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Supplemental Value of Fish Meal Protein in Relation to Other Sources of Protein in the Test Diet
1936
R. H. HARMS AND P. W. WALDROUP
for making the oxytetracycline (OTC) analyses of the blood serum and Dr. R. E. Cook for assisting with the progesterone injection. REFERENCES
Supplemental Value of Fish Meal Protein in Relation to Other Sources of Protein in the Test Diet H. N. WATERHOUSE1 AND H. M. SCOTT Illinois Agricultural Experiment Station, Urbana, Illinois (Received for publication May 11, 1962)
T
HE AVAILABILITY of low cost vegetable protein concentrates, synthetic vitamins and numerous unidentified factor sources has resulted in a shift of interest in fish meal as a source of these factors in poultry rations to one of fish meal as a source of amino acids. Bioassay methods have been developed which can be used for evaluating fish meal as a source of amino acids in poultry diets. Grau and Williams (1955) evaluated a large number of fish meal samples when 1 Present address: General Mills, Inc., Pet Food Nutrition Laboratory, P.O. Box 278, Indianola. Iowa.
used as the source of amino acids at the 20% protein level. Heiman et al. (1939) and more recently Carpenter et al. (1955) evaluated fish meals on the basis of their ability to supplement mixtures of cereal grain proteins. Attempts to correlate the relative protein quality of fish meals as the sole source of amino acids with their values as a source of supplemental amino acids in poultry diets have not come to the authors' attention. This report concerns an experiment comparing two samples of fish meal as the sole source and as sources of supplemental amino acids in assay diets with growing chickens.
Downloaded from http://ps.oxfordjournals.org/ at Purdue University Libraries ADMN on June 11, 2015
Brown, R. G., and H. J. Bachmann, 1959. Physiology and pharmacology of the potentiation of Aureomycin. Proc. of 10th Animal Feed Symposium. American Cyanamid Co., New York 20, New York. Dunham, H. H., and O. Riddle, 1942. The effects of a series of steroids on ovulation and reproduction in pigeons. Physiol. Zool. 15: 385. Grove, D. C , and W. H. Randall, 1955. Assay methods of antibiotics. Medical Encyclopedia, Inc., New York. Harms, R. H., and P. W. Waldroup, 1961a. Potentiation of Terramycin. I. Evaluation of terephthalic acid and low dietary calcium in broiler diets. Avian Diseases, 5: 183-188.
Harms, R. H., and P. W. Waldroup, 1961b. The influence of dietary calcium level and supplementary ascorbic acid and/or dienestrol diacetate upon performance of egg production type hens. Poultry Sci. 40: 1345-1348. Peterson, E. H., 1958. The potentiation effect of terephthalic acid upon the absorption of chlorotetracycline from avian alimentary tract. Report Series 74, Arkansas Agr. Exp. Sta., March 1958. Price, K. E., and Z. Zolli, 1959. The influence of dietary calcium, phosphorus and terephthalic acid on antibiotic control of experimental infectious synovites. Avian Diseases, 3 : 135-156. Riddle, O., and L. B. Dotti, 1945. Pituitary and sex hormones which increase plasma calcium in birds and mammals. Proc. Am. Phil. Soc. 89: 499-516. Waldroup, P. W., and R. H. Harms, 1961. Potentiation of Terramycin. II. Evaluation of low dietary calcium in laying hen diets. Avian Diseases, 5: 409-414.
1937
SUPPLEMENTAL VALUE OF FISH MEAL TABLE 1.—Composition of basal diets A Cereal grain mix Ground yellow corn Soybean oil meal Glucose Corn oil
c
B
1
60.50
— —
93.45 1.00
33.95
33.41 13.49 47.55
—
—
Constant ingredients 5.34 0.20 0.01
Total
+ + 100.00
1 Cereal grain mix: Ground yellow corn 46%; ground wheat 12%; ground oats 15%; wheat bran 18%; dehydrated alfalfa 6%; dried whey 3 % . 2 See Snetsinger and Scott (1958).
