Possible implication of melatonin receptor 1A and Arylalkylamine N acetyltransferase genes polymorphisms for seasonal reproduction in Egyptian sheep breeds

This study was carried out for detection of polymorphisms in melatonin receptor 1A 
(MTNR1A) and Arylalkylamine N acetyltransferase (AA-NAT) genes and their association with 
reproductive traits. Blood samples of 126 Animal from three Egyptian sheep breeds were collected. 
DNA was extracted and subjected to PCR-RFLP using RsaI and SmaI enzymes. Two alleles (C and 
T), three genotypes (CC, CT and TT) for MTNR1A gene also (A and G), (GG, GA, and AA) for AA
NAT gene were detected. Alleles C and A, genotypes CT and GA showed the highest frequency for 
MTNR1A and AA-NAT genes respectively. Association analysis of MTNR1A SNP revealed a 
significant association in Ossimi and Rhmani breeds with age of first lambing and C allele seems to 
be the favorable allele. Results for AA-NAT SNP demonstrate significant differences in Ossimi with 
age of first lambing and litter size and in Rhmani with lambing interval and G allele seems to be the 
desirable allele. Concerning to first conception season the study revealed that ewes carrying CT 
exhibited significantly lower age of first lambing in unfavorable season. Also, GG ewes exhibited 
significantly lower age of first lambing in early favorable followed by unfavorable seasons. 
According to personal knowledge this is the first study concerned with this association in Egyptian 
sheep breed. In conclusion: the polymorphisms achieved in this study could be measured as genetic 
markers suitable for improving reproductive efficiency during unfavorable season and the obtained 
desirable genotypes could be taken into account in new genetic selective schemes.