Journal of Animal Research

The study was undertaken to assess the ovarian and fertility responses following ovulation of dominant follicle (DF) from second follicular wave (2^nd FW) through application of modified synchronization protocols in 46 cyclic postpartum buffaloes. All buffaloes were administered PGF2α (PGF; Cloprostenol, 500 mcg) on day-2, gonadotrophin releasing hormone (GnRH; Buserelin) on days 0 (10 mcg) and 7 (20 mcg). After that, all buffaloes were randomly divided into 2 groups on the basis of administration of second dose of PGF (500 mcg) on day 14 (Group I, n= 20) and 15 (Group II, n= 26). Third dose of GnRH (10 mcg) was administered on day 16 (Evening) and 17 (Morning) in group I and II, respectively, followed by artificial insemination (AI) at 12–16 h later. The pregnancy diagnosis was performed at day 45 post AI. Progesterone (P₄) concentrations remained higher during 2FW in buffaloes that became pregnant compared to nonpregnant ones. A larger (P<0.01) diameter of the DF was observed on day of third GnRH and AI in group II compared to group I buffaloes. A comparable corpus luteum (CL) diameter was observed on all days of protocols in both groups. Ovulatory response following last GnRH administration and first AI pregnancy rate were 90 vs. 96% and 35 vs. 46% in group I vs. II, respectively. In conclusion, ovarian and fertility responses following ovulation of DF from 2^nd FW showed an improved trend in buffaloes where growth of DF was extended by delaying the luteolysis.