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Further Experiments in Feeding Thyroid to Fowls 1
FURTHER EXPERIMENTS IN FEEDING THYROID TO FOWLS i L. J. COLE AND P. B. HtJTT
MOULTING
Forty White Leghorn hens were divided into two equal lots and fed identical rations. To make the environment natural and equal for both lots, ten birds to receive thyroid and ten controls were put in each of two identical colony houses, both of which had out-door yards. For a period of six weeks, beginning November 1st, the twenty thyroid-fed hens were given desiccated thyroid (Armour and Co., 0.2% iodine) at the rate of 196 mg. per bird daily. This was equivalent to approximately 59 mg. per pound of live weight. The powder was administered individually in gelatine capsules. Each bird was leg-banded and cheeked over weekly. To make observations easier, the primaries and secondaries of one lot were stained with "liehtgrun" and the other with eosin. At the start of the experiment, several of the hens in both lots had already started to moult and some were practically finished. Of those receiving thyroid, seven had not yet started to moult, and three more had just begun. Of the controls, five showed no sign whatever of moulting, and four others had just started. As the experiment progressed, seven of the ten thyroid-fed birds which had undergone little or no moult at the start went i Papers from the Department of Genetics, Agricultural Experiment Station, University of Wisconsin, No. 86. Published with the approval of the Director of the Station.
60
Downloaded from http://ps.oxfordjournals.org/ at New York University on May 12, 2015
(Received for Publication 10-17-27) In an attempt to learn more of the properties and functions of the thyroid gland, several investigators have tried feeding fresh or desiccated thyroids to fowls. During 1924 and 1925 experiments of this nature were made by the writers. In view of the varying reports of other investigators, our results are considered of sufficient interest to warrant their presentation. They include effects of thyroid feeding on moulting, egg production, weight, plumage color and plumage structure.
FEEDING THYROID TO FOWLS
61
Two of the controls did not moult at all d u r i n g the six weeks of the experiment, and t h e others moulted slowly. They grew new feathers in all regions before all the old ones were gone, in contrast to the thyroid-fed birds, which seemed to drop all feathers at once ( p a r t i c u l a r l y on the breast and neck) a n d then grow a new crop uniformly. This faculty of shedding m a n y feathers simultaneously with a resultant naked condition is not necessarily a distinctive characteristic of thyroid-fed birds, for it is commonly seen in hens which moult late. I n this experiment, however, such a condition was not noted among the controls, b u t was evident in seven of the birds receiving thyroid. I t seems reasonable to conclude, therefore, t h a t the thyroid feeding was here responsible for the precipitate moult. Since this experiment, Giacomini ; (1924), B. Zavadovteky (1925) and Crew (1925) have reported precipitate moulting in fowls, induced, however, b y much larger doses. WEIGHT Results of weekly weighings are reported in Table 1. TABU; 1.
November November November November November December December
1 8 15 21 27 4 12
AVERAGE WEIGHT PER BIRD IN POUNDS
Thyroid-Fed 3.30 3.30 3.28 3.27 3.28 3.30 3.34
Controls 3.34 3.25 3.23 3.33 3.32 3.40
These d a t a indicate t h a t t h e dosage given in this experiment (59 mg. daily per pound of live weight) had no effect on body
Downloaded from http://ps.oxfordjournals.org/ at New York University on May 12, 2015
into more or less precipitate moult at various stages of feeding. Three showed decided body moult at the end of the first week, t h r e e more a t the end of t h e second week, a n d one d u r i n g the t h i r d week. These hens seemed to lose their feathers most r a p i d l y from t h e tracts on the breast a n d neck. I t was sometimes possible t o p u l l a h a n d f u l of feathers from these regions by' the lightest touch. I n some cases two or three primaries could be plucked out at once with almost no effort. Three of these ten birds moulted more slowly a n d were never in a seminaked or " q u i l l y " condition as were some of the others.
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POULTRY SCIENCE
weight. Other workers have reported rapid loss in weight, when much larger doses of raw thyroid were fed. EGG PRODUCTION
All hens were trap-nested. Egg records for a period of four months from the start of the experiment are shown in Table 2. TABLE 2.
