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Some Observations on Feeding Dyes to Laying Chickens
Some Observations on Feeding Dyes to Laying Chickens CHARLES A.
DENTON
Agricultural Research Center, Bureau of Animd Industry, Beltsville, Maryland
D
ADDI (1896) observed that animal
the feed to various parts of the chicken's
tissues were colored by Sudan III, body and the subsequent transfer of these a fat soluble dye. Later Riddle (1908), materials to the egg it seems feasible that Gage and Gage (1908), Rogers (1910), dyes which would contrast rather than and, more recently, Warren and Conrad blend with the natural pigments could be (1939) used the deposition of this dye in used advantageously. In an effort to find egg yolk to study yolk growth. Warren such dyes a number of water and alcohol and Conrad injected the dye directly into soluble dyes were fed to laying pullets. The the blood stream of the chicken instead purpose of this paper is to put on record of feeding it as did the other investiga- the names of these dyes and the observators. Rogers (1910) fed Rhodamine Red, tions made concerning their behavior. Auramine Yellow, and Saf(f)ranine Red K ' ' . EXPERIMENTAL METHOD as well as Sudan III. The Rhodamine Red colored the shell and the white of the egg A diet that contained very little of the and tinted the yolk slightly. The other carotenoid pigments and d-riboflavin was two dyes were deposited only in the yolk. fed to Rhode Island Red pullets. It was Grossfeld and Kanitz (1935) fed Regina compounded as follows: Red, a coal-tar dye, to laying chickens and ,. Parts, by found that some of the dye was deposited Ground white corn 41.1 in the yolks of the resulting eggs. These Pulverized oats 41.1 workers also outlined a chemical method Limestone411 'C. 5 " ^ . . . . . . . . . . . 2.7 for the determination of coal-tar dyes in Salt mixture 0.5 eggs. Later they (193 7) made the observa- F o r t i f i e d c o d l i v e r oil J± tion that Sudan Red B colored the body Total 100.0 fat and egg yolk deeply, and that Sudan _ , . ,. ^ , , ., 4, „ TTT i j ^ u J f l u * * .-L. ii This diet was fed until the yolk was 111 colored the body fat but not the yolk. , , , ,„ , „ . . _ , rrU , .. .: . , ,., , almost colorless (7 on the Heiman-Carver The observation that cSudan TTT III did not „ „, , , .. , ,, ... , . . . yolk color rotor ) and the white was water color the yolk is not in agreement with \ . ' . . , , , , , , ,, . ,. ° clear. On the average it required about IS reports of other investigators. , . . . . ,..„,,. A ii J ... j.-. ° . days to obtain this condition. This reducc TWT-i T.I All dyes with the exception of Nile Blue .J , . , , , „ , ^ ,-p. J m-j^N i t T • I U tion in color in both the yolk and the (Drummond, 1926) that previously have ,. , . , , . . ., , . j . , ., „ i-, white was desired because the dyes would been reported to color the yolk or white , .... .,, ., , •* i , ., n j „ , be more easily discernible, even if deposited of the egg are yellow, orange, or red. Sudan . ,, .. , , ., j ., . , , in rather small quantities. TTT . ,, I l l is the only one of these dyes that had , , , . i i m , , . . , . j . , ,, The dyes were fed in capsules, the water r been used extensively in studies of the physiological development of the yolk. In
a study of the transfer of materials from
»Heiman, V., and J. S. Carver, 193S. The yolk
color index. U. S. Egg and Poul. Mag. 41:40-4i.
[281]
Downloaded from http://ps.oxfordjournals.org/ at University of South Dakota and School of Medicine on April 13, 2015
(Received for publication December 4, 1939)
282
CHARLES A. DENTON TABLE 1.—Dyes studies; their structural classification, solubility, and effect on color of the white and yolk Trade name
Color Designation given by Food & index Type of dye Drug Admin. number"
Resulting color or Soluble in Egg white
Egg yolk
Section 1 FD&C Blue No. 1
Ponceau 3R
FD&C Red No. 1
Fast Green FCF
FD&C Green No. 3
Light Green FS Yellowish
Tri-phenylmethane
Water Alcohol
No change
No change
Mono-azo
Water Slightly alcohol
No change
No change
None
Tri-phenylmethane
Water Slightly alcohol
No change
No change
FD&C Green No. 2
670
Tri-phenylmethane
Water Slightly alcohol
No change
No change
Amaranth
FD&C Red No. 2
184
Mono-azo
Water Slightly alcohol
No change
No change
Orange 1
FD&C Orange No. 1
ISO
Mono-azo
Water Slightly alcohol
No change
No change
Metanil Yellow
Ext. D&C Yellow No. 1
138
Mono-azo
Water Alcohol
No change
No change
Resorcin Brown
D&C Brown No. 1
234
Dis-azo
Water Alcohol
No change
No change
Anthraquinone
Water Alcohol
No change
No change
Alizarin Red S
—
None 80
1034
Section 2 Sudan I I
—
Yellow AB
FD&C Yellow No. 3
Naphthol Blue Black
D&C Black No. 1
Cumidine Red
73
Mono-azo
Oil Moderately alcohol.
