l l w H HHI \l W LIBRARY Michigan §me Univu'nty THE USE OF AUTOLYZED LIQUID BREWERS YEAST AND BREWERS' WET GRAINS AS A SOLE SOURCE OF SUPPLEMENTAL PROTEIN FOR DAIRY HEIFERS By Edgar Omar Bautista A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Dairy Science 1978 ABSTRACT THE USE OF AUTOLYZED LIQUID BREWERS YEAST AND BREWERS' WET GRAINS AS A SOLE SOURCE OF SUPPLEMENTAL PROTEIN FOR DAIRY HEIFERS by Edgar Omar Bautista Studies were conducted during the summer of 1977 to determine the feeding value of liquid brewers yeast and brewers' wet grains as a sole source of supplemental protein. Five groups of ten Holstein heifers were fed during a period of 90 days one of the following rations: positive control 11.5% C.P.; low level of yeast 11.0% C.P.; high level of yeast 13.1% C.P.; brewers' wet grains 12.4% C.P.; and negative control 8.5% C.P. Values for rumen fluid ammonia and VFA, plasma urea and plasma glucose were not affected by the different rations. It was found that autolyzed liquid brewers yeast can be used as a sole source of supplemental protein in a ration 13.1% C.P. Heifers in this ration gave as good or better performance than heifers in the positive control.ration, when soybean meal was used as a sole source of protein in a ration containing 11.5% C.P. To my Wife, Cecilia, who generously encouraged me during my studies, To my Son Omar To my Daughter Erika ACKNOWLEDGMENTS The author extends his sincere appreciation to his major professor, Dr. Robert M. Cook, for his guidance, and encouragement throughout the pursuit of this degree. Sincere appreciation is extended to Dr. J. William Thomas for his valuable assistance during the trial. The author is grateful to Dr. Roger Neitzel for his valuable assistance of the computer analysis, and Dr. John Gill for his assistance in the statistical design. Thanks are extended to Laurie J. Allinson, Carlos Godoy and Bill Neppach for their help in feeding the cattle, and Bill Wheeler for his assistance in technical analysis. This work was made possible by a grant from the Stroh Brewery Company. The author's graduate studies at Michigan State University were financed by the Foundation "Gran Mariscal de Ayacucho" of the Republic of Venezuela. iii TABLE OF CONTENTS page LIST OF TABLES 0.0.0.000...0.000.000.0000...OOOOOOOOOOOOOOOOOOO Vi Uflmmmflflm..u.u.u.u.n.u.u.n.n.u.u.u.u.u.u.u. 1 LITERATURE REVIEW ............................................. Brewers' Grains in Animal Feeding ........................ Chickens ............................................. Pigs ................................................. fibbits 0.00.0000...I.........OOOOOOOOCOOOOOOO00...... C» \n t~ to \n \» cattle ......OOOOOOOOOOOOOC0....OOOOOOOOOOOOOOOOOOOOOO q YeastinA-nimal Feeding ......OOOOOOOOOOOOOOOOOO0.0.0.0... ChiCkens 0......O0.00.0000.........OOOOOOOOOO00.0.0... 7 Pigs ......OOOOOOOCOOOOOO......OOOOOCOOOOOOOO0.0.0.... 12 fits 0.00.00.00.00.00000000000000000.....OOOOOOOOOOOOO 13 Sheep ......OOOOOOOOOOOOO0.0......OOOO...0.00.00.00.00 13 cattle 0.0.0.000...OOOOOOOOOOOOOOOOO00......0.00.00... 1-4 EXPERIMENTAL PROCEDURE ........................................ 17 Experimental Design ...................................... l7 Treatments ............................................... 17 Feeding and General Management ........................... 18 Sample Collection .... 20 Analytical Methods ... 20 Statistical AnBlYSiS .....OOOOOOOOOOOOOOOOO ..... 0000...... 22 page RESULTS AND DISCUSSION .0.........0..0..OOOOOOOOOOOOOOOOOOOOOO u CONCIIIJSIONS .....OOOOOOOO......OOOOOOOOOOOOO......OOOOOOOOOOOO 39 mmm ......OOOOOOOOOOOOOOOOOOOOOOOOO...OOOOOOOOOOOOOOOOOOO LO LITERATURE CITE OOOIOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO. 55 LIST OF TABLES Table Page 1 Rations used in Brewers' Wet Grains and Autolyzed Liquid Yeast Study .0.........OOO0..........OOOOOOOOOOOOO. 40 2 The effects of three different protein supplements on growth and feed consumption in dairy heifers (soybean meal, autolyzed yeast, brewers' wet grains) ..... 41 3 Percentage of total protein from each feed within a diet and dry matter content of the rations ............. 