Reprod Domest Anim. 2021 Aug 9. doi: 10.1111/rda.14001. Online ahead of print.
ABSTRACT
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 estrous cycle and delayed ovulation. For these concerns, effects of oxytocin injection on postpartum follicular dynamics, postpartum estrous interval (PEI), estrus 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 one 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 PEIfor the study period of 154 days. At subsequent estrus, three buffaloes from each group (not served) were selected randomly to monitor two cycles for six weeks. Trans-rectal ultrasonography was performed to evaluate follicular and corpus luteum (CL) development, while blood sampling was done for progesterone (P4) analysis. These results revealed that postpartum estrous interval (PEI) decreased significantly in oxytocin-treated groups. The number of small, medium and total follicles on the left ovary was significantly higher in 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 right ovary among all treatment groups. The same was true for the size of pre-ovulatory follicles, CL, P4 concentrations and estrous cycle length. The intervals from onset of estrus to ovulation and from standing estrus to ovulation were increased considerably in HIGH group. It is concluded that exogenous oxytocin administration resulted in the shortening of PEIbut 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.
PMID:34370879 | DOI:10.1111/rda.14001
