Taniguchi M, Ikeda A, Arikawa E, Shimizu R, Seki M, Karaki M, Rajamahendran R, Otoi T
Laboratory of Animal Reproduction, The United Graduate School of Veterinary Science, Yamaguchi University, Yamaguchi, Japan.
Anim Reprod Sci. 2007 Jun;99(3-4):389-94. doi: 10.1016/j.anireprosci.2006.08.015. Epub 2006 Aug 14.
The objectives of the present study were to investigate the effects of the stage of the estrous cycle at the start of an estradiol benzoate (EB) and progesterone (P) based treatment protocol on new follicular wave emergence, subsequent estrus and ovulation. The experiment was conducted using a crossover design with each cow (five cross-bred cows) being assigned to one of three groups at 3-month intervals within a 1-year period. Estrous cycle stage in individual cows was initially synchronized with prostaglandin F(2)alpha. After detection of estrus, each cow was injected intramuscularly (i.m.) with 2 mg EB and 200 mg P (EB/P) on day 5, 12 or 17 of the estrous cycle (estrus=day 0), followed by 1 mg EB i.m. 12 days after the EB/P treatment. Ovarian ultrasonographic examinations showed that the emergence of a new follicular wave occurred after EB/P treatment in all groups and the mean interval from EB/P treatment to wave emergence did not differ among the groups (3.2-3.8 days). All cows in each group exhibited behavioral estrus and ovulated the newly formed dominant follicle. However, cows in the day-17 group exhibited estrus 1-3 days before the second EB injection. The concentrations of progesterone showed faster reduction, during the treatment period, in the day-12 and -17 groups compared to the day-5 group. These results indicate that the EB/P treatment induces an emergence of a new follicular wave, irrespective of the estrous cycle stage at the start of treatment, but the effect of EB/P protocol on estrous/ovulation synchronization is influenced by the stage of the estrous cycle.
本研究的目的是调查在基于苯甲酸雌二醇(EB)和孕酮(P)的治疗方案开始时,发情周期阶段对新卵泡波出现、随后的发情和排卵的影响。实验采用交叉设计,在1年时间内,每隔3个月将每头奶牛(5头杂交奶牛)分配到三组中的一组。个体奶牛的发情周期阶段最初用前列腺素F2α进行同步。在检测到发情后,每头奶牛在发情周期的第5、12或17天(发情=第0天)肌肉注射2毫克EB和200毫克P(EB/P),随后在EB/P治疗后12天肌肉注射1毫克EB。卵巢超声检查显示,所有组在EB/P治疗后均出现新的卵泡波,且从EB/P治疗到卵泡波出现的平均间隔在各组间无差异(3.2 - 3.8天)。每组中的所有奶牛均表现出行为发情,并排卵新形成的优势卵泡。然而,第17天组的奶牛在第二次EB注射前1 - 3天出现发情。与第5天组相比,第12天和第17天组在治疗期间孕酮浓度下降更快。这些结果表明,EB/P治疗可诱导新卵泡波的出现,无论治疗开始时的发情周期阶段如何,但EB/P方案对发情/排卵同步的影响受发情周期阶段的影响。