黄牛同期发情和超数排卵及取卵时间的研究

OESTRUS SYNCHRONY SURPEROVULATlON AND EMBRYO COLLECTING TIME OF CATTLE

本地黄牛24头,利用二次PG(15-甲基前列腺素F_(2a))调整,进行同期发情,3个不同剂量组的效果表明:中等剂量每次5支(7.2mg)的效果较好达87.5％。不同年龄组比较发现:2.5～4.5岁黄牛同期发情效果(89％)明显高于4.5～8.5岁黄牛(57％)。进一步利用PMSG(孕马血清)超排处理表明:反应良好、一般,无反应各占1/3,且以3～5岁牛超排效果好;分析超排牛的排卵规律发现:排卵5个以上的牛排卵相对集中,排卵持续时间约在24h左右。进一步对卵子发育情况加以分析,发现要取到原核期前的受精卵,取卵时间宜在最后一次PG后74～76h或出现发情后的26～40h。且以后者推算为佳。

24 local cattle were injected twice with PG_F2a (Prostaglandin _F2a) for oestrus synchrony. The results of three different dosages of PGF_2a indicate that median-dose (7.2mg every time) produces good result and the rate of oestrus synchrony reachs 87.5％. The effect of oestrus synchrony of 2.5～4.5 years old cattle was obviously better than that of 4.5～85 years old cattle. The proportion of excellent, average and no respones to surperovulation with PMSG and PGF_2a is one-third each. Ovulations of more than five ova are finished within 24 hours. In order to collect l-cell embryos prior to the stage of pronuclei. We operated on cattle between 74～76 hours after last PGF_2a injection or 26～40 hours after heat starting.