Effects of prepartum melatonin treatment and suckling on postpartum reproductive performance of Beetal goats under subtropical conditions

Abstract

The current study determines the effect of prepartum melatonin treatment on postpartum reproductive cyclicity, uterine involution, the onset of estrus, and ovarian activity in restricted or continuous suckled Beetal goats. Forty-six pregnant goats of 110 days gestation were either inserted with melatonin implants (M; n = 24) or left untreated (control, C; n = 22). Each group was subdivided into continuous (CS) and restricted suckling (RS) groups i.e., MCS (n = 11), CCS (n = 11), a ” ”MRS (n = 13), and CRS (n = 11) to monitor estrous response while uterine involution and ovarian activity were monitored in a subset of goats (n = 8 in each group) via transrectal ultrasonography (7.5 MHz transducer) twice a week. Blood BHBA and glucose levels were monitored 40 days before and 28 days after kidding. Data were analyzed using multifactor analysis of variance (ANOVA) designs, Chi-square, and Student’s t-test (SPSS version 20). Estrous response of goats was similar in MRS (30.8 %), CRS (45.4 %), and MCS (18.2 %) groups; however, MRS and CRS goats had better (P < 0.05) estrous response than those of CCS (0 %) goats. Between the groups, the ovulatory response and interval to 1st postpartum estrus were similar (P > 0.05). Melatonin tended to have shortened (P = 0.07) the interval to 1st postpartum ovulation and placental expulsion time (P < 0.05) in melatonin-treated than untreated goats. Melatonin or suckling treatment did not affect Gestation length, kidding time, uterine involution, and regression of caruncles (P > 0.05). BHBA levels were higher (P < 0.05) at 28 days postpartum than 40 days before kidding in all groups; however, glucose levels were similar in all groups except CCS. In conclusion, restricted suckling and prepartum melatonin treatment have more impact on postpartum reproductive performance than prepartum melatonin treatment alone in Beetal goats.