Nov. Deo. Jan. Feb. Total 26 23 36 44 129 27 19 35 46 127
It seemed possible that an early quick moult, such as is favored by the thyroid feeding, might lead to an earlier increased egg production. There is, however, no evidence that egg production was at all affected by the dosage fed in this experiment. Crew and Huxley (1923) reported similar results with fowls receiving small doses of thyroid. Crew has since found (1925) that senile females were markedly stimulated to egg production by larger doses. PLUMAGE
(COLOR AND STRUCTURE)
Hen feathering in the male fowl has been reported as a result of thyroid-feeding by Torrey and Hornjng (1922), Cole and Reid (1924) and Crew (1925), and the authors of the last two papers also noted increased melanism in feathers growing in exposed to the influence of the thyroid. Torrey (1926) has noted the same effect in barred feathers of Barred Plymouth Rock males. All of these workers fed desiccated thyroid powder. In direct contrast to this, Giacomini (1924) reported depigmentation of plumage as a result of feeding raw ox thyroid to fowls. Subsequent experiments of B. Zavadovsky (1925), M. Zavadovsky (1925), Torrey and Horning (1925), Krizenecky (1926a, 1926b), and Podhradsky (1926) confirm the toxic effect of large doses of thyroid in producing abnormal feather structure and decrease of pigmentation. In many cases the feathers grown under these conditions are largely or entirely white. It seemed possible that there might be some difference in the physiological properties of raw and desiccated thyroid. Accordingly an experiment was planned to find the effects of both on plumage color and structure in males and females of different breeds. Twenty-two birds were given dosages as follows:
Downloaded from http://ps.oxfordjournals.org/ at New York University on May 12, 2015
Thyroid-fed (20) Controls (20)
EGGS LAID PER MONTH
FEEDING
THYROID
TO
FOWLS
63
SECONDARY SEX CHARACTERS
The lanceolate, pointed appearance of neck, wing bow and saddle feathers of male fowl is due to a lack of barbules and hooks in the margin of the web. It constitutes a secondary sex character. In this experiment, various degrees of hen-feathering were noted in all males receiving either desiccated or raw thyroid, with the exception of the Rhode Island Red. It was quite evident that after six weeks of feeding the influence
Downloaded from http://ps.oxfordjournals.org/ at New York University on May 12, 2015
Raw pig thyroid—0.42 grams daily per pound of live weight. Males—Barred Rock, Buff Leghorn, Silver Laced Wyandotte, Rhode Island Red, Silver Spangled Hamburg, Golden Sebright. Females—Barred Rock, Buff Leghorn, Ancona, Black Minorca. Desiccated thyroid—84 mg. daily per pound of live weight. Males—Barred Rock, Buff Leghorn, Silver Laced Wyandotte, Golden Sebright. Females—Barred Rock, Buff Leghorn, Blue Andalusian, Ancona. Controls—Males, Golden Sebright. Females—Barred Rock, Buff Leghorn, Ancona. On the assumption that one gram of the desiccated powder (Armour and Co., 0.2% iodine) is equivalent to five grams of fresh normal thyroid gland, the actual doses of active thyroid substance were approximately equal for all birds whether they received raw or desiccated gland. Feeding began on March 2. On March 11, small areas on the neck, .wing bow and saddle of each bird were plucked free of feathers and samples of the latter were saved for future comparison. Weights were taken every two weeks. Feeding was discontinued on May 8th. No lack of pigmentation was observed except very small white spots in the normally black marginal lacing of new neck and saddle feathers in both thyroid-fed Sebrights. The two Silver Wyandotte males grew distinctly darker feathers, particularly in the neck region. The Silver Spangled Hamburg and Rhode Island Red males showed a slight but perceptible tendency toward increased melanism in new feathers, but no appreciable change in color was evident in any of the females or the other males on either raw or desiccated thyroid. Torrey and Horning (1926) have subsequently noted increased melanism induced in males but not in females by thyroid feeding.
