propionic acid treatments might be explained by the findings of Weise and Daniel (1970) who found that this acid has a strong fungicidal activity and therefore inhibited the growth of mold and fungi even after aeration or fermentation. With the increase in the amount of Spoilage by the third week NPN was higher for all treatments, but the 1% pr0pionic acid treatments packed or unpacked maintained the lowest levels. ADF The acid detergent fiber procedure provides a method for lignocellulose determination. Van Soest (1965) Showed an increase in lignin content when feed samples were exposed to high temperatures. Also, he Observed an increase in the nitrogen content of the lignin fraction of these feeds. The ADF method removes the protein and other acid soluble material which would interfere with the lignin 62 determination. The ADF consists of cellulose, lignin, cutin and acid- insoluble ash (mainly silica). The nitrogen content of the ADF is suggested as a sensitive assay for nonenzymic browning which occurs in over heated feeds. At the beginning of the study the ADF content averaged about 40% of the OM (Table 31). By the first week the ADF content of the control was the highest (42.7%) followed by the 0.5% packed formic acid treatment indicating more oxidation of soluble carbohydrates on these two treatments. The highest temperature and most Spoilage were also reported at 4 days for these treatments. At the end of this study control forage had the highest amount of AOF (45.2% on OM basis) followed by the 0.5% acid levels. The 1% acid levels seemed to main- tain Slightly lower AOF levels probably due to less oxidation of $01- uble carbohydrates (Henderson and McDonald, 1971). The smaller in- creases in ADF were also associated with lower OM losses (Table 25). ADF-N The ADF-N averaged less than 0.1% on OM basis at the begin- ning of the study (Table 32). Even though considerable variation was noted, average ADF-N showed little change during the three week ex- perimental period. This could be related to the relatively low temperatures observed for the packed treatments which averaged less 63 than 40 C. Thomas and Hillman (1972) only detected carmelization in forages which reached 46 C, a level that was not attained in this study. Trial IV Milk Production, Persistengy and Milk Composition as Affected_by Formic Acid Treatment of Rye Silage The average milk production and persistencies on the different silages are given in Table 33. Milk yields were slightly higher dur- ing the pretreatment period as compared to the average of five weeks' production on the different Silages. However, the pretreatment- treatment differences were not statistically Significant (P > .05). The persistency of milk production, based on that of pretreatment, was slightly higher on the formic acid-treated rye silage (96.7%) compared to 95.0% and 94% for the alfalfa haylage and control rye silage, re- Spectively. Milk was sampled bi-weekly and milk composition was determined (Table 33). Differences between treatments in milk solids, proteins and butterfat percentages were not Significant (P > .05). 64 Cows were fed the same concentrate mixture at the ratio of 1:3 and silages were fed ad libitum. The OM content of the alfalfa haylage was much higher than the rye silages (Table 34). This could explain the Slightly higher intakes of the alfalfa haylage. Also, more OM was consumed on the formic treated rye silage compared to the control but this difference was not significant. The results of this study are in agreement with those of Waldo et_gl, (1966 and 1968) who observed that heifers consumed more OM on hay than formic acid silage but the digestibility of the silage was higher. They also found that animals fed direct cut silages treated with formic acid consumed more digestible energy and used this energy more efficiently on a net or gross basis than those fed untreated silage. Heifers consuming alfalfa Silage required 1.4 times as much digestible energy per unit gain as those fed the fonnic acid treated silages. These results also are in strong agreement with Derbyshire and Gordon (1970) who reported that formic acid treatment had no Signifi- cant effect on average milk production, percent butterfat and percent SNF even though milk yields for cows receiving treated silages were slightly higher. Increases in feed efficiencies have been consistently observed in heifers fed Silages treated with formic acid (Waldo et 31, 1966, 1968), but this has not been Shown in lactating cows (Derbyshire and Gordon, 1971) perhaps due to the compounding effect of the con- centrate. Castle and Watson (1970) found that the digestibility and 65 OM intakes were increased in cows fed formic acid Silages. They con- cluded in another study that because of the increase in OM intake an increase in milk was obtained. However, contrary to the results of our study and the results reported by other researchers, Castle and Watson (1970) reported a significant increase in SNF and protein con- tent of milk for cows fed formic acid Silages. Also, Fisher et_gl: (1971), found Significantly higher milk yields when they fed formic acid silages. However, contrary to previous reports they observed lower energy digestibility for the formic Silages but higher efficiency of energy utilization. Effect of Formic Acid Treatment on Nitrogen Content of the Silgges The percent nitrogen, expressed on OM basis, was not statis- tically significant (P > .01) for the three silages used in this study (Table 35). Because of slightly higher milk production on the formic acid treatment the protein of the acid-treated rye was appar- ently better utilized than that in alfalfa haylage or control rye; similar results from formic treated silages were Obtained by Derby- shire and Gordon, 1970; Waldo et_gl,, 1969; Fisher et_gl,, 1971. The NPN content of the alfalfa haylage was significantly lower (P < .01) than that of the rye Silages, but no differences due to formic acid treatment was noted. More proteolysis occurred in the 66 rye silages compared to the alfalfa haylage probably due to the lower OM content. Also, the more favorable storage conditions (conventional silos) may have minimized the effect of the low level (0.4% on wet basis) of formic acid used; however, our previous trials indicate that formic acid prevented proteolysis under poor storage conditions. 67 TABLE 1 EXPERIMENTAL TREATMENTS FOR RYE FORAGE. PART 1, TRIAL II NBMEZr Acid Treatment Total Acid Added (%) 1 Control _-_- 2 Formic acid (F) 0.5 3 Acetic-Propionic (AP)* 0.5 4 1 F : 1 AP 1.0 5 1 F : 3 AP 1.0 6 3 F : 1 AP 1,0 7 1 F : 1 AP 1.5 3 F 0.25 9 AP 0 25 10 F 0.75 11 AP 0.75 *60 acetic : 4O pr0pionic acid. 68 TABLE 2 EXPERIMENTAL TREATMENTS FOR RYE FORAGE. PART 1, TRIAL III Acid Treatment* Total Acid Added (%) Control --- PrOpionic (P) 0.5 p 1.0 Formic (F) 0.5 F 1.0 1 P : 1 F 0.5 l P : 1 F 1.0 Treatments were in duplicate with and without packing. 