Comparison of superovulation effect and hormone change of Brahman with BMY cattle in whole year grazing

Chinese. 为了比较婆罗门牛和BMY牛的雌二醇（E2）、孕酮（P4）水平及胚胎生产潜力，并探讨MOET技术在BMY牛扩繁中的应用前景，采用进口激素（日本产FSH 24～36 mg＋美国产PG 35 mg）和国产激素（国产FSH 10～12 mg＋国产PG 0.8 mg）对全放牧婆罗门牛和BMY牛进行超排，并于超排前（同期发情第7天）、超排开始、超排第3天、超排发情当天和胚胎回收当天采集血液，采用RIA法分析血浆中的E2和P4水平。结果表明，BMY牛的黄体数和获胚（卵）数、可用胚数分别较婆罗门牛高2.09个和0.95、0.36枚，但差异不显著（P＞0.05）；BMY牛的排卵率较婆罗门牛高18.46%（P＜0.01），而可用胚率则较婆罗门牛低2.55%（P＜0.01）。BMY牛在5个处理时段的E2和P4平均值分别较婆罗门牛高0.58 pg/mL（P＜0.01）和1.44 ng/mL（P＞0.05），在各处理时段的P4水平变化规律几乎与婆罗门牛一致，E2/P4值为婆罗门牛的5.16倍。结果提示，BMY母牛的E2和P4水平高于婆罗门牛，在激素水平和繁殖性能方面表现出一定的杂种优势；E2水平低是婆罗门牛发情微弱和排卵率低的主要原因之一；在同等放牧管理和超排处理条件下，婆罗门牛及其杂种BMY牛对外源激素的敏感性基本一致，具有同等的胚胎生产潜力。

English. To compare Estradiol (E2), Progesterone (P4) and potentialities of embryo production between Brahman cattle and its crossbreed-BMY cattle, and probe into the applying foreground of MOET technology in the expanding reproduction of BMY cattle, the experiment of superovulation with import hormone (FSH 24~36 mg of Japan plus PG 35 mg of USA) or native hormone (FSH 10~12 mg plus PG 0.8 mg) among Brahman cattle and BMY cattle in whole year grazing was carried out, then E2 and P4 levels of blood sample were collected and analyzed in five treatment times of superovulation i.e.on 7th day of synchronization estrous, starting superovulation or on the 10 th day of synchronization estrous, on the 3rd day of superovulation and the day of standing heat after superovulation or the first time for AI and the day of recovered embryo or on the 7th day after AI by RIA. The results showed that average number of corpus luteum, recovered embryos, transferable embryos of BMY cattle were in turn 10.19, 6.90 and 3.69, higher than those of Brahman, which were 8.10 (P0.05), 5.95 (P0.05) and 3.33 (P0.05), respectively. The rates of ovulation and transferable embryo in BMY cattle were 83.59% and 53.43%, higher and lower than those of Brahman, which were 65.16% (P0.01) and 56% (P0.01), respectively. Although E2 and P4 change rules in five treatment times of BMY were nearly the same as Brahman, average E2 and P4 of BMY were 0.66 pg/mL and 6.71 ng/mL, higher than those of Brahman, which were 0.10 pg/mL (P0.01) and 5.27 ng/mL (P0.05), respectively. And average P4/E2 of five treatment times of Brahman was 5.34 times as the same as BMY. It was indicated that the levels of E2 and P4 of BMY were higher than those of Brahman, so BMY cow showed a certain degree of heterosis at hormone and reproductive performance; and the low level of E2 in Brahman cows maybe was a main reason of the estrous feebleness and low ovulation rate; pure Brahman and its crossbreed-BMY cattle were equivalent on sensitivity of exogenous hormone and potentialities of embryo production under the same condition of feeding management and superovulation.