摘要
We compared the fertility of thawed ram semen, frozen according to different prefreezing semen handling protocols and previously well-defined in vitro, after cervical artificial insemination (AI) during natural estrus in Corriedale sheep. Following primary extension 1+1, we adjusted the final sperm concentration before packaging (200×106/straw) either by centrifugation, in order to reconcentrate the extended semen (Protocol 1: P1), or without centrifugation, by adjusting the final sperm number by stepwise extension (Protocol 2: P2). We evaluated sperm motility (assessed both subjectively and with a computer-assisted sperm analysis instrument [CASA]), membrane integrity (SYBR-14/PI), and capacitation status (chlortetracycline [CTC]) in vitro in three pooled straws of frozen–thawed semen. Three hundred Corriedale ewes, having shown spontaneous estrus during the breeding season (i.e., April, in the southern hemisphere) under extensive management conditions in Uruguay, were cervically inseminated with thawed semen from the same freezing operations as studied in vitro. The semen evaluation in vitro yielded higher percentages (P<0.05) of damaged spermatozoa in the samples where sperm numbers were adjusted by extension before freezing (P2), compared with when adjustment was done by centrifugation (P1). However, due to the higher sperm concentration finally achieved by P2, the calculated total number of viable spermatozoa was almost equal in the two AI doses. We observed no differences in fertility between P1 and P2 for either nonreturn rates (NRRs) 21 (30.8 vs. 29.7%) and 36 (28.5 vs. 27.8%) days after AI or lambing rate (21.9 vs. 21.4%), respectively. Fertility did not differ significantly between the two different procedures of adjusting sperm numbers prior to freezing. This may indicate that the simplified protocol with adjusted extension of the semen, resulting in higher numbers of viable spermatozoa, should be the procedure of choice when freezing ram semen under field conditions. Further studies aimed at improving the modified protocol need to be performed.
摘要译文
我们比较了解冻的公羊精液的生育能力，根据不同的预冷冻精液处理方案和以前在体外明确定义的冷冻，在Corriedale绵羊的自然发情期间的颈椎人工授精（AI）之后。在主扩展1 + 1之后，我们通过离心来调整包装前的最终精子浓度（200×10 6 /秸秆），以便再浓缩延长的精液（方案1：P1）或者不进行离心，通过逐步延伸（Protocol 2：P2）调整最终的精子数目。我们评估精子活力（主观评估和计算机辅助精子分析仪[CASA]），（SYBR-14 / PI）和获能状态（金霉素[CTC]）在冷冻精液的三个混合秸秆体外。三百只科里代尔母羊，在乌拉圭的广泛管理条件下，在繁殖季节（即四月，南半球）表现出自发性发情，在与体外研究相同的冷冻操作中用解冻的精液经颈部授精。精液体外评估产生更高的百分比（P 0。（P2）进行精子数量调整的样品中与受到离心（P1）调整的情况相比，精子受损的精子数量（图05）。然而，由于P2最终获得更高的精子浓度，在两次AI剂量中计算的活精子总数几乎相等。我们观察到AI和产羔率（21.9对21.4％）之间的非返回率（NRR）21（30.8对29.7％）和36（28.5对27.8％）天的P1和P2之间的育性没有差异。在冻结之前调整精子数量的两种不同程序之间的生育率没有显着差异。这可能表明简化的方案调整了精液的延伸，导致更高数量的活精子，应该是在野外条件下冷冻精液的选择程序。需要进一步研究旨在改进修改的协议。
JGil[a][b];MRodriguez-Irazoqui[c];LSöderquist[a][d];HRodriguez-Martinez[a][d];. Influence of centrifugation or low extension rates prefreezing on the fertility of ram semen after cervical insemination[J]. Theriogenology, 2002,57(7): 1781-1792