Busch D C, Wilson D J, Schafer D J, Leitman N R, Haden J K, Ellersieck M R, Smith M F, Patterson D J
Division of Animal Science, S132 ASRC, University of Missouri, Columbia 65211, USA.
J Anim Sci. 2007 Aug;85(8):1933-9. doi: 10.2527/jas.2006-845. Epub 2007 Mar 30.
The objective of the experiment was to compare pregnancy rates resulting from fixed-time AI after administration of either 1 of 2 controlled internal drug release (CIDR)-based protocols. Heifers at 3 locations (location 1, n = 78; location 2, n = 61; and location 3, n = 78) were assigned to 1 of 2 treatments within reproductive tract scores (1 = immature to 5 = cycling) by age and BW. Heifers assigned to CIDR Select received a CIDR insert (1.38 g of progesterone) from d 0 to 14 followed by GnRH (100 mug, i.m.) 9 d after CIDR removal (d 23) and PGF2alpha (PG, 25 mg, i.m.) 7 d after GnRH treatment (d 30). Heifers assigned to CO-Synch + CIDR were administered GnRH and received a CIDR insert on d 23 and PG and CIDR removal on d 30. Heifers at location 1 were fitted with a HeatWatch estrus detection system transmitter from the time of PG until 24 d after fixed-time AI to allow for continuous estrus detection. Artificial insemination was performed at predetermined fixed times for heifers in both treatments at 72 or 54 h after PG for the CIDR Select and CO-Synch + CIDR groups, respectively. All heifers were administered GnRH at the time of AI. Blood samples were collected 10 d before and immediately before treatment initiation (d 0) to determine pretreatment estrous cyclicity (progesterone > or = 0.5 ng/mL). At location 1, the estrous response during the synchronized period was greater (P = 0.06; 87 vs. 69%, respectively), and the variance for interval to estrus after PG was reduced among CIDR Select- (P < 0.01) compared with CO-Synch + CIDR-treated heifers. Fixed-time AI pregnancy rates were significantly greater (P = 0.02) after the CIDR Select protocol (62%) compared with the CO-Synch + CIDR protocol (47%). In summary, the CIDR Select protocol resulted in a greater and more synchronous estrous response and significantly greater fixed-time AI pregnancy rates compared with the CO-Synch + CIDR protocol.
该实验的目的是比较在采用两种基于控制内部药物释放（CIDR）的方案之一给药后定时人工授精（AI）的妊娠率。三个地点（地点1，n = 78；地点2，n = 61；地点3，n = 78）的小母牛根据年龄和体重在生殖道评分（1 = 未成熟至5 = 发情周期）内被分配到两种处理中的一种。分配到CIDR Select组的小母牛从第0天到第14天接受一个CIDR插入物（1.38克孕酮），然后在取出CIDR后9天（第23天）注射促性腺激素释放激素（GnRH，100微克，肌肉注射），在GnRH处理后7天（第30天）注射前列腺素F2α（PG，25毫克，肌肉注射）。分配到同期发情+CIDR组的小母牛在第23天注射GnRH并接受一个CIDR插入物，在第30天注射PG并取出CIDR。地点1的小母牛从PG注射时起至定时AI后24天佩戴HeatWatch发情检测系统发射器，以便进行连续发情检测。两种处理的小母牛分别在PG注射后72小时或54小时的预定固定时间进行人工授精，CIDR Select组和同期发情+CIDR组的授精时间分别为PG注射后72小时或54小时。所有小母牛在人工授精时都注射了GnRH。在治疗开始前10天和治疗开始时（第0天）采集血样，以确定治疗前的发情周期（孕酮≥0.5纳克/毫升）。在地点1，同期发情期间的发情反应更大（P = 0.06；分别为87%和69%），与同期发情+CIDR处理的小母牛相比，CIDR Select组PG注射后至发情间隔的方差减小（P < 0.01）。与同期发情+CIDR方案（47%）相比，CIDR Select方案后的定时AI妊娠率显著更高（P = 0.02）（62%）。总之，与同期发情+CIDR方案相比，CIDR Select方案导致更大且更同步的发情反应以及显著更高的定时AI妊娠率。
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