Effects of melatonin supplementation prior to Ovsynch protocol on ovarian activity and conception rates in anestrous Murrah buffalo heifers during out of breeding season.

Buffalo heifers have tendency to show anestrus during summer season. Melatonin has been used for correcting summer dependent anestrous via inducing resumption of ovarian activity. Therefore, the investigation was conducted to compare efficacy of melatonin for induction of estrus and conception rate with Ovsynch protocol in summer anestrous Murrah buffalo heifers. Thirty, summer anestrous Murrah buffalo heifers were selected and divided into two groups- treatment (n = 20; 12 melatonin implants) and control (n = 10; no treatment). On day 28 post-implant insertion, animals of both the groups were subjected to Ovsynch protocol. Blood sampling and ovarian ultrasonography were conducted to measure plasma melatonin, progesterone concentration and ovarian dynamics, respectively. No animal in either group showed estrus during first 28 days post-implant insertion. However, estrus induction rate was 100% after Ovsynch protocol in both groups. As compared to controls, treatment group exhibited higher (p < 0.05) plasma melatonin on days 1, 4, 8, 15, 22 and 28 post-melatonin, with highest concentration on day 4. The progesterone concentration increased (p < 0.05) on days 15 and 22 post-melatonin treatment. The treatment group had larger (p < 0.05) preovulatory follicle on day of AI, subsequently developed larger (p < 0.05) corpus luteum and higher plasma progesterone concentrations by day 12 post-AI as compared to the control group. The overall conception rate was 50 and 20% in treatment and control groups, respectively. In conclusion, melatonin treatment along with Ovsynch protocol improved the luteal profiles as well as the conception rate in buffalo heifers when compared with animals treated with Ovsynch protocol alone during summer season.