EXPERIMENTAL
The basal rations used in this study are recorded in Table 1. Basal diet A was used to compare the two fish meals with egg white protein as the sole source of amino acids. Basal diet. B permitted comparison of the two fish meals with casein as a source of supplemental amino acids in
TABLE 2.—Experimental design and results of growth assay Percent of total protein from: Diet Basal No. diet
Source of supplemental protein
Supplemental protein
1 2 3
A A A
Egg white Fish meal " H " Fish meal "V"
1002 100 100
4 5 6 7
B B B B
Cereal mix Casein Fish meal " H " Fish meal "V"
302 30 30
8 9 10
C C C
Soybean oil meal Fish meal " H " Fish meal "V"
14 14
11 12
C C
Fish meal " H " Fish meal "V"
70 70
1 2 3 4
Cereal grain mix
Corn
— 100 70 70 70
Av. gain1 Soybean (gm.) 14-27 oil days meal
—
Feed
Relative protein quality 4
135A3 86C 131A
.32 .22 .32
100.0 63.7 97.0
SOD 149B, E 133A 141A, B
.14 .28 .26 .27
100.0 89.3 94.6
Gain
—
—
—
30 30 30
702 56 56
140A, B 132A 158E
.30 .29 .32
100.0 94.3 112.8
—
30 30
—
135A 141A, B
.28 .32
96.4 100.7
Average of triplicate groups of 10 chicks per treatment with an initial starting weight of 168 grams. Protein used as standard for each basal diet. Duncan's multiple range test. (P<0.01) Duncan (1955). Calculation based on relative growth only using gain on each basal diet as 100.
Downloaded from http://ps.oxfordjournals.org/ at Purdue University Libraries ADMN on June 11, 2015
Salts2 Choline CI. ZnC0 3 Penicillin, 11 mg./kg. diet Vitamins 2
— —
a manner similar to the technique used by Heiman et al. (1939) in which the fish meal supplied 30% of the total proteins and cereal grain proteins furnished the remaining 70%. Since protein concentrates provide approximately 70% of the protein in practical broiler rations, basal diet C, a corn-soybean oil meal diet in which soybean oil meal supplied 70% of the protein and corn the remainder, was used as a standard to compare the two fish meals in their ability to supplement corn-soybean oil meal rations when replacing either 20 or 100% of the soybean protein. All diets contained a complete vitamin and mineral mixture commonly used in purified and semi-purified diets in our laboratory to insure that the diets were limiting only in quantity and quality of protein. All diets were fed at the level of 10% protein except diet 4 (Table 2) which was fed at the level of 7% protein. The individual sources of protein were analyzed by the macro-Kjeldahl method for nitrogen and added to the diet on a protein
1938
H. N. WATERHOUSE AND H. M. SCOTT
RESULTS AND DISCUSSION Fish meal "V" was significantly (P < 0.01) superior to fish meal "H" in promoting chick growth in basal diet A as the sole source of amino acids, and as a source of supplemental amino acids to corn and soybean protein in basal diet C when replacing one-fifth of the soybean protein. Fish meal "V" was consistently superior to fish meal "H" in all assays but significantly superior only in the two diets just cited. Fish meal "V" was nutritionally equivalent to egg white as the sole source of amino acids, equal to casein as a source of amino acids supplementing cereal grains and superior to soybean protein (diet 10 vs. diet 8) as a source of amino acids supplementing soybean and corn protein when the fish meal replaced one-fifth of the soybean protein. However, when fish meal "V" replaced the soybean oil meal in entirety (diet 12) gains were only equal to
those noted on soybean protein when both were supplementing corn protein. Moreover, the supplemental value of fish meal "H" was not significantly different than fish meal "V" with the complete replacement of soybean protein (diet 8 vs. diet 11 vs. diet 12). Fish meal "H" was significantly (P < 0.01) inferior to egg white protein as the sole source of amino acids in basal diet A and to casein as a source of supplemental amino acids in basal diet B. When the two samples of fish meal supplemented diets in which lysine was probably the first limiting amino acid (diets 6-7) the weight gains were not significantly different. In basal diet C (diets 9 and 10), however, in which lysine was probably not the first limiting amino acid, significant differences between the two fish meals in growth promoting ability were noted. These data suggest that the marked nutritional differences between the two fish meals when used as the sole source of amino acids in diet A cannot be explained on the basis of a differential concentration in lysine. As the sole source of dietary amino acids or as a source of supplemental amino acids in a' corn-soybean oil meal diet, the two fish meal samples used in these assays were not nutritionally equivalent. As a source of supplemental amino acids to a mixture of cereal grains and to corn protein even when furnishing 70% of the protein in a fish meal corn diet (diets 11 and 12) the two fish meals were nutritionally equivalent. The data recorded in Table 2 substantiate the reports of Grau and Williams (19SS) and Hinners and Scott (1960) that feeding fish meal as the sole source of amino acids is an excellent method to detect differences in the nutritive value per se of different fish meal samples. The relative nutritive value of fish meal as the only source of amino acids is not always directly
Downloaded from http://ps.oxfordjournals.org/ at Purdue University Libraries ADMN on June 11, 2015
(N X 6.25) basis. The nitrogen content of the mixed diets was determined as a check and found to be essentially as calculated from ingredient analysis. The crossbred male chicks originating from the mating of New Hampshire males and Columbian females were fed a cornsoybean oil meal pre-test diet for the first 14 days, weighed to the nearest gram, wing banded and assigned to the experimental groups on the basis of the 14 day weight to insure that the average starting weight of all groups was equal. The chicks were placed in thermostatically controlled electrically heated batteries equipped with raised wire floors. Feed and water were furnished ad libitum. The 12 experimental diets were fed to triplicate groups of 10 chicks each. Individual chick weights were recorded after 7 and 13 days on the test diets, at which time feed consumption was also determined. Only the final results are presented in Table 2.
