Department of Animal Sciences, The Ohio State University, Columbus, OH, 43210, USA.
ST Genetics - Ohio Heifer Center, South Charleston, OH, 45368, USA.
Theriogenology. 2022 Aug;188:71-78. doi: 10.1016/j.theriogenology.2022.05.017. Epub 2022 May 29.
The objective of the present study was to evaluate effects of synchronization of timing of follicle wave emergence, before ovarian superstimulation and ovum pick-up (OPU), on ovarian response and embryo production in pregnant heifers. Pregnant (47-69 days of gestation) Holstein heifers (n = 64), 19.0 ± 0.3 months of age, were assigned in a completely randomized design to one of two groups: synchronization of follicular wave emergence using follicle ablation (Synchronized) or untreated control (Non-synchronized). Superstimulatory treatments consisting of 160 mg (280 IU) of porcine follicle stimulating hormone (p-FSH), administered in four decreasing dose treatments 12 h apart, were initiated 36 h after follicle ablation or at random stages of the follicular wave in heifers of the Synchronized and Non-synchronized group, respectively. Ovum pick-up was performed in all heifers 40 h after the last p-FSH administration and retrieved cumulus oocyte complexes (COCs) were subjected to in vitro embryo production (IVEP) procedures. Ultrasonography was performed immediately before OPU to determine number and size of ovarian follicles. Differences in treatment responses between groups were evaluated using generalized linear mixed models. Total number of follicles at the time of OPU was not different between treatment groups (P = 0.61), however, the number of small follicles (<6 mm) was greater (P = 0.05) in heifers of the Non-synchronized group, whereas number of medium size follicles (6-10 mm) tended (P = 0.09) to be greater in heifers of the Synchronized group. Heifers in the Synchronized group had a greater (P = 0.01) percentage of medium sized follicles and a lesser (P = 0.01) percentage of smaller sized follicles than heifers in the Non-synchronized group. There were no differences (P > 0.15) in total number of recovered COCs, or number of viable COCs between groups. Cleavage percentage (84.5% and 72.8%) and blastocyst percentage (48.2% and 33.4%) were greater (P < 0.01) in heifers of the Synchronized than Non-synchronized group, respectively. As a result, mean number of blastocysts per OPU/heifer was greater (P = 0.006) in the heifers of the Synchronized (8.9 ± 1.0) than the Non-synchronized (5.5 ± 0.9) group. In conclusion, synchronizing the time of follicle wave emergence in pregnant heifers, prior to ovarian superstimulation with FSH and OPU results in a greater superstimulatory response and oocyte competence leading to greater embryo production.
本研究的目的是评估在卵巢超刺激和卵母细胞采集（OPU）前同步卵泡波出现的时间对妊娠小母牛的卵巢反应和胚胎生产的影响。将 64 头处于妊娠（妊娠 47-69 天）的荷斯坦小母牛（n = 64），年龄 19.0 ± 0.3 个月，按照完全随机设计分为两组之一：使用卵泡消融同步卵泡波出现（同步）或未处理对照（非同步）。超刺激处理由 160 mg（280 IU）猪促卵泡激素（p-FSH）组成，每 12 小时分四次递减剂量给药，分别在消融后 36 小时或小母牛的同步和非同步组中卵泡波的随机阶段开始。在最后一次 p-FSH 给药后 40 小时对所有小母牛进行 OPU，并对收集的卵丘卵母细胞复合物（COC）进行体外胚胎生产（IVEP）程序。在 OPU 前立即进行超声检查，以确定卵巢卵泡的数量和大小。使用广义线性混合模型评估组间治疗反应的差异。OPU 时两组的总卵泡数无差异（P = 0.61），但非同步组的小卵泡（<6mm）数量较多（P = 0.05），而同步组的中卵泡数量（6-10mm）趋于较大（P = 0.09）。同步组的小母牛具有更大比例的中等大小卵泡（P = 0.01）和更小比例的较小卵泡（P = 0.01），而非同步组的小母牛则较小。两组之间的总 COC 回收率或活 COC 数量无差异（P > 0.15）。卵裂率（84.5%和 72.8%）和囊胚率（48.2%和 33.4%）在同步组的小母牛中均高于非同步组（P < 0.01）。结果，每头 OPU/小母牛的囊胚平均数（P = 0.006）在同步组（8.9 ± 1.0）中高于非同步组（5.5 ± 0.9）。总之，在卵巢超刺激和 OPU 前同步妊娠小母牛的卵泡波出现时间可导致更大的超刺激反应和卵母细胞活力，从而提高胚胎生产。