No change
No change
22
Mono-azo
Oil Alcohol
No change
No change
Dis-azo
Oil-suspension Moderately alcohol Water
No change
No change
None
Mono-azo
Oil-suspension Alcohol
No change
No change
246
Toluidine Red
D&C Red No. 35
69
Mono-azo
Oil-suspension Alcohol
No change
No change
Tetrabromoflucrescein
D&C Red No. 21
768
Xanthene
Oil-suspension Alcohol Water
No change
No change
Alizarol Purple
Ext. D&C Violet No. 2
1073
Anthraquinone
Oil-suspension Alcohol Water
No change
No change
Downloaded from http://ps.oxfordjournals.org/ at University of South Dakota and School of Medicine on April 13, 2015
Brilliant Blue FCF
283
SOME OBSERVATIONS ON FEEDING DYES TO LAYING CHICKENS TABLE 1—Continued
Trade name
Color Designation given by Food & index Type of dye number" Drug Admin.
Resulting color of Soluble in Egg white
Egg yolk
Oil-suspension Alcohol Water
No change
No change
Section 2—continued Wool Violet 5 BN
698
Tri-phenylmethane Section 3 b
Spirit soluble Nigrosine (1)
—
864
Azine
Oil-suspension Alcohol Water
No change
Slight green
Coomassie Fast Black (2)
Ext. D&C Black No. 1
307
Dis-azo
Oil-suspension Alcohol Water
No change
Pink
Oil Brown D (3)
—
None
Mixture of dyes
Oil Alcohol
No change
Magenta
Alizarin Cyanine Green F (4)
D&C Green No. 6
1078 Unsulfonated
Anthraquinone
Oil Alcohol
No change
Green
Alizarol Purple SS (5)
D&C Violet No. 2
1073 Unsulfonated
Anthraquinone
Oil Alcohol
No change
Green
Hexyl Blue (6)
Ext. D&C Blue No. 5
None
Anthraquinone
Oil Alcohol
No change
Blue
Oil Red 0 (7)
D&C Red No. 18
None
Dis-azo
Oil Alcohol
No change
Red
» Color Index. The Society of Dyers and Colorists. 1924. Edited by E. M. Rowe. Published by the society. b The dyes indicated by the numbers in parenthesis may be obtained from the following companies: (1) to (7), inclusive—Pylam Products, Inc., 799 Greenwich Street, New York, New York. (1), (2), (3), (4), (6), (7)—E. I. du Pont de Nemours & Company, Wilmington, Delaware. (1), (2), (4), (5), (6), (7)—National Analine and Chemical Co., 40 Rector Street, New York, New York. (3), (4)—Calco Chemical Company, Bound Brook, New Jersey.
