Fish meal as a protein supplement in ruminant diets: a review

Fish meal (FM) as a protein supplement in ruminant diets is presented to illustrate production responses to FM supplementation and to explain the possible factors that may affect the magnitude of these responses. Positive responses are consistently detected when FM is fed to nonruminants, but the responses when fed to ruminants have lacked consistency. Research indicates that ruminal protein degradation of FM is affected by processing factors including type and freshness of fish, addition of preservatives, stabilization of fat, type of dryer used, temperature and duration of heating, and the amount of fish solubles added back to the meal. Performance data published in the last two decades have been categorized into body weight gain and milk yield and composition. Fish meal was more effective in improving body weight gain in young than in finishing ruminants and in males than in females or castrated males. Daily gains and feed efficiencies were higher when FM supplemented medium- or poor-quality silages than when it was added to high-quality silages. No significant advantage was found for replacing protein sources that were highly ruminally degradable with FM in high-corn diets fed to growing ruminants. Milk yield and milk protein concentration were improved by FM supplementation of low-concentrate diets fed to cows in early lactation. However, milk fat percentage was negatively affected by FM supplementation. Reproduction data indicated that body gain and conception rates of high-producing cows were improved by supplementing their diets with FM during early lactation. Results suggest a significant advantage of FM supplementation to ruminant diets if the physiological status of the animal and the quality of the dietary ingredients are taken into account.     

Protein requirements of collared peccary (<Emphasis Type="Italic">Pecari tajacu</Emphasis>)

A nitrogen (N) balance digestion trial was conducted to determine the protein requirement of collared peccaries (Pecari tajacu). In a 4 × 4 Latin square design, four captive adult male peccaries were fed four isoenergy diets containing four different levels of N (11.7, 16.3, 22.8, and 26.7 g N/kg of dry matter—DM). After 15 days of adaptation, a total collection of feces and urine was carried out for five consecutive days. Regression analyses between N intake and N in feces and urine allowed to calculate the metabolic fecal nitrogen (MFN = 2.3 g N/kg of dry matter intake—DMI) and daily endogenous urinary N (EUN = 185 mg N/kg^0.75). Likewise, by regression analyses between consumption of nitrogen and the nitrogen balance (NB = N ingested ? N excreted, mg N/kg^0.75), a daily requirement of 514 mg N/kg^0.75 was calculated. Therefore, if food intake is unrestricted, collared peccaries require a minimum in their diet of about 5.4% crude protein on DM basis. These values are almost as low as those found for browsing and frugivorous wild ruminants, which reinforce the proposition that peccaries’ digestive physiology is nearer to that of domestic and wild ruminants than domestic pigs. This relatively low protein requirement of collared peccary and its great ability to digest protein reveal the relevance of the forestomach for the species on nitrogen/protein metabolism and allow the use of diets with lower crude protein levels than the commercial ones used for the domestic pig, which reduces feed costs.     

Performance, methanogenesis and nitrogen metabolism of finishing steers fed monensin and nickel

Sixty-four Angus steers initially averaging 354 kg were allotted to a 2 X 2 factorial arrangement of treatments to determine the effects of dietary Ni (0 or 5 mg/kg supplemental), monensin (0 or 33 mg/kg) and their possible interaction on performance, methane production and N metabolism. The basal diet was a high energy, corn-cottonseed hull based diet containing 10.2% crude protein and .30 mg/kg Ni on a dry matter basis. Monensin reduced (P less than .05) feed intake, did not affect average daily gain and improved (P less than .05) feed conversion over the 102-d study. Nickel supplementation did not significantly alter or interact with monensin to affect steer performance. However, steers fed Ni tended to have higher average daily gains and improved feed conversions. Monensin decreased (P less than .05) in vitro methane production, altered several carcass traits, increased (P less than .05) molar proportion of ruminal propionate and decreased (P less than .05) molar proportion of ruminal acetate. Nickel did not alter methane production, carcass characteristics or ruminal volatile fatty acid proportions. Both monensin and Ni increased (P less than .05) ruminal fluid urease activity when samples were obtained before feeding. A significant monensin X Ni interaction was found to affect ruminal epithelial urease activity. Monensin increased ruminal epithelial urease in steers not receiving supplemental Ni, but had no effect on ruminal epithelial urease activity in steers fed supplemental Ni. Ruminal fluid protein and ammonia-N were decreased (P less than .05) by monensin. Results of this study indicate that Ni may interact with monensin to affect ruminal epithelial urease activity but not performance or methane production in finishing steers.     

