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PARKER (1943) fed graded amounts of thyroactive iodocasein to five lots of Rhode Island Red chicks during a period of 12 weeks. At the optimum level a slightly greater rate of growth was observed in comparison to the controls and a rather marked stimulation of feather growth. Irwin, Reineke and Turner (1943) confirmed these results using White Plymouth Rock chicks. The effect of thyroactive iodocasein, hereafter referred to as protamone ** on certain gland and organ weights was also reported. In this experiment it was noted that the carcass of the protamone-fed chicks at 12 weeks contained decidedly less fat than the control chicks, indicating that the growth process was being stimulated at the expense of fat deposition. Further, the feeding of protamone had caused a marked suppression of the thyroid gland weight and probably its function. It seemed of interest to determine the effects on body weight, fattening, and gland . . .

MANY investigators during the past three decades have reported on the various effects of feeding fresh or desiccated thyroid to chickens. Results have been variable, dependent upon dosage level and potency of the material. Most of the work reported has concerned adult stock, and the data relative to chicks and young growing stock appears to be meager. Crew and Huxley (1923) fed dried thyroid to 12 chicks and found no significant difference in weight between the control and experimental group. It is known that thyroid given in excessive amount will retard the rate of growth or even cause a loss of body weight. However, some investigators have reported acceleration of the growth rate in dogs, rats, and mice when thyroid was fed in optimum amounts. Recently Koger and associates (1942 (1943) reported improvement of growth and appetite in mice receiving subcutaneous injections of crystalline thyroxine and the feeding of thyroactive . . .

In an investigation at this station on the weights of organs in White Rocks at 12–14 weeks of age, an individual female chick was found with one kidney. † Kaupp (1918) describes the urinary system of the bird as consisting of two kidneys, from each of which a ureter extends and empties into the cloaca. The kidneys are made up of three irregular lobes; the anterior lobe is usually the largest and the middle lobe the smallest. The body weight of the bird was 1,340 grams and the kidney weight was 7.5 grams. Five normal females from the same lot had an average body weight of 1,324 grams and an average weight of 9.2 grams for the two normal kidneys. Thus the single kidney weighed 81.5 percent of the normal weight of two kidneys. This enlarged single kidney indicates that compensatory hypertrophy had taken place. The presence of the normal . . .