RESUMO
The economy in Mediterranean areas is tightly linked to the evolution of the sheep-farming system; therefore, improvement in ewe's reproductive performance is essential in the developing countries of this area. MTNR1A is the gene coding for Melatonin receptor 1 (MT1), and it is considered to be involved in the reproductive activity in sheep. The aims of this study were: (1) identifying the polymorphisms from the entire MTNR1A coding region and promoter in Lebanese Awassi sheep flocks, and (2) investigating the association between the found polymorphisms and the reproductive performance, assessed as lambing rate, litter size, and days to lambing (DTL). The study was conducted in two districts of Lebanon, where 165 lactating ewes, aged 5.2 ± 1.5 years, with body condition score (BCS) 3.3 ± 0.4, were chosen and exposed to adult and fertile rams. From 150 to 220 days after ram introduction, lambing dates and litter sizes were registered. This study provided the entire coding region of the MTNR1A receptor gene in the Awassi sheep breed. Thirty-one single nucleotide polymorphisms (SNPs) were detected, five of which were missense mutations. The H2, H3, and H4 haplotypes were associated with lower DTL (p < 0.05), as well as the SNPs rs430181568 and rs40738822721, named from now on SNP20 and SNP21, respectively. These SNPs were totally linked and can be considered as a single marker. The ewes carrying the C allele at both these polymorphic sites advanced their reproductive recovery (p < 0.05). These results are essential for improving reproductive management and obtaining advanced lambing in Awassi ewes.
RESUMO
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 54â¯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⯱â¯7.35 vs 54.7⯱â¯4.4% at 0 and 90 days respectively; pâ¯<â¯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⯱â¯1.70â¯at day 0-9.65⯱â¯2.89 AU (Arbitrary Units) after 90 days, then decreased to reach the level of the untreated ram after 120 days (pâ¯<â¯0.05). During 90 days after melatonin treatment, an increase (pâ¯<â¯0.05) in seminal plasma concentrations of glutamic acid (6.28⯱â¯1.53 vs 14.93⯱â¯1.53 AU at 0 and 90 days respectively), glutamine (16.89⯱â¯4.65 vs 54.51⯱â¯4.65 AU), carnitine (22.97⯱â¯9.81 vs 104.30⯱â¯9.81 AU), acetyl-carnitine (48.15⯱â¯17.32 vs 217.69⯱â¯17.32 AU), choline (1.82⯱â¯1.55 vs 14.16⯱â¯1.55 AU) and arginine (1.31⯱â¯1.08 vs 14.25⯱â¯1.08 AU) was detected. Tyrosine concentration increased during 30 days from melatonin treatment (12.79⯱â¯3.93 vs 27.08⯱â¯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.