69 TABLE 3 EFFECT OF ACID TREATMENT ON RYE FORAGE TEMPERATURES (PART 1, TRIAL I) Weeks After Treatment Treatment 0 1 2 3 4 --------------------- Average °C---------------------- Control 28.3a 43.7a 51.8a 53.9a 41.8a AP 21.9” 27.9b 38.4” 40.0” 34.4” F 25.5” 29.8” 38.1b 39.1” 32.3” a’bValues with different superscript are statistically Significant (P < .05). TABLE 4 EFFECT OF ACID TREATMENT 0N RYE FORAGE PH (PART 1, TRIAL I) Weeks After Treatment Treatment 0 1 2 3 4 Control 6.36a 6.52a 6.14a 6.99a 5.96a AP 4.49” 4.43” 4.28” 4.33” 4.64” F 4.26” 3.78” 3.80” 3.96” 3.97” a’bValueS with different superscript are statistically significant (P < .05). 70 TABLE 5 EFFECT OF ACID TREATMENT ON VFA AND FORMIC ACID CONTENT OF RYE FORAGE (PART 1, TRIAL I) Weeks After Treatment Acid . Treatment Determined 0 1 2 3 4 ------------------ % OM------------------ Acetic Control ---- 0.55 0.60 0.26 0.41 AP 1.88 3.73 2.34 2.95 1.92 F ---- 0.29 0.66 0.50 0.58 PrOpionic Control ---- 0.35 0.10 ---- 0.09 AP 1.23 2.46 1.30 1 52 0.77 F ---- 0.06 0.10 ---- ---- Butyric Control 0.32 0.44 0.25 ---- 0.26 AP 0.11 0.32 0.32 ---- ---- F 0.55 0.25 0.16 ---- 0.55 FOrmic F 3.53 3.30 3.22 3.12 3.19 TABLE 6 EFFECT OF ACID TREATMENT 0N LACTIC ACID CONTENT OF RYE FORAGE (PART 1, TRIAL I) Weeks After Treatment Treatment (10 days) 2 3 4* ------------------ (% Ory Matter)------------------- Control 0.75 0.28 0.64 3.58 AP ---- ---- 0.81 4.19 F 0.49 0.33 0.90 3.34 *From forage sampled after spoilage was removed. 71 TABLE 7 EFFECT OF ACID TREATMENT ON CRUDE PROTEIN CONTENT OF RYE FORAGE (PART 1, TRIAL I) Weeksb After Treatment Treatmenta 0 l 2 3 4 -------------------- % Dry Matter--------------------- Control 13.59 14.26 16.23 15.45 13.45 AP 12.68 14.06 13.50 13.81 13.58 F 13.01 14.33 14.74 14.56 14.38 aDifferences among treatments were not significant (P > .05). bDifferences among treatments due to time were not significant (P > .01). TABLE 8 EFFECT OF ACID TREATMENT ON NPN CONTENT OF RYE FORAGE (PART 1, TRIAL I) Weeks After Treatment Treatment 0 l 2 3 4 ------------------ % Dry Matter----------------------- Control 0.45a 1.08” 1.31” 1.19” 1.14” AP 0.41a 0.83” 1.09” 0.77” 0.95” F 0.41a 0.70” 0.84” 0.98” 1.06” a’bValues with different superscript are statistically significant (P < .05). 72 TABLE 9 EFFECT OF ACID TREATMENT ON ON OF RYE FORAGE (PART 1, TRIAL I) Weeks After Treatment Treatment* 0 l 2 3 4 ......................... %-_--------------_---------- Control 28.92 30.06 31.30 30.38 26.08 AP 28.08 28.44 29.38 26.99 26.87 F 28.28 28.03 27.52 24.77 25.80 *Treatment differences were not statistically significant (P > .05). Differences with time are not statistically significant (P > .01). EFFECT OF ACID TREATMENT ON FORAGE TEMPERATURE AND TIME OF SPOILAGE (PART 1, TRIAL II) 73 TABLE 10 Days After Treatment Treatment Spoilage Time 0 4 8 15 21 (days) ................... C°------------------- 1 -Control 36.0 37.1 28.7 35.7 35.1 2 2 -0.5 (F) 16.0 32.3 37.7 35.5 34.7 5 3 -0.5 (AP) 16.0 26.5 38.6 38.6 39.8 4 4 -l.0 (1F:1AP) 15.0 15.1 13.1 27.9 38.6 15 5 -1.0 (1F:3AP) 17.0 16.8 24.2 37.9 37.5 5 6 -l.0 (3F:1AP) 16.0 16.4 21.4 43.4 39.8 9 7 -l.5 (1F:1AP) 15.0 15.0 12.9 26.2 41.1 18 8 -0.25 (F) 20.0 37.0 27.7 34.5 36.9 3 9 -0.25 (AP) 20.0 36.4 31.5 39.2 36.1 3 10-0.75 (F) 16.5 17.0 32.1 37.1 41.6 6 11-0.75 (AP) 17.0 17.6 30.4 39.0 40.4 5 Amb‘ent 16.5 17.5 13.0 20.0 24.1 Temperature TABLE 11 EFFECT OF ACID TREATMENT ON pH 0F FORAGES (PART 1, TRIAL 11) Weeks After Treatment Treatment 0 1 2 3 1 -Control 6.2 7.3 6.5 8.2 2 -0.5 (F) 4.1 5.3 5.9 7.1 3 -0.5 (AP) 4.7 5.3 4.8 4.3 4 -1.0 (1F:1AP) 3.9 3.9 4.3 4.8 5 -l.0 (1F:3AP) 3.6 4.5 5.6 5.9 6 -l.0 (3F:1AP) 3.7 3.7 5.7 6.0 7 -1.5 (1F:1AP) 3.7 3.7 3.8 4.2 8 -0.25 (F) 5.2 6.4 5.8 7.1 9 -0.25 (AP) 5.1 5.9 4.5 4.7 10-0.75 (F) 3.9 4.5 4.4 5.3 ll-0.75 (AP) 4.5 4.7 5.2 5.8 EFFECT OF ACID TREATMENT ON ACETIC ACID CONCENTRATIONS 74 TABLE 12 (PART 1, TRIAL II) Weeks After Treatment Treatment 0 l 2 3 ------------------ % of DM------------------ 1. Control 0.15 0.39 0.66 0.31 2. 0.5 (F) ---- 0.16 0.59 0.63 3. 0.5 (AP) 1.38 0.71 1.92 3.33 4. 1.0 (1F:1AP) 1.26 1.01 0.97 0.66 5. 1.0 (1F:3AP) 1.85 1.17 0.95 1.04 6. 1.0 (3F:1AP) 0.70 0.50 1.06 1.25 7. 1.5 (1F:1AP) 1.60 1.73 1.34 1.00 8. 0.25 (F) ---- 0.59 1.25 1.14 9. 0.25 (AP) 0.60 0.69 0.96 1.83 10. 0.75 (F) ---- 0.06 0.58 1.29 11. 0.75 (AP) 1.78 1.22 1.05 1.58 TABLE 13 EFFECT OF ACID TREATMENT ON PROPIONIC ACID CONCENTRATIONS (PART 1, TRIAL II) Weeks After Treatment Treatment 0 1 2 3 ------------------ % of OM------------------ 1. Control ---- 0.27 ---- ---- 2. 0.5 (F) ---- ---- ---- ---- 3. 0.5 (AP) 0.81 0.36 0.29 0.37 4. 1.0 (1F:1AP) 0.78 0.48 0.41 0.09 5. 1.0 (1F:3AP) 1.12 0.75 0.33 0.24 6. 1.0 (3F:1AP) 0.36 0.27 0.05 ---- 7. 1.5 (1F:1AP) 0.91 1.04 0.71 0.42 8. 0.25 (F) ---- 0.10 ---- ---- 9. 0.25 (AP) 0.18 0.15 ---- ---- 10. 0.75 (F) ---- ---- ---- ---- 11. 0.75 (AP) 1.18 0.93 0.32 0.12 75 TABLE 14 EFFECT OF ACID TREATMENT 0N BUTYRIC ACID CONCENTRATIONS (PART 1, TRIAL II) Weeks After Treatment Treatment 0 1 2 3 ------------------ % of DM------------------ 1. Control 0.32 0.10 0.09 ---- 2. 0 5 (F) 0.42 0.11 0.21 ---- 3. 0.5 (AP) 0.22 0.24 0.15 ---- 4. 1.0 (1F:1AP) 0.56 0.32 0.40 0.14 5. 1.0 (1F:3AP) 0.36 0.31 0.28 0.15 6. 1.0 (3F:1AP) 0.47 0.25 0.16 --—— 7. 1.0 (1F:1AP) 0.34 0.28 0.36 0.41 8. 0.25 (F) 0.34 0.17 0.28 ---- 9. 0.25 (AP) 0.11 0.25 0.10 —--- 10. 0.75 (F) 0.23 0.37 0.16 ---- 11. 0.75 (AP) 0.21 0.38 0.09 --—- TABLE 15 EFFECT OF ACID TREATMENT ON LACTIC ACID CONCENTRATIONS (PART 1, TRIAL II) Weeks After Treatment Treatment (10 days) 2 3 ----------------- % of OM----------------- 1. Control 2.05 0.41 ---- 2. 0.5 (F) ---- 0.30 0.10 3. 0.5 (AP) 1.17 2.45 2.21 4. 1.0 (1F:1AP) ---- ---- 0.48 5. 1.0 (1F:3AP) ---- ---- 0.78 6. 1.0 (3F:1AP) 0.48 1.52 0.91 7. 1.5 (1F:1AP) ---- ---- 0.50 8. 0.25 (F) 0.52 1.27 1.23 9. 0.25 (AP) 3.99 1.97 2.71 10. 0.75 (F) 0.90 0.47 2.33 11. 0.75 (AP) 0.78 0.95 2.66 76 TABLE 16 FORMIC ACID CONTENT AND RECOVERY (PART 1, TRIAL II) Weeks After Treatment Treatment % Recovery 0 1 2 3 ------------ % of OM------------ 2. 0.5 (F) 1.92 1.38 1.01 0.83 43.5 4. 1.0 (1F:1AP) 2.01 1.82 1.68 1.21 60.1 5. 1.0 (1F:3AP) 1.00 0.83 0.45 0.54 54.0 6. 1.0 (3F:1AP) 2.73 2.42 1.55 1.93 70.6 7. 1.5 (1F:1AP) 2.91 2.72 2.09 2.32 79.7 8. 0.25 (F) 1.12 0.77 ---- ---- Trace 10. 0.75 (F) 2.84 2.37 1.17 1.53 53.9 TABLE 17 EFFECT OF ACID TREATMENT 0N DM CONTENT OF THE FORAGES (PART 1, TRIAL II) Weeks After Treatment Change Treatment 0 l 2 3 (0‘3 Wk) ................. z................ 1. Control 28 4 30.6 36.7 36.3 + 7.9 2. 0.5 (F) 28.8 30.6 27.8 24.9 - 3.9 3. 0.5 (AP) 27.7 29.6 28.2 25.9 - 1.8 4. 