Department of Clinical Sciences, Bahauddin Zakariya University, Multan, Pakistan.
Department of Theriogenology, University of Veterinary and Animal Sciences (UVAS), Lahore, Pakistan.
Reprod Domest Anim. 2021 Nov;56(11):1369-1376. doi: 10.1111/rda.14001. Epub 2021 Aug 19.
Based on different surveys, dairy farmers are concerned about extensive use of exogenous oxytocin in buffaloes, which is being held responsible for reproductive problems including irregular oestrous cycle and delayed ovulation. For these concerns, effects of oxytocin injection on postpartum follicular dynamics, postpartum oestrous interval (PEI), oestrous length, the interval from onset of estrus to ovulation and blood progesterone (P4) were studied in Nili-Ravi buffaloes. For this purpose, 23 animals within 1 week after calving were randomly divided into three groups: without oxytocin (CON; n = 7), 10 i.u. oxytocin (LOW; n = 8), 30 i.u. oxytocin - (HIGH; n = 8) and used to record the PEI for the study period of 154 days. At subsequent estrus, three buffaloes from each group (not served) were selected randomly to monitor two cycles for 6 weeks. Transrectal ultrasonography was performed to evaluate follicular and corpus luteum (CL) development, and blood sampling was done for progesterone (P4) analysis. These results revealed that postpartum oestrous interval (PEI) decreased significantly in oxytocin-treated groups. The number of small, medium and total follicles on the left ovary was significantly higher in the HIGH group. However, an overall number of small and total follicles on both right and left ovaries was significantly higher in CON and HIGH groups. On the other hand, there was no difference in the number of follicles on the right ovary among all treatment groups. The same was true for the size of pre-ovulatory follicles, CL, P4 concentrations and oestrous cycle length. The intervals from onset of estrus to ovulation and from standing estrus to ovulation were increased considerably in the HIGH group. It is concluded that exogenous oxytocin administration resulted in the shortening of PEI but triggered a delay in ovulation. Moreover, a higher dose of oxytocin could stimulate the growth of small, medium, and total follicles in postpartum Nili-Ravi buffaloes.
基于不同的调查，奶农对水牛广泛使用外源性催产素表示担忧，因为这被认为是导致生殖问题的原因之一，包括不规律的发情周期和排卵延迟。针对这些担忧，本研究旨在探讨催产素注射对尼里-拉菲水牛产后卵泡动态、产后发情间隔（PEI）、发情持续时间、发情开始到排卵的间隔时间和血液孕酮（P4）的影响。为此，将产后 1 周内的 23 头水牛随机分为三组：不注射催产素（CON；n=7）、10IU 催产素（LOW；n=8）和 30IU 催产素（HIGH；n=8），并记录研究期间的 154 天 PEI。在随后的发情期，每组随机选择三头未配种的水牛，监测两个周期 6 周。通过直肠超声评估卵泡和黄体（CL）发育，并进行血液取样以分析孕酮（P4）。结果显示，催产素处理组的产后发情间隔（PEI）显著缩短。HIGH 组左侧卵巢上的小、中、总卵泡数量显著增加。然而，CON 和 HIGH 组两侧卵巢的小卵泡和总卵泡数量总体上更高。另一方面，所有治疗组右侧卵巢上的卵泡数量没有差异。右侧卵巢上的卵泡大小、黄体、P4 浓度和发情周期长度也如此。发情开始到排卵和静立发情到排卵的间隔时间在 HIGH 组显著增加。综上所述，外源性催产素的使用导致 PEI 缩短，但触发了排卵延迟。此外，较高剂量的催产素可刺激产后尼里-拉菲水牛小、中、总卵泡的生长。
