Effect of polymorphism at Mtnr1a melatonin receptor gene on fertility in Sarda breed sheep subjected to artificial insemination in late spring
2011
Mura, M.C., Università degli Studi di Sassari, (Italia). Dipertimento di Biologia Animale | Luridiana, S. | Daga, C. | Paludo, M. | Vacca, G.M. | Carcangiu, V.
Reproductive activity in the sheep reared in the Mediterranean area shows a seasonal pattern driven by circannual photoperiodic trend which lead to have lambing in spring, the most favourable season to ensure the development of offspring and milk production of mother (Chemineau et al., 1995). In seasonal reproductive species the duration of melatonin secretion indicates day-length and this has an effect on the reproductive system (Reiter et al., 2009). In sheep high melatonin secretion for many hours stimulates the GnRH and LH secretion by hypothalamic-pituitary axis, allowing reproductive activity resumption (Viguiè et al., 1995). The aim of the present study was to assess, in Sarda sheep breed, the influence of MTNR1A/MnII genotype on the pregnancy and lambing rate after vaginal AI in two different periods, during increasing day length. MnII genotype has positively influenced response at synchronization treatment and AI during out of breeding season in Sarda sheep. Further studies on the mechanism underlying the interactions between follicular dynamics during non breeding season and MTNR1A genotype influence are needed to amplify the knowledge about the reproductive activity in small ruminants. However the ability to improve fertility rates resulting from synchronization treatments and AI out of breeding season simply with a genetic investigation opens a number of opportunities for Sarda sheep. Because of the high number of subject carrying the +/+ genotype, in fact, this breed could be a good example of selection aimed at overcoming some of the most complex barriers related to reproduction. Genotyping at MTNR1A locus could become an important requirement to be taken into account in the plans for genetic improvement.
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