1.0 (1F:1AP) 27.2 28.9 30.2 32.3 + 5.1 5. 1.0 (1F:3AP) 25.0 27.4 28.1 26.2 + 1.2 6. 1.0 (3F:1AP) 27.2 29.5 27.8 23.6 - 3.6 7. 1.5 (1F:1AP) 26.6 27.2 28.8 32.3 + 5.7 8. 0.25 (F) 27.2 29.5 23.7 19.2 + 8.0 9. 0.25 (AP) 28.2 28.7 27.5 28.5 + 0.3 10. 0.75 (F) 27.5 27.1 27.5 23.2 - 4.3 11. 0.75 (AP) 27.9 27.0 31.0 25.5 - 2.4 77 TABLE 18 EFFECT OF ACID TREATMENT ON CRUDE PROTEIN (PART 1, TRIAL II) Weeks After Treatment Treatment Change 0 l 2 3 (0-3 wk) -------------- % of OM-------------- 1. Control 13.52 22.22 --- --- + 8.70* 2. 0.5 (F) 12.95 16.24 15.59 17.40 +-4.45 3. 0.5 (AP) 12.96 14.01 13.45 13.69 + 0.73 4. 1.0 (1F:1AP) 13.23 12.79 13.20 12.98 - 0.25 5. 1.0 (1F:3AP) 13.56 14.23 14.17 15.56 + 2.00 6. 1.0 (3F:1AP) 13.75 13.12 15.30 17.67 + 3.93 7. 1.5 (1F:1AP) 13.42 12.44 13.03 12.95 - 0.47 8. 0.25 (F) 14.12 19.42 18.73 24.91 +10.79 9. 0.25 (AP) 13.16 19.26 14.33 14.67 + 1.51 10. 0.75 (F) 13.56 14.75 14.34 15.80 + 2.24 11. 0.75 (AP) 12.83 14.30 13.52 15.95 + 3.08 *Only 1 wk change. TABLE 19 EFFECT OF ACID TREATMENT 0N NPN CONTENT (PART 1, TRIAL II) Weeks After Treatment Treatment 0 l 2 3 --------------- % Dry Matter---------------- 1. Control 0.47 1.39 ---- ---- 2. 0.5 (F) 0.41 0.78 1.02 1.10 3. 0.5 (AP) 0.42 0.49 0.79 0.84 4. 1.0 (1F:1AP) 0.44 0.52 0.85 0.77 5. ‘1J)(1F:3AP) 0.41 0.71 0.85 0.84 6. 1.0 (3F:1AP) 0.51 0.61 0.90 1.05 7. 1.5 (1F:1AP) 0.39 0.61 0.72 0.77 8. 0.25 (F) 0.57 0.88 0.84 0.88 9. 0.25 (AP) 0.41 0.97 0.99 1.11 10. 0.75 (F) 0.54 0.69 0.87 0.90 11. 0.75 (AP) 0.51 1.00 1.25 1.48 78 TABLE 20 DRY MATTER CONTENT OF RYE FORAGES (PART 1, TRIAL III) Weeks After Treatment Treatment 0 1 UPK and PK* PK UPK PK UPK PK ............................. z----------------------------- Contro1 33.7” 32.8” ---- 31.5” ---- 26.7a 0.5% P 40.5” 38.7” 42.0 37.6” ---- 36.1” 1.0% P 39.5” 40.0” 40.1 40.8” 42.5 39.7” 0.5% F 35.0” 33.3” ---- 31.4” ---- 30.2” 1.0% F 35.7”” 39.4” ---- 37.6” ---- 32.6”” 0.5% Mix 40.5” 42.9” ---- 38.5” ---- 33.0” 1.0% Mix 40.0” 38.6” 39.4 39.2b 41.7 35.6” *UPK = Unpacked; PK = Packed. a,b Va1ues with different superscript are significant (P < .05). 79 .Amo. v av ucmgmwywu xppmuwumwpmum mew mpawgumgmazm pcmgm$$wc saw: mmzpm> n.m .Umxuma u 2m muwxumacz u xa:« . . . . mgzumgmaemh o m. N om 0 mp o a. “gown NF FF mm.mm m.mm mm.mw o.¢m mm.mp m.NN wm.mN o.mN xwz No.p _F OF nam.mm ---- na~.- m.~e nas.mu m.mm nao.m~ o.N~ x_z Rm.o —~ 0— amo.nm 1111 nw©.nm N.m¢ amm.om m.~m awo.ww o.m~ u Ro.p ¢ ¢ amo.nm 1111 nwm.mN m.mN amm.Nm m.mm amo.mm o.m~ m am.o VF ep wo.Nm o.mN wu.o~ o.m~ om.w~ o.- wo.wm m.vm a Ro.~ ¢~ mp amo.mm 1111 amo.mm 0.0m nmN.mN N.m~ noo.mm o.¢N a Rm.o v c no.¢m 1111 no.mN m.mm nm.om o.m¢ no.0m o.mm Pogucou IIIIUI-II'IIIII'IUIIII'OI-IIII'IUDOUIUIII'O'I"I'DII-II||III||IIII-l xm xm: xa xm: xm xm: xa xm: «x; 2a: mmmpwoam m N acmeummCP to week newspmmgp gmuw< mxmmz AHHH 4 .05). 81 TABLE 24 EFFECT OF ACID TREATMENT AND PACKING 0N ACETIC ACID CONCENTRATIONS OF RYE FORAGE (PART 1, TRIAL III) Weeks After Treatment Treatment 0 1 2 3 UPK and PK* PK UPK PK UPK PK ---------------------------- % of DM--------------------- Contro1 0.15 2.10” ---- 2.47” ---- 4.68” 0.5% P ---- 1.94ab 1.07 1.53ab ---- 1.53ab 1.0% P ---- 0.50a 0.34 0.50a 0.55 0.34a 0.5% F ---- 0.75ab ---- 1.28ab ---- 3.07ab 1.0% F ---- 0.36a ---- 0.79a ---- 1.20a 0.5% Mix ---- 0.58a ---- 0.80a ---- 1.30a 1.0% Mix 0.12 0.67a 0.43 0.64a -—-- 1.13a *UPK = Unpacked; PK = Packed a’bVa1ues with different superscripts are significant (P < .05). TABLE 25 EFFECT OF ACID TREATMENT AND PACKING 0N PROPIONIC ACID CONCENTRATIONS 0F RYE FORAGE (PART 1, TRIAL III) Weeks After Treatment % Recovery Treatment 0 1 2 3 at 3 wks. UPK and PK* PK UPK PK UPK PK UPK PK ------------------- % of DM--—----------------- Contro1 0.13 ---- ---- 0.15 ---- 0.24 0.5% P 1.43 1.81 1.19 1.33 ---- 1.04 ---- 72.7 1.0% P 3.10 3.07 2.52 3.03 2.52 2.60 81.3 83.9 0.5% F ---- ---- ---- ---- ---- 0.14 1.0% F ---- ---- ---- ---- ---- 0.06 0.5% Mix 0.98 0.77 ---- 0.65 ---- 0.55 ---- 56.1 1.0% Mix 1.31 1.70 1.55 1.33 ---- 0.75 ---- 57.3 *UPK = Unpacked; PK = Packed. 82 TABLE 26 EFFECT OF ACID TREATMENT AND PACKING ON BUTYRIC ACID CONCENTRATIONS OF RYE FORAGE (PART 1, TRIAL III) Weeks After Treatment Treatment 0 1 UPK and PK* PK UPK UPK PK ------------------------ % of DM------------------------- Contro1 0.88 0.77 ---- 0.43 ---- 0.13 0.5% P 1.17 0.69 1.18 0.65 ---- 0.40 1. 0% P 1.10 1.63 1.30 1.03 1.25 0.66 0. 5% F 1.45 0.69 ---- 0.60 ---- 0.25 1. 0% F 1.32 1.48 ---- 1.85 ---- 1.20 0. 5% Mi 1.28 1.07 ---- 0.82 ~--- 0.65 1. 0% Mix 1.33 1.60 1.6 1.90 ---- 1.10 *UPK= Unpacked; PK= TABLE 27 EFFECT OF ACID TREATMENT AND PACKING 0N LACTIC ACID CONCENTRATIONS 0F RYE FORAGE (PART 1, TRIAL III) Weeks After Treatment Treatment 1 Pkab UPK” PK UPK PK --------------------- % Dry Matter--------------------- Contro1 6.71 ---- 9.59 ---- 7.09 0. 5% P 10.23 3.17 5.31 ---- 10.83 1. 0% P 2.71 2.68 5.60 3.72 7.16 0. 5% F 7.73 ---- 7.91 ---- 4.26 1. 0% F 2.03 ---- 4.01 ---- 5.17 0. 5% Mi 5.61 ---- 9.91 ---- 7.53 1. 0% Mi 3.56 3.36 3.40 0.79 5.28 :UPK = Unpacked; PK = Changes in 1actic acid concentrations of packed treatments are not significant1y different (P > .05). 83 TABLE 28 EFFECT OF ACID TREATMENT AND PACKING ON FORMIC ACID CONTENT AND RECOVERY IN RYE FORAGE (PART 1, TRIAL III) Weeks After Treatment % Recovery Treatment 0 1 2 3 at 3 wks. UPK and PK* PK UPK PK UPK PK UPK PK .................... z--------------------- 0.5% F 1.75 0.60 --- Trace ---- Trace ---- ---- 1.0% F 3.43 3.35 --— 3.26 ---- 1.90 ---- 55.4 0.5% Mix 1.02 1.32 --- Trace ---— Trace ---- ---- 1.0% Mix 2.06 1.95 2.0 2.0 1.96 0.85 95.1 41.3 *UPK = Unpacked; PK = Packed. TABLE 29 EFFECT OF ACID TREATMENT AND PACKING ON TOTAL NITROGEN CONTENT OF RYE FORAGE (PART 1, TRIAL III) Weeks After Treatment Treatment 0 1 2 3 UPK and PK* PK UPK PK UPK PK ---------------------- % Dry Matter---------------------- Contro1 1.58 1.70 ---- 1.78 ---- 1.81 0.5% P 1.58 1.51 1.50 1.76 ---- 1.68 1. 0% P 1.50 1.47 1.47 1.61 1.40 1.41 O. 5% F 1.68 1.62 ---- 1.60 -—-- 1.61 1. 0% F 1.52 1.51 ---- 1.45 ---- 1.61 0. 5% Mix 1.60 1.46 ---- 1.53 ---- 1.70 1. 0% Mix 1.52 1.65 1.51 1.39 1.68 1.55 *UPK = Unpacked; PK = Packed. 84 TABLE 30 EFFECT OF ACID TREATMENT AND PACKING ON NPN CONTENT OF RYE FORAGE (PART 1, TRIAL III) Weeks After Treatmentb Treatment 0 1 2 UPK and Pk”C ‘15:” UPK PK UPK PK ----------------------- % of DM-------------------------- Contro1 0.51 1.02 ---- 0.95 ---- 1.32 0.5% P 0.49 1.04 0.89 1.00 ---- 1.36 1.0% P 0.51 0.65 0.67 0.52 0.90 0.88 0.5% F 0.59 0.87 ---- 1.08 ---- 1.12 1.0% F 0.66 0.87 ---- 0.95 ---- 1.02 0.5% Mix 0.74 0.83 ---- 1.00 ---- 0.89 1.0% Mix 0.53 0.81 0.85 0.95 0.84 1.08 aUPK = Unpacked; PK = packed. bMeans of weeks 1, 2, and 3 in packed forage are higher (P < .05) than for the initia1 samp1ing time. CChanges in NPN content of packed treatments are not significant1y different (P > .05). 