- Email: [email protected]
Nutritional Investigations with Turkey Hens1
TRANSMISSION OF ASPERGILLOSIS monellosis in chicks. J. Infect. Dis. 106: 197210. O'meara, D. C , and H. L. Chute, 1960. Aspergillosis experimentally produced in hatching chicks. Avian Dis. 3 : 404-406. Wright, M. L., G. W. Anderson and N. A. Epps, 1959. Hatchery sanitation. Can. J. Comp. Med. 33: 288-290.
731
Wright, M. L., G. W. Anderson and N. A. Epps, 1960. Hatchery sanitation as a control measure for aspergillosis in fowl. 32nd Northeastern Conference on Avian Diseases, U. of Maine, Orono. Wright, M. L., and N. A. Epps, 1958. Hatchery sanitation. Can. J. Comp. Med. 22: 396-399.
Nutritional Investigations with Turkey Hens 1 2. REQUIREMENT FOR UNIDENTIFIED FACTORS LEO S. JENSEN AND JAMES MCGINNIS Department of Poultry Science, Washington State University, Pullman (Received for publication, August 2, 1960)
D
URING the past decade, workers at the Texas Agricultural Experiment Station have published reports showing that turkey breeder hens require certain dietary unidentified factor supplements for optimum reproductive performance (Atkinson et al., 1951, 1953, 1955; Ferguson et al, 1956; Feldman et al., 1957; and Whiteside et al., 1960). Addition of such supplements as dried brewer's yeast, condensed fish solubles, fermentation residue, and dehydrated alfalfa meal to a milo-corn-soybean oil meal basal diet, markedly improved hatchability of fertile eggs, (Whiteside et al., 1960). An experiment to study the effect of adding several unidentified factor supplements to a corn-soybean oil meal diet on the performance of Broad Breasted Bronze hens is reported in this paper. EXPERIMENTAL
Twelve pens of 10 Broad Breasted Bronze turkey hens in an enclosed house with mechanical ventilation were used. The birds had been on a protein requirements study (Jensen and McGinnis, 1961). For eleven weeks, they were fed a diet similar 1
Scientific Paper No. 1982 Washington Agricultural Experiment Stations, Pullman. Project No. 71S.
to the basal diet used in the present experiment, except that the corn and soybean oil meal levels were varied to obtain different levels of protein. No sources of unidentified factors used in the present experiment had been included in the diet. The percentage composition of the diet was: yellow corn, 69.8; soybean oil meal (44% protein), 22.0; steamed bone meal, 5.0; limestone, 2.0; iodized salt, 0.5. The following were added per kilogram of diet: vitamin A, 6600 I.U.; vitamin D 3 , 1100 I.C.U.; vitamin E, 22 I.U.; menadione sodium bisulfate, 2.2 mg.; riboflavin, 3.3 mg.; vitamin B12, 6.6 meg.; Ca pantothenate, 19.6 mg.; folic acid, 6.6 meg.; niacin, 33 mg.; choline chloride, 660 mg.; BHT, 125 mg.; MnS0 4 (70%), 125 mg. Each of the experimental diets was fed to two groups as shown in Table 1. With addition of unidentified factor supplements, adjustments were made in the levels of corn, soybean oil meal and bone meal so that similar levels of crude protein, calcium and phosphorus were present in all experimental diets. The following supplements were added individually at the 5% level: dehydrated alfalfa meal (17% protein), dried whey product, delactosed (18% protein), herring fish meal (73% protein) and dried
732
L. S. JENSEN AND J. MCGINNIS TABLE 1.—Effect
of unidentified factor supplements on egg production, egg weight, fertii and hatchability in turkey breeders
Supplement
Egg. production
Average egg weight
Fertility
Hatchability of fertile eggs. Weeks of experiment 0-8
None 5% dehydrated alfalfa meal 5% dried whey product 5% herring fish meal 5% dried brewer's yeast All supplements
%
S3.3 51.6 46.6 47.2 49.7 49.9
brewer's yeast (47% protein). One treatment included all four supplements, each at the 5% level. The hens were placed on experimental diets in February, 1959, and were on experiment for 16 weeks. Fourteen hours of light was provided daily. One Broad Breasted Bronze torn was present in each pen and the toms were rotated from pen to pen weekly. All "sound" eggs were incubated bi-weekly. Records were kept on rate of egg production, percentage fertility, percentage hatchability of fertile eggs, and average egg weight. Egg weight was determined by weighing individually all sound eggs laid during the experiment. RESULTS Results are in Table 1. Neither egg production, egg weight, nor fertility was improved by adding the unidentified factor supplements individually or in combination to the basal diet. During the first eight weeks, there was little difference among the treatments in hatchability of fertile eggs, and statistical treatment of the data by analysis of variance revealed no significant differences. During the last eight weeks, none of the birds receiving the individual unidentified factor supplements showed any marked superiority in hatchability over the birds fed the basal ration. Those fed all four supplements had a 10% higher hatch-
gms. 86.1 84.6 84.1 84.1 85.7 85.4
