Department of Animal Sciences and Industry, Kansas State University, Manhattan, KS, USA.
Theriogenology. 2011 May;75(8):1506-15. doi: 10.1016/j.theriogenology.2010.12.012. Epub 2011 Feb 4.
We hypothesized that administration of hCG to recipients at embryo transfer (ET) would induce accessory CL, increase serum progesterone concentrations, and reduce early embryonic loss (as measured by increased transfer pregnancy rates). At three locations, purebred and crossbred Angus, Simmental, and Hereford recipients (n = 719) were assigned alternately to receive i.m. 1,000 IU hCG or 1 mL saline (control) at ET. Fresh or frozen-thawed embryos were transferred to recipients with a palpable CL on Days 5.5 to 8.5 (median = Day 7) of the cycle (Locations 1 and 2), or on Day 7 after timed ovulation (Location 3). Pregnancy diagnoses (transrectal ultrasonography) were done 28 to 39 d (median = 35 d) and reconfirmed 58 to 77 d (median = 67 d) post-estrus. At Location 1 (n = 108), ovaries were examined at pregnancy diagnosis to enumerate CL. More (P < 0.001) pregnant hCG-treated cows (69.0%) had multiple CL than pregnant controls (0%). Serum progesterone (ng/mL) determined at Locations 1 and 2 (n = 471) at both pregnancy diagnoses in pregnant cows was greater (P ≤ 0.05) after hCG treatment than in controls (first: 8.1 ± 0.9 vs 6.1 ± 0.8; second: 8.8 ± 0.9 vs 6.6 ± 0.7), respectively. Unadjusted pregnancy rates at the first diagnosis were 61.8 and 53.9% for hCG and controls. At the second diagnosis, pregnancy rates were 58.6 and 51.3%, respectively. Treatment (P = 0.026), embryo type (P = 0.016), and BCS (P = 0.074) affected transfer pregnancy rates. Based on odds ratios, greater pregnancy rates occurred in recipients receiving hCG, a fresh embryo (66.3 vs 55.5%), and having BCS >5 (62.3 vs 55.3%). We concluded that giving hCG at ET increased incidence of accessory CL, serum progesterone in pregnant recipients, and transfer pregnancy rates. Furthermore, we inferred that increased progesterone resulting from hCG-induced ovulation reduced early embryonic losses after transfer of embryos to recipients.
我们假设在胚胎移植（ET）时给受体注射 hCG 会诱导副黄体，增加血清孕激素浓度，并降低早期胚胎丢失率（通过增加移植妊娠率来衡量）。在三个地点，纯种和杂交安格斯、西门塔尔和海福特受体（n = 719）被交替分配接受肌肉注射 1000 IU hCG 或 1 毫升生理盐水（对照）在 ET。新鲜或冷冻解冻的胚胎在周期的第 5.5 天至 8.5 天（中位数 = 第 7 天）（地点 1 和 2）或定时排卵后第 7 天（地点 3）转移给可触及 CL 的受体。妊娠诊断（直肠超声检查）在发情后 28 至 39 天（中位数 = 35 天）进行，并在发情后 58 至 77 天（中位数 = 67 天）再次确认。在地点 1（n = 108），在妊娠诊断时检查卵巢以计数 CL。接受 hCG 治疗的妊娠母牛（69.0%）比对照组（0%）有更多的多黄体（P < 0.001）。在地点 1 和 2（n = 471）在两个妊娠诊断中，接受 hCG 治疗的怀孕母牛的血清孕激素（ng/mL）分别高于对照组（第一次：8.1 ± 0.9 对 6.1 ± 0.8；第二次：8.8 ± 0.9 对 6.6 ± 0.7）。第一次诊断时的未调整妊娠率分别为 hCG 和对照组的 61.8%和 53.9%。第二次诊断时，妊娠率分别为 58.6%和 51.3%。治疗（P = 0.026）、胚胎类型（P = 0.016）和体况评分（P = 0.074）影响了移植妊娠率。基于优势比，接受 hCG 治疗、接受新鲜胚胎（66.3%对 55.5%）和体况评分 >5（62.3%对 55.3%）的受体妊娠率更高。我们得出结论，在 ET 时给予 hCG 增加了副黄体、怀孕受体的血清孕激素和移植妊娠率的发生率。此外，我们推断 hCG 诱导排卵导致的孕激素增加减少了胚胎转移到受体后的早期胚胎丢失。