SUPPLEMENTAL VALUE OF FISH MEAL
SUMMARY
Evidence has been presented demonstrating that short-term rapid assays of fish meal as supplemental sources of protein
for chicks are feasible. It was shown that two fish meals, which were markedly different in promoting chick growth as the sole source of amino acids, did not differ significantly from each other when assayed in diets containing certain other sources of amino acids. The data would suggest that assays designed to evaluate fish meals as a supplemental source of protein should be conducted with the specific ration in which they are to be used. REFERENCES Carpenter, K. J., G. M. Ellinger and D. H. Shrimpton, 195S. The evaluation of whaling by-products as feeding-stuffs. J. Sci. Food Agric. 6: 296-304. Duncan, D. B., 1955. Multiple range and multiple F tests. Biometrics 2 : 1-42. Grau, C. R., and M. A. Williams, 1955. Fish meals as amino acid sources in chick rations. Poultry Sci. 34: 810-817. Heiman, V., J. S. Carver and J. W. Cook, 1939. A method for determinating the gross value of protein concentrates. Poultry Sci. 18: 464474. Hinners, S. W., and H. M. Scott, 1960. A bioassay for determining the nutritional adequacy of protein supplements for chick growth. Poultry Sci. 34 : 176-183. Snetsinger, D. C , and H. M. Scott, 1958. The adequacy of soybean oil meal as a sole source of protein for chick growth. Poultry Sci. 37: 1400-1403.
NEWS AND NOTES (Continued from page 1924) sin poultry producers out of business in the late 1940's, Hayes worked with veterinarians, disease control specialists at the State Department of Agriculture, and the University in setting up an inoculation program. Another achievement with which he is credited came when he laid the groundwork for the Lakeland Egg Co-operative, a poultry marketing association, started in 1949, in 15 eastern counties of the State. When the broiler industry began turning out more birds than the market could absorb, Hayes took to the church social and village centennial
circuit to show how mass broiling could be done. Under his direction, cement block pits were set up for broiling of birds clipped two dozen at a time in wire frames. His aides got "master chef" certificates to hang in their homes—and the multitudes got fed. Later he switched to lightweight portable aluminum pits. He was very effective in presenting his program to farmers and to other persons in the poultry industry, and to consumers. He was effective in making such contacts by speaking before groups, by appearing on television and radio, by participating in conferences, or by correspondence. He
(Continued on page 1946)
Downloaded from http://ps.oxfordjournals.org/ at Purdue University Libraries ADMN on June 11, 2015
correlated with its supplemental value. There is still a place for assays of this type. The ease and rapidity of testing fish meal as the sole source of amino acids (Hinners and Scott, 1960) makes it a logical one to use in studying the effect of processing variables on protein quality. This assay is in contrast to assays designed to study the supplemental value of fish meal in a diet containing other sources of amino acids. The latter evaluates fish meal in the role in which it will be used in actual practice, namely as a source of supplemental amino acids. The differences between the two fish meals in supplementing basal diet C, but not basal diet B, precludes the testing of any fish meal in one diet and generalizing with respect to its supplemental value for use in other diets. These data show that while assays designed to examine the supplemental value of the protein in fish meal are quite feasible, such assays should be conducted with the diet in which one intends to use the fish meal.
