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The Effect of Feeding Thiouracil on the Fleshing of New Hampshire Broilers*
94
RESEARCH NOTES TABLE II
Average Weight Sept. 3 Average egg prod. 44 wks. Percentage production Percentage hatchability of eggs Percentage livability
Milk Fed Lot 4.52 lbs.
No Milk Lot 4.11 lbs.
172.16 55.89
175.05 56.83
86.73 74.00
70.00 74.00
L. F. PAYNE A. E. SCHUMACHER L. D. BUSHNELL
Department of Poultry Husbandry Department ofBacteriology Kansas State College Received for publication, December 4,1944
THE EFFECT OF FEEDING THIOURACIL ON THE FLESHING OF NEW HAMPSHIRE BROILERS* It is a well known fact that during periods of rapid growth the amount of body fat is at a minimum. As fowls mature the amount of body fat increases. It has been assumed that the rate of thyroxine secretion by the thyroid gland plays an important role in regulating the rate of growth and fattening. Thus a slight hyperthyroid condition was thought to be favorable for rapid growth and a slightly hypothyroid condition would be conducive to fattening. Experimental demonstration of this concept has been presented in a recent study (Schultze and Turner, 1944, and unpublished data) in which it was shown that the rate of thyroxine secretion per 100 gm. body weight progressively decreases in fowls with increasing body weight and age. However, when the thyroprotein, protamone, was fed to chicks to 12 weeks of age and the thyroxine level of the blood prevented from declining normally the carcasses contained decidedly less fat * Missouri College of Agriculture Journal Series No 968.
than the control chicks (Turner, Irwin and Reineke, 1944). Experimental proof that a hypothyroid condition is conducive to increased fattening in fowls has become possible as a result of the discovery that the chemical compounds thiourea and thiouracil when fed to chicks either in the feed or water will inhibit the secretion of thyroxine by the thyroid gland (Mixner, Reineke & Turner, 1944). Examination of the carcasses of chicks fed these compounds for periods of two or three weeks showed marked increases in body fat. It seemed desirable to determine whether the feeding of thiouracil for varying periods would improve the market grade of broiler chicks. Experimental Ten week old New Hampshire chicks were divided into two groups of equal average body weight. To the ration fed one group was added 0.2% thiouracil. The other group served as controls. At the conclusion of a 16 day feeding period, the birds were dressed by the F. M. Stamper
Downloaded from http://ps.oxfordjournals.org/ at University of Arizona on June 7, 2016
An interesting observation in connection with these results is that the hens performed as well as they did in spite of the worm infestation. While both flocks were probably infested with round and ceca worms as growing chicks on the
range the tapeworm infestation probably did not occur until the summer of 1944 when the pullets were mature. The use of liquid milk as a beverage during the growing period and an infestation of tapeworms at an early age might have proved more harmful.
RESEARCH NOTES TABLE II
Average Weight Sept. 3 Average egg prod. 44 wks. Percentage production Percentage hatchability of eggs Percentage livability
Milk Fed Lot 4.52 lbs.
No Milk Lot 4.11 lbs.
172.16 55.89
175.05 56.83
86.73 74.00
70.00 74.00
L. F. PAYNE A. E. SCHUMACHER L. D. BUSHNELL
Department of Poultry Husbandry Department ofBacteriology Kansas State College Received for publication, December 4,1944
THE EFFECT OF FEEDING THIOURACIL ON THE FLESHING OF NEW HAMPSHIRE BROILERS* It is a well known fact that during periods of rapid growth the amount of body fat is at a minimum. As fowls mature the amount of body fat increases. It has been assumed that the rate of thyroxine secretion by the thyroid gland plays an important role in regulating the rate of growth and fattening. Thus a slight hyperthyroid condition was thought to be favorable for rapid growth and a slightly hypothyroid condition would be conducive to fattening. Experimental demonstration of this concept has been presented in a recent study (Schultze and Turner, 1944, and unpublished data) in which it was shown that the rate of thyroxine secretion per 100 gm. body weight progressively decreases in fowls with increasing body weight and age. However, when the thyroprotein, protamone, was fed to chicks to 12 weeks of age and the thyroxine level of the blood prevented from declining normally the carcasses contained decidedly less fat * Missouri College of Agriculture Journal Series No 968.
than the control chicks (Turner, Irwin and Reineke, 1944). Experimental proof that a hypothyroid condition is conducive to increased fattening in fowls has become possible as a result of the discovery that the chemical compounds thiourea and thiouracil when fed to chicks either in the feed or water will inhibit the secretion of thyroxine by the thyroid gland (Mixner, Reineke & Turner, 1944). Examination of the carcasses of chicks fed these compounds for periods of two or three weeks showed marked increases in body fat. It seemed desirable to determine whether the feeding of thiouracil for varying periods would improve the market grade of broiler chicks. Experimental Ten week old New Hampshire chicks were divided into two groups of equal average body weight. To the ration fed one group was added 0.2% thiouracil. The other group served as controls. At the conclusion of a 16 day feeding period, the birds were dressed by the F. M. Stamper
Downloaded from http://ps.oxfordjournals.org/ at University of Arizona on June 7, 2016
An interesting observation in connection with these results is that the hens performed as well as they did in spite of the worm infestation. While both flocks were probably infested with round and ceca worms as growing chicks on the
range the tapeworm infestation probably did not occur until the summer of 1944 when the pullets were mature. The use of liquid milk as a beverage during the growing period and an infestation of tapeworms at an early age might have proved more harmful.