Further studies of hexoestrol implantation of Blackface wether lambs

Abstract

1. In the summer of 1958, 15 mg. of hexoestrol was administered to Blackface wether lambs in one of the following ways; 5 mg. before weaning followed by two 5 mg. tablets at weaning, three 5 mg. tablets at weaning, and thirdly a single 15 mg. tablet at weaning. In a further series of experiments in 1959 the effect of both raising the pre-weaning implantation to 10 mg., and the total hexoestrol dosage to 20 mg. was studied.2. Suckled lambs implanted with 5 mg. of hexoestrol at the milk clip gained significantly more in live-weight (18%) up to weaning in 1958 than did untreated lambs; in 1959 the difference was only 11%.3. Between weaning and the end of the trial all treatments with the exception of that in which hexoestrol dosage was raised to 20 mg. showed a very highly significant increase in live-weight gain over untreated lambs, the increases ranging from 26 % to 54%.4. In neither year was the overall gain in live-weight from pre-weaning to the end of the trial significantly increased by implanting part of the hexoestrol dose prior to weaning.5. Live-weight gain of the lambs was not significantly increased when three 5 mg. tablets of hexoestrol replaced a single 15 mg. tablet.6. The implanting of lambs with 20 mg. hexoestrol failed to give a response superior to that obtained with 15 mg. hexoestrol.7. Each group of lambs receiving hexoestrol treatment showed an increased average carcass weight.