42 Effects of diets on Rumen Ammonia levels (mg% NeNH4) ..... 43 Effects of diets on Plasma Urea levels (mgfl N-NHA)_....... 43 Effects of diets on Plasma Glucose levels (mg% N-NHL) .... 44 Effects of diets on Rumen pH values ...................... 44 o: «J ox U1 p~ The concentration of Rumen fluid VFA Cqmoles%) within treatments at day 0 of the experiment .................... 45 9 The concentration of Rumen fluid VFA.(qmoles%) within treatments at day 30 of the experiment ................... 46 10 The concentration of Rumen fluid VFA (qmoles%) within treatments at day 60 of the experiment ................... 47 11 The concentration of Rumen fluid VFA (qmoles%) within treatments at day 90 of the experiment ................... 48 12 The molar percent of Rumen fluid VFA within treatments at daYOOf the experiment ..........OOOOOOOOOOOOOOOOOO... 49 13 The molar percent of Rumen fluid VFA within treatments at day 30 Of the experiment 0............OCCOOOOOOOOOOOOOO 50 14 The molar percent of Rumen fluid VFA within treatments at daywOf the experiment .....OOOOOOOOOOOOOOOOOO0...... 51 15 The molar percent of Human fluid VFA within treatments at, day%0f the experiment .....0......OOOOIOOOOOOOOOOOOO 52 vi Table Page 16 Analysis of Variance for body weight athays ....O.....OOOOOOOOOO00.........OOOOOOOQOOOOOOOOO 53 17 Crude protein (% dry matter basis) and dry matter composition of brewers liquid yeast, brewers' wet grains and soybean meal ..................... 54 18 Unadjusted average body weight (lbs.) per treatment at different periods during the trial .......... 54 vii INTRODUCTION As a large processor of farmpgrown grain, the brewing industry is an important source of income for the farmer. By converting its bybproducts into feed ingredients, it fully utilizes this grain without waste. In fact, approximately 25% of the grain by volume and a much higher percentage by nutritive value is returned to the farm in the form of feedstuff with prOperties and nutrients not possessed by the raw grain. water soluble vitamins and other nutrients are developed in the barley during germination, while the proteins are modified into more readily assimilable and, therefore, more efficient nutrients for animal feeding, (Anonymous, 1950). In the United States all brewers yeast are strains of the genus Saccharomyces cerevisiae, a single-cell, egg shaped microorganism consisting of an outer membrane which protects the protOplasm in the cell and its constituents. This membrane is of selective permeability and plays an important part in the nutrition of the yeast cell as well as in the assimilability of its nutrients, (Anonymous, 1950). Brewers yeast represents the richest natural source of the highly important vitamins of the B-complex group. It contains ergosterol or pro-vitamin D, which upon irradiation with ultra-violet rays, is transformed into vitamin D. Brewers yeast is also an important source of proteins of high biological value and of minerals such as phosphoric acid, potassium, magnesium, calcium, and iron, (Fischer, 1944). The use of brewers yeast in veterinary medicine antedates the discovery of vitamins. The application of yeast was exterior for the treatment of eczema, as well as internal as a purgative, as a preventive of hoof and mouth disease and distemper in dogs, (Fischer, 1944). The National Academy of Sciences (1971) defined brewers' grains as the course, insoluble residue from brewed malt, and calssified them as protein supplements. It is apparent that brewers dried grains contribute a wide variety of essential nutrients which are considered in feed formulations for livestock and poultry rations. Brewers dried grains contribute primarily to the protein, amino acid, and energy content of feeds when this ingredient is used in formulation. The ingredient also furnishes trace minerals, B-vitamins and vitamin E. Linoleic acid in brewers’ dried grains can furnish a significant percentage of this essential fatty acid for poultry and swine, (Couch, 1976). The objective of the work in this thesis was to determine the feeding value of liquid brewers yeast and brewers' wet grains as a source of natural