85 TABLE 31 EFFECT OF ACID TREATMENT AND PACKING ON ADF CONTENT OF RYE FORAGE (PART 1, TRIAL III) Weeks After Treatment Treatment 0 1 2 3 UPK and PK* PK UPK PK UPK PK -------------------- % Dry Matter--—------------------—- Contro1 40.9 42.7 ---- 42.8 ---- 45.2 0.5% P 40.2”” 40.5”” 40.7 41.1”” ---- 44.1”” 1.0% P 39.2”” 41.3”” 40.2 39.8”” 40.9 42.6”” 0.5% F 39.5”” 42.6”” ---- 42.2”” ---- 44.3”” 1.0% F 40.4”” 40.1”” ---- 41.2”” ---- 42.1”” 0.5% Mix 40.5””” 41.6””d ---- 41.2””” ---- 43.1””d 1.0% Mix 40.2”” 40.7”” 41.0 40.7”” 40.4 42.2”” a a a a *UPK = Unpacked; PK = Packed. a’b’c’dVa1ues with different superscripts are significant1y different (P < .05). Differences due to time of samp1ing are significant (P < .05). 86 TABLE 32 EFFECT OF ACID TREATMENT AND PACKING ON ADF-N OF RYE FORAGE (PART 1, TRIAL III)a Weeks After Treatment Treatment 0 1 2 UPK and PK” ”1;:— UPK PK UPK PK --------------------- % Dry Matter----------------------- Contro1 .098 .116 ---- .119 ---- .110 0.5% P .100 .108 .084 .125 ---- .098 1.0% P .078 .101 .080 .080 .109 .095 0.5% F .111 .101 ---- .108 ---- .096 1.0% F .078 .094 ---- .107 ---- .088 0.5% Mix .067 .090 ---- .093 ---- .128 1.0% Mix .067 .069 .082 .091 .085 .097 aNone of the treatment or time differences were significant (P < .05). bUPK = Unpacked; PK = Packed. 87 TABLE 33 MILK PRODUCTION PERSISTENCY AND MILK COMPOSITION ON THE DIFFERENT SILAGES (PART 1, TRIAL IV)a Treatment Mi1k Pers1s- Mi1k Mi1k Mi1k tencyb Protein Fat So1ids kg/day -------------- % -------------- A1f-Hay1age 20.8 95.0 2.93 3.6 12.38 Contro1-Rye 19.6 94.0 3.06 3.7 12.80 Formic-Rye 21.1 96.7 2.91 3.4 12.26 3Differences among treatments were not significant (P > .05) for any of the parameters used. b Treatmentgyie1d Standardization yie1d X 100 TABLE 34 DRY MATTER CONTENT AND CONSUMPTION OF SILAGES AND CONCENTRATE (PART 1, TRIAL IV) Treatment DM Si1age DM DM Intake Concentrate % kg/day (% of body kg/day weight) A1f-Hay1age 60.75” 9.5 1.6 7.5 ControT Rye 26.17” 7.6 1.3 7.1 Formic Rye 25.62b 8.3 1.5 7.6 a b ’ Va1ues with different superscript are statistica11y significant (P < .05). 88 TABLE 35 AVERAGE NITROGEN AND NPN CONTENT OF THE SILAGES (PART 1, TRIAL IV) Treatment Tota1 N* NPN --------------- % of DM------------ A1fa1fa hay1age 3.00 1.24” Contro1-rye 2.72 1.69b Formic-rye 2.70 1.66b a,b Va1ues not sharing a common superscript are significant1y different (P < .01). *Differences in tota1 N were not significant (P > .01). 89 Fig. 1.-—The Effect of Acid Treatment on Rye Forage Temperature (Part 1, Tria1 1). 9O [Lu—- ‘—\-\‘\ o \ s 4/ \ O ’7 o/./’/ ./ Control ’/ __-_.AP .__...... F 1 2 3 WEEKS AFTER TREATMENT rm 91 Fig. 2.-—The Effect of Acid Treatment on Rye Forage pH (Part 1, Tria1 I). 92 6 1'. 5 pH ____ ’/ 4 \,\ ...-«- ..... _ \_ _____ ___, .. Control 3 -—-— AP __.__ F 0 1 2 3 4 WEEKS AFTER TREATMENT 93 Fig. 3.--Temperatures of Packed Rye Forages Treated With Varying Leve1s of Formic (F) or PrOpionic (P) Acids.(Part 1, Tria1 III). 94 40 “in. 1.5.4.1411 1%. 15 TREATMENT AFTER WEEKS i 1'1 .P. ; 95 Fig. 4.--Changes in pH of Packed Rye Forages Treated With Varying Leve1s of Formic (F) or Propionic (P) Acids (Part 1, Tria1 III). Il/ 96 V A . V..\ «:7 6 5 5 4 u” o. TREATMENT WEEKS AFTER PART 2 EFFECT OF ACID TREATMENT ON THE PRESERVATION OF UNPROTECTED CORN FORAGE INTRODUCTION In the rye experiments, increased DM recoveries resu1ted from treatment of forages which were 1eft under comp1ete1y aerobic condi- tions with minima1 protection. Propionic acid was superior to formic acid as a preservative of poor1y protected forage. The acids probab1y inhibited microbia1 growth which de1ayed fermentation and heating of acid-treated forages. In addition, forages preserved with up to 1.5% acid (on a wet basis) were readi1y accepted by anima1s. The purpose of this study was to further examine the preserva- tive effect of different organic acids on corn, which is a high energy forage cr0p, when 1eft under conditions simi1ar to those used in the rye forage studies. A150, the best 1eve1 and combination of acids needed to preserve corn forage as we11 as stabi1ity and acceptabi1ity of acid treated forages were studied. 97 MATERIALS AND METHODS Tria1 I Ch0pped corn forage (38% DM) was used in this tria1. Treat- I” ments were: contro1, 1% AP, 1% formic, 1% AP + formic, 1% pr0pionic, and 1% acetic acid. The acids were di1uted 1:1 with water and added to chapped corn at the b1ower. The forages were ensi1ed in temporary si1os (3 x 1.5 m) in a manner simi1ar to the first rye tria1. Forages were samp1ed immediate1y before and after treatment and samp1es were frozen at -5 C for ana1yses simi1ar to those performed on rye samp1es. Dai1y temperatures and spoi1age dates were recorded for the different treatments. Six weeks after harvest the spoi1ed 1ayers were removed, weighed and samp1ed for DM determination. The preserved materia1, except for the acetic acid treatment, was fed in a short acceptabi1ity tria1 to 5 groups of 14 heifers each (437 kg body wt.). In addition to the forage each group was a1so fed 6.4 kg of a high protein con- centrate (85% SBM) per day. The acceptabi1ity tria1 1asted for 5 days during which forages were observed for heating. 98 99 Tria1 II In the second tria1 corn forage of the same cut as in tria1 I was p1aced 1oose in 220 1iter experimenta1 si1os. The different acid 1eve1s and combinations shown in Tab1e 36 were tested. The acids were di1uted 1:1 with water and mixed for severa1 minutes with 32 kg por- tions of the Chopped corn forage in a cement mixer. Temperatures were recorded dai1y and dates when 5p0i1age was first observed were moni- tored. At the end of five weeks the drums were emptied and spoi1ed forage was removed. RESULTS AND DISCUSSION Tria1 I Temperature and Amount of Spoi1age Temperatures during the experimenta1 period are given in Tab1e 37. As in previous tria1s the first temperature recorded was 4 hours after treatment. At this time temperatures of the contro1 treatment were a1ready higher (27 C) than those of acid treatments (24 C). Within two days the contro1 forage reached 40 C; which corresponded to the first detection of spoi1age. This observation is in agreement with that of Zimmer and Gordon (1964), of Honig (1969) and Federson (1971) who observed that oxidation was accompanied by 1arge rises in temperature and DM 1osses. The pr0pionic acid, the AP and formic acid treatments maintained the 1owest temperatures (25-26 C) during the first week. These 10w temperatures indicate that 1itt1e fermentation occurred and that microbia1 action was in- hibited. The contro1 and acetic acid treatments had the highest temperatures during the first week; they averaged 37 and 31 C, re- spective1y. In ten days, mo1d was detected on the acetic acid treatment at a temperature of 43 C. At 13 days after treatment mo1d 100 101 was detected on the AP treatment and a temperature of 39 C was re- corded. On day 20 mo1d was detected on the formic acid treatment which had a temperature of 52 C. This temperature was as high as that obtained for contro1 rye forage. The AP + F treatment mo1ded in 24 days at which time a temperature of 50 C was recorded. The 1 temperature of the pr0pionic acid treatment started to increase be- tween the 3rd and 4th week. However, it maintained the 1owest tem- Lf‘f‘.u..