% 95.6 97.1 95.1 95.6 94.7 94.4
%
73.8 76.4 74.5 68.2 70.6 78.9
9-16
%
63.0 63.6 67.7 63.4 58.5 73.3
ability, but this difference was not statistically significant. DISCUSSION Results of the experiment reported show that reproductive performance in turkey breeder hens was satisfactory on a ration composed only of corn and soybean oil meal plus vitamin and mineral supplements. During the latter part of the experiment, there was some indication that hatchability of fertile eggs was better for the birds receiving all four unidentified factor supplements, but this could not be proved statistically. A greater number of replicates in such a turkey breeder experiment would be required to detect small differences among treatments. Titus (1953) discused the high variability of egg production and hatchability in hens and the need for large numbers to show significant differences. In studies with chickens in our laboratory, no improvement in hatchability was obtained by adding distiller's dried solubles or forage juice to either a purified or practical ration (Jensen and McGinnis, 1957). In later work, hatchability was improved by substituting corn for glucose in a semi-purified diet (Jensen et al., 1958). Workers at the Texas Agricultural Experiment Station have consistently reported responses to unidentified factor supplements
REQUIREMENT OF TURKEY HENS FOR UNIDENTIFIED FACTORS
similar to those used in the present experiment. Recently, Whiteside et al. (1960) obtained responses of 11 to 27% in hatchability of fertile eggs by addition of 5% dried brewer's yeast, 5% condensed fish solubles, 5% dehydrated alfalfa meal, 1% fermentation residue, singly or in combination. Egg production was increased by dried brewer's yeast and average egg weight was increased by all supplements. It is quite obvious that these results differ markedly from those obtained in our laboratory. An explanation for these contrasting results may lie in differences between the strain of turkeys used, in climatic difference, in variation in ingredients, or basal diets, or in stresses imposed upon the birds. Depletion of the birds would not appear to be a factor, because the birds used in the Texas experiment were reared on range and fed a complete practical ration supplemented with unidentified factor sources. Yet, these birds, as breeding hens, showed a marked response to dietary supplements during the first 13 weeks of production. Birds in our experiment showed little response, even though an unsupplemented diet was fed for 27 weeks. It is interesting that several medicant drugs were used in the Texas basal ration. Included were 5 mg. procaine penicillin, 20 mg. chlortetracycline hydrochloride, 36 mg. sulfaquinoxaline, and 100 mg. furazoladone per pound of diet. None of these was included in our diet. It is possible that the use of these drugs imposed a stress on the birds which was counteracted by addition of unidentified factor supplements. Smyth et al. (1959) reported that addition of 100 mg. of furzolidone per pound of feed markedly lowered fertility and hatchability of fertile eggs in turkeys. Furthermore, in a report on a vitamin E. experiment with turkey breeders from Texas (Creger et al., 1960), no
733
response in hatchability of fertile eggs was obtained by addition of 5% dried brewer's yeast, either in the presence of absence of supplemental vitamin E. The basal diet was similar to that used for unidentified factor experiments except that it did not contain furazolidone, sulfaquinoxaline or the antibiotics. In the experiment conducted at about the same time (Whiteside et al., 1960), a marked response in hatchability of fertile eggs, egg production, and egg weight was obtained by addition of 5% dried brewer's yeast to the basal diet containing these drugs. It is possible that the addition of furazolidone and the other drugs increased the requirement of turkey breeders for unidentified factors. Perhaps more likely, is the possibility that the drugs increased the requirement of the birds for known nutrients. Newberne and McEuen (1957) showed that a high level of nitrofurazone produced symptoms of riboflavin and thiamine deficiencies in chicks fed a practical ration. SUMMARY
Addition of 5% dehydrated alfalfa meal, 5% dried whey product, 5% herring fish meal and 5% dried brewer's yeast, singly or a combination of all four of these supplements to a corn-soy-mineral-vitamin diet for turkey breeders, failed to improve rate of egg production, average egg weight, or percent fertility. Hatchability of fertile eggs was increased slightly for the birds receiving all four supplements during the last half of the experiment, but the difference was not significant statistically. REFERENCES Atkinson, R. L., J. H. Quisenberry and J. R. Couch, 1951. The effect of vitamin B,2, APF concentrates, aureomycin, streptomycin, liver "L" and fish meal on egg production and hatchability of Broad Breasted Bronze turkeys. Poultry Sci. 30: 90S.