protein, when compared with soybean meal which is the standard source of supplemental protein in most dairy cattle rations. LITERATURE REVIEW Brewers' Grains in Animal Feeding Limited investigations on wet brewers' grains indicate that this product varies in nutrient composition, particularly in the moisture, capper and calcium content. The variable capper content is probably related to the type of tank lining in which the beer is prepared or to some other source of contamination in the manufacturing plant. The calcium level is determined largely by the calcium content of the water used by a particular brewery producing the grains, (Maclean, 1969). Spoiled wet brewers' grains can cause serious health problems when fed to animals. Oleas, (1977) recommends the use of propionic acid at the level of 2% or a mixture of formic acid (1.4%) and paraformaldehyde (0.1%) in order to avoid spoilage of wet brewers' grains when stored in silos. Some research on the nutritional value of brewers' grains for livestock has been conducted. Chickens Ademosun, (1973) found in growing chickens that increasing levels of brewers dried grains (BDG) resulted in significant increase in food intake. He also found that both the control diet (21.9% C.P.) and the 10% BDG diet (22.3% C.P.) supported a similar growth rate. However, higher levels of BBC in the diet significantly reduced growth rate. Couch, (1976) reported that BDG can be used at a level as high as 40% in commercial layer rations. Fertility and hatch- ability were improved when BDG were included in breeder and in turkey breeder rations. Eldred et al (1975 b) showed that cumulative egg production was significantly improved by the addition of 5% BDG to the diet. The addition of 10% BDG and 5% BDG plus yeast to the diet containing 0.528% sulfur amino acids significantly improved egg weights. The addition of 10% BDG or 10% BDG plus yeast to any diet resulted in a numerical increase of Haugh units when compared to the 5% level of ingredients. Eldred et al (1975 a) found that the presence of 10% BDG in diets containing 0.470% sulfur containing amino acids resulted in a significant decrease in egg weights. ' Some studies indicate that the inclusion of up to 10% BDG or a grain-yeast mixture in the diet is acceptable to the laying hen if the diet formulation is based on the nutrient composition of BDG (Damron and Harms, 1973 and Eldred et al 1975 a). Riga YOung and Ingram, (1968) found that there was a consistent decrease in average daily gain as the level of BDG in the diet supplied, from 50 to 100% of the supplemental protein in a corn-based diet for market hogs. They also indicate that BDG may supply up to 50% of the supplemental protein in a swine diet based on corn, without affecting rate of gain or carcass quality. BDG were reported to replace all of the soybean meal without significantly reducing reproductive performance, (Harmon et a1 1975). Wahlstrom and Libel, (1977) found that sows fed 20% BDG gained more and those fed 40% BDG gained less than control sows when all were fed diets calculated to be equal in energy and lysine content. The data reported showed that reproductive performance was very acceptable when either 20 or 40% of the total diet was BDG. Ademosun, (1976) stated that the high crude fibre content of the diets containing BDG has been responsible for low feed digestibility and; therefore, poor performance in terms of average daily weight gain or the quantity of feed required per unit of gain in finishing pigs. In one trial with pigs back-fat thickness and percent ham and loin decreased as the levels of BDG increased in the test rations. Rabbits 0mole and Ajayi, (1976) fed white rabbits with diets containing 0%, 15%, 30% or 45% BDG. BDG significantly improved food consumption in all the treatments, but the 30% and 45% BDG significantly depressed efficiency of feed utilization. while the 15% dietary BDG gave the highest rate of growth, the 45% dietary BDG treatment depressed daily body gains. Kidney fat significantly increased with increases in BDG levels of the diets. Dietary levels of BDG did not seem to have any significant