Objective: The aim of the current study was to evaluate the fertility response of anestrous buffaloes and associated follicular growth and hormonal profiles to eCG-Modified (eCG2-ovsync) or eCG plus Norgestomet ear implant-Modified (Norgestomet-eCG6-ovsync) GnRH-Based ovsync protocols.
Methods: Buffaloes (n=42) were randomly allocated into three treatment protocols: Basic-ovsync, Norgestomet-eCG6-ovsync and eCG₂-ovsync (14 each). Each buffalo-cow in the Basic-ovsync protocol received two GnRH agonist injections on Days 0 (GnRHa1) and Day 9 (GnRHa2) and an injection of PGF_2α on Day 7 with TAI at 16 h after GnRHa2 injection. Buffaloes in Norgestomet eCG6-ovsync (n=14) received the same treatment as Basic –ovsync plus IM injection of 250 mg of long-lasting progesterone and S/C insertion of Norgestomet ear implant in the ear Conca on Day 0 and an injection of 500 IU eCG on Day 6. Buffaloes in eCG2-ovsync received the same treatment of Basic ovsync in addition to an injection of 1000 IU eCG on Day 2. Simultaneous transrectal ultrasonography (TUS) and blood sampling were performed on Days -10, 0, 7, 9 and 10 as well as on post-TAI Days 11 and 22.
Results: The largest follicle diameter (LFD) was significantly larger (p < 0.05) in eventually diagnosed pregnant (EDP) than in eventually diagnosed non-pregnant (EDnP) buffaloes in all treatment protocols on Day 9. The serum progesterone (P4) concentration was significantly higher (p < 0.05) in either EDP or EDnP buffaloes in Noegestomet eCG6-ovysync compared with other protocols on Day 7. There was a highly significant (r=0.74, P<0.01) positive correlations between corpus luteum volume (CLV) and LFD in EDP buffaloes.
Conclusions: It is concluded that modifying Basic-ovsync via P4 supplementation by injection of long-lasting P4 on Day 0 and insertion of Norgestomet ear implant from day 0 to day 7 plus an injection of eCG on Day 6 improve the fertility response in true anestrus in buffaloes.