64
POULTRY
SCIENCE
OTHER EFFECTS
No significant change in weight was noticed in any of the birds. Giacomini and M. Zavadovsky have noticed a stimulus for
Downloaded from http://ps.oxfordjournals.org/ at New York University on May 12, 2015
of the thyroid was completely lost, so far as feather structure was concerned. The Hamburg male grew a crop of femaletype feathers on his neck and saddle, lost all on his neck by fighting, and subsequently replaced them with feathers of the normal male type. One of the Barred Rock males first grew " h e n n y " feathers on the wing bow, then feathers of intermediate structure on the neck, and finally, after five weeks of feeding, saddle feathers of the normal male type. The other birds showed instances of the same phenomenon. The Rhode Island Red did not grow any new feathers till after six weeks of thyroid feeding, hence they were not henny, as were the earlier feathers of the other males. The most interesting changes were observed in the Silver Wyandotte male receiving desiccated thyroid. This bird grew female feathers on neck, wing bow and saddle. The new neck feathers tended toward solid black rather than the typical black feather with white lacing. On the wing bow, however, where the male feathers had been white with a black base, there were produced feathers entirely female both in structure and color pattern, viz., white with black lacing. Similarly on the saddle, the new feathers were white with a black lacing oneeighth to one-quarter inch wide where those plucked had been black with a white margin. These effects were also present in the Silver Wyandotte male receiving raw thyroid, but were less distinct because his feathers grew in more slowly and hence partially escaped the influence of the thyroid. The Silver Wyandotte is a dimorphically colored breed, i. e., the male differs from the female in plumage pattern as well as feather structure. In this experiment both of these secondary sex characters were completely suppressed in the males and altered to the female expression as a result of thyroid feeding. No change was noticed in feather structure of the Sebright males, a breed in which the male is normally hen feathered.
FEEDING
THYROID
TO
FOWLS
65
It was noticeable that in all birds the saddle feathers developed more slowly than those in the neck and wing bow regions. SUMMARY
1. Hen-feathering was induced in male fowls by feeding both desiccated and raw thyroid. 2. In males of a dimorphically-colored breed the color pattern of the feathers was changed from that of the male to that of the female by thyroid feeding. 3. At our dosage there was no appreciable evidence of the lack of pigmentation in new feathers described by other investigators. 4. Raw thyroid appeared to have less stimulating effect on feather growth than desiccated thyroid at approximately the same level of feeding (based on assumed iodine content). 5. Feather structure in Sebright males was unaffected by thyroid feeding. 6. A daily dose of 59 mg. desiccated thyroid per pound of live weight hastened the normal moult of yearling hens. 7. The same dosage did not have any appreciable effect on body weight or egg production during the period of four months.
Downloaded from http://ps.oxfordjournals.org/ at New York University on May 12, 2015
feather growth in birds fed large doses of fresh thyroid. In our experiments, the desiccated thyroid seemed to have a much more stimulating effect on feather growth than had the raw thyroid. The fowls receiving desiccated thyroid were, with only one exception practically full feathered by May 8th, while many of those receiving raw thyroid had made very little feather growth. This difference was more noticeable in the females than in the males. Two of the former had made no feather growth except a few quills on the neck and wing bow by May 8th, and one had not even a new quill. The latter was given her raw thyroid dose till May 26th, at which time she still had not a quill. After feeding was discontinued the other two made a fairly good growth of feathers and were well covered in the neck and wing bow regions by May 26th. The number of birds used was too small to warrant any conclusion regarding this apparent difference between raw and desiccated thyroid.
