Division of Animal Sciences, University of Missouri, Columbia, Missouri 65211, USA.
J Anim Sci. 2013 Sep;91(9):4158-67. doi: 10.2527/jas.2013-6348. Epub 2013 Jul 3.
The objective was to examine the relationship between ovulatory follicle size and embryo and fetal survival by using circulating concentrations of bovine pregnancy associated glycoproteins (bPAG) to detect the presence of an embryo or fetus and monitor placental function. Before examining the relationship between bPAG, ovulatory follicle size, and embryo and fetal survival, the half-life of bPAG was determined in Exp. 1. The half-life of bPAG after PGF2α-induced abortion on d 32 to 36 postinsemination was 35.8 ± 21.9 h (mean ± SD; range 7.1 to 78.5 h). In Exp. 2, suckled beef cows (n = 91) were treated with the CO-Synch protocol (GnRH on d -9, PGF2α on d -2, and GnRH and AI 48 h later [d 0]) and classified into 1 of 2 ovulatory follicle size groups: 1) small follicle (<12.5 mm; n = 25) or 2) large follicle (≥ 12.5 mm; n = 66). The first increase (P < 0.0001) in serum bPAG occurred in pregnant cows on d 24 after insemination and circulating bPAG decreased before a decrease in progesterone in 3 of 4 cows that lost an embryo or fetus. Pattern of secretion of bPAG in serum from d 24 to 60 after insemination (d 0) was affected by day (P < 0.0001), but not ovulatory follicle size. In Exp. 3, suckled beef cows (n = 1164) were administered the CO-Synch protocol either with (donor cows; n = 810) or without (recipient cows; n = 354) AI on d 0. Single embryos (n = 394) or oocytes (n = 45) were recovered from the donor cows [d 7; embryo transfer (ET)] and all live embryos were transferred into recipients the same day. Cows were classified on d 0 as having a small (<12.5 mm) or large (≥ 12.5 mm) ovulatory follicle, and randomly chosen as donors or recipients to remove confounding effects of ovulatory follicle size on fertility. Serum concentration of bPAG at d 28 was not affected by ovulatory follicle size (P = 0.85), embryo stage at ET (P = 0.75), embryo quality at ET (P = 0.64), estradiol at GnRH2 (P = 0.62) or serum progesterone at ET (d7; P = 0.14). Compared with cows that maintained pregnancy (n = 176), cows that exhibited late embryonic or fetal mortality (n = 19) after d 28 had decreased (P < 0.05) concentrations of bPAG on d 28. In summary, there was no relationship between serum bPAG and ovulatory follicle size or embryo stage or quality at ET; however, cows that lost an embryo after d 28 had reduced concentrations of bPAG on d 28 compared with cows that maintained pregnancy.
目的是通过使用牛妊娠相关糖蛋白（bPAG）的循环浓度来检测胚胎和胎儿的存在并监测胎盘功能，从而检查排卵卵泡大小与胚胎和胎儿存活率之间的关系。在检查 bPAG、排卵卵泡大小与胚胎和胎儿存活率之间的关系之前，在实验 1 中确定了 bPAG 的半衰期。在 PGF2α 诱导的流产后第 32 至 36 天，bPAG 的半衰期为 35.8 ± 21.9 h（平均值 ± SD；范围为 7.1 至 78.5 h）。在实验 2 中，哺乳期奶牛（n = 91）接受 CO-Synch 方案（GnRH 于 d-9，PGF2α 于 d-2，GnRH 和 AI 于 48 小时后[d0]），并分为 2 个排卵卵泡大小组之一：1）小卵泡（<12.5mm；n = 25）或 2）大卵泡（≥ 12.5mm；n = 66）。第一次增加（P < 0.0001）在受孕后 24 天怀孕的奶牛血清 bPAG 中发生，并且在 3 头牛中的 4 头中，在孕激素下降之前，bPAG 的循环量下降，这些牛丢失了胚胎或胎儿。在受孕后 24 至 60 天（d0）血清中 bPAG 的分泌模式（d0）受天的影响（P < 0.0001），但不受排卵卵泡大小的影响。在实验 3 中，哺乳期奶牛（n = 1164）在 d0 时接受 CO-Synch 方案，其中 810 头奶牛（供体奶牛）接受 AI，354 头奶牛（受体奶牛）未接受 AI。从供体奶牛中回收单个胚胎（n = 394）或卵母细胞（n = 45）[d7；胚胎移植（ET）]，并在同一天将所有活胚胎转移到受体中。在 d0 时，根据排卵卵泡大小将奶牛分为小（<12.5mm）或大（≥ 12.5mm），并随机选择作为供体或受体，以消除排卵卵泡大小对生育能力的混杂影响。在 d28 时，血清 bPAG 浓度不受排卵卵泡大小（P = 0.85）、ET 时的胚胎阶段（P = 0.75）、ET 时的胚胎质量（P = 0.64）、GnRH2 时的雌二醇（P = 0.62）或 ET 时的血清孕酮（d7；P = 0.14）的影响。与维持妊娠的奶牛（n = 176）相比，在 d28 后出现晚期胚胎或胎儿死亡的奶牛（n = 19）的 d28 血清 bPAG 浓度降低（P <0.05）。总之，血清 bPAG 与排卵卵泡大小或 ET 时的胚胎阶段或质量之间没有关系；然而，在 d28 后丢失胚胎的奶牛的 bPAG 浓度在 d28 时降低，与维持妊娠的奶牛相比。