~n-\-9Mi‘ F peratures during the entire 6 week period. This treatment mo1ded at 32 days at which time temperatures of 44 C were recorded. The time of spoi1age detection was negative1y corre1ated (-0.81) with the average temperature for the entire 6 weeks. This was in agreement with the findings of the rye study which suggested that as the temperature increased to about 40-50 C spoi1age wou1d occur. Even though acetic acid has bactericidic properties, it was 1ess effective (52% of DM spoi1ed) than pr0pionic or formic acids in preserving unprotected corn forage (Tab1e 39). Contrary to what was observed on the previous tria1s, re1ative1y 1itt1e spoi1age (33.6%) was detected on the contro1 treatment. This might be due to a 1arger amount of forage (6 tons) used in the contro1 compared to AP (5 tons) or other treatments (4.5 tons). The 1east spoi1age (27%) was observed on the AP treatment which agrees with resu1ts of the first rye tria1, when AP Spoi1age was 1ess than that on formic or contro1 treatments. 102 It a1so agrees with the work of Gordon and Goering (1972) who added twice the 1eve1 of acid under minima11y protected conditions. Spoi1age on pr0pionic acid, formic acid and AP + F amounted to 32.3, 43.1, and 44.1% of the DM, respective1y. As noted with rye forage (tria1 3) invisib1e 1osses were probab1y 1owest for forages treated with pr0pionic acid. Danie1 gt_al, (1970) observed 4.5 times more C0 production on contro1 forage than that treated with 1% pro- 2 pionic acid (18 vs 4 g COZ/kg DM). A corre1ation of +0.4 (simi1ar to the rye experiment) was ob- tained between temperature and amount of spoi1age. Data on tempera- ture, time of spoi1age, and amount of preservation again showed the superiority of pr0pionic acid over formic or acetic acids in preserv- ing uncompacted and unprotected corn forage. Fermentation Characteristics Changes in pH and VFA concentrations are given in Tab1e 38. In order to avoid excessive exposure of the forage mass, samp1es were on1y taken immediate1y after treatment and after the remova1 of spoi1ed materia1. Simi1ar to previous observations, the contro1 forage had the highest and the formic acid treated forage the 1owest pH va1ues at the beginning of the study (5.5 vs 3.5). Other treatments were intermediate. The 10w pH va1ues observed for formic acid treatments 'i LI..h-_. - 3-042 “4 fi 103 are due to the strong1y acidic nature of formic acid (Carpintero _t_al,, 1969). At the end of storage 1itt1e difference in pH was obtained for the different treatments. In genera1, the pH va1ues observed at the end of the study were not different from those re- ported or recommended for good qua1ity si1ages. Because materia1 was samp1ed on1y twice during this study a 10w positive corre1ation, +0.11 (compared to previous tria1s) was obtained between average temperature and pH va1ues. A negative corre1ation (-0.61) was observed between pH and the days after harvest when spoi1age was first detected; indicating that spoi1age occurred at an ear1ier date in forages with higher pH va1ues. Organic Acids On1y acetic acid treatments contained this acid in significant concentrations at the beginning of the study (Tab1e 38). Acetic acid was detected on the pr0pionic acid treatment but at a very 10w 1eve1 (0.2%). By the end of the study acetate concentrations had increased on a11 treatments except that treated with on1y acetic acid. The de- crease on the acetic treatment might be re1ated to the poor preserva- tion qua1ities of acetic re1ative to other acids as indicated by the. faster rise in temperatures. However, specific inhibition of added acetate on production of the acid was observed previous1y (Huber 104 _t_al,, 1972) and appears a more 1ogica1 exp1anation in view of the 1eve1s of 1actic acid (2.4% of DM) on this treatment. Greatest in- creases in acetic acid were noted on forages not treated with acetate (contro1, pr0pionic and formic acids) which substantiates the specific inhibition of acetic acid on si1age acetate production. PrOpionic acid was on1y detected in forages with added propi- onate. Concentrations decreased to 25% of origina1 by the end of 6 weeks on AP with 1itt1e change for the pr0pionic or AP + F treatments. Formic acid apparent1y inhibits micro-organisms which produce pr0pionic acid and has a genera1 depressing effect on fermentation of corn forage as indicated by decreased 1actic acid 1eve1s (Huber gt_al, 1972). The absence of propionic acid on the acetic acid and contro1 treatments may be re1ated to the high temperatures observed during ear1y fermentation. Butyric acid was detected 4 hours after treatment on1y in forages containing pr0pionic acid. At 6 weeks some butyric acid had appeared (0.61%) in formic-treated forage and it had disappeared on the AP treatment. At the end of the six week period, 1actic acid was highest on the contro1 (3.5% of DM) and 1ower in a11 treatments with added acid. This finding is in genera1 agreement with Huber gt 31. (1972) who observed marked decreases in 1actic acid of norma1 corn si1age after formic acid treatment, but sma11er decreases with added acetic or 105 pr0pionic acids. However, their studies used 1ower 1eve1s of acid (0.4-0.6%). More tota1 acid production was observed on the contro1 com- pared to acid treatments. Formic acid in these unprotected conditions did not have as strong or depressing effect on fermentation re1ative to pr0pionic and acetic as has been previous1y observed (Huber gt_al,, 1972). The recovery of acetic acid was very 10w (8%) on the acetic treatment indicating faster metabo1ism by micro-organisms (Tab1e 39). When pr0pionic acid was mixed with acetic the recovery of the 1atter was increased by more than three-fo1d. However, the recovery of pro- pionic acid was 10w on this treatment. When on1y pr0pionic acid or pr0pionic p1us formic (AP + F) were added, essentia11y a11 the propi- onic was recovered indicating the strong inhibitory effect of these acids on factors which might degrade or re1ease pr0pionate. The formic acid recovery was 66 and 69% of that added which is consider- ab1y higher than that reported for si1age addition (Huber et_al,, 1972). Protein