Journal of the Faculty of Fisheries and Animal Husbandry, Hiroshima University Volume 5 Issue 2
1964-12-20 発行

The environmental factors on the lamb growth, analytically studied with extra-seasonal-lambs II : Extra-seasonal-lamb-production by the combined treatment

季節外生産羊を利用しためん羊発育に及ぼす環境要因の分析的研究II : 単日処理とホルモン処理併用法による子羊の季節外生産
Mimura, Ko
Asahida, Yasushi
Morita, Haruka
Following decreasing daylight treatment for 7 days, twenty four anoestrous ewes of Japanese Corriedale were injected with P.M.S. 750 i. u. after 3-5 injections of progesterone 25mg daily. The ewes in pretreatment of light were hooded with black thick-cloth, and were under control hours of daylight.

This combined treatment was studied over three years 1959-1961, and the incidence of oestrus, presence of corpora lutea, and the state of follicular development was studied.

Total 13 lambs were produced by nine of twenty-one ewes treated with the method, and average percentage of lamb-production per ewe was 1.44.

The presence of corpora lutea and Graafian follicle was observed cytologically in 8 of I 0 ewes when their ovaries were examined at slaughter time. Seventeen of twenty-one ewes were induced oestrus and the percentage is about 81%.

In the sixth trial, three ewes were under progesterone-P.M.S. treatment alone, and only one cytologically was observed in fertile. The percentage is 33%. Therefore, the hypothesis may be probably explained that the light treatment prior to hormone administration will reduce the threshold in pituitary activity to induce the ovarian activity to much lower level.

There is no difference between the method of three days injection daily and the method of five days injection. Thus the method combined the pretreatment of decreasing daylight by a black hood with progesterone 25mg x 3 and P.M.S. 750 i. u. may be considered of practical application.

The highest response was observed two days after the time of P.M.S. injection, followed by next day, and this is agreed with GoRDON's result.
The authors wish to express grateful thanks to the Ministry of Education for grants in aid and to Mr. M. YosHIOKA, Mr. T. KIMURA, Mr. N. FUJIMOTO, Mr. K. SHIMAKAWA and Mr. K. KoMATSU for the general assistance.
 本報の一部は「三村・岡本他.肉緬羊の研究.輿文社,東京, 1961」 および昭和34年度, 35 年度文部省科学研究費による研究報告集録農学編(II) .肉緬羊造成に関する試験(代表者.三村耕)にそれぞれ速報している.