Department of Large Animal Clinical Sciences, University of Florida, Gainesville 32610; Department of Animal Sciences, University of Florida, Gainesville 32608.
Department of Large Animal Clinical Sciences, University of Florida, Gainesville 32610.
J Dairy Sci. 2020 Jun;103(6):5591-5603. doi: 10.3168/jds.2019-17870. Epub 2020 Apr 3.
We hypothesized that delaying by approximately 12 h the artificial insemination (AI) of heifers with sex-sorted semen increases pregnancy per AI (P/AI). Holstein heifers (n = 1,207) were fitted with a collar containing an automated estrus-detection device (HR-LDn tags, SCR Engineers Ltd., Netanya, Israel) at 10.7 ± 0.02 mo of age. Once they reached 330 kg, heifers were enrolled in an ovulation synchronization protocol (5-d Cosynch + controlled internal drug release; Zoetis, Parsippany-Troy Hills, NJ). Study personnel recorded the heifers that were in estrus according to the DataFlow II software (SCR Engineers Ltd., Netanya, Israel) twice daily at 0500 and 1500 h from the day of the first PGF (Estrumate; Merck Animal Health, Madison, NJ) injection to 72 h later. Heifers enrolled in the conventional (CONV) and early sex-sorted (SSEarly) semen treatments detected in estrus at 0500 and 1500 h were AI at 0600 and 1600 h of the same day, respectively. Heifers enrolled in the late sex-sorted (SSLate) semen treatment detected in estrus at 0500 and 1500 h were AI at 1600 h of the same day and 0600 h of the following day, respectively. All heifers not detected in estrus by 72 h after the first PGF injection received a GnRH (Fertagyl; Merck Animal Health, Madison, NJ) injection at 0500 h. Heifers in the CONV and SSEarly treatments were AI at fixed time at 0600 h, whereas heifers in the SSLate treatment were AI at fixed time at 1600 h. Among heifers detected in estrus, the ranges of the interval from the onset of estrus to AI were 3.6 to 28.5 h, 0.0 to 25.5 h, and 9.4 to 36.8 h for the CONV, SSEarly, and SSLate treatments, respectively. Among heifers AI at fixed time, the ranges of the interval from the GnRH injection to AI were 0 h for heifers in the CONV and SSEarly treatments and 8.5 to 11.7 h for heifers in the SSLate treatment. The P/AI at 62 ± 1 d after the first AI was greater for CONV (63.1 ± 2.6%) compared with SSEarly (43.3 ± 2.6%) and SSLate (44.8 ± 2.7%). A greater percentage of heifers enrolled in the SSEarly (65.8 ± 2.5%) and SSLate (70.0 ± 2.5%) treatments produced a live female calf compared with the CONV treatment (40.5 ± 2.7%). When the values of 1-d-old female and male calves were USD $0 and the cost of replacement heifers was $750, the cost of raising heifers from enrollment to calving was lesser for the CONV treatment than the SSEarly treatment, but SSLate treatment did not differ from CONV and SSEarly treatments. When the values of a 1-d-old female calf ≥$130 and 1-d-old male calf ≥$30 and the cost of replacement ≥$1,000, no differences were observed among treatments in the cost from enrollment to calving. We conclude from this experiment that the P/AI with sex-sorted semen is not improved when insemination is delayed by approximately 12 h.
我们假设，将性控精液的人工授精（AI）延迟约 12 小时，可以提高每次 AI 的妊娠率（P/AI）。选择荷斯坦小母牛（n=1207），在 10.7±0.02 月龄时佩戴含有自动发情检测装置（HR-LDn 标签，SCR 工程师有限公司，以色列内坦亚）的项圈。一旦它们达到 330 公斤，小母牛就会参加排卵同步方案（5-d Cosynch+受控内部药物释放；Zoetis，帕西帕尼-特洛伊山，NJ）。研究人员根据 DataFlow II 软件（SCR 工程师有限公司，以色列内坦亚）记录每天 0500 和 1500 小时发情的小母牛，从第一次 PGF（Estrumate；默克动物健康，麦迪逊，NJ）注射后 72 小时。参加常规（CONV）和早期性控（SSEarly）精液处理的小母牛，在 0500 和 1500 小时发情，分别在当天 0600 和 1600 小时进行 AI。参加晚期性控（SSLate）精液处理的小母牛，在 0500 和 1500 小时发情，分别在当天 1600 小时和次日 0600 小时进行 AI。所有在第一次 PGF 注射后 72 小时内未发情的小母牛，在 0500 小时接受 GnRH（Fertagyl；默克动物健康，麦迪逊，NJ）注射。CONV 和 SSEarly 处理的小母牛在固定时间 0600 小时进行 AI，而 SSLate 处理的小母牛在固定时间 1600 小时进行 AI。在发情的小母牛中，从发情开始到 AI 的间隔时间范围为 CONV、SSEarly 和 SSLate 处理的 3.6 至 28.5 小时、0.0 至 25.5 小时和 9.4 至 36.8 小时。在固定时间进行 AI 的小母牛中，从 GnRH 注射到 AI 的间隔时间范围为 CONV 和 SSEarly 处理的 0 小时和 SSLate 处理的 8.5 至 11.7 小时。第一次 AI 后 62±1 天的 P/AI ，CONV（63.1±2.6%）高于 SSEarly（43.3±2.6%）和 SSLate（44.8±2.7%）。与 CONV 处理（40.5±2.7%）相比，参加 SSEarly（65.8±2.5%）和 SSLate（70.0±2.5%）处理的小母牛生产活雌性犊牛的比例更高。当 1 日龄雌性和雄性犊牛的价值分别为 0 美元和替代小母牛的成本为 750 美元时，CONV 处理的小母牛从入群到产犊的饲养成本低于 SSEarly 处理，但 SSLate 处理与 CONV 和 SSEarly 处理没有差异。当 1 日龄雌性犊牛的价值≥$130 和 1 日龄雄性犊牛的价值≥$30 和替代的成本≥$1000 时，处理之间从入群到产犊的成本没有差异。我们从这个实验中得出结论，当精液的人工授精延迟约 12 小时时，性控精液的 P/AI 并没有提高。