734
L. S. JENSEN AND J.
Atkinson, R. L., J. H. Quisenberry and J. R. Couch, 1953. A factor in liver necessary for hatchability of turkey eggs. Poultry Sci. 32: 887. Atkinson, R. L., T. M. Ferguson, J. H. Quisenberry and J. R. Couch, 1955. Dehydrated alfalfa meal, condensed fish solubles, distiller's dried solubles and dried whey as supplements to an all-vegetable protein turkey laying diet. Poultry Sci. 34: 730-735. Creger, C. R., R. H. Mitchell, R. L. Atkinson, T. M. Ferguson, B. L. Reid and J. R. Couch, 1960. Vitamin E activity of selenium in turkey hatchability. Poultry Sci. 39: 59-63. Feldman, G. L., R. L. Atkinson, B. G. Creech, T. M. Ferguson, B. L. Reid and J. R. Couch, 1957. The effect of dehydrated alfalfa meal, dried brewer's yeast, and condensed fish solubles on the reproductive performance of turkeys. Poultry Sci. 36: 792-797. Ferguson, T. M., H. P. Vaught, B. L. Reid and J. R. Couch, 1956. The effect of vitamin E, dehydrated alfalfa meal, and condensed fish solubles upon hatchability of eggs from Broad Breasted Bronze hens maintained on litter. Poultry Sci. 35: 872-875. Jensen, L. S., and J. McGinnis, 1957. Effect of
MCGINNIS
different diets and unidentified factor supplements on reproduction in chickens and early chick growth. Poultry Sci. 36: 312-319. Jensen, L. S., J. B. Allred, R. E. Fry and J. McGinnis, 1958. Evidence for an unidentified factor necessary for maximum egg weight in chickens. J. Nutrition, 65: 219-233. Jensen, L. S., and J. McGinnis, 1961. Nutritional investigations with turkey hens. 1. Quantitative requirement for protein. Poultry Sci. 40: 288-290. Newberne, P. M., and G. L. McEuen, 1957. Studies on drug toxicity in chicks. 4. The influence of various levels of nitrofurazone on growth and development of chicks. Poultry Sci. 36: 739743. Smyth, J. R., D. L. Anderson and T. W. Fox, 1959. The effects of furazolidone and vitamin E on turkey reproduction. Poultry Sci. 38: 288296. Titus, H. W., 1953. Variation of egg production and hatchability. Poultry Sci. 32: 593-601. Whiteside, C. H., T. M. Ferguson, B. L. Reid and J. R. Couch, 1960. The effect of dehydrated alfalfa meal, dried brewer's yeast, condensed fish solubles and fermentation residue on the reproductive performance of turkeys. Poultry Sci. 39: 77-81.
Reproductive Studies on Chickens Fed Glycarbylamide1 D. POLIN, C. C. PORTER AND W. COBB Merck Institute for Therapeutic Research, Rahway, New Jersey (Received for publication August 2, 1960)
LYCARBYLAMIDE (4,5-imidazoledicarboxamide, see Cuckler et al., 1958) is a medicant in use for prevention of coccidiosis in chickens. The drug is not recommended for use in adult birds, yet the possibility exists that it may inadvertently be fed to them. This raises the question of its effect on the reproductive performance of adult chickens and the possibility of its deposition in eggs. To obtain these data the following experiments were conducted.
G
'Trademark for this compound is Glycamide, by Merck & Co., Inc. Rahway, New Jersey.