66
POULTRY
SCIENCE
Downloaded from http://ps.oxfordjournals.org/ at New York University on May 12, 2015
REFERENCES COLE, L. J., AND REID, D. H. (1924). The effect of feeding thyroid on the plumage of t h e fowl. Journ. Agric. Res., 29, 6, 285-287. CREW, F . A. E., AND HUXLEY, J. S. (1923). T h e effect of thyroid feeding on growth rate, feathering, and egg production. Vet. Journ., 79, 343-348. CREW, F . A. E. (1925). Rejuvenation of t h e aged fowl t h r o u g h thyroid medication. Proc. Roy. Soc. Edin., 45, 21. 252-260. GIACOMINI, ERCOLE (1924). Color changes in plumage of poultry after thyroid a d m i n i s t r a t i o n . Report of Second World's Poultry Congress, 45-47. KRIZENECKY, J. (1926 a ) . Vyznam s t i t n e zlazy pro vznik t. zv. intersexualnich t v a r u u hospodarskych zvirat. (The importance of the thyreoidea for the occurrence of so called intersexual forms in domestic a n i m a l s ) . Vestnik ceskoslavenske akademie Zemedelske. (Bull. Czech. Acad. Agric.) Rocnik II. Cislo 5-6. pp. 1-5. KRIZENECKY, J. (1926 b ) . iiber den Einflusz der Schilddriise und der T h y m u s auf die E n t d e c k u n g des Gefieders bei Hiihnerkuken. Zeit. f. wiss. Biol., Bd. 107, Heft 4, pp. 583-604. PODHRADSKY, J. (1926). Der Einflusz des H y p e r t h y r o i d i s m u s aiif Wachstum und P i g m e n t i e r u n g des Gefieders bei ausgewachsenen H u h n e r n . Zeit. f. wiss. Biol., Bd. 107, Heft 3, pp. 407-422. TORREY, H. B., AND HORNING, B. (1922). Hen-feathering induced in t h e made fowl by feeding thyroid. Proc. Soc. Exp. Biol, and Med., 19. 6, 275-279. KRIZENECKY, J. (1926 a) Vyznam stetne zlazy pro vznik t. zv.. intersexualnich t v a r u u hospodarskych zvirat. ( T h e importance of the Thyreoidea for the occurrence of so called intersexual forms in domestic a n i m a l s ) . Vestnik Ceskoslavenske akademie Zemedelske. (Bull. Czech. Acad. Agric.) Rocnik II. Cislo 5-6, pp. 1-5. TORREY, H. B., AND HORNING, B. (1925). The effect of thyroid feeding on t h e moulting process and feather s t r u c t u r e of the domestic fowl. Biol. Bull., 49, pp. 275-287. TORREY, H. B., AND HORNING, B. (1926). [News item in Science], Vol. 63, No. 1619, p. xiv. ZAVADOVSKY, BORIS (1925). The effect of feeding fowls on thyroid gland. Endocrin. 9, 125-136. ZAVADOVSKY, M. (1925). The effect of single doses of thyroid gland in fowls. Endocrin. 9, 232-241.
MOULTING
Forty White Leghorn hens were divided into two equal lots and fed identical rations. To make the environment natural and equal for both lots, ten birds to receive thyroid and ten controls were put in each of two identical colony houses, both of which had out-door yards. For a period of six weeks, beginning November 1st, the twenty thyroid-fed hens were given desiccated thyroid (Armour and Co., 0.2% iodine) at the rate of 196 mg. per bird daily. This was equivalent to approximately 59 mg. per pound of live weight. The powder was administered individually in gelatine capsules. Each bird was leg-banded and cheeked over weekly. To make observations easier, the primaries and secondaries of one lot were stained with "liehtgrun" and the other with eosin. At the start of the experiment, several of the hens in both lots had already started to moult and some were practically finished. Of those receiving thyroid, seven had not yet started to moult, and three more had just begun. Of the controls, five showed no sign whatever of moulting, and four others had just started. As the experiment progressed, seven of the ten thyroid-fed birds which had undergone little or no moult at the start went i Papers from the Department of Genetics, Agricultural Experiment Station, University of Wisconsin, No. 86. Published with the approval of the Director of the Station.
60
Downloaded from http://ps.oxfordjournals.org/ at New York University on May 12, 2015
(Received for Publication 10-17-27) In an attempt to learn more of the properties and functions of the thyroid gland, several investigators have tried feeding fresh or desiccated thyroids to fowls. During 1924 and 1925 experiments of this nature were made by the writers. In view of the varying reports of other investigators, our results are considered of sufficient interest to warrant their presentation. They include effects of thyroid feeding on moulting, egg production, weight, plumage color and plumage structure.
