Effect of Leptin Gene Polymorphism on Reproductive Efficiency in Awassi Ewes

LEPtin (LEP) is a hormone that strongly associate with nutritional state, glucose homeostasis and reproduction. Study performed to identify the linkage between LEP polymorphism and reproductive efficiency such as Seasonality and litter size. Forty mature non-pregnant Awassi ewes were utilized between 1st July/2017 to 1st May/2018 in Salah Aldin province/Iraq. Twenty ewes were demonstrated estrus heat at August/2017which considered Seasonal group, and the others showed estrus signs at April/2018, which considered Non-Seasonal group.Genomic DNA was extracted from blood specimens and four primers were utilized to amplify exon II, intron II (fragment 1) and exon III (fragment 1) of LEP geneby polymerase chain reaction (PCR). Polymorphisms were revealed via sequencing and compared with the sequencing of the ovine LEP gene in NCBI. One single nucleotide polymorphism (SNP) A(99)R was detected in intron II and three SNPs G(425)R, T(541)K and G(587)R were in exon III. Two genotypes of each SNP were observed with higher significant differences (P<0.01) between frequencies 47.50 and 52.50 for AA and AG of A(99)R, 42.50 and 57.50 for GG and GA of G(425)R, 55.00 and 45.00 for TT and TC of T(541)K, lastly, 37.50, 62.50 for GG and GA of G(587)R. The finding demonstrated AG genotypic frequency of Non-Seasonal ewes (55.00) was significantly increased (P<0.05) than AA (45.00) for A(99)R SNPs. The mutant GA, TC and GA genotypic frequencies (80.00, 40.00 and 85.00) were recorded higher significant increased (P<0.01) than wild genotype GG, TT and GG (20.00, 60.00 and 15.00) for G(425)R, T(541)K and G(587)R SNPs in Non-Seasonal group. Higher significant increased (P<0.01) were observed in GG, TT and GG genotypic frequencies (65.00, 70.00 and 60.00) than GA, TC and GA (35.00, 30.00 and 40.00) for G(425)R, T(541)K and G(587)R SNPs respectively in Seasonal group, while non-significant differences were observed between AA and AG (50.00 for each) genotypic frequency for A(99)R SNPs of Seasonal group. Non-significant differences in litter size were recorded between GA (1.39) and GG (1.29) for G(425)R and between GG (1.4) and GA (1.32) for G(587)R, while significant differences (P<0.05) were observed between AG (1.26) and AA (1.42) and between TT (1.18) and TC (1.55) for A(99)R and T(541)K respectively. In Awassi breed, exon III polymorphisms of LEP gene have an expected effect on the Seasonality and the wild genotypes find majorly in Seasonal ewes. Intron II and exon III polymorphisms (2 SNPs) caused an increment in litter size.