Pancarci Sükrü Metin, Güngör Örsan, Harput Osman, Calisici Oguz
Faculty of Veterinary Medicine, Balıkesir University, 10145 Balıkesir, Turkey.
Faculty of Veterinary Medicine, Burdur Mehmet Akif Ersoy University, 15030 Burdur, Turkey.
Animals (Basel). 2021 May 14;11(5):1402. doi: 10.3390/ani11051402.
Effect of one-day delaying progesterone administration at the beginning of 5-day Cosynch protocol was investigated in Holstein heifers for the first artificial insemination (AI). Heifers received a synchronized ovulation and timed AI (TAI) with CIDR inserted on day (d) 0 (CIDR-5; = 206) or d 1 (CIDR-4; = 192). In both group, GnRH was administered on d 0 followed by a single PGF injection and CIDR removal five days later from GnRH. On d 8, TAI and GnRH administration were concurrently conducted. Heifers detected in estrus up to 24 h prior to TAI were inseminated without GnRH administration. Rates of ovulation, accessory CL formation and new dominant follicle development following initial GnRH injection did not differ between groups. P/AI did not differ between CIDR-4 (44.3%, [85/192]) and CIDR-5 (51.9%, [107/206]) groups, respectively. Pregnancy per AI (P/AI) was significantly ( < 0.01) declined as heifers' age (12-13, 14, 15, 16 and17-21 months) proceeded in CIDR-4 group (55.6%, 52.1%, 37.9%, 35.7%, 32.4%) compared to those in CIDR-5 group (60.0%, 50.0%, 53.9%, 51.5%, 46.2%) respectively. In conclusion, there is no benefit for delaying CIDR administration in 5-day Cosynch protocol in dairy heifers. However, higher P/AI in CIDR-5 group in older heifers can be considered for reproductive management.
在荷斯坦小母牛首次人工授精（AI）时，研究了在5天同步发情方案开始时推迟一天给予孕酮的效果。小母牛接受同步排卵和定时人工授精（TAI），在第0天（d0）插入阴道孕酮释放装置（CIDR-5；n = 206）或第1天（d1）插入（CIDR-4；n = 192）。在两组中，均在d0给予促性腺激素释放激素（GnRH），随后单次注射前列腺素F2α（PGF），并在GnRH注射5天后取出CIDR。在d8，同时进行TAI和GnRH给药。在TAI前24小时内检测到发情的小母牛在不给予GnRH的情况下进行授精。初始GnRH注射后，两组的排卵率、副黄体形成率和新优势卵泡发育率没有差异。CIDR-4组（44.3%，[85/192]）和CIDR-5组（51.9%，[107/206]）的妊娠率/人工授精率（P/AI）分别没有差异。在CIDR-4组中，随着小母牛年龄（12 - 13、14、15、16和17 - 21个月）的增加，妊娠率/人工授精率（P/AI）显著（P < 0.01）下降（分别为55.6%、52.1%、37.9%、35.7%、32.4%），而CIDR-5组（分别为60.0%、50.0%、53.9%、51.5%、46.2%）则没有。总之，在奶牛小母牛的5天同步发情方案中，推迟CIDR给药没有益处。然而，对于年龄较大的小母牛，CIDR-5组较高的P/AI可用于繁殖管理。