effect on the weight of offals, skin and dressing value. (£12319. Preston et al (1973) improved feedlot performance by adding brewers grains to the rations of finishing cattle at either the 25 or 50% level. Problems associated with rumen keratosis when a high corn ration was fed were overcome by feeding brewers grains; liver abscesses were also markedly reduced. The net energy value of brewers grains was nearly the same as corn grain. Loosli and warner (1958) showed that cows receiving BDG produced more milk and more fat-corrected milk than those on the low-protein diet. They also gained more weight. In the same trial urea apparently was not as efficient as the nitrogen in BDG for milk yield or weight gain. Griffiths, (1971) working with dairy heifers found that levels of total fatty acids were depressed by the introduction of BDG to diets containing hay and BDG and BDG containing 5% molasses plus silage. Addition of BDG to either hay or silage depressed the digestibility of the total dry matter in the diet, but increased the digestibility of the oil fraction. In these experiments an increasing percentage of grains in the diets was associated with a decreasing calcium retention, which suggest that calcium supplementation is desirable, particularly for lactating animals. An extensive review of published reports show that BDG can be used effectively in dairy rations in levels ranging from 30-40% of the grain mixture, (Couch, 1976). Trials performed at Cornell University showed that BDG was an excellent source of protein for the lactating cow and was superior to ma, (Couch, 1976) . Hatch et a1 (1972) found that the effects of adding a mixture of 95% BDG and 5% brewers dried yeast as 5% of a semipurified, high-urea type ration for hereford steers produced significantly increased nitrogen retention.- There was also decreased rumen ammonia and plasma urea concentrations. These results point to increase urea utilization and its conversion to animal protein. Yeast in Animal Feeding Yeast was formerly evaluated according to its fermentation power. It was assumed that a yeast which had retained its ability to ferment had also retained unchanged all of its other characteru istics. It was overlooked, however, that in the living yeast cell reciprocal activities occur among the very labile and unstable substances. These activities continue during the storage of living yeast, with the result that the uninterrupted activities of the fermentative and other enzymes bring abouta degradation or even destruction of primary cell constituents. Live yeast has no advantage over dried dead yeast from a therapeutic view point. With preper drying of live yeast vitamin losses do not occur. It should also be mentioned that the animal organism can utilize only 60% of the living yeast cells, while dried dead yeast is completely utilized. It should be noted that the enzyme zimase is damaged by the digestive enzymes and consequently is without effect in metabolism, (Fischer, 1942). Chickens Balloun and Khajarern, (1974) reported that dried brewers' yeast did not improve feather meal protein utilization in poults. Yeast levels of 2.5 and 5.0% caused no significant effect on weight gain or feed utilization, nitrogen retention or protein digestibility, waldroup et a1 (1971) observed that broiler chicks fed diets with hydrocarbon yeast protein at levels of up to 15% in all mash- diets or up to 25% in pelleted diets grew as well as chicks fed ‘ the basal diet with no yeast (29.75% soybean meal). When the experimental diets were offered to the chicks on an ad libitum basis, there were no significant differences in body weight gains, average feed intake, or feed:gain ratios between chicks fed the diet with no yeast and those fed the diet with 15% yeast protein. It seems that the problems associated with high level feeding of hydrocarbon yeast protein are due primarily to problems associated with feed intake, such as appearance, dustiness, or other factors. waldroup and Hazen, (1975 b) found that the rate of egg production of hens fed diets containing up to 15% yeast derived from high pure alkane fractions was