BOARD-INVITED REVIEW: Use of distillers by-products in the beef cattle feeding industry

The ethanol industry is expanding rapidly. This expansion in production of renewable energy also increases production of by-products. These byproducts, primarily distillers grains plus solubles (DGS), are utilized very efficiently by ruminants. When the starch in corn is fermented to produce ethanol, the remaining nutrients (protein, fat, fiber) are concentrated about 3-fold. Whereas DGS is an excellent protein source for ruminants, the large supply and the price relative to corn make DGS an attractive energy source as well. This is especially important with reduced availability and higher price of corn because of demand by the ethanol industry. A meta-analysis of 9 experiments, where various levels of wet DGS were fed to feedlot cattle, shows that wet DGS produced higher ADG and G:F compared with cattle fed corn-based diets without DGS. A similar analysis with dry DGS showed similar type of responses but with less apparent feeding value for dry DGS compared with wet DGS. Metabolism studies suggest the fat in DGS may be partially protected from ruminal degradation leading to greater proportion of unsaturated fatty acids at the duodenum and greater total tract fat digestibility. Both the fat and the undegradable protein in DGS appear to explain some but not all of the greater feeding value of DGS compared with corn. Lower quality roughages may be used in feedlot diets containing wet DGS because of the protein, moisture, and physical characteristics the DGS contains. The feeding value of DGS is greater than dry-rolled corn or high moisture corn; however, the feeding value of DGS appears to be less when fed in finishing diets based on steam-flaked corn than in those based on dry-rolled or high-moisture corn.     

Brewing by-products: their use as animal feeds.

Brewers grains, a by-product of beer production, are often used as a livestock feed. Because brewers grains provide protein, fiber, and energy, they can be useful in a variety of diets. Protein in brewers grains can meet a significant portion of supplemental protein requirements; in addition, they provide fiber and needed bulk in the diets of ruminants and horses. Brewers grains and other brewers by-products have also been fed to pigs, sheep, and poultry. Currently, the primary market for wet brewers grains is as a dairy cattle feed; however, some may be fed to beef cattle in feedlots. Brewers grains have historically been marketed wet or dry, but wet brewers grains currently make up the majority of the marketed product. Brewers grains provide protein, energy, and fiber in livestock diets, but product variability can influence their utilization and necessitate a testing program to determine nutrient content.     

Protein requirement and amino acid imbalance in quail

1. Growing Japanese quail were fed on purified diets based either on dried egg albumen or casein supplemented with methionine. 2. At low protein concentration body mass, N-intake and N-growth requirement of chicks fed on diets containing casein were impaired compared to those fed on diets with egg albumen: in contrast at higher protein concentrations performance was better among those fed on diets with casein. 3. Increased protein requirement was observed among birds fed on diets containing casein compared with those given dried egg albumen. 4. One of the reasons for the increased requirement was attributed to amino acid imbalance in the casein.     

Effects of a high-protein, low-energy diet in finishing lambs: 1. Feed intake, estimated nutrient uptake, and levels of plasma metabolites and metabolic hormones

Patterns of tissue mobilisation in ruminants are ill-understood. This hinders nutritional management to mitigate the effects of energy deprivation on protein mass, and nutritional regimens designed to change body composition. An experiment was conducted to comprehensively evaluate the effects of a low-energy high-protein diet in growing lambs. Three diets (CON = concentrate diet ad libitum, STR = straw ad libitum, SFM = straw ad libitum plus 150 g/d fish meal) were fed to growing white-face lambs. Analysis of feed intake and metabolite data provided evidence that greater available N did not have a synergistic effect on intake of low quality forage. Metabolite and hormone profiles of lambs in negative energy balance, supplemented with duodenally available protein, revealed that SFM animals did not respond with an accelerated rate of fat mobilization or maintain protein mass due to available N. This was particularly evident from the leptin profiles, which indicated higher circulating leptin levels for SFM compared to STR animals. Further, the data revealed that in sheep fed below requirements for maintenance, leptin levels did not correspond with acute ME intake, whereas the opposite was true for well-fed animals. Conversely, the response of the GH/IGF-1 axis to high protein–energy ratio (PER) diets was indicative of effects not explained by the difference in energy provided by the two experimental diets.