FEEDING THYROID TO FOWLS
61
Two of the controls did not moult at all d u r i n g the six weeks of the experiment, and t h e others moulted slowly. They grew new feathers in all regions before all the old ones were gone, in contrast to the thyroid-fed birds, which seemed to drop all feathers at once ( p a r t i c u l a r l y on the breast and neck) a n d then grow a new crop uniformly. This faculty of shedding m a n y feathers simultaneously with a resultant naked condition is not necessarily a distinctive characteristic of thyroid-fed birds, for it is commonly seen in hens which moult late. I n this experiment, however, such a condition was not noted among the controls, b u t was evident in seven of the birds receiving thyroid. I t seems reasonable to conclude, therefore, t h a t the thyroid feeding was here responsible for the precipitate moult. Since this experiment, Giacomini ; (1924), B. Zavadovteky (1925) and Crew (1925) have reported precipitate moulting in fowls, induced, however, b y much larger doses. WEIGHT Results of weekly weighings are reported in Table 1. TABU; 1.
November November November November November December December
1 8 15 21 27 4 12
AVERAGE WEIGHT PER BIRD IN POUNDS
Thyroid-Fed 3.30 3.30 3.28 3.27 3.28 3.30 3.34
Controls 3.34 3.25 3.23 3.33 3.32 3.40
These d a t a indicate t h a t t h e dosage given in this experiment (59 mg. daily per pound of live weight) had no effect on body
Downloaded from http://ps.oxfordjournals.org/ at New York University on May 12, 2015
into more or less precipitate moult at various stages of feeding. Three showed decided body moult at the end of the first week, t h r e e more a t the end of t h e second week, a n d one d u r i n g the t h i r d week. These hens seemed to lose their feathers most r a p i d l y from t h e tracts on the breast a n d neck. I t was sometimes possible t o p u l l a h a n d f u l of feathers from these regions by' the lightest touch. I n some cases two or three primaries could be plucked out at once with almost no effort. Three of these ten birds moulted more slowly a n d were never in a seminaked or " q u i l l y " condition as were some of the others.
62
POULTRY SCIENCE
weight. Other workers have reported rapid loss in weight, when much larger doses of raw thyroid were fed. EGG PRODUCTION
All hens were trap-nested. Egg records for a period of four months from the start of the experiment are shown in Table 2. TABLE 2.
Nov. Deo. Jan. Feb. Total 26 23 36 44 129 27 19 35 46 127
It seemed possible that an early quick moult, such as is favored by the thyroid feeding, might lead to an earlier increased egg production. There is, however, no evidence that egg production was at all affected by the dosage fed in this experiment. Crew and Huxley (1923) reported similar results with fowls receiving small doses of thyroid. Crew has since found (1925) that senile females were markedly stimulated to egg production by larger doses. PLUMAGE
(COLOR AND STRUCTURE)
Hen feathering in the male fowl has been reported as a result of thyroid-feeding by Torrey and Hornjng (1922), Cole and Reid (1924) and Crew (1925), and the authors of the last two papers also noted increased melanism in feathers growing in exposed to the influence of the thyroid. Torrey (1926) has noted the same effect in barred feathers of Barred Plymouth Rock males. All of these workers fed desiccated thyroid powder. In direct contrast to this, Giacomini (1924) reported depigmentation of plumage as a result of feeding raw ox thyroid to fowls. Subsequent experiments of B. Zavadovsky (1925), M. Zavadovsky (1925), Torrey and Horning (1925), Krizenecky (1926a, 1926b), and Podhradsky (1926) confirm the toxic effect of large doses of thyroid in producing abnormal feather structure and decrease of pigmentation. In many cases the feathers grown under these conditions are largely or entirely white. It seemed possible that there might be some difference in the physiological properties of raw and desiccated thyroid. Accordingly an experiment was planned to find the effects of both on plumage color and structure in males and females of different breeds. Twenty-two birds were given dosages as follows:
Downloaded from http://ps.oxfordjournals.org/ at New York University on May 12, 2015
Thyroid-fed (20) Controls (20)
EGGS LAID PER MONTH
FEEDING
THYROID
TO
FOWLS
63
SECONDARY SEX CHARACTERS
The lanceolate, pointed appearance of neck, wing bow and saddle feathers of male fowl is due to a lack of barbules and hooks in the margin of the web. It constitutes a secondary sex character. In this experiment, various degrees of hen-feathering were noted in all males receiving either desiccated or raw thyroid, with the exception of the Rhode Island Red. It was quite evident that after six weeks of feeding the influence
Downloaded from http://ps.oxfordjournals.org/ at New York University on May 12, 2015