equal or superior to that of hens fed either an all-vegetable corn-soybean meal diet or a diet containing 5% peruvian fish-meal. Haldroup and Flynn, (1975 a) observed that chicks fed the diet containing the reference soybean protein had significantly greater body weight gain, consumed more nitrogen, and had superior nitrogen efficiency ratios: and net protein utilization scores than chicks fed any of the diets containing yeast grown on hydrocarbon feed stocks under varying processing conditions. Significant differences were observed among the various yeast samples indicating that the conditions under which these organisms are grown or stored may influence their subsequent nutritional value. Thus, standardization of processing and storage conditions should be established for the production of yeast grown on hydrocarbon fractions to obtain maximum nutritional value. Short-term experiments with poultry have consisted of evaluating various levels of both gas oil and npalkane grown yeast, ranging from 7.5 to 15% of the rations for broiler birds. The general finding is that levels of yeast up to 10% of the diet are invariably satisfactory. Above this level, results are some- what variable as they are for fish meal, (Shacklady, 1972). Van weerden and Shacklady, (1970) working with hydrocarbon grown yeast in rations for chicks found that growth rates of chicks were not adversely affected until the percentage of the L—type yeast reached 15% in contrast to the poorer growth rate observed when similar amount of torula yeast were fed. General results indicate that, 7.5% and possibly 10% of L—type yeast may be used to replace fish meal of equivalent protein content on a weight basis in the rations of broilers. Beck and Gropp, (1974) reported that alkane grown yeast can be used in quantities of 10% in broiler rations and 20% in rations for laying birds. 10 Tiews et a1, (1974) found that both the alkane grown yeast Lavera and Taprina supplemented with methionine could replace effectively fishmeal or soybean oil meal in diets for broiler chicks when used at about 15% of the diet. Shannon et a1, (1972) studying the effect of a n-paraffin grown yeast plus methionine on the growth and food intake of broiler chicks at 4 and 8 weeks of age found that the broiler chicks on the 20% yeast diet gained significantly less body weight than those on the control, 5 or 10% yeast diets at 4 and 8 weeks of age. At 8 weeks of age chicks fed the 5% yeast diet weighed significantly more than chicks fed any of the other diets. »Food intake was significantly higher for birds given 10% yeast than for birds receiving the control diet at 4 weeks of age or the 20% yeast diet at 4 and 8 weeks of age. Paliev et a1, (1972) found broilers averaged 1300g when 8 weeks by feeding a well-balanced mash composed of 18% torula yeast plus 16% fishmeal plus 44% of raw sugar, or 14% of torula yeast plus 13% of fish meal plus 52% yellow corn. Yoshida et a1, (1972 a), (1971. b), (1971. c), (1971. d) and (1975 e) observed in a multigeneration feeding experiment of hens fed either a control diet or a diet containing 15% of yeast grown on n-paraffin that there was a consistent trend of slower growth with less feed intake for chicks fed the yeast diet in all of the five generations. These authors suggest that the delay in growth of the chicks on the yeast diet was mainly due to the unbalance of nutrients in the yeast diet. 11 Yoshida et al, (1972) obtained excellent viability during growing and laying stages, high egg production with good feed conversion, normal egg size and adult body size, high fertility and hatchability when a diet containing 15% of hydrocarbon yeast was fed to chicks. Fertility of the yeast group of the fourth and fifth generations and hatchability of fertile eggs of the yeast group of-the fourth generation were higher and that of the fifth generation was lower than those on the control diet. The egg production and feed conversion by hens from the third generation fed a diet containing 15% of yeast grown on n—paraffin were higher than that on the control diet. Daily feed intake, average body weight, egg weight, fertility