PROCEDURE AND METHODS
Ten White Leghorn hens and one rooster were housed in each of IS wire-floored cages in a frame building. They were fed a commercial breeder ration for a 10-day period (Control Period), then diets containing glycarbylamide at levels ranging from 0.02 to 0.16% for 21 days (Experimental Period No. 1), and finally refed non-medicated diets for 21 days (Recovery Period). The cages were randomly reassigned to the treatments and the birds again fed the diets containing glycarbylamide for 21 days (Ex-
731
Wright, M. L., G. W. Anderson and N. A. Epps, 1960. Hatchery sanitation as a control measure for aspergillosis in fowl. 32nd Northeastern Conference on Avian Diseases, U. of Maine, Orono. Wright, M. L., and N. A. Epps, 1958. Hatchery sanitation. Can. J. Comp. Med. 22: 396-399.
Nutritional Investigations with Turkey Hens 1 2. REQUIREMENT FOR UNIDENTIFIED FACTORS LEO S. JENSEN AND JAMES MCGINNIS Department of Poultry Science, Washington State University, Pullman (Received for publication, August 2, 1960)
D
URING the past decade, workers at the Texas Agricultural Experiment Station have published reports showing that turkey breeder hens require certain dietary unidentified factor supplements for optimum reproductive performance (Atkinson et al., 1951, 1953, 1955; Ferguson et al, 1956; Feldman et al., 1957; and Whiteside et al., 1960). Addition of such supplements as dried brewer's yeast, condensed fish solubles, fermentation residue, and dehydrated alfalfa meal to a milo-corn-soybean oil meal basal diet, markedly improved hatchability of fertile eggs, (Whiteside et al., 1960). An experiment to study the effect of adding several unidentified factor supplements to a corn-soybean oil meal diet on the performance of Broad Breasted Bronze hens is reported in this paper. EXPERIMENTAL
Twelve pens of 10 Broad Breasted Bronze turkey hens in an enclosed house with mechanical ventilation were used. The birds had been on a protein requirements study (Jensen and McGinnis, 1961). For eleven weeks, they were fed a diet similar 1
Scientific Paper No. 1982 Washington Agricultural Experiment Stations, Pullman. Project No. 71S.
to the basal diet used in the present experiment, except that the corn and soybean oil meal levels were varied to obtain different levels of protein. No sources of unidentified factors used in the present experiment had been included in the diet. The percentage composition of the diet was: yellow corn, 69.8; soybean oil meal (44% protein), 22.0; steamed bone meal, 5.0; limestone, 2.0; iodized salt, 0.5. The following were added per kilogram of diet: vitamin A, 6600 I.U.; vitamin D 3 , 1100 I.C.U.; vitamin E, 22 I.U.; menadione sodium bisulfate, 2.2 mg.; riboflavin, 3.3 mg.; vitamin B12, 6.6 meg.; Ca pantothenate, 19.6 mg.; folic acid, 6.6 meg.; niacin, 33 mg.; choline chloride, 660 mg.; BHT, 125 mg.; MnS0 4 (70%), 125 mg. Each of the experimental diets was fed to two groups as shown in Table 1. With addition of unidentified factor supplements, adjustments were made in the levels of corn, soybean oil meal and bone meal so that similar levels of crude protein, calcium and phosphorus were present in all experimental diets. The following supplements were added individually at the 5% level: dehydrated alfalfa meal (17% protein), dried whey product, delactosed (18% protein), herring fish meal (73% protein) and dried
732
L. S. JENSEN AND J. MCGINNIS TABLE 1.—Effect
of unidentified factor supplements on egg production, egg weight, fertii and hatchability in turkey breeders
Supplement
Egg. production
Average egg weight
Fertility
Hatchability of fertile eggs. Weeks of experiment 0-8
None 5% dehydrated alfalfa meal 5% dried whey product 5% herring fish meal 5% dried brewer's yeast All supplements
%
S3.3 51.6 46.6 47.2 49.7 49.9
brewer's yeast (47% protein). One treatment included all four supplements, each at the 5% level. The hens were placed on experimental diets in February, 1959, and were on experiment for 16 weeks. Fourteen hours of light was provided daily. One Broad Breasted Bronze torn was present in each pen and the toms were rotated from pen to pen weekly. All "sound" eggs were incubated bi-weekly. Records were kept on rate of egg production, percentage fertility, percentage hatchability of fertile eggs, and average egg weight. Egg weight was determined by weighing individually all sound eggs laid during the experiment. RESULTS Results are in Table 1. Neither egg production, egg weight, nor fertility was improved by adding the unidentified factor supplements individually or in combination to the basal diet. During the first eight weeks, there was little difference among the treatments in hatchability of fertile eggs, and statistical treatment of the data by analysis of variance revealed no significant differences. During the last eight weeks, none of the birds receiving the individual unidentified factor supplements showed any marked superiority in hatchability over the birds fed the basal ration. Those fed all four supplements had a 10% higher hatch-
