Effects of melatonin administration on seminal plasma metabolites and sperm fertilization competence during the non-reproductive season in ram

Abstract The purpose of this study was to investigate the effects of ram melatonin treatment on the sperm quality and metabolite composition of the seminal plasma in the non-breeding season. Four mature rams were treated with 54 mg melatonin in March subcutaneous implants and four untreated rams served as control. At 0, 30, 90 and 120 days semen samples were collected and sperm, separated from seminal plasma, was evaluated for its capacity to fertilize and produce embryos in vitro. Seminal plasma metabolites were extracted and analyzed by capillary electrophoresis/mass spectroscopy. In the resulting electropherograms, the area corresponding to selected metabolites was extracted and quantified. Ram melatonin treatment affected the in vitro fertilization competence of sperm. Blastocyst output increased until 90 days after treatment (27.20 ± 7.35 vs 54.7 ± 4.4% at 0 and 90 days respectively; p  In treated rams, the concentration of melatonin in seminal plasma increased from 3.34 ± 1.70 at day 0–9.65 ± 2.89 AU (Arbitrary Units) after 90 days, then decreased to reach the level of the untreated ram after 120 days (p