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(続報)

抄録

Further experiment of out-season of lamb production by PMS pretreated with progesterone was carried out with 23 ewes (two of them was lost by accidents) at the University Farm. Two groups of experimental consisted of PMS (Exp. I) and PMS followed with LH-rich gonadotrophin treatment (Exp. II). Four ewes with the same condition as to age and previous lambing results were allotted to one of the non-treated control (Cont. I). The other control (Cont. II) with another eight ewes untreated was also employed to refer the result obtained from the treatment. The reason of setting the non-treated control was due to the fact of a tendency of early lambing within the year. The mode and the name of hormones used were progesterone, Luteogen-Tomoda 12.5mg twice-daily for three days, followed 2 days intermission, and then PMS, Peamex-Tomoda 1, 000 i u. Exp. II was further administered with LH, rich gonadotrophin Synahorin-Teizo 200 Rb. u. on the next morning of PMS injection. During oestrus last from 2 to 4 days after about 48 hrs. of PMS treatment, ewes were properly served with two rams once a day. Before and after the treatment the ewes were put on the pasture. Taking pregancy period for 145±5 days, lambing date between 18 th and 28th November, was accounted for a positive. Results in lambing were as followed: Exp. I, 3/5, Exp. II, 2/4, Cont. I, 0/3, Cont. II, 0/5. Assuming no differences existed between I and II, experimental and control sum up to 5/9 and 0/8, respectively. So that it was again demonstrated the successive percentage of nearly a half. Negative cases proved fertility of ewes and some of them showed early lambing. As was reported in the previous report, oestrus was not so prominent that holding ewes by head for mating was needed, and was variable in its length. Since the authors had obtained some cases of failure in inducing ovulation (unpublished data, '59) LH-rich gonadotrophin was introduced to test the effectiveness in the lambing result, however, no advantage seemed to be expected so far as in the final result.
Further studies aiming improvement in the result and producing Autmn lambs are on progress.