association of melatonin receptor 1a gene polymorphisms with production and reproduction traits in zandi sheep

melatonin regulates some major physiological processes such as maturation and function of reproductive system, pubertal development, seasonal reproduction and adaptation. the activation of melatonin hormone is mediated by melatonin receptor. previous studies showed melatonin receptor 1a gene (mtnr1a) is highly polymorphic in seasonally breeding species. the aim of the present study was detection of mtnr1apolymorphism and its association with production (body weights at birth, 1, 3, 6, 9 and 12 month of age) and reproduction (litter size) traits in zandi sheep using pcr-rflp methodology. hundred blood samples were randomly collected and genomic dna was isolated using modified salting out method. a large fragment of exon 2 of mtnr1a gene was amplified by pcr using specific primer pairs. after amplification, the pcr product was digested with mnii endonuclease. restricted digestion allowed the determination of two alleles (m, m) and two genotypes (mm, mm) with frequencies of 0.91, 0.09 and 0.82, 0.18, respectively. least square means showed that mm individuals had higher body weight at one month of age (bw1) than mm individuals (p