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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 < 0.05) while the untreated group did not show statistical differences. 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 < 0.05). During 90 days after melatonin treatment, an increase (p < 0.05) in seminal plasma concentrations of glutamic acid (6.28 ± 1.53 vs 14.93 ± 1.53 AU at 0 and 90 days respectively), glutamine (16.89 ± 4.65 vs 54.51 ± 4.65 AU), carnitine (22.97 ± 9.81 vs 104.30 ± 9.81 AU), acetyl-carnitine (48.15 ± 17.32 vs 217.69 ± 17.32 AU), choline (1.82 ± 1.55 vs 14.16 ± 1.55 AU) and arginine (1.31 ± 1.08 vs 14.25 ± 1.08 AU) was detected. Tyrosine concentration increased during 30 days from melatonin treatment (12.79 ± 3.93 vs 27.08 ± 3.04 AU) but at 90 days its levels were similar to the untreated group. In conclusion, melatonin treatment during the non-breeding season improves the concentration of several metabolites in seminal plasma and sperm fertilization competence in Sarda breed ram.

The importance of postnatal pituitary activation as regards female reproductive development is not yet understood. By taking advantage of the experimental model developed in a previous study, i.e. ewe lambs expressing markedly different ovarian phenotypes at 50 days of age, we designed this study to determine whether differences found in ovarian status during the early prepubertal period are due to different patterns of postnatal pituitary activation, and to assess whether these differences have long lasting effects on subsequent reproductive performance. Results showed that ewe lambs with high antral follicle count (AFC) at 50 days of age had significantly lower plasma FSH concentrations and higher anti-Mullerian hormone (AMH) concentrations during the first 9 weeks of age compared with low AFC ewe lambs (P<0.0001).With a longitudinal experiment we showed that a high AFC in the early prepubertal period is associated with consistently higher AMH concentrations and numbers of antral follicles up to the postpubertal period, and with higher pregnancy rates in the first breeding season. In addition, the effect of age in decreasing AMH concentrations was more marked in the low AFC group. Results of the present study demonstrate that ewe lambs undergo different patterns of postnatal pituitary activation. A high AFC at 50 days of age indicates an advanced phase of ovarian maturation, which was accompanied by constantly higher AMH concentrations up to the postpubertal period, a greater ovarian response to FSH stimulation and by higher pregnancy rates at first mating, as compared with the low AFC group. © 2016 Society for Reproduction and Fertility.