Raw pig thyroid—0.42 grams daily per pound of live weight. Males—Barred Rock, Buff Leghorn, Silver Laced Wyandotte, Rhode Island Red, Silver Spangled Hamburg, Golden Sebright. Females—Barred Rock, Buff Leghorn, Ancona, Black Minorca. Desiccated thyroid—84 mg. daily per pound of live weight. Males—Barred Rock, Buff Leghorn, Silver Laced Wyandotte, Golden Sebright. Females—Barred Rock, Buff Leghorn, Blue Andalusian, Ancona. Controls—Males, Golden Sebright. Females—Barred Rock, Buff Leghorn, Ancona. On the assumption that one gram of the desiccated powder (Armour and Co., 0.2% iodine) is equivalent to five grams of fresh normal thyroid gland, the actual doses of active thyroid substance were approximately equal for all birds whether they received raw or desiccated gland. Feeding began on March 2. On March 11, small areas on the neck, .wing bow and saddle of each bird were plucked free of feathers and samples of the latter were saved for future comparison. Weights were taken every two weeks. Feeding was discontinued on May 8th. No lack of pigmentation was observed except very small white spots in the normally black marginal lacing of new neck and saddle feathers in both thyroid-fed Sebrights. The two Silver Wyandotte males grew distinctly darker feathers, particularly in the neck region. The Silver Spangled Hamburg and Rhode Island Red males showed a slight but perceptible tendency toward increased melanism in new feathers, but no appreciable change in color was evident in any of the females or the other males on either raw or desiccated thyroid. Torrey and Horning (1926) have subsequently noted increased melanism induced in males but not in females by thyroid feeding.
64
POULTRY
SCIENCE
OTHER EFFECTS
No significant change in weight was noticed in any of the birds. Giacomini and M. Zavadovsky have noticed a stimulus for
Downloaded from http://ps.oxfordjournals.org/ at New York University on May 12, 2015
of the thyroid was completely lost, so far as feather structure was concerned. The Hamburg male grew a crop of femaletype feathers on his neck and saddle, lost all on his neck by fighting, and subsequently replaced them with feathers of the normal male type. One of the Barred Rock males first grew " h e n n y " feathers on the wing bow, then feathers of intermediate structure on the neck, and finally, after five weeks of feeding, saddle feathers of the normal male type. The other birds showed instances of the same phenomenon. The Rhode Island Red did not grow any new feathers till after six weeks of thyroid feeding, hence they were not henny, as were the earlier feathers of the other males. The most interesting changes were observed in the Silver Wyandotte male receiving desiccated thyroid. This bird grew female feathers on neck, wing bow and saddle. The new neck feathers tended toward solid black rather than the typical black feather with white lacing. On the wing bow, however, where the male feathers had been white with a black base, there were produced feathers entirely female both in structure and color pattern, viz., white with black lacing. Similarly on the saddle, the new feathers were white with a black lacing oneeighth to one-quarter inch wide where those plucked had been black with a white margin. These effects were also present in the Silver Wyandotte male receiving raw thyroid, but were less distinct because his feathers grew in more slowly and hence partially escaped the influence of the thyroid. The Silver Wyandotte is a dimorphically colored breed, i. e., the male differs from the female in plumage pattern as well as feather structure. In this experiment both of these secondary sex characters were completely suppressed in the males and altered to the female expression as a result of thyroid feeding. No change was noticed in feather structure of the Sebright males, a breed in which the male is normally hen feathered.
FEEDING
THYROID
TO
FOWLS
65
It was noticeable that in all birds the saddle feathers developed more slowly than those in the neck and wing bow regions. SUMMARY
1. Hen-feathering was induced in male fowls by feeding both desiccated and raw thyroid. 2. In males of a dimorphically-colored breed the color pattern of the feathers was changed from that of the male to that of the female by thyroid feeding. 3. At our dosage there was no appreciable evidence of the lack of pigmentation in new feathers described by other investigators. 4. Raw thyroid appeared to have less stimulating effect on feather growth than desiccated thyroid at approximately the same level of feeding (based on assumed iodine content). 5. Feather structure in Sebright males was unaffected by thyroid feeding. 6. A daily dose of 59 mg. desiccated thyroid per pound of live weight hastened the normal moult of yearling hens. 7. The same dosage did not have any appreciable effect on body weight or egg production during the period of four months.