1939
R. H. HARMS AND P. W. WALDROUP
for making the oxytetracycline (OTC) analyses of the blood serum and Dr. R. E. Cook for assisting with the progesterone injection. REFERENCES
Supplemental Value of Fish Meal Protein in Relation to Other Sources of Protein in the Test Diet H. N. WATERHOUSE1 AND H. M. SCOTT Illinois Agricultural Experiment Station, Urbana, Illinois (Received for publication May 11, 1962)
T
HE AVAILABILITY of low cost vegetable protein concentrates, synthetic vitamins and numerous unidentified factor sources has resulted in a shift of interest in fish meal as a source of these factors in poultry rations to one of fish meal as a source of amino acids. Bioassay methods have been developed which can be used for evaluating fish meal as a source of amino acids in poultry diets. Grau and Williams (1955) evaluated a large number of fish meal samples when 1 Present address: General Mills, Inc., Pet Food Nutrition Laboratory, P.O. Box 278, Indianola. Iowa.
used as the source of amino acids at the 20% protein level. Heiman et al. (1939) and more recently Carpenter et al. (1955) evaluated fish meals on the basis of their ability to supplement mixtures of cereal grain proteins. Attempts to correlate the relative protein quality of fish meals as the sole source of amino acids with their values as a source of supplemental amino acids in poultry diets have not come to the authors' attention. This report concerns an experiment comparing two samples of fish meal as the sole source and as sources of supplemental amino acids in assay diets with growing chickens.
Downloaded from http://ps.oxfordjournals.org/ at Purdue University Libraries ADMN on June 11, 2015
Brown, R. G., and H. J. Bachmann, 1959. Physiology and pharmacology of the potentiation of Aureomycin. Proc. of 10th Animal Feed Symposium. American Cyanamid Co., New York 20, New York. Dunham, H. H., and O. Riddle, 1942. The effects of a series of steroids on ovulation and reproduction in pigeons. Physiol. Zool. 15: 385. Grove, D. C , and W. H. Randall, 1955. Assay methods of antibiotics. Medical Encyclopedia, Inc., New York. Harms, R. H., and P. W. Waldroup, 1961a. Potentiation of Terramycin. I. Evaluation of terephthalic acid and low dietary calcium in broiler diets. Avian Diseases, 5: 183-188.
Harms, R. H., and P. W. Waldroup, 1961b. The influence of dietary calcium level and supplementary ascorbic acid and/or dienestrol diacetate upon performance of egg production type hens. Poultry Sci. 40: 1345-1348. Peterson, E. H., 1958. The potentiation effect of terephthalic acid upon the absorption of chlorotetracycline from avian alimentary tract. Report Series 74, Arkansas Agr. Exp. Sta., March 1958. Price, K. E., and Z. Zolli, 1959. The influence of dietary calcium, phosphorus and terephthalic acid on antibiotic control of experimental infectious synovites. Avian Diseases, 3 : 135-156. Riddle, O., and L. B. Dotti, 1945. Pituitary and sex hormones which increase plasma calcium in birds and mammals. Proc. Am. Phil. Soc. 89: 499-516. Waldroup, P. W., and R. H. Harms, 1961. Potentiation of Terramycin. II. Evaluation of low dietary calcium in laying hen diets. Avian Diseases, 5: 409-414.
1937
SUPPLEMENTAL VALUE OF FISH MEAL TABLE 1.—Composition of basal diets A Cereal grain mix Ground yellow corn Soybean oil meal Glucose Corn oil
c
B
1
60.50
— —
93.45 1.00
33.95
33.41 13.49 47.55
—
—
Constant ingredients 5.34 0.20 0.01
Total
+ + 100.00
1 Cereal grain mix: Ground yellow corn 46%; ground wheat 12%; ground oats 15%; wheat bran 18%; dehydrated alfalfa 6%; dried whey 3 % . 2 See Snetsinger and Scott (1958).
