Melatonin along with eCG improves fresh semen quality and plasma concentrations of melatonin and testosterone during non-breeding season in Beetal bucks

Under subtropical regions, the breeding activities of goats are restricted to a specific season. Several hormonal regimens have been used to improve reproductive performance. However, different hormonal protocols have certain limitations. The effect of melatonin + eCG therapy on fresh semen, plasma testosterone, and melatonin profiles of bucks was evaluated during the non-breeding season. Nine bucks were assigned to three treatments (control; normal saline, melatonin alone, and melatonin + eCG; n = 3 in each group). Except for control, all bucks were implanted melatonin subcutaneously and eCG was administered every fourth day to melatonin + eCG treated bucks. Weekly two fresh ejaculates per buck for 10 weeks (n = 180) were evaluated for sperm con-centration, motility, kinematics (VCL, VSL, VAP, and ALH), non-viability, morphological abnormality, DNA fragmentation/damage, acrosomal and mitochondrial integrity. Weekly plasma profiles of testosterone and melatonin were monitored. From the 4th week onward, non-viable and morphological abnormal sperms and decreased (P < 0.05) while sperm progressive motility and kinematics, acrosomal and DNA integrity improved (P < 0.05) in melatonin + eCG than melatonin alone and control treatments. The concentrations of testosterone (ng/mL) increased (P < 0.05) from the 3rd week onward in melatonin + eCG (4.2 +/- 0.2) than melatonin alone (1.2 +/- 0.1) and control treatments (0.28 +/- 0.1). An increase (P < 0.05) in the concentration of melatonin (pg/mL) was observed at 5th week in melatonin + eCG (12.5 +/- 0.2) than melatonin alone (10.2 +/- 0.1) and control treatments (3.89 +/- 0.2); however, by 9th-week melatonin alone and melatonin + eCG had similar melatonin profiles. Compared to other treatments, melatonin + eCG therapy quickly improves and sustains fresh semen quality and plasma testosterone profile of bucks during the non-breeding season.