These results contrast with observations from intra-gastric infusion experiments testing similar PERs and previous conventional feeding trials and provide evidence of: (1) specific differences associated with PER in lambs fed via intra-gastric infusion vs. a conventional feeding approach, and (2) lack of usefulness of high PER diets in the post hoc modification of body composition of growing lambs. While positive N balance is known to occur in ruminants in negative energy balance, the determinants of relative proportions of muscle and adipose tissue catabolised under energy deprivation remain unknown.     

Application and Regulatory Mechanisms of Cereal Diets Treated with Lactic Acid in Ruminants北大核心CSCD

近年来,反刍动物集约化养殖中为追求快速高产,常饲喂高精料饲粮,但随之也带来一系列的危害。乳酸处理谷物饲粮通过改性淀粉,可调控反刍动物瘤胃发酵,增加其瘤胃消化抗性,使更多淀粉进入小肠消化,增加饲粮效率,并在缓解瘤胃酸中毒方面有积极的意义。本文主要分析了乳酸处理谷物饲粮对反刍动物瘤胃pH、胃肠道微生物、生产性能、饲粮中磷消化率、机体代谢组和炎性反应的影响及其潜在调控机制,为有效利用乳酸处理谷物饲粮、促进反刍动物健康养殖提供理论依据。     

脲酶抑制剂和粗料类型对育肥羊生长性能及内脏器官的影响

选择小尾寒羊母羔羊24只，体重20.5 kg左右，采用2×2析因试验设计。秸秆型日粮的粗料组成是玉米秸秆，苜蓿＋秸秆型日粮的粗料组成是苜蓿和玉米秸秆，每种粗料日粮设添加与不加20 mg/kg脲酶抑制剂共2个水平。进行90 d育肥试验，以研究在不同类型粗料日粮中添加脲酶抑制剂对育肥羊生长性能和内脏器官的影响。结果表明：①在不同粗料类型日粮中，添加脲酶抑制剂均能提高育肥羊的日增重，苜蓿＋秸秆型日粮较秸秆型日粮的育肥羊有较高的日增重。②粗料类型及脲酶抑制剂对试验羊的内脏器官没有影响。③日粮中添加苜蓿较添加脲酶抑制剂更能提高养羊者的经济效益。     

低蛋白质日粮中添加苏氨酸对北京鸭生长性能和血浆生化指标的影响

本试验采用单因素完全随机试验设计,通过测定不同日粮苏氨酸水平对1~21日龄北京鸭生长性能、屠宰性能和血浆生化指标的影响,研究低蛋白质日粮北京鸭苏氨酸需要量。240只1日龄雄性北京鸭按体重随机分为5个处理,每个处理6个重复,每个重复8只北京鸭,分别饲喂苏氨酸水平为0.41%、0.48%、0.55%、0.62%和0.69%的低蛋白质（17.65%）日粮,试验期为1~21日龄。结果表明,低蛋白质日粮中添加苏氨酸可以提高北京鸭体重、日增重、采食量和胸肌率（P<0.01）,降低料重比（P<0.01）。低蛋白质日粮中添加苏氨酸对北京鸭腿肌率,血浆ALT和AST活性,以及TP、ALB、GLB和GLU含量均无显著影响（P>0.05）,但是降低了血浆CHO、TG、HDLC和LDLC含量（P<0.05）。用直线-断线回归模型以体重、日增重、采食量、料重比和胸肌率为指标,拟合1~21日龄北京鸭苏氨酸需要量分别为0.594%、0.594%、0.595%、0.513%和0.607%。综合试验结果,当日粮蛋白质水平为17.65%时,1~21日龄北京鸭苏氨酸需要量为0.607%,此时,虽不能满足北京鸭的最大生长性能,但可以降低氮排放。     

Effects of Threonine in Low Protein Diet on Growth Performance and Plasma Biochemical Index of Pekin Duck