EXPERIMENTAL
The basal rations used in this study are recorded in Table 1. Basal diet A was used to compare the two fish meals with egg white protein as the sole source of amino acids. Basal diet. B permitted comparison of the two fish meals with casein as a source of supplemental amino acids in
TABLE 2.—Experimental design and results of growth assay Percent of total protein from: Diet Basal No. diet
Source of supplemental protein
Supplemental protein
1 2 3
A A A
Egg white Fish meal " H " Fish meal "V"
1002 100 100
4 5 6 7
B B B B
Cereal mix Casein Fish meal " H " Fish meal "V"
302 30 30
8 9 10
C C C
Soybean oil meal Fish meal " H " Fish meal "V"
14 14
11 12
C C
Fish meal " H " Fish meal "V"
70 70
1 2 3 4
Cereal grain mix
Corn
— 100 70 70 70
Av. gain1 Soybean (gm.) 14-27 oil days meal
—
Feed
Relative protein quality 4
135A3 86C 131A
.32 .22 .32
100.0 63.7 97.0
SOD 149B, E 133A 141A, B
.14 .28 .26 .27
100.0 89.3 94.6
Gain
—
—
—
30 30 30
702 56 56
140A, B 132A 158E
.30 .29 .32
100.0 94.3 112.8
—
30 30
—
135A 141A, B
.28 .32
96.4 100.7
Average of triplicate groups of 10 chicks per treatment with an initial starting weight of 168 grams. Protein used as standard for each basal diet. Duncan's multiple range test. (P<0.01) Duncan (1955). Calculation based on relative growth only using gain on each basal diet as 100.
Downloaded from http://ps.oxfordjournals.org/ at Purdue University Libraries ADMN on June 11, 2015
Salts2 Choline CI. ZnC0 3 Penicillin, 11 mg./kg. diet Vitamins 2
— —
a manner similar to the technique used by Heiman et al. (1939) in which the fish meal supplied 30% of the total proteins and cereal grain proteins furnished the remaining 70%. Since protein concentrates provide approximately 70% of the protein in practical broiler rations, basal diet C, a corn-soybean oil meal diet in which soybean oil meal supplied 70% of the protein and corn the remainder, was used as a standard to compare the two fish meals in their ability to supplement corn-soybean oil meal rations when replacing either 20 or 100% of the soybean protein. All diets contained a complete vitamin and mineral mixture commonly used in purified and semi-purified diets in our laboratory to insure that the diets were limiting only in quantity and quality of protein. All diets were fed at the level of 10% protein except diet 4 (Table 2) which was fed at the level of 7% protein. The individual sources of protein were analyzed by the macro-Kjeldahl method for nitrogen and added to the diet on a protein
1938
H. N. WATERHOUSE AND H. M. SCOTT
RESULTS AND DISCUSSION Fish meal "V" was significantly (P < 0.01) superior to fish meal "H" in promoting chick growth in basal diet A as the sole source of amino acids, and as a source of supplemental amino acids to corn and soybean protein in basal diet C when replacing one-fifth of the soybean protein. Fish meal "V" was consistently superior to fish meal "H" in all assays but significantly superior only in the two diets just cited. Fish meal "V" was nutritionally equivalent to egg white as the sole source of amino acids, equal to casein as a source of amino acids supplementing cereal grains and superior to soybean protein (diet 10 vs. diet 8) as a source of amino acids supplementing soybean and corn protein when the fish meal replaced one-fifth of the soybean protein. However, when fish meal "V" replaced the soybean oil meal in entirety (diet 12) gains were only equal to
those noted on soybean protein when both were supplementing corn protein. Moreover, the supplemental value of fish meal "H" was not significantly different than fish meal "V" with the complete replacement of soybean protein (diet 8 vs. diet 11 vs. diet 12). Fish meal "H" was significantly (P < 0.01) inferior to egg white protein as the sole source of amino acids in basal diet A and to casein as a source of supplemental amino acids in basal diet B. When the two samples of fish meal supplemented diets in which lysine was probably the first limiting amino acid (diets 6-7) the weight gains were not significantly different. In basal diet C (diets 9 and 10), however, in which lysine was probably not the first limiting amino acid, significant differences between the two fish meals in growth promoting ability were noted. These data suggest that the marked nutritional differences between the two fish meals when used as the sole source of amino acids in diet A cannot be explained on the basis of a differential concentration in lysine. As the sole source of dietary amino acids or as a source of supplemental amino acids in a' corn-soybean oil meal diet, the two fish meal samples used in these assays were not nutritionally equivalent. As a source of supplemental amino acids to a mixture of cereal grains and to corn protein even when furnishing 70% of the protein in a fish meal corn diet (diets 11 and 12) the two fish meals were nutritionally equivalent. The data recorded in Table 2 substantiate the reports of Grau and Williams (19SS) and Hinners and Scott (1960) that feeding fish meal as the sole source of amino acids is an excellent method to detect differences in the nutritive value per se of different fish meal samples. The relative nutritive value of fish meal as the only source of amino acids is not always directly
Downloaded from http://ps.oxfordjournals.org/ at Purdue University Libraries ADMN on June 11, 2015
(N X 6.25) basis. The nitrogen content of the mixed diets was determined as a check and found to be essentially as calculated from ingredient analysis. The crossbred male chicks originating from the mating of New Hampshire males and Columbian females were fed a cornsoybean oil meal pre-test diet for the first 14 days, weighed to the nearest gram, wing banded and assigned to the experimental groups on the basis of the 14 day weight to insure that the average starting weight of all groups was equal. The chicks were placed in thermostatically controlled electrically heated batteries equipped with raised wire floors. Feed and water were furnished ad libitum. The 12 experimental diets were fed to triplicate groups of 10 chicks each. Individual chick weights were recorded after 7 and 13 days on the test diets, at which time feed consumption was also determined. Only the final results are presented in Table 2.