gms. 86.1 84.6 84.1 84.1 85.7 85.4
% 95.6 97.1 95.1 95.6 94.7 94.4
%
73.8 76.4 74.5 68.2 70.6 78.9
9-16
%
63.0 63.6 67.7 63.4 58.5 73.3
ability, but this difference was not statistically significant. DISCUSSION Results of the experiment reported show that reproductive performance in turkey breeder hens was satisfactory on a ration composed only of corn and soybean oil meal plus vitamin and mineral supplements. During the latter part of the experiment, there was some indication that hatchability of fertile eggs was better for the birds receiving all four unidentified factor supplements, but this could not be proved statistically. A greater number of replicates in such a turkey breeder experiment would be required to detect small differences among treatments. Titus (1953) discused the high variability of egg production and hatchability in hens and the need for large numbers to show significant differences. In studies with chickens in our laboratory, no improvement in hatchability was obtained by adding distiller's dried solubles or forage juice to either a purified or practical ration (Jensen and McGinnis, 1957). In later work, hatchability was improved by substituting corn for glucose in a semi-purified diet (Jensen et al., 1958). Workers at the Texas Agricultural Experiment Station have consistently reported responses to unidentified factor supplements
REQUIREMENT OF TURKEY HENS FOR UNIDENTIFIED FACTORS
similar to those used in the present experiment. Recently, Whiteside et al. (1960) obtained responses of 11 to 27% in hatchability of fertile eggs by addition of 5% dried brewer's yeast, 5% condensed fish solubles, 5% dehydrated alfalfa meal, 1% fermentation residue, singly or in combination. Egg production was increased by dried brewer's yeast and average egg weight was increased by all supplements. It is quite obvious that these results differ markedly from those obtained in our laboratory. An explanation for these contrasting results may lie in differences between the strain of turkeys used, in climatic difference, in variation in ingredients, or basal diets, or in stresses imposed upon the birds. Depletion of the birds would not appear to be a factor, because the birds used in the Texas experiment were reared on range and fed a complete practical ration supplemented with unidentified factor sources. Yet, these birds, as breeding hens, showed a marked response to dietary supplements during the first 13 weeks of production. Birds in our experiment showed little response, even though an unsupplemented diet was fed for 27 weeks. It is interesting that several medicant drugs were used in the Texas basal ration. Included were 5 mg. procaine penicillin, 20 mg. chlortetracycline hydrochloride, 36 mg. sulfaquinoxaline, and 100 mg. furazoladone per pound of diet. None of these was included in our diet. It is possible that the use of these drugs imposed a stress on the birds which was counteracted by addition of unidentified factor supplements. Smyth et al. (1959) reported that addition of 100 mg. of furzolidone per pound of feed markedly lowered fertility and hatchability of fertile eggs in turkeys. Furthermore, in a report on a vitamin E. experiment with turkey breeders from Texas (Creger et al., 1960), no
733
response in hatchability of fertile eggs was obtained by addition of 5% dried brewer's yeast, either in the presence of absence of supplemental vitamin E. The basal diet was similar to that used for unidentified factor experiments except that it did not contain furazolidone, sulfaquinoxaline or the antibiotics. In the experiment conducted at about the same time (Whiteside et al., 1960), a marked response in hatchability of fertile eggs, egg production, and egg weight was obtained by addition of 5% dried brewer's yeast to the basal diet containing these drugs. It is possible that the addition of furazolidone and the other drugs increased the requirement of turkey breeders for unidentified factors. Perhaps more likely, is the possibility that the drugs increased the requirement of the birds for known nutrients. Newberne and McEuen (1957) showed that a high level of nitrofurazone produced symptoms of riboflavin and thiamine deficiencies in chicks fed a practical ration. SUMMARY
Addition of 5% dehydrated alfalfa meal, 5% dried whey product, 5% herring fish meal and 5% dried brewer's yeast, singly or a combination of all four of these supplements to a corn-soy-mineral-vitamin diet for turkey breeders, failed to improve rate of egg production, average egg weight, or percent fertility. Hatchability of fertile eggs was increased slightly for the birds receiving all four supplements during the last half of the experiment, but the difference was not significant statistically. REFERENCES Atkinson, R. L., J. H. Quisenberry and J. R. Couch, 1951. The effect of vitamin B,2, APF concentrates, aureomycin, streptomycin, liver "L" and fish meal on egg production and hatchability of Broad Breasted Bronze turkeys. Poultry Sci. 30: 90S.