The present study was conducted to evaluate the threonine requirement for Pekin ducks in low protein diets by determining the effects of threonine on growth performance,carcass traits,and serum parameters.In total,240 1-day-old were randomly allocated to one of five dietary treatments with six replicate cages with eight duck for each treatment according to average body weight.They were fed low protein diets (17.65%) with 0.41%,0.48%,0.55%,0.62% or 0.69% threonine from 1 to 21 days of age,respectively.The results showed that threonine supplementation in low protein diets improved body weight,weight gain,feed intake,and breast muscle percentage,and reduced the ratio of feed to gain (P<0.01).Threonine supplementation in low protein diets had no influence on thigh muscle percentage,and the activity of ALT and AST,and the contents of TP,ALB,GLB and GLU in serum (P>0.05),but reduced the contents of CHO,TG,HDLC and LDLC in serum (P<0.05).The evaluated threonine requirement in low protein diets based on linear broken-line regression with weight,weight gain,feed intake,ratio of feed to gain,and breast muscle percentage were 0.594%,0.594%,0.595%,0.513% and 0.607%,respectively.In summary,the optimal dietary threonine levels would be 0.607% for Pekin ducks fed low protein diets from 1 to 21 days of age.Although which failed to support equal growth performance to that of high protein diets,it was possible to reduce nitrogen emissions.     

Effects of Excess Methionine from Meeting Needs for Total Sulfur Amino Acids on Utilization of Diets Low in Crude Protein by Broiler Chicks

Failure to obtain optimum performance by broilers fed low CP diets supplemented with amino acids may be due to a number of factors, including potential toxic effects of amino acids in excess of requirements. The objective of the present study was to evaluate the effect of excess levels of Met on performance of broilers fed low CP diets. Corn and soybean meal of known composition were used to formulate diets with 22, 20, 18, and 16% CP with 100 and 110% of NRC recommendations. DL-Methionine was used to meet Met and TSAA requirements; the dietary levels of Met exceeded minimum needs. Within each CP level, 2 additional series were prepared. For one series, only the amount of DL-methionine needed to reach the Met requirement was added, leaving a calculated deficit of TSAA. For a second series, excess Met was replaced with sufficient Cys to meet Met and TSAA exactly. Each of the test diets and a 23% CP positive control were fed to 6 replicate pens of 5 male broiler chicks from 1 to 21 d of age. Performance of the birds fed 22% CP diets did not differ significantly from that of chicks fed the positive control. Chicks fed diets with less than 22% CP had significantly lower BW and increased FCR regardless of level of amino acid supplementation. There was no significant effect of Met status on performance, indicating that corn-soybean meal diets do not appear to be deficit in Cys and do not respond to levels of Met greater than minimum NRC recommendations for Met. Excess levels of Met in this study did not appear to contribute to the reduced performance at low CP levels.     

Recent information on processing of grain for ruminants

When excessively processed cereals are given to ruminants a vast surface area of highly fermentable substrate is exposed to the rumen microorganisms. The subsequent effect on digestion and metabolism will depend largely on whether the cereal based diets are fed as the main or sole part of the diet or whether they are given as supplements to roughage based diets.Given as sole feeds, excessively processed grains can give rise to alterations in carcass quality (soft fat) in lambs, and problems of acidosis and rumenitis.Given as supplements to diets based on roughage, excessively processed grains can seriously reduce the rate of cellulose digestion with a consequent decrease in roughage intake and digestibility.The optimum extent of processing appears to be the minimum required to avoid an unacceptably low digestibility. The processing required is different for small ruminants (e.g. sheep, goats and calves) than for large (e.g. cattle).For sheep, grain should be fed whole; in general, processing does not increase digestibility or food utilization and can result in depressed cellulose digestion and in soft fat.For cattle some processing is required to ensure adequate digestion but the optimum is that required to give entrance through the seed coats to microorganisms and digestive enzymes. New methods, such as chemical treatment of whole grain, have given promising results.     

The role of ciliate protozoa in nutrition of the ruminant

The effects of ciliate protozoa on the ruminal ecosystem, digestion in different parts of the gut, the nature of nutrients available for absorption and their effects upon the nutrition and productivity of their host are reviewed. Compared with fauna-free ruminants, the presence of ciliate protozoa results in a more stable ruminal fermentation, higher levels of ammonia, reduced numbers of bacteria, as well as changes in dry matter (%), liquid volume and turnover rate of ruminal contents. Associated with these differences in the rumen are higher ruminal and total tract digestion of organic matter and fiber in faunated animals. A reduction in net microbial synthesis and an increase in dietary protein degradation in the rumen results in the flow of protein to the small intestine being lower in faunated ruminants. The major nutritional effect of the ciliate protozoa is to change the ratio of protein to energy in the nutrients absorbed, with faunated animals having lower protein and higher energy availabilities compared with ciliate-free ruminants. Of the nutrients available for absorption, the ciliates have no consistent effect on the proportions of volatile fatty acids or amino acids. However, there is evidence that hydrogenation of lipids is increased, as is the supply of choline, and that the bioavailability of copper is reduced by the presence of ciliates. Defaunation of young growing ruminants that are fed high energy diets, containing low levels of ruminal nondegradable protein, results in increased growth rate and feed efficiency. It is unlikely, with the possible exception of wool growth, that there are other situations in which defaunation will be beneficial; and it is more likely to be detrimental to animal productivity. It remains to be determined whether manipulation of the types of ciliate protozoa in the rumen could improve animal performance. Information for this review was largely derived from comparisons of faunated and fauna-free animals. However, it is indicated that there are large differences in protozoa numbers and types between naturally faunated individuals in the same flock or herd, and that the effects of such variations on their host's nutrition are unknown.     