soluble ones in aqueous solution and the alcohol soluble ones in soybean oil. Doses ranging from 10 to 50 mg. per bird per day were given. It was found, however, that 20 mg. per bird per day was sufficient in most cases to give maximum color intensity. The effect of the dyes was observed by breaking the eggs into white porcelain dishes and transferring the white to 50 ml. clear glass vials. Twenty-four dyes were studied (Table 1). Nine of them were water soluble, the other 15 alcohol soluble. Only six of the alcohol-soluble dyes were completely solu-
ble in soybean oil, the others were only partially soluble or formed suspensions. None of the water soluble dyes (Table 1, sec. 1) colored any part of the egg. Two of them, Brilliant Blue FCF and Ponceau 3R were injected intravenously. They were not absorbed and were excreted within 30 minutes after injection. Eight of the alcohol-soluble dyes were not deposited in the yolk, whereas the other seven were (Table 1, sees. 2 and '3). One of them, Spirit Soluble Nigrosine, colored the yolk only very slightly. Spirit Soluble Nigrosine and Coomassie Fast Black are
Downloaded from http://ps.oxfordjournals.org/ at University of South Dakota and School of Medicine on April 13, 2015
D&C Violet No. 1
284
CHARLES A. DENTON
with the natural yellow pigment. Henderson and Wilcke (1933) state: "It seemed logical that if the body fat contributed to the color of the egg yolk independently of the feed, a fat stain such as Sudan III would follow the same path." They concluded from their work that the hen cannot withdraw Sudan III from her body fat for deposition in egg yolks. However, as is reported in this paper, Hexyl Blue was withdrawn from fat depots in the body and deposited in the yolk. SUMMARY
Twenty-four dyes were fed to laying pullets. Nine of these dyes were water soluble and the other IS were alcohol soluble. None of the water-soluble dyes were deposited in any part of the egg, whereas seven of the alcohol-soluble dyes were deposited in the yolk. Observations were made which indicate that Hexyl Blue dye is withdrawn from body-fat depots and deposited in the yolk. The names of the dyes, a few of their chemical properties, and their effects, when fed to chickens, on the color of the yolks of the resulting eggs are given in Table 1. ACKNOWLEDGEMENT
The author wishes to express his appreciation to Mr. James A. Kime and Mr. Stanley S. Forrest of the Food and Drug Administration, U. S. Department of Agriculture, for assistance in identification of the dyes. REFERENCES
Daddi, L., 1896. Nouvelle methode pour colour la graisse dans les tissus. Arch. Ital. de Biol. 26:143-146. Drummond, J. C , 1926. New aspects of the chemistry of fats and oils. Chem. and Ind. 45 :994-999. Gage, S. H., and S. P. Gage, 1908. Sudan III deposited in the egg and transmitted to the chick. Science (n.s.) 28:494. Grossfeld, J., and H. R. Kanitz, 1935. Uber den Nachweis von Teerfarbstoffen in Huhnerei.
Downloaded from http://ps.oxfordjournals.org/ at University of South Dakota and School of Medicine on April 13, 2015
both black dyes but the former imparted a green color and the latter a pink color to the yolk. It is of interest to note that Alizarol Purple SS, a purple dye colored the yolk green, a shade very similar to that caused by the deposition of Alizarin Cyanine Green F. Color appeared in the yolks two to three days after the first feeding of the dyes and it was just as intense when it was first noted as at any time during the period the dyes were being fed. When the feeding of the dyes was stopped the most pronounced decrease in the intensity of the color took place within the first three or four days. After this there was a gradual decrease in color until the yolk attained the faint yellow color regularly obtained with the basal diet. The most interesting effects were obtained by feeding Hexyl Blue. This dye gave a deep blue color to all abdominal and external fat. The fat in the muscle tissues, that around the joints, and that in the feather follicles was also deeply colored. The skin color of the Rhode Island Red pullets that received this dye resembled somewhat that of Silkies. The depletion of this color after the feeding of the dye was stopped did not follow the usual behavior. A pronounced color change took place after the third day and the yolk became a greenish blue, then for several days the color faded slightly and the green became more predominant. Thereafter the change in color was so slight that it could hardly be noticed from day to day. In the case of one particular pullet four months elapsed between the last dose of Hexyl Blue dye and the disappearance of color from the yolk. During this period the pullet laid 76 eggs. At the end of this period the skin color was faded. The abdominal fat had become light green in color, probably as the result of admixture of the small quantity of residual blue dye
SOME
OBSERVATIONS ON F E E D I N G
TO L A Y I N G
CHICKENS
285
white and yellow yolk in the ova of vertebrates. Science (n.s.) 27 :94S. Rogers, C. A., 1910. Feeding color—an aid in studying physiological development. Internatl. Assoc. Instructors and Investigators in Poultry Husb. Proc. (1908-10) 1:77-81. Warren, D. C , and R. M. Conrad, 1939. Growth of the hen's ovum. Jour. Agri. Res. 58:875893.
