提高奶牛受胎率的卵泡和黄体活动调控研究

在夏季和秋季对经产荷斯坦奶牛进行定时排卵-输精程序（TAI）处理并在输精后进行HCG处理（第5d和第10d分别肌注HCG2000IU／头），另于冬季单独对自然发情人工授精母牛进行输精后HCG处理。从各季节HCG处理组及其对照组中抽取部分奶牛，在输精后第0d（输精当天）、7d、14d、和21d分别采血，以测定孕酮和雌二醇水平。所有试验牛在输精后45-60d进行直肠妊娠检查以确定是否受胎。结果显示：夏季TAI＋HCG组、TAI组、对照组母牛输精后的受胎率差异不显著（p〉0．05），分别为26．67％（4／15）、16．67％（2／12）和10．71％（3／28）。秋季TAI＋HCG组、TAI组、对照组情期受胎率差异也不显著（p〉0．05），分别为：55．00％（11／20）、42．11％（8／19）和31．43％（11／35）。冬季HCG组和对照组的受胎率分别为63．16％（12／19）和45．00％（9／20）（P〉0．05）。在夏秋冬三个季节，输精后HCG处理相应显著提高第7d、14d和21d血液中孕酮水平（p〈0．05），但稍稍降低雌二醇水平（p〉0．05），显著降低E2／P比值（p〈0．05）。与受胎率的差异相关，秋冬季各组牛输精后血浆P水平高于（p〉0．05）或（极）显著高于（p〈0．01或p〈0．05）夏季相应组；血浆E2水平则稍高于（p〉0．05）夏季相应组。以上结果说明，TAI单独处理可以将受胎率提高约10～15个百分点；输精后单独HCG处理可以将爱胎率又提高约10-15个百分点，这主要是促进黄体功能的结果，而且提高的幅度在秋冬季要高于夏季。

Study on Regulating Ovarian and Luteal Activities in Improving Conception Rate in Holstein Cows

Postparious Holstein cows were selected to receive Timed Artificial Insemination (TAI) and post-insemination HCG treatment(on 5th and 10th day after insemination with HCG 2000IU/cow) in summer and autumn,while in winter were treated with HCG only,with appropriate numbers of non-treated control cows.Blood samples were withdrawn from HCG treated and the non-HCG treated control cows on 0th,7th,14th and 21st day post-inseminaiton in each season for measurement of progesterone and estradiol.Conception was determined by rectal palpation between 45th to 60th day post-insemination.Conception rate(CR) for TAI HCG,TAI,and control cows were not statistically different in summer,being 26.67%(4/15),16.67%(2/12) and 10.71%(3/28) respectively;nor were the parameters different(P>0.05) in autumn, being 55.00%(11/20),42.11%(8/19) and 31.43%(11/35) respectively. In winter CR in HCG treated cows was 63.16%(12/19) in contrast to the 45.00%(9/20)(P>0.05) in non-treated control cows. In all 3 seasons, HCG treatment significantly(P<0.05) increased blood progesterone levels on 7th,14th and 21th day post-insemination, but only slightly(P>0.05) reduced estradiol levels, resulting significant (P<0.05) reductions in E2/P ratio. In relation to seasonal variations in CR, progesterone levels in blood in autumn and winter were generally higher than those in summer and estradiol levels also slightly higher than summer values(P>0.05).These results demonstrated that CR of TAI alone was capable of increasing by10~15 percentage, and CR of post-insemination HCG treatment also increased by 10~15 percentage.