and NPN Content of Corn Forages The crude protein content of the different forages averaged about 9% of the DM (Tab1e 40). This 1eve1 did not change appreciab1y 106 for any of the treatments during the 6 weeks of storage. However, highest decreases were observed on contro1 and acetic acid treatments which probab1y resu1ted from the faster temperature rises. These observations support those of Huber et_al, (1972) who observed higher increases in tota1 nitrogen on acid than contro1 treated si1ages. Increases in NPN content during storage did not differ be- tween treatments. Thus, no apparent decrease in proteo1ysis resu1ted from acid treatment as shown in previous studies (Huber et al,, 1972; Saue and Breirem, 1969), which did not use unprotected forages. Acceptabi1ity of Corn Forage A11 forages except that treated with acetic acid were fed ad 1ibitum to 70 heifers averaging 437 kg in body weight (14 per group). In addition to the forages 6.4 kg protein supp1ement was fed (0.45 kg/ heifer). The acceptabi1ity tria1 was on1y for a short duration (5 days) because of the 1imited amount of si1age avai1ab1e and tested whether heifers wou1d consume corn forage treated with about doub1e the norma1 1eve1 of acid. Highest intakes (Tab1e 41) were recorded for the contro1 forage (14.4 kg of 0M) and the 1owest on pr0pionic acid (9.7 kg). This 1ower intake on pr0pionate might be re1ated to a greater depression in fermentation or the pungent sme11 usua11y re- ported for pr0pionate treatments. More data are needed to definite1y 107 estab1ish the re1ative inf1uence of high 1eve1s of the acids on intake of ruminants, but these do show that forages treated with as high as 3% acid (on DM basis) wi11 be consumed by catt1e. During the feeding tria1 the temperature was recorded for the different forages (Tab1e 41). Lowest temperatures were observed on the AP and pr0pionic treatments. These data support the depression in after-fermentation by pr0pionic acid which was reported with rye forage and is in agreement with observations of Danie1 gt_gl, (1970) and Weise and Danie1 (1970). The high temperature observed on the contro1 treatment during the feeding tria1 might be expected to de- crease intake and increase spoi1age if the forages were he1d for a 1onger period of time. Tria1 II Temperature and Amount of Spoi1age In this study, changes in temperature and time when spoi1age first occurred were recorded. Resu1ts are given in Tab1e 42 and treatments are referred to according to number given in Tab1e 36. Dry matter of the first 47 treatments averaged 38%, whi1e that of the 1ast 4 treatments averaged 44%. The initia1 temperature for the first 47 treatments ranged from 18-23 C whi1e that of higher DM 108 treatments averaged 27.5 C. Simi1ar to previous findings, spoi1age was first detected on the contro1 treatment, at 3 days. The 1ast treatments to spoi1 were 1.5, 1.0, and 1.25% pr0pionic acid, at 28, 25, and 23 days after storage, respective1y. Nineteen to twenty days after treatment Spoi1age was detected on treatments 25, 4, 20, 32, and 33. When comparisons are made according to 1eve1 of acid used (Figure 5), pr0pionic acid treatments seemed to de1ay spoi1age more than any other acid or combination of acids. The combination of propionic acid and formic acid at (1.0, 1.25, 1.5, and 0.75%) was more effective in de1aying spoi1age than when acetic was present. When a11 three acids were used in different combinations and 1eve1s spoi1age was detected ear1ier as the contribution of the acetic acid increased. A1so, as the pr0pionic acid 1eve1 increased spoi1age was de1ayed whi1e the effect of formic acid retarding Spoi1age was inter- mediate. These resu1ts agree with those of the previous tria1s and of other researchers (Danie1 gt 31,, 1970; Weise and Danie1, 1970) who observed strong fungicida1 properties for propionic acid whi1e formic acid was the most effective in retarding bacteria1 growth. Simi1ar to previous resu1ts, a negative corre1ation was found between average temperature and time of spoi1age (-0.54). At the end of the five weeks experimenta1 period most treatments had spoi1ed com- p1ete1y and on1y very 1itt1e recovery occurred on treatments 3, 16, 24, which were pr0pionic acid treatments. 109 The resu1ts are in agreement with those reported ear1ier indi- cating the superiority of pr0pionic acid as a preservative under aerobic conditions fo11owed by formic acid. A1so, they suggest that acetic acid is not as good a preservative for minima11y protected forages as pr0pionic or formic. 110 mN.— g F u a F om mN.P m p u < _ mp mN.F a F n < _ mp 34 a 2 mm; a 2 mm; < 2 o.P u ¢.o " a P u < m.o vp 0.9 u m.o ” m p n < ¢.o m— o.P u «.0 u a m.o " < p N— o.P m m.o " a ¢.o " < P FF o._ m p u a m.o " < ¢.o op o.— m p u a e.o ” < m.o o o.F u — n a P u < F m o; n. _ u a P N o.P m p u < F o o.~ a F u < — m o.F any twum owELom e o.P Aav 6266 uw=o_aoca m o.~ Acmz 8m__oam mxmmz mxmmz “cmspmmcp 26848 mama so AQOV mmgzumemqemh a so AH 4m omhumum< m< mwmo mm m4m68 888888808 88.8 88.8 -- -- -- -- -- 88.8 88.8 _.8 8.8 8 88.8 88.. -- 88.8 88.8 88.8 88.8 88.8 88.8 8.8 8.8 8 88._ 88._ 88._ 88._ -- 88.8 88.8 88.8 88.8 88.. 88.8 8.8 8.8 8 + 88 88.8 88._ 88.8 88._ -- _8.8 --- -- -- 88.8 --- 8.8 8.8 8 88.8 88.8 -- -- 88.8 88.8 88._ _8.8 88._ 8.8 8.8 88 88.8 _8.8 --- -- -- -- -- _8.8 -- 8.8 8.8 _868888 -----------------868882 880 811-1----------1---------- 8 8 8 8 8 8 8 8 8 8 8 8 8 8888888888 886588688 8888 8888» 885808 888884 8888888 888888088 uwumu< m AH 88888 .8 88888 82888888288288 oHo< uHhu<4 oz< <8> .za mw .05). Also, silage DM intakes did not differ between treatments (P > .05). The average milk production and persistencies for the 4-week experimental period were not significantly different (P > .05) among treatments but were slightly higher on the formic acid plus urea than other groups. Butterfat content was not affected by the HMEC treat- ments (P > .05). However, highest fat percentage (3.7%) was observed on the formic acid treatment. The formic acid treated HMEC with or without urea were ap- parently consumed as well as the control or Pro-Sil treatments. How- ever, differences in palatability of the rations were not detected because intake was limited to l kg/2.5 kg milk. The primary concern at the beginning of the trial was whether the cows would readily con- sume the HMEC treatments, which they did. It was thought that ad libitum feeding might depress appetite and milk yields and make inter- pretation of differences very difficult. Our findings agree with reports indicating no effect on palatability due to pr0pionic acid treatment of high moisture corn (HMC). The small differences in butterfat percent between treatments are in agreement with a recent 136 report by Jones (1972), who concluded that depression