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Inseminations at estrus induced by the presynch protocol before timed artification insemination

机译:在定时人工授精之前,由presynch协议诱发的发情期授精

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摘要

A controlled field study examined conceptionrates after two timed-AI (TAI) breedingprotocols conducted on two commercial dairyfarms. Estrous cycles in postpartum lactatingcows were presynchronized with two injectionsof PGF2" given 14 days apart (Presynch) andthen, after 12 days, the standard Ovsynch protocol(injection of GnRH 7 days before and 48 hafter an injection of PGF2", with one TAI at 12to 16 hours after the second GnRH injection) orHeatsynch protocol (injection of GnRH 7 daysbefore an injection of PGF2", followed 24 h laterby 1 mg of estradiol cypionate (ECP) and oneTAI 48 hours after ECP) was applied. Experimentaldesign allowed for AI to occur any timeafter the second Presynch injection and duringthe designed breeding week when estrus wasdetected. Of the 1,846 first services performed,only 1,503 (rate of compliance = 81.4%) wereperformed according to protocol. Numbers ofcows inseminated, logistic-regression-adjustedconception rates, and days in milk (DIM) werefor inseminations made: 1) during 14 days afterfirst Presynch injection (n = 145; 22.6%; 54 ±0.4 DIM); 2) during 12 days after second Presynchinjection (n = 727; 33%; 59 ± 0.2 DIM);3) during 7 days after the first GnRH injectionof Ovsynch or Heatsynch (n = 96; 32.1%; 74 ±0.5 DIM); 4) after estrus as part of Heatsynch (n= 212; 44.6%; 76 ± 0.3 DIM); 5) after TAI aspart of Heatsynch (n = 154; 21.1%; 76 ± 0.4DIM); 6) after estrus as part of Ovsynch (n =43; 48.7%; 77 ± 0.7 DIM); and 7) after TAI aspart of Ovsynch (n = 271; 24.4%; 77 ± 0.3DIM). Conception rates when AI occurred afterone Presynch injection were less than when AIoccurred after two Presynch injections. Conceptionrates for those inseminated after eitherPresynch injection did not differ from thoseinseminated after combined Heatsynch +Ovsynch. Cows in the Ovsynch and Heatsynchprotocols inseminated after estrus during thebreeding week had greater conceptions ratesthan those receiving the TAI, but overall conceptionrates did not differ between protocols.Among cows inseminated after detected estrus,conception was greater for cows in theHeatsynch + Ovsynch protocol (77 ± 0.4 DIM)than for those inseminated after either Presynchinjection (54 ± 0.4 or 59 ± 0.2 DIM). Weconcluded that conception rates after Heatsynchand Ovsynch were similar under these experimentalconditions, and that delaying first AIimproved fertility for cows inseminated afterdetected estrus.
机译:一项对照实地研究对两个商业奶牛场进行了两次定时AI(TAI)育种协议后检查了受孕率。产后哺乳期牛的发情周期与两次注射的PGF2“(间隔14天)同步(Presynch),然后在12天后进行标准的Ovsynch方案(在注射PGF2的7天之前和之后48小时注射GnRH),在12至12第二次GnRH注射后16小时)或采用热同步方案(在注射PGF2“前7天注射GnRH,然后在24小时后再注射1 mg环丙二醇雌二醇(ECP),在ECP后48小时注射一个TAI)。实验设计允许AI发生在第2次Presynch注射后和设计的繁殖周中发现发情的任何时间,在1846项首次服务中,只有1503例(依从率= 81.4%)根据协议进行操作,精子数,经logistic回归调整的受孕率和天数牛奶(DIM)中进行的授精:1)在第一次Presynch注射后14天(n = 145; 22.6%; 54±0.4 DIM); 2)在第二次Presynchinjectio注射后12天n(n = 727; 33%; 59)±0.2 DIM); 3)在首次GnRH注射Ovsynch或Heatsynch之后的7天内(n = 96; 32.1%; 74±0.5 DIM); 4)发情后作为Heatsynch的一部分(n = 212; 44.6%; 76±0.3 DIM); 5)在TAI出现在Heatsynch之后(n = 154; 21.1%; 76±0.4DIM); 6)发情后作为Ovsynch的一部分(n = 43; 48.7%; 77±0.7 DIM);和7)TAI在Ovsynch后进行(n = 271; 24.4%; 77±0.3DIM)。一次Presynch注射后AI发生时的受孕率低于两次Presynch注射后AI发生时的受孕率。两种预同步注射后受精的受精率与热同步+卵巢同步化后受精的受精率没有差异。在育种周发情后受精的Ovsynch和Hotsynchprotocols的受胎率高于接受TAI的受胎率,但总体受孕率没有差异。在检测到发情后受精的母牛中,Heatsynch + Ovsynch方案的受胎率更高(77± (0.4 DIM)比预同步注射后的受精者(54±0.4或59±0.2 DIM)高。我们得出结论,在这些实验条件下,Heatsynchand Ovsynch之后的受孕率是相似的,并且延迟第一批AI可以提高发情后受精的母牛的受精能力。

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