SUPPLEMENTAL VALUE OF FISH MEAL
SUMMARY
Evidence has been presented demonstrating that short-term rapid assays of fish meal as supplemental sources of protein
for chicks are feasible. It was shown that two fish meals, which were markedly different in promoting chick growth as the sole source of amino acids, did not differ significantly from each other when assayed in diets containing certain other sources of amino acids. The data would suggest that assays designed to evaluate fish meals as a supplemental source of protein should be conducted with the specific ration in which they are to be used. REFERENCES Carpenter, K. J., G. M. Ellinger and D. H. Shrimpton, 195S. The evaluation of whaling by-products as feeding-stuffs. J. Sci. Food Agric. 6: 296-304. Duncan, D. B., 1955. Multiple range and multiple F tests. Biometrics 2 : 1-42. Grau, C. R., and M. A. Williams, 1955. Fish meals as amino acid sources in chick rations. Poultry Sci. 34: 810-817. Heiman, V., J. S. Carver and J. W. Cook, 1939. A method for determinating the gross value of protein concentrates. Poultry Sci. 18: 464474. Hinners, S. W., and H. M. Scott, 1960. A bioassay for determining the nutritional adequacy of protein supplements for chick growth. Poultry Sci. 34 : 176-183. Snetsinger, D. C , and H. M. Scott, 1958. The adequacy of soybean oil meal as a sole source of protein for chick growth. Poultry Sci. 37: 1400-1403.
NEWS AND NOTES (Continued from page 1924) sin poultry producers out of business in the late 1940's, Hayes worked with veterinarians, disease control specialists at the State Department of Agriculture, and the University in setting up an inoculation program. Another achievement with which he is credited came when he laid the groundwork for the Lakeland Egg Co-operative, a poultry marketing association, started in 1949, in 15 eastern counties of the State. When the broiler industry began turning out more birds than the market could absorb, Hayes took to the church social and village centennial
circuit to show how mass broiling could be done. Under his direction, cement block pits were set up for broiling of birds clipped two dozen at a time in wire frames. His aides got "master chef" certificates to hang in their homes—and the multitudes got fed. Later he switched to lightweight portable aluminum pits. He was very effective in presenting his program to farmers and to other persons in the poultry industry, and to consumers. He was effective in making such contacts by speaking before groups, by appearing on television and radio, by participating in conferences, or by correspondence. He
(Continued on page 1946)
Downloaded from http://ps.oxfordjournals.org/ at Purdue University Libraries ADMN on June 11, 2015
correlated with its supplemental value. There is still a place for assays of this type. The ease and rapidity of testing fish meal as the sole source of amino acids (Hinners and Scott, 1960) makes it a logical one to use in studying the effect of processing variables on protein quality. This assay is in contrast to assays designed to study the supplemental value of fish meal in a diet containing other sources of amino acids. The latter evaluates fish meal in the role in which it will be used in actual practice, namely as a source of supplemental amino acids. The differences between the two fish meals in supplementing basal diet C, but not basal diet B, precludes the testing of any fish meal in one diet and generalizing with respect to its supplemental value for use in other diets. These data show that while assays designed to examine the supplemental value of the protein in fish meal are quite feasible, such assays should be conducted with the diet in which one intends to use the fish meal.
1939