in fat percent is not caused by feeding acid treated HMC as the only cereal grain. The results of this study indicate that formic acid (0.5%) can be used on HMEC (54% DM) without adverse effects on feed intake, milk production, and milk fat percent. Trial II The HMEC used in this trial averaged 66% DM. Urea-treated HMEC was higher in crude protein (Table 48) than when no urea was added. Also, urea treatment doubled the NPN in HMEC. The higher level of crude protein in the formic-treated HMEC is difficult to explain. It might have been due to application or sampling errors, but this is doubtful. Perhaps the formic acid was more effective in decreasing proteolysis and nitrogen losses, but this was not reflected in a lower NPN content. The pH was determined during the feeding trial and Pro-Sil treatment had the highest pH (7.0), while the lowest pH value was on the control treatment without urea. This observation indicates that the low level of acid used in this study was not sufficient to compete with high buffering effect of 1% urea. The pH values on the different treatments were not much higher than those found by Jones (1970) to inhibit mold formation and Spoi1age of HMC. 137 Acetic acid was the only VFA detected on the different HMEC samples. The highest level of acetate was found in the acetic treated material, indicating that greatest fermentation had occurred on this treatment. The pr0pionic acid treatment had the highest lactic acid concentration, followed by the urea and the acetic acid treatments. Formic acid depressed lactic acid production, which agrees with find- ings of the previous trials. However, contrary to what was observed before, Pro-Sil treatment in this study depressed lactic acid produc- tion probably because of the high levels used (3.6% on a fresh basis). Milk production, persistency, milk composition and feed intake are given in Table 49. Differences in milk production among treatments were not significant (P > .05). However, persistency of milk produc- tion during this study was highest on the urea treatment followed by acetic acid with the pr0pionic acid group the lowest. These differences in milk yields might be related to differences in HMEC intakes which were also lower for cows fed pr0pionic-treated HMEC. Butterfat percentages were not affected on acid treated HMEC; which is in agreement with the observation of Jones (1972). Neither differ in milk protein or SNF between treatments, which is also in agreement with the findings of Jones (1970), when he compared acid treated and untreated HMC. The combination of acid plus urea treatment of HMEC did not adversely effect the intake or production of animals. However, HMEC I38 intake was highest on control treatment without urea and lowest on the propionic acid-urea treatment, even though differences among treatments were not significant (P > .05). Cows fed the propionic acid treated HMEC also ate less alfalfa haylage even though differ- ences were also not significant (P > .05). These observations are in apparent contrast to those reported by Marion gt_al, (1972), and Bridson (1972), who noted more gain and better efficiencies in steers fed acid treated compared to control HMC. However, more data is needed to establish this effect because none of the differences were significant and the duration of the trial was quite short. The changes in temperature are given in Table 50. The acid treatments had the lowest temperature during the last week of stand- ardization period and also during the three weeks of the experimental period. The lower temperatures on the acid treatments suggests 1ess chances of spoi1age or mold development. Therefore, less proteolysis and better preservation might be expected over an extended feeding period. The results of this short feeding trial are in agreement with those of the previous tria1 indicating that acid treatment of HMEC did not adversely affect the performance of lactating dairy cows. 139 TABLE 46 DRY MATTER, NITROGEN, NPN, pH AND LACTIC ACID CONCENTRATIONS OF HMEC AS INFLUENCED BY ACID OR NPN TREATMENT (PART 4, TRIAL I) Total Lactic Treatment DM Nitrogen NPN Acid H -------------- % Dry Matter--------------- Control 53.22 2.54 0.65 2.92 4.0 Prosil (2%) 55.30 2.95 0.78 4.25 4.3 Formic (0.5) 53.70 2.48 0.66 1.94 3.9 Formic (0.5) + Urea (0.5) 53.52 3.18 0.91 1.83 3.8 TABLE 47 MILK PRODUCTION, PERSISTENCY, BUTTERFAT AND FEED INTAKE 0F CONS FED VARIOUS HMEC TREATMENTS (PART 4, TRIAL I) Mi1k Persis- b HMECb Si1ageb Treatment Yieldb tencyab Fat Intake Intake kg/day % % kg DM kg DM Control 18.8 87.3 3.3 4.5 5.9 Prosil (2%) 19.6 90.3 3.4 4.3 5.3 Formic (0.5%) 19.2 89.4 3.7 4.5 5.3 Formic (0.5%) + Urea (0.5%) 20.6 92.4 3.2 4.7 5.7 Treatment Standardization X 100 bNone of the differences between treatments were significant (P > .05) 140 TABLE 48 CHEMICAL COMPOSITION OF HMEC TREATED WITH NPN AND ORGANIC ACIDS (PART 4, TRIAL II) . Acetic Lactic * Treatment DM Protein NPN Acid Acid pH ------------------ % Dry Matter-—---------------- (0.7) F + U 64.84 14.03 0.69 0.34 0.74 4.6 (3.6) Prosil 67.41 11.42 0.60 0.69 0.73 7.0 (0.6) A + U 67.90 12.06 0.69 3.30 1.31 4.4 (0.6) P + U 61.80 11.35 0.72 0.11 1.52 4.6 (1.0) U 67.58 12.22 0.74 0.42 1.38 5.6 Control 68.53 9.07 0.35 0.11 0.99 4.3 *Acid treatments contained 1% urea. 141 .Amo. A n: HCMwawcmwm wLmZ mucmEHQmLu. :mm3umn mmucmeLin 0.3. $0 mcoz 8 88888888888888m co. x 888288888 8 8.8 8.. 88.8 .8.8 8.8 88.88 ..8. .888888 8.8 ..8 88.8 88.8 8.8 8...8 8.8. 8 .8... 8.8 8.8 88.8 88.8 8.8 88..8 8... 8 + 8 .8.8. 8.8 8.. 8..8 88.8 8.8 88.88 ..8. 8 + 8 .8.8. 8.8. 8.8 .8.8 88.8 8.8 88.88 ..8. .88888 .8.8. ..8. 8.8 88.8 88.8 8.8 88.88 8.8. 8 8 8 ...8. 88 88 88 88 8 8 8 8 888.88 8688.888 8888 88.68888 8Z8 888868888 8888868 8..: 88688868. 88.88.8 8 8..8 8 8 -888868 8 . AH. 4 own mzou mo mxuzmhm.mmma oz< onHuaooaa xAHz mv w4m .05). Cows consumed 7.9, 7.4, and 9.6 kg of DM/day on control, formic and AP, reSpectively. In a second trial using 220 liter drums, best preservation occurred on treatments containing 1.0 and l.5% mixture of (lF:lAP). This material was readily consumed by animals and correlations fol- lowed a trend similar to those observed in trial I. In trial III, a combination of acid treatment and packing was examined in an effort to determine the possibilities of reducing the level of acid needed for good preservation. Correlation again followed a trend similar to those reported above. PrOpionic acid was superior to formic acid as preservative for minimally protected forages. Packing with acid treatment increased DM recovery even when ensiled material was aerated every week. Changes in ADF and ADF-N were not different among treat- ments (P > .05). In trial IV, the intake of 0.4% formic acid-treated rye silage, stored in conventional