Downloaded from http://ps.oxfordjournals.org/ at New York University on May 12, 2015
feather growth in birds fed large doses of fresh thyroid. In our experiments, the desiccated thyroid seemed to have a much more stimulating effect on feather growth than had the raw thyroid. The fowls receiving desiccated thyroid were, with only one exception practically full feathered by May 8th, while many of those receiving raw thyroid had made very little feather growth. This difference was more noticeable in the females than in the males. Two of the former had made no feather growth except a few quills on the neck and wing bow by May 8th, and one had not even a new quill. The latter was given her raw thyroid dose till May 26th, at which time she still had not a quill. After feeding was discontinued the other two made a fairly good growth of feathers and were well covered in the neck and wing bow regions by May 26th. The number of birds used was too small to warrant any conclusion regarding this apparent difference between raw and desiccated thyroid.
66
POULTRY
SCIENCE
Downloaded from http://ps.oxfordjournals.org/ at New York University on May 12, 2015
REFERENCES COLE, L. J., AND REID, D. H. (1924). The effect of feeding thyroid on the plumage of t h e fowl. Journ. Agric. Res., 29, 6, 285-287. CREW, F . A. E., AND HUXLEY, J. S. (1923). T h e effect of thyroid feeding on growth rate, feathering, and egg production. Vet. Journ., 79, 343-348. CREW, F . A. E. (1925). Rejuvenation of t h e aged fowl t h r o u g h thyroid medication. Proc. Roy. Soc. Edin., 45, 21. 252-260. GIACOMINI, ERCOLE (1924). Color changes in plumage of poultry after thyroid a d m i n i s t r a t i o n . Report of Second World's Poultry Congress, 45-47. KRIZENECKY, J. (1926 a ) . Vyznam s t i t n e zlazy pro vznik t. zv. intersexualnich t v a r u u hospodarskych zvirat. (The importance of the thyreoidea for the occurrence of so called intersexual forms in domestic a n i m a l s ) . Vestnik ceskoslavenske akademie Zemedelske. (Bull. Czech. Acad. Agric.) Rocnik II. Cislo 5-6. pp. 1-5. KRIZENECKY, J. (1926 b ) . iiber den Einflusz der Schilddriise und der T h y m u s auf die E n t d e c k u n g des Gefieders bei Hiihnerkuken. Zeit. f. wiss. Biol., Bd. 107, Heft 4, pp. 583-604. PODHRADSKY, J. (1926). Der Einflusz des H y p e r t h y r o i d i s m u s aiif Wachstum und P i g m e n t i e r u n g des Gefieders bei ausgewachsenen H u h n e r n . Zeit. f. wiss. Biol., Bd. 107, Heft 3, pp. 407-422. TORREY, H. B., AND HORNING, B. (1922). Hen-feathering induced in t h e made fowl by feeding thyroid. Proc. Soc. Exp. Biol, and Med., 19. 6, 275-279. KRIZENECKY, J. (1926 a) Vyznam stetne zlazy pro vznik t. zv.. intersexualnich t v a r u u hospodarskych zvirat. ( T h e importance of the Thyreoidea for the occurrence of so called intersexual forms in domestic a n i m a l s ) . Vestnik Ceskoslavenske akademie Zemedelske. (Bull. Czech. Acad. Agric.) Rocnik II. Cislo 5-6, pp. 1-5. TORREY, H. B., AND HORNING, B. (1925). The effect of thyroid feeding on t h e moulting process and feather s t r u c t u r e of the domestic fowl. Biol. Bull., 49, pp. 275-287. TORREY, H. B., AND HORNING, B. (1926). [News item in Science], Vol. 63, No. 1619, p. xiv. ZAVADOVSKY, BORIS (1925). The effect of feeding fowls on thyroid gland. Endocrin. 9, 125-136. ZAVADOVSKY, M. (1925). The effect of single doses of thyroid gland in fowls. Endocrin. 9, 232-241.