and hatchability were similar between those fed the yeast diet and the control group, (Yoshida et a1 1974). Yoshida et a1, (1975 e) observed that feed conversion and viability during the growing stage was almost identical between the hens on both the yeast and control diets. Both fertility and hatchability of fertile eggs was better on the yeast diet than those on the control diet. In the same trial no evidence was obtained indicating that the yeast contained a large quantity of heavy metals and polycyclic aromatic compounds to be injurious to human health through the meat and egg produced by the yeast feeding. Yoshida, (1974) showed during a test panel integrated for 116 people that the difference in the flavor of both meat and eggs from 12 hens fed either the control or yeast diet was so small that most of the people could not distinguish one from the other. Pigs Veum and Bowman, (1973) determined the effects of supplementing the diets with Saccharogzces cervisiae yeast culture (8.0.1.0.) as measured by the performance of piglets fed individually. At the 1.5 or 2.0% level S.C.Y.C. fed from 20 to 23 days of age did not produce any significant effect on the average daily gain and gain/feed of the piglets compared to the control diet. 8.0.1.0. fed at the 2.5% level from 2 to 23 days of age significantly depressed performance of the piglets compared to the control and 1.5% 8.0.1.0. diets. 3.0.1.0. fed at 1.5, 2.0 or 2.5% of the diet from 23 to 65 or 72 days of age did not have any significant effect on the performance of the pigs. Bowman and Veum, (1973) showed that the supplementation of swine diets with 2.0 or 1.5% S.C.Y.C. from 14 to 34 kgs. or 34 to 100 kgs. respectively did not significantly affect the performance or carcass characteristics of swine. Beck and Gropp, (1974) reported that 15, 20, and 10% of the yeast can be incorporated in rations for piglets, growing-fattening pigs and breeding sows, respectively without negative effects. ' Fevrier et a1, (1973) showed that 13% sulphite yeast or 25% yeasted—whey could replace 16.20% of the soybean meal in the ration for growing-finishing pigs. 13 Barber et a1, (1971) concluded that, in general, paraffin- grown yeast plus methionine and white fish meal are equally effective as protein supplements in cereal-based diets for growing pigs. Pigs fed barley meal plus yeast grown on hydrocarbon has as good a growth rate and feed conversion as pigs fed barley plus fish meal. There was a trend for the treatment in which half the protein added was from fish meal and half from yeast to give a better daily live weight gain and better food conversion, (Kneale, 1972). 3523 There were neither deleterious effects of feeding rats on diets containing up to 30% of yeast grown on gas-oil or yeast growing on pure n-paraffins as long as 1 year nor on rats fed diets containing up to 30% of yeast grown on gas-oil for a 2 year period (Groot de, et al., 1970 a, b, and c). Yeast grown on gas-oil diets had no effect on mortality, general condition or behaviour of the animals. Haematological values were not affected, liver and kidney function tests showed no unfavorable effects. There were no significant changes in the weight of the major organs nor in the gross and histological appearance (Groot de, et a1, 1970 a and c). Sheep Lambs receiving the ration containing yeast as a source of unidentified factors stimulatory to cellulose digestion in the rumen 14 consumed 2.24 lb. of feed daily per lamb and made daily liveweight gains of 0.21 lb. compared with 1.58 lb. of feed consumed and 0.05 lb. daily gain made by lambs not receiving yeast (Ruf, et al., 1953). From preliminary experiments, dried "fodder yeast" given as a supplement in relatively small quantities (about 3% of dry matter of the diet), greatly increased the utilization of poor quality hay (0.73%N) as measure by the hay intake and steady gain in the body weight, (Thomson and Tosic, 1949). gas: Mimura et al., (1973) showed that cattle fed hydrocarbon grown yeast as a substitution for fish soluble, fish meal and soybean meal had carcass grades which were a little higher than those of