非繁殖季に於ける牝緬羊のホルモン処理による仔羊生産について(予報)

抄録

An experiment was conducted in which five Corriedale ewes were treated with hormones to produce outseasonal lambs. After the administration of 75 mg of progesterone, 12.5 mg twice-daily or 25 mg daily for three successive days, 1, 000 i. u. of PMS was given on the third day of final progesterone injection. Some of them showed rather weak and irregular oestrus, but all were mated with rams within fortyeight hrs. after PMS treatment. Three out of five thus treated produced four lambs. Case numbers were considered not sufficient to draw a final conclusion, however, the results showed that ewe fertilty during non-breeding season could be expected with Corriedale to a certain extent. Factors which seemed to influence the lambing rate were discussed in the light of the exsisting knowledge of physiology of reproduction in sheep.