upright silos, were slightly higher than those of control rye (8.3 vs 7.6 kg of DM), but differences were not significant. Also, changes in milk persistencies were in favor of the treated silage. In experiment 11, chOpped corn forage (38% DM) was treated with different acids and left unprotected. Similar to the previous observations, the control molded first and had the highest early tem- peratures. Acetic acid treated forage molded next and propionic acid treatment maintained the lowest temperature throughout the six weeks 145 period and was the last treatment to Spoil. The AP, AP + F and formic treatments were intermediate with respect to time of first spoilage detection and increased temperatures. Correlations fol- lowed a pattern similar to that observed for rye forage. Formic acid treatment maintained the lowest pH values. However, total organic acid production was higher on the control than on formic and propionic acid treatments. The protein and NPN contents were not affected by the different acid treatments. All corn forages except the acetic acid treatment were fed to heifers (for 5 days) and least intake occurred on pr0pionic acid treatment. However, AP and pr0pionic treatments had the lowest temperatures during the feeding period indicating an inhibition of after fermentation and better preservation if the corn were fed for an extended period. In the second trial, Sl forages were treated with different levels and combinations of formic, acetic and pr0pionic acids. Treatments containing 1.5, l.0, and 1.25% pr0pionic acid were the last to Spoil. Earlier spoilage was detected as the portion of acetic acid increased. Experiment III was conducted to determine the effectiveness of acid treatment on peripheral preservation. In trial I, more silage was lost on the control compared to AP treatment (64 vs 23.8%). Addi- tion of pr0pionic to formic decreased the amount of molded DM by 38% when compared to formic alone. Preserved material was fed to lactating 146 cows and intakes of 9.5, 9.4, 8.3, and 9.0 kg of DM recorded for the AP + F, AP, formic, and control treatments, respectively. When high DM (50%) corn silage was used the control treatment resulted in the highest amount of molded DM (90%) and the pr0pionic acid treatment had the least (9.7%), whereas, formic acid resulted in better preser- vation than AP or acetic acid treatments. Hhen acids were sprinkled on t0p layers of horizontal silos (trial II) similar observations to those reported above were observed indicating the superiority of pr0pionic acid as silage preservation even under poor ensiling condition. Experiment IV was conducted to determine the influence of or- ganic acid treatment on urea-treated HMEC. Formic acid depressed lactate formation, indicating a depression in fermentation. However, the concentrations of lactic were normal when urea was added to formic acid treatment. The urea-formic acid treated HMEC resulted in higher intakes even though differences were not significant (P > .05). Also, milk production and persistency and milk composition were not affected by the acid treatments. In trial II, acetic acid-urea-treated HMEC resulted in higher intakes and milk production when compared to treat- ments with or without urea and treated with pr0pionic or formic acids even those differences were not significant. The control and Pro-Sil treated HMEC had the highest temperatures during the feeding trial. 147 The results of these studies clearly indicate the superiority of pr0pionic acid over formic and acetic acids or combination of acids as a silage preservative under minimal protection conditions. PrOpionic acid might be used by farmers to protect silage placed in Open silos and allow them to expand their Operations with minimal losses even if they lack storage facilities. Presently, farmers avoid Open storage because of the high losses. Also, the techniques used in this study could be used by farmers who would rather not treat all their silages but want to avoid peripheral losses. Treatment of the t0p l0 to l5% of the silage placed in upright silos with l% propionic acid at the blower will reduce spoilage. For horizontal silos pro- pionic acid application to the one ft of surface material will decrease losses. These data also show that moderate compacting greatly in- creases the effectiveness of pr0pionic acid in reducing wastage. Thus, less acid would be needed for moderately packed material. The fermentation characteristics observed in these studies are similar to those reported for acid treated silages. Formic acid addition (l%) to loose forage depressed fermentation and retarded Spoilage at least for 7-l0 days. The same level of pr0pionic retarded Spoilage for about twice as long but did not have a depressing effect on fermentation as formic. Intake of silages by animals was not ad- versely affected by high acid treatments. 148 These studies clearly showed a direct relationship of pH to the amount of DM spoiled. Acid treatments, especially formic and propionic acid, resulted in lower pH values and less loss. However, intakes of animals were not depressed by the low pH of the silages. The results indicate that spoilage can occur if temperatures in forages exceed 35 C. PrOpionic and formic acids were shown to delay the rises in temperature and therefore protected the forages for longer periods. The farmer must take extreme precautions when applying these acids. Also, the acids should be applied or sprinkled as uniformly as possible in order to obtain the most desirable response. 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APPENDIX APPENDIX TABLE A1 SIMPLE CORRELATION COEFFICIENTS Part & Tria1 Var1ab1e I Var1ab1e II d.f. 1, I Changes in Temperature Amount of Molded DM 1 +0.98 Changes in Temperature Changes in pH 1 +0.98 Changes in Temperature Changes in VFA 1 -O.46 Changes in Temperature Changes in Crude Protein 1 -O.62 Changes in Temperature Changes in NPN 1 +0.82 Changes in pH Amount of Molded DM 1 +0.92 Changes in pH Changes in VFA 1 -O.29 Amount of Molded DM Changes in VFA 1 -O.61 1, II Changes in Temperature Date of First Mold Detection 9 -O.93* Changes in Temperature Changes in pH 9 +0.76* 1, III Changes in Temperature Amount of Molded DM 5 +0.53 Changes in Temperature Amount of Invisible Loss 5 +0.69 Changes in Temperature Changes in pH 5 +0.37 Changes in pH Amount of Molded DM 5 +0.13 Changes in pH Amount of Invisible Loss 5 +0.29 2, I Changes in Temperature Date of First Mold Detection 4 -O.81* Changes in Temperature Amount of Molded DM 4 +0.40 Changes in Temperature Changes in pH 4 +0.11 Changes in pH Date of First Mold Detection 4 -O.46 2, II Changes in Temperature Date of First Mold Detection 49 -0.54* 3, II Changes in pH Amount of Molded DM 3 +0.66 *(P < .05). 157