INDUCTION OF MATING BEHAVIOR IN MALE AND FEMALE CHICKS FOLLOWING INJECTION OF SEX HORMONES INCLUDING NOTATIONS ON BODY WEIGHT AND COMB GROWTH1

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Abstract
[male] white leghorn chicks given daily injs. of 0.5 mg. of testosterone propionate in oil exhibited all the sexual behavior patterns typical of the adult cock. When treatment was initiated on the 2d day after hatching crowing appeared at 4 days of age and treading of an anesthetized or dead chick occurred at 15 days. Injected chicks raised in isolation crowed and treaded as early as the birds reared together. [female] chicks which received daily injs. of 0.166 mg. of estradiol benzoate in oil starting on the 15th day of age squatted for treading [male][male] after 18-26 treatments. The behavior was identical to that of the sexually mature hen. [female][female] in which estrogen injs. were begun at 2 days of age were never seen to squat for a [male] despite prolonged treatment. The growth rate of injected [male][male] was uniformly depressed. Augmentation or depression of the growth rate of estrogen treated [female][female] was obtained depending upon the age of the birds used and the dosages administered. Combs of exptl. [male][male] underwent a rapid regression after the cessation of injs. to a point where they were considerably smaller than those of controls. [female] combs were unaffected by estrogen injs.