Downloaded from http://ps.oxfordjournals.org/ at University of South Dakota and School of Medicine on April 13, 2015
Zeitschrift fiir Untersuchung der Lebensmittel. 69 :582-584. , 1937. Versuche uber kiinstliche Farbung von Huhnereidottern durch Futterung. Zeitschrift fiir Untersuchung der Lebensmittel. 74:471-474. Henderson, E. W., and H. L. Wilcke, 1933. Effect of ration on yolk color. Poul. Sci. 12:266-273. Riddle, Oscar, 1908. The rate of growth of the egg yolk in the chick and the significance of
DYES
DENTON
Agricultural Research Center, Bureau of Animd Industry, Beltsville, Maryland
D
ADDI (1896) observed that animal
the feed to various parts of the chicken's
tissues were colored by Sudan III, body and the subsequent transfer of these a fat soluble dye. Later Riddle (1908), materials to the egg it seems feasible that Gage and Gage (1908), Rogers (1910), dyes which would contrast rather than and, more recently, Warren and Conrad blend with the natural pigments could be (1939) used the deposition of this dye in used advantageously. In an effort to find egg yolk to study yolk growth. Warren such dyes a number of water and alcohol and Conrad injected the dye directly into soluble dyes were fed to laying pullets. The the blood stream of the chicken instead purpose of this paper is to put on record of feeding it as did the other investiga- the names of these dyes and the observators. Rogers (1910) fed Rhodamine Red, tions made concerning their behavior. Auramine Yellow, and Saf(f)ranine Red K ' ' . EXPERIMENTAL METHOD as well as Sudan III. The Rhodamine Red colored the shell and the white of the egg A diet that contained very little of the and tinted the yolk slightly. The other carotenoid pigments and d-riboflavin was two dyes were deposited only in the yolk. fed to Rhode Island Red pullets. It was Grossfeld and Kanitz (1935) fed Regina compounded as follows: Red, a coal-tar dye, to laying chickens and ,. Parts, by found that some of the dye was deposited Ground white corn 41.1 in the yolks of the resulting eggs. These Pulverized oats 41.1 workers also outlined a chemical method Limestone411 'C. 5 " ^ . . . . . . . . . . . 2.7 for the determination of coal-tar dyes in Salt mixture 0.5 eggs. Later they (193 7) made the observa- F o r t i f i e d c o d l i v e r oil J± tion that Sudan Red B colored the body Total 100.0 fat and egg yolk deeply, and that Sudan _ , . ,. ^ , , ., 4, „ TTT i j ^ u J f l u * * .-L. ii This diet was fed until the yolk was 111 colored the body fat but not the yolk. , , , ,„ , „ . . _ , rrU , .. .: . , ,., , almost colorless (7 on the Heiman-Carver The observation that cSudan TTT III did not „ „, , , .. , ,, ... , . . . yolk color rotor ) and the white was water color the yolk is not in agreement with \ . ' . . , , , , , , ,, . ,. ° clear. On the average it required about IS reports of other investigators. , . . . . ,..„,,. A ii J ... j.-. ° . days to obtain this condition. This reducc TWT-i T.I All dyes with the exception of Nile Blue .J , . , , , „ , ^ ,-p. J m-j^N i t T • I U tion in color in both the yolk and the (Drummond, 1926) that previously have ,. , . , , . . ., , . j . , ., „ i-, white was desired because the dyes would been reported to color the yolk or white , .... .,, ., , •* i , ., n j „ , be more easily discernible, even if deposited of the egg are yellow, orange, or red. Sudan . ,, .. , , ., j ., . , , in rather small quantities. TTT . ,, I l l is the only one of these dyes that had , , , . i i m , , . . , . j . , ,, The dyes were fed in capsules, the water r been used extensively in studies of the physiological development of the yolk. In
a study of the transfer of materials from
»Heiman, V., and J. S. Carver, 193S. The yolk
color index. U. S. Egg and Poul. Mag. 41:40-4i.
[281]
Downloaded from http://ps.oxfordjournals.org/ at University of South Dakota and School of Medicine on April 13, 2015
(Received for publication December 4, 1939)
282
CHARLES A. DENTON TABLE 1.—Dyes studies; their structural classification, solubility, and effect on color of the white and yolk Trade name
Color Designation given by Food & index Type of dye Drug Admin. number"
Resulting color or Soluble in Egg white
Egg yolk
Section 1 FD&C Blue No. 1
Ponceau 3R
FD&C Red No. 1
Fast Green FCF
FD&C Green No. 3
Light Green FS Yellowish
Tri-phenylmethane
Water Alcohol
No change
No change
Mono-azo
Water Slightly alcohol
No change
No change
None
Tri-phenylmethane
Water Slightly alcohol
No change
No change
FD&C Green No. 2
670
Tri-phenylmethane
Water Slightly alcohol
No change
No change
Amaranth
FD&C Red No. 2
184
Mono-azo
Water Slightly alcohol
No change
No change
Orange 1
FD&C Orange No. 1
ISO
Mono-azo
Water Slightly alcohol
No change
No change
Metanil Yellow
Ext. D&C Yellow No. 1
138
Mono-azo
Water Alcohol
No change
No change
Resorcin Brown
D&C Brown No. 1
234
Dis-azo
Water Alcohol
No change
No change
Anthraquinone
Water Alcohol
No change
No change
Alizarin Red S
—
None 80
1034
Section 2 Sudan I I
—
Yellow AB
FD&C Yellow No. 3
Naphthol Blue Black
D&C Black No. 1
Cumidine Red
73
Mono-azo
Oil Moderately alcohol.