Dietary management of chronic renal disease in dogs: A critical appraisal

Diets low in protein have been recommended for dogs with chronic renal failure (CRF) since 1948, and for apparently healthy old dogs since 1960. These recommendations were based on studies of rats and poorly documented clinical experiences with dogs. Since 1979, a series of eight experiments on partially nephrectomised dogs and four clinical trials on naturally occurring chronic renal disease have demonstrated serious disadvantages of diets that contained high (38 to 49 per cent on a metabolisable energy (ME) basis) or very low (3 to 10 per cent) protein. In addition to poor acceptance of low protein (12 and 16 per cent) diets, undesired responses included exacerbation of depressed renal functions, reduced renal reserve, severe hyperfiltration in single nephrons, metabolic acidosis, hypercholesterolaemia, and hypertension. Protein deficiency may not have caused the complications observed, and may have been due to another feature of the diets fed. In seven studies, diets with a moderate (20 to 31 per cent ME) protein level fared better in regard to reduced renal pathology and proteinuria, better renal functions and reserve, and improvement of clinical status, azotaemia, hyperphosphataemia and anaemia. In the first instance, preferred products for CRF should contain moderate (20 to 24 per cent) protein and minimal phosphorus. Taking into consideration these 12 kidney studies a protein content of 30 per cent is recommended for apparently healthy old dogs. Current recommendations are to introduce a diet that is low in protein at a ‘critical point’ in the course of CRF, when its advantages are likely to outweigh its possible disadvantages. When this critical point has been reached has not been determined, but it is likely to be based on an assessment of the individual case.     

Protein requirements of growing pups fed practical dry-type diets containing mixed-protein sources

The protein requirement of Pointer pups fed practical diets was assessed in 3 experiments. Eight-week-old pups required 25.2% protein when fed a combination of corn gluten meal, soybean meal, and meat and bone meal for 2 weeks. However, when a poor-quality poultry by-product meal was substituted for some of the corn gluten meal and meat and bone meal, the requirement increased to 27.5%. This increased requirement was explained by decreased digestibility of the poultry by-product meal diet. Pups fed each of the diets required 18% digestible protein to maximize growth rate. Sixteen-week-old pups were more efficient at utilizing the experimental diets, requiring only 23% crude protein (17.2% digestible protein) to maximize growth rate.     

Urinary pseudouridine excretion in lactating dairy cows

Introduction   A number of systems based on metabolizable protein, such as that adopted in the UK (A gricultural and F ood R esearch C ouncil 1992) have been developed to improve the accuracy of protein rationing for ruminants. Quantification of microbial protein synthesis in the rumen is a fundamental requirement of all such systems. In the UK system, microbial protein supply is predicted from an estimate of fermentable metabolizable energy intake, using a correction for the effects of level of feeding on the energetic efficiency of microbial protein synthesis. Use of such an approach is however subject to considerable error due to large variations in the energetic efficiency of microbial protein synthesis (A gricultural R esearch C ouncil 1984). Consequently there is an urgent requirement for an on-farm diagnostic marker of microbial protein supply as a basis for adjusting diets to maximize efficiency of dietary nitrogen utilization by dairy cows (D ewhurst et al. 1996). Urinary purine derivative excretion has been proposed as a noninvasive index of microbial protein supply in ruminant animals (T opps and E lliot 1965). Use of this microbial marker is based on the assumption that purines entering the duodenum are essentially microbial in origin (M c A llan 1982), and that following metabolism, their derivatives are quantitatively recovered in the urine (C hen et al. 1990; V erbic et al. 1990). Purine metabolites excreted in ruminant urine are primarily derived from the metabolism of absorbed purines, but as a consequence of tissue adenosine triphosphate and nucleic acid turnover, a proportion of purine bases are not salvaged and re-utilized, but enter catabolic pathways, constituting an endogenous loss.     