the control group. The cattle here was in good health throughout the experiment. There were no abnormalities in urine or internal organs. Results indicated that hydrocarbon grown yeast may be substituted for fish or soybean meal. Two different alkane yeast meal preparations (particle size 50 or 200 microns) plus methionine, or soybean meal plus methionine were incorporated into a milk replacer for calves to provide 70-75% of the total protein. The live weight gains obtained with the diet containing yeast particles of 50 microns were satisfactory, whereas they were unsatisfactory with the other two diets (Parvelle et., 1972). Skimmed milk powder was replaced by 5.0, 7.5 and 10% alkane- yeast in isonitrogenous and isocaloric milk replacer diets for male 15 calves. Weight gains and feed conversion were unfavorable influenced by 10% alkane yeast in the diet. There were no differences between treatments in carcass grading or serum urea content at the end of the experiment, (Kirchgessner and Roth, 1973). Beck and Gropp, (1974) reported that in calf rearing 20% skim milk powder could be replaced by 10% of toprina yeast plus 10% of whey powder. Hereford steers approximately 10 months old were used in a series of three digestion and nitrogen balance trials. In these studies, nitrogen retention expressed either as a percentage of the intake or as a percentage of the digestible nitrogren was not improved significantly by addition of the live-yeast cells to low quality roughage, high quality roughage or fattening rations, (Legendre, 1957). Lifestock sometimes consumes high levels of nitrates from high-nitrate water or feed such as drouth-stricken, high-nitrate silage. According to the University of Missouri (Feedstuffs, 1977), a yeast culture that has been termed a "lifesaving" feed ingredient will counteract the effect of nitrate poisoning. Baker et a1, (1955) and Richardson et a1, (1956) working with live yeast suspensions of ngglg’gpili§_and Saccharomypes cerevisiae feeding fattening rations for beef cattle found that the rate of gain and feed efficiency were essentially the same for the yeast groups as for the control group, the same results were found when 16 the digestibility of the rations were determined. Richardson et al. (1956) working with live yeast suspension of ngglgggtilig’and Saccharomyces cerevisiae in beef cattle rations showed that animals that had been fed yeast did not gain as well as those that did not receive yeast during the grazing phase of the experiment. Also animals receiving‘zggglg_gtili§ did not gain so well in the fattening phase as the others. The workers concluded that the addition of live yeast suspensions (3 billion live yeast cells/head/day) to beef cattle rations is not desirable. In Canadian experiments brewers' dried yeast equalled linseed meal for dairy cows. In Hawaiian trials, dried yeast fed as 25 to 35% of the concentrate mixture for dairy cows gave as nearly as good results as soybean oil meal, (Merrison, 1957). In summary, most of the research using yeast and brewers' grains have been done in chickens, pigs, rats, sheep and cattle. Workers have used hydrocarbon yeast, brewers yeast and brewers' grains in their experiments. Results indicate that both yeast and brewers' grains can be used in animal feeding without causing any negative effect on the productive life or health of the animal. More research needs to be performed on the toxic effects of peOple consuming products from animals which have been fed with yeast grown on pure n—paraffins. I EXPERIMENTAL PROCEDURE The experiment was conducted at the Michigan State University's dairy farm, from July 23 to October 21 of 1977. The objective was to test autolyzed liquid brewers' yeast and brewers' wet grains as a supplemental protein source in corn silage rations for dairy heifers. Experimental Desigg Fifty Holstein heifers from 10 to 22 months of age and from 827 to 940 1b.. of body weight were assigned in ten blocks of five animals each (one animal per treatment per block) in a complete block design with three covariates. The heifers were blocked by breeding group and the covariates were: age of the heifers, days of pregnancy at the beginning of the experiment and initial body weight of the heifers. There were 16 pregnant heifers at the beginning of the experiment and 24 at the end of it. According to the breeding group* there were four blocks catalogued as Worst, four as Best and two as Control. Treatments The experiment consisted of five treatments with ten heifers each. The treatments were designed to consist of five rations as follows: * M.S.U. Dairy Farm participates in a project where the sires are classified into three groups termed Control, Worst and Best according to the predicted differences in milk (PD milk). Offspring are also classified according to these three groups of sire which artificial inseminates or mate them. 17 18 1. Positive Control. 12.0% crude protein (C.P.) from corn silage and soybean meal. 2. Negative Control. 8.5% C.P. from corn silage. 3. Autolyzed liquid yeast. 12.0% from corn silage and liquid yeast. 4. Autolyzed liquid yeast. 14.75% C.P. from corn silage and liquid yeast. 5. Brewers' wet grains (B W G). 12.0% C.P. from corn silage and B W C. After the analysis for crude protein and dry matter were done on each of the rations the crude protein content for the treatments were as follows: (Table 1) 1. Positive Control. 11.5% C.P. from corn silage and soybean meal. 2. Negative Control. 8.5% C.P. from corn silage. 3. Autolyzed liquid yeast. 11.0% C.P. from corn silage and liquid yeast. 4. Autolyzed liquid yeast. 13.1% C.P. from corn silage and liquid yeast. 5. Brewers' wet grains. 12.4% C.P. from corn silage and brewers' wet grains. 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III use sesame Sb own. web he do.» 43 TABLE 4 EFFECTS OF DIETS 0N RUMEN AMMONIA LEVELS (mg% N—NHL) Treatment Grogp Time of Experimental Period (days) 0 3O 60 90 a ab As a Positive Control 11.5% C.P. 1.0 3.2 9.7 4.1 a ab BCD a Low Yeast 11.0% C.P. 1.1 4.2 4.5 3.5 a a A0 a High Yeast 13.1% C.P. 1.6 5.6 7.5 4.2 _ a ab ABCDb a BUG 12.4% C.P. 1.2 4.7 5.7 3.9 a b BD Negative Control 8.5% C.P. 1.3 2.2 2.9 -- * Figures within a column followed by the same capital letter superscript are not significantly different (P(0.0l). Figures within a column followed by the same small letter superscript are not significantly different (PC0.05). TABLE 5 EFFECTS ON DIETS ON PLASMA UREA LEVELS (mg% N-NHA) Treatment Group Time of Experimental Period (days) 0 3o 60 90 Positive Control 11.5% C.P. 3.0a 6.5A 9.7A 11.08 Low Yeast 11.0% C.P. 2.9a 7.2AB 8.0AB 9.6a High Yeast 13.1% C.P. 3.2a 9.6BC 9.2ABC 10.1.a ewe 12.4% C.P. 3.5a 9.0ABC 9.0ABC 11.3a Negative Control 8.5% C.P. 3.0a 3.4D 3.2D .... * Figures within a column followed by the same capital letter superscript are not significantly different (P<0.0l). Figures within a column followed by the same small letter superscript are not significantly different (P(0.05). 44 TABLE 6 EFFECTS OF DIETS ON PLASMA GLUCOSE LEVELS (mg%) -_..fi_ -1 vi“. h Treatment Group Time of Experimental Period (days) 0 30 6O 90 Positive Control 11.5% C.P. 57.08. 60.73 51.1Aa 63.98‘ Low Yeast 11.0% C.P. 57.0a 59.0a 60.7b 61.5a High Yeast 13.1% C.P. 58.38 62.58 57.7ab 68.0a ch 12.4% C.P. 56.8a 61.1a 60.0b 63.7a Negative Control 8.5% C.P. 57.0a 52.1a 62.4Bb --- * Figures within a column followed by the same capital letter superscript are not significantly different (P<0.0l). Figures within a column followed by the same small letter superscript are not significantly different (P<0.05). TABLE 7 EFFECTS OF DIETS ON RUMEN PH VALUES Treatment Group Time of Experimental Period (days) 0 3O 6O 90 Positive Control 11.5% C.P. 7.5a 7.411C 7.1AB 7.6ab Low Yeast 11.0% C.P. 7.5a 7.3ABa 7.0AB 7.78 High Yeast 13.1% C.P. 7.5a 7.4ACD 6.6A 7.2b ewe 12.4% C.P. 7.48 7.1Bb 7.1“!B 7.43b Negative Control 8.5% C.P. 7.3a 7.5CD 7.43 7.6ab * Figures within a column followed by the same capital letter superscript are not significantly different (P<0.01). Figu res within a column followed by the same small letter superscript are not significantly different (P<0.05). a>wrw 0 ea 82323582 on Hafiz 3:3 5..» $5380 :5le $9328 5. e: o 2.. 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