No change
No change
22
Mono-azo
Oil Alcohol
No change
No change
Dis-azo
Oil-suspension Moderately alcohol Water
No change
No change
None
Mono-azo
Oil-suspension Alcohol
No change
No change
246
Toluidine Red
D&C Red No. 35
69
Mono-azo
Oil-suspension Alcohol
No change
No change
Tetrabromoflucrescein
D&C Red No. 21
768
Xanthene
Oil-suspension Alcohol Water
No change
No change
Alizarol Purple
Ext. D&C Violet No. 2
1073
Anthraquinone
Oil-suspension Alcohol Water
No change
No change
Downloaded from http://ps.oxfordjournals.org/ at University of South Dakota and School of Medicine on April 13, 2015
Brilliant Blue FCF
283
SOME OBSERVATIONS ON FEEDING DYES TO LAYING CHICKENS TABLE 1—Continued
Trade name
Color Designation given by Food & index Type of dye number" Drug Admin.
Resulting color of Soluble in Egg white
Egg yolk
Oil-suspension Alcohol Water
No change
No change
Section 2—continued Wool Violet 5 BN
698
Tri-phenylmethane Section 3 b
Spirit soluble Nigrosine (1)
—
864
Azine
Oil-suspension Alcohol Water
No change
Slight green
Coomassie Fast Black (2)
Ext. D&C Black No. 1
307
Dis-azo
Oil-suspension Alcohol Water
No change
Pink
Oil Brown D (3)
—
None
Mixture of dyes
Oil Alcohol
No change
Magenta
Alizarin Cyanine Green F (4)
D&C Green No. 6
1078 Unsulfonated
Anthraquinone
Oil Alcohol
No change
Green
Alizarol Purple SS (5)
D&C Violet No. 2
1073 Unsulfonated
Anthraquinone
Oil Alcohol
No change
Green
Hexyl Blue (6)
Ext. D&C Blue No. 5
None
Anthraquinone
Oil Alcohol
No change
Blue
Oil Red 0 (7)
D&C Red No. 18
None
Dis-azo
Oil Alcohol
No change
Red
» Color Index. The Society of Dyers and Colorists. 1924. Edited by E. M. Rowe. Published by the society. b The dyes indicated by the numbers in parenthesis may be obtained from the following companies: (1) to (7), inclusive—Pylam Products, Inc., 799 Greenwich Street, New York, New York. (1), (2), (3), (4), (6), (7)—E. I. du Pont de Nemours & Company, Wilmington, Delaware. (1), (2), (4), (5), (6), (7)—National Analine and Chemical Co., 40 Rector Street, New York, New York. (3), (4)—Calco Chemical Company, Bound Brook, New Jersey.