Protein and body weight accretion of chicks on diets with widely varying contents of soyabean meal supplemented or unsupplemented with its limiting amino acids

1. Two studies were conducted to evaluate the effects of relative deficiencies of methionine and threonine on the growth performance of 8- to 21-d-old chicks fed on isoenergetic diets containing a wide range of crude protein (CP) concentrations from dehulled soyabean meal (SBM). 2. Chicks fed on graded levels of SBM containing supplemental methionine and threonine (BAL) accreted whole-body protein more efficiently (P < 0.05) than those receiving graded levels of unsupplemented SBM (DEF), and superior (P < 0.05) growth performance was also obtained at lower CP levels when chicks were fed on the BAL diets. 3. Voluntary food intake increased between 30 and 220 g CP/kg in chicks fed on DEF diets, whereas food intake of chicks fed on BAL diets increased only between 30 and 100 g CP/kg, after which it decreased between 100 and 220 g CP/kg. 4. Protein efficiency ratio (g gain per g protein intake) decreased with each incremental increase in CP between 30 and 260 g CP/kg, regardless of whether diets were BAL or DEE 5. These data indicate that maintaining a balanced ratio of amino acids is a preferable approach when poultry producers are interested in employing low CP diets for economic, physiological or environmental reasons.     

An update of a dynamic model of ruminant digestion

The progressive development of a dynamic model of ruminant digestion for evaluation of factors affecting nutritive value of feedstuffs is outlined. Significant changes have been introduced in many of the interactive subunits that accommodate the digestion of 12 chemical constituents (soluble carbohydrate, organic acids, starch, pectin, hemicellulose, cellulose, lipids, soluble protein, insoluble protein, nonprotein N, lignin and ash), microbial growth, animal interactions and summary computations. Explicit consideration of soluble carbohydrates, organic acids and pectins has been replaced by an aggregate fraction. A section has been added to follow dynamic aspects of volatile fatty acid metabolism in the rumen. Evaluations of the model were made by comparing its behavior with that observed experimentally for sheep fed a number of diets. These included an alfalfa diet fed at two intake levels either hourly or once daily, a dried subterranean clover diet fed hourly, a forage oat diet fed every 3 h and an 80% concentrate diet fed twice daily. For frequently fed diets, model estimates, in general, agreed very well with experimental estimates. Although changes in representations of protein metabolism were helpful, the pool size of ruminal ammonia N was not simulated well. Digestion and passage in the model occurred more rapidly than was observed when animals were fed high-quality forages once daily and rates of particle size reduction, fermentation and passage were lower than observed when low-quality diets were fed. It was concluded that the model can serve as a useful and adaptable tool for analyzing factors affecting nutritive value. Particle size reduction and passage from the rumen, dynamics of protein metabolism and utilization, and water dynamics were identified as areas requiring further research.     

Effect of reovirus infection and dietary levels of selected vitamins on immunocompetence of chickens

The immunocompetence of 8-week-old reovirus WVU 2937-infected and uninfected chickens fed various dietary levels of biotin, niacin, choline, or folic acid was evaluated in four experiments. Antibody production to sheep red blood cells (SRBC), wattle responses to phytohemagglutinin-P (PHA-P), and wattle responses of tuberculin-sensitized chickens to bovine-purified protein derivative (PPD) were examined in five chickens per treatment. Dietary deficiencies had no effect on the in vivo T-cell immune responses to PPD, PHA-P, or humoral hemagglutinating-antibody production to SRBC. Reovirus-infected and uninfected chickens fed biotin at double the National Research Council (1977) requirement demonstrated decreased PPD responses. Lower hemagglutinating-antibody titers in the uninfected chickens and increased titers in the infected chickens were observed in those fed 200% of the requirement of biotin when compared with the chickens fed 20% and 100% biotin diets. Reovirus infection had no effect on PPD and PHA-P responses. However, in the choline experiment, reovirus-infected chickens had elevated titers. These data indicate that reovirus infection had no adverse effect on the immunocompetence of chickens 8 weeks postinfection. Dietary deficiencies also had no adverse effect on the immunocompetence of 8-week-old reovirus-infected and uninfected chickens.