Studies on the Use of Hormones in Lamb Feeding

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Abstract
Estrogen bioassays were conducted on extracts of tissues from lambs implanted with progesterone and estradiol, and lambs fed stilbestrol or benzestrol, or combinations of either thiouracil or thyroprotein with stilbestrol. Measurable amounts of estrogenic substances were found in the livers of lambs fed stilbestrol or lambs implanted with progesterone plus estradiol, and in lean meat from these implanted lambs. In one of two trials, a small but statistically significant amount of estrogenic activity was found in the fat from lambs fed stilbestrol at the rate of 5 and 2.5 mg. per day for the first and second halves of the feeding period, respectively. In another trial, in which the level of stilbestrol was reduced from 5 mg. per day to 1 mg. per day at approximately the middle of the feeding period, no measurable estrogenic activity was found in the meat. In two trials detectable amounts of estrogenic activity were found in the meat of lambs fed benzestrol. All hormone treatments resulted in increased size of accessory sex glands of wethers and in most cases in increased uterine weights and decreased ovarian weights of ewes. Pituitary glands of wethers on all hormone treatments were considerably heavier than those of untreated wethers, but hormone treatments did not affect pituitary weights of ewe lambs. Highly significant differences due to hormone treatments were found in thyroid activities as assessed by thyroid epithelial cell heights. The thyroid epithelial cell heights in decreasing order according to hormone treatment were as follows: stilbestrol, stilbestrol plus thiouracil, benzestrol, untreated, stilbestrol plus thyroprotein and thyroprotein. Copyright © . .

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