Xu Z Z, Burton L J
Livestock Improvement Corporation Ltd., Hamilton, New Zealand.
J Dairy Sci. 1999 May;82(5):910-7. doi: 10.3168/jds.S0022-0302(99)75309-9.
The reproductive performance of heifers after estrus synchronization and fixed-time AI was compared with nonsynchronized heifers in 25 spring-calving herds. Within herds, heifers were divided into a synchronized (n = 1123) or a control (n = 1125) group. Heifers in the synchronized group were treated with a combination of progesterone, estradiol benzoate, and PGF2 alpha and were inseminated between 50 and 54 h after progesterone treatment. Returns to first service were resynchronized with progesterone treatment between 16 and 21 d after the fixed-time AI. The conception rate of synchronized heifers to the fixed-time AI (53.2%) and to AI after resynchronization (53.1%) was lower than that of control heifers (63.7%). However, pregnancy rate in the first 24 d was higher for the synchronized group (72.4%) than for the control group (67.8%). More control heifers (5.7%) than synchronized heifers (4.0%) failed to conceive. The interval from start of breeding to calving was earlier for synchronized (296.2 d) than for control (299.5 d) heifers. Jersey heifers had lower reproductive performance than did Friesian heifers. Synchronized heifers gave birth to more female calves (53.8%) than did control heifers (45.7%). It is concluded that the above program can be used successfully to synchronize dairy heifers for fixed-time AI.
在25个春季产犊的牛群中，对经过发情同步化和定时人工授精的小母牛与未同步化的小母牛的繁殖性能进行了比较。在每个牛群中，小母牛被分为同步化组（n = 1123）或对照组（n = 1125）。同步化组的小母牛接受孕酮、苯甲酸雌二醇和前列腺素F2α的联合处理，并在孕酮处理后50至54小时进行人工授精。首次输精未受孕的牛只在定时人工授精后16至21天再次用孕酮处理进行同步化。同步化小母牛定时人工授精的受孕率（53.2%）和再次同步化后人工授精的受孕率（53.1%）低于对照组小母牛（63.7%）。然而，同步化组在前24天的妊娠率（72.4%）高于对照组（67.8%）。未受孕的对照组小母牛（5.7%）比同步化组小母牛（4.0%）更多。同步化小母牛从开始配种到产犊的间隔（296.2天）比对照组小母牛（299.5天）更早。泽西牛小母牛的繁殖性能低于弗里斯兰牛小母牛。同步化小母牛所产雌性犊牛（53.8%）比对照组小母牛（45.7%）更多。结论是，上述方案可成功用于使奶牛小母牛同步化以进行定时人工授精。