soluble ones in aqueous solution and the alcohol soluble ones in soybean oil. Doses ranging from 10 to 50 mg. per bird per day were given. It was found, however, that 20 mg. per bird per day was sufficient in most cases to give maximum color intensity. The effect of the dyes was observed by breaking the eggs into white porcelain dishes and transferring the white to 50 ml. clear glass vials. Twenty-four dyes were studied (Table 1). Nine of them were water soluble, the other 15 alcohol soluble. Only six of the alcohol-soluble dyes were completely solu-
ble in soybean oil, the others were only partially soluble or formed suspensions. None of the water soluble dyes (Table 1, sec. 1) colored any part of the egg. Two of them, Brilliant Blue FCF and Ponceau 3R were injected intravenously. They were not absorbed and were excreted within 30 minutes after injection. Eight of the alcohol-soluble dyes were not deposited in the yolk, whereas the other seven were (Table 1, sees. 2 and '3). One of them, Spirit Soluble Nigrosine, colored the yolk only very slightly. Spirit Soluble Nigrosine and Coomassie Fast Black are
Downloaded from http://ps.oxfordjournals.org/ at University of South Dakota and School of Medicine on April 13, 2015
D&C Violet No. 1
284
CHARLES A. DENTON
with the natural yellow pigment. Henderson and Wilcke (1933) state: "It seemed logical that if the body fat contributed to the color of the egg yolk independently of the feed, a fat stain such as Sudan III would follow the same path." They concluded from their work that the hen cannot withdraw Sudan III from her body fat for deposition in egg yolks. However, as is reported in this paper, Hexyl Blue was withdrawn from fat depots in the body and deposited in the yolk. SUMMARY
Twenty-four dyes were fed to laying pullets. Nine of these dyes were water soluble and the other IS were alcohol soluble. None of the water-soluble dyes were deposited in any part of the egg, whereas seven of the alcohol-soluble dyes were deposited in the yolk. Observations were made which indicate that Hexyl Blue dye is withdrawn from body-fat depots and deposited in the yolk. The names of the dyes, a few of their chemical properties, and their effects, when fed to chickens, on the color of the yolks of the resulting eggs are given in Table 1. ACKNOWLEDGEMENT
The author wishes to express his appreciation to Mr. James A. Kime and Mr. Stanley S. Forrest of the Food and Drug Administration, U. S. Department of Agriculture, for assistance in identification of the dyes. REFERENCES
Daddi, L., 1896. Nouvelle methode pour colour la graisse dans les tissus. Arch. Ital. de Biol. 26:143-146. Drummond, J. C , 1926. New aspects of the chemistry of fats and oils. Chem. and Ind. 45 :994-999. Gage, S. H., and S. P. Gage, 1908. Sudan III deposited in the egg and transmitted to the chick. Science (n.s.) 28:494. Grossfeld, J., and H. R. Kanitz, 1935. Uber den Nachweis von Teerfarbstoffen in Huhnerei.
Downloaded from http://ps.oxfordjournals.org/ at University of South Dakota and School of Medicine on April 13, 2015
both black dyes but the former imparted a green color and the latter a pink color to the yolk. It is of interest to note that Alizarol Purple SS, a purple dye colored the yolk green, a shade very similar to that caused by the deposition of Alizarin Cyanine Green F. Color appeared in the yolks two to three days after the first feeding of the dyes and it was just as intense when it was first noted as at any time during the period the dyes were being fed. When the feeding of the dyes was stopped the most pronounced decrease in the intensity of the color took place within the first three or four days. After this there was a gradual decrease in color until the yolk attained the faint yellow color regularly obtained with the basal diet. The most interesting effects were obtained by feeding Hexyl Blue. This dye gave a deep blue color to all abdominal and external fat. The fat in the muscle tissues, that around the joints, and that in the feather follicles was also deeply colored. The skin color of the Rhode Island Red pullets that received this dye resembled somewhat that of Silkies. The depletion of this color after the feeding of the dye was stopped did not follow the usual behavior. A pronounced color change took place after the third day and the yolk became a greenish blue, then for several days the color faded slightly and the green became more predominant. Thereafter the change in color was so slight that it could hardly be noticed from day to day. In the case of one particular pullet four months elapsed between the last dose of Hexyl Blue dye and the disappearance of color from the yolk. During this period the pullet laid 76 eggs. At the end of this period the skin color was faded. The abdominal fat had become light green in color, probably as the result of admixture of the small quantity of residual blue dye
SOME
OBSERVATIONS ON F E E D I N G
TO L A Y I N G
CHICKENS
285
white and yellow yolk in the ova of vertebrates. Science (n.s.) 27 :94S. Rogers, C. A., 1910. Feeding color—an aid in studying physiological development. Internatl. Assoc. Instructors and Investigators in Poultry Husb. Proc. (1908-10) 1:77-81. Warren, D. C , and R. M. Conrad, 1939. Growth of the hen's ovum. Jour. Agri. Res. 58:875893.
Downloaded from http://ps.oxfordjournals.org/ at University of South Dakota and School of Medicine on April 13, 2015
Zeitschrift fiir Untersuchung der Lebensmittel. 69 :582-584. , 1937. Versuche uber kiinstliche Farbung von Huhnereidottern durch Futterung. Zeitschrift fiir Untersuchung der Lebensmittel. 74:471-474. Henderson, E. W., and H. L. Wilcke, 1933. Effect of ration on yolk color. Poul. Sci. 12:266-273. Riddle, Oscar, 1908. The rate of growth of the egg yolk in the chick and the significance of
DYES