734
L. S. JENSEN AND J.
Atkinson, R. L., J. H. Quisenberry and J. R. Couch, 1953. A factor in liver necessary for hatchability of turkey eggs. Poultry Sci. 32: 887. Atkinson, R. L., T. M. Ferguson, J. H. Quisenberry and J. R. Couch, 1955. Dehydrated alfalfa meal, condensed fish solubles, distiller's dried solubles and dried whey as supplements to an all-vegetable protein turkey laying diet. Poultry Sci. 34: 730-735. Creger, C. R., R. H. Mitchell, R. L. Atkinson, T. M. Ferguson, B. L. Reid and J. R. Couch, 1960. Vitamin E activity of selenium in turkey hatchability. Poultry Sci. 39: 59-63. Feldman, G. L., R. L. Atkinson, B. G. Creech, T. M. Ferguson, B. L. Reid and J. R. Couch, 1957. The effect of dehydrated alfalfa meal, dried brewer's yeast, and condensed fish solubles on the reproductive performance of turkeys. Poultry Sci. 36: 792-797. Ferguson, T. M., H. P. Vaught, B. L. Reid and J. R. Couch, 1956. The effect of vitamin E, dehydrated alfalfa meal, and condensed fish solubles upon hatchability of eggs from Broad Breasted Bronze hens maintained on litter. Poultry Sci. 35: 872-875. Jensen, L. S., and J. McGinnis, 1957. Effect of
MCGINNIS
different diets and unidentified factor supplements on reproduction in chickens and early chick growth. Poultry Sci. 36: 312-319. Jensen, L. S., J. B. Allred, R. E. Fry and J. McGinnis, 1958. Evidence for an unidentified factor necessary for maximum egg weight in chickens. J. Nutrition, 65: 219-233. Jensen, L. S., and J. McGinnis, 1961. Nutritional investigations with turkey hens. 1. Quantitative requirement for protein. Poultry Sci. 40: 288-290. Newberne, P. M., and G. L. McEuen, 1957. Studies on drug toxicity in chicks. 4. The influence of various levels of nitrofurazone on growth and development of chicks. Poultry Sci. 36: 739743. Smyth, J. R., D. L. Anderson and T. W. Fox, 1959. The effects of furazolidone and vitamin E on turkey reproduction. Poultry Sci. 38: 288296. Titus, H. W., 1953. Variation of egg production and hatchability. Poultry Sci. 32: 593-601. Whiteside, C. H., T. M. Ferguson, B. L. Reid and J. R. Couch, 1960. The effect of dehydrated alfalfa meal, dried brewer's yeast, condensed fish solubles and fermentation residue on the reproductive performance of turkeys. Poultry Sci. 39: 77-81.
Reproductive Studies on Chickens Fed Glycarbylamide1 D. POLIN, C. C. PORTER AND W. COBB Merck Institute for Therapeutic Research, Rahway, New Jersey (Received for publication August 2, 1960)
LYCARBYLAMIDE (4,5-imidazoledicarboxamide, see Cuckler et al., 1958) is a medicant in use for prevention of coccidiosis in chickens. The drug is not recommended for use in adult birds, yet the possibility exists that it may inadvertently be fed to them. This raises the question of its effect on the reproductive performance of adult chickens and the possibility of its deposition in eggs. To obtain these data the following experiments were conducted.
G
'Trademark for this compound is Glycamide, by Merck & Co., Inc. Rahway, New Jersey.
PROCEDURE AND METHODS
Ten White Leghorn hens and one rooster were housed in each of IS wire-floored cages in a frame building. They were fed a commercial breeder ration for a 10-day period (Control Period), then diets containing glycarbylamide at levels ranging from 0.02 to 0.16% for 21 days (Experimental Period No. 1), and finally refed non-medicated diets for 21 days (Recovery Period). The cages were randomly reassigned to the treatments and the birds again fed the diets containing glycarbylamide for 21 days (Ex-