Determination of leptin gene polymorphisms and their effects on milk yield and composition in some culture and native cattle breeds

The objective of this study was to detect leptin gene polymorphisms, to determine genotype and allele frequencies for the polymorphisms and to investigate their effects on milk yield and composition in culture (Holstein, Brown Swiss and Jersey) and native (Anatolian Black and East Anatolian Red) cattle breeds raised in Turkey.For this purpose, a total of 480 blood and milk samples were collected from Holstein, Brown Swiss, Jersey, Anatolian Black and East Anatolian Red cattle breeds. In addition, milk production records of culture (Holstein, Brown Swiss and Jersey) cattle breeds were obtained. Protein, fat, lactose, solids, solids non-fat (SNF) contents and density were determined in collected milk samples. After DNA was extracted from the blood samples, C1180T, C2059T-A2584G and C3100T polymorphisms in exon 2, intron 2 and exon 3 were detected, respectively by PCR-RFLP technique. Association between genotypes for polymorphisms and milk yield records and milk composition was analyzed by statistical methods.Allele frequencies for C1180T polymorphism were determined as C=0.625, T=0.375 for Holstein, C=0.625, T=0.375 for Brown Swiss, C=0.539, T=0.461 for Jersey, C=0.560, T=0.440 for Anatolian Black and C=0.600, T=0.400 for East Anatolian Red. The corresponding numbers for C2059T/A2584G polymorphisms were A=0.822, B=0.084, C=0.094 for Holstein, A=0.675, B=0.271, C=0.104 for Brown Swiss, A=0.811, B=0.189, C=0.000 for Jersey, A=0.720, B=0.220, C=0.060 for Anatolian Black and A=0.714, B=0.271, C=0.014 for East Anatolian Red. The frequencies for C3100T polymorphism were C=0.653, T=0.347 for Holstein, C=0.908, T=0.092 for Brown Swiss, C=0.654, T=0.346 for Jersey, C=0.880, T=0.120 for Anatolian Black and C=0.900, T=0.100 for East Anatolian Red.The effect of C1180T polymorphism on 100 days yield was found significant in Holstein and Jersey Breeds (P<0.05). While significance level of the effect of this polimorphism on 200 day milk yield was found as P<0.1 in these breeds. Similarly, the effect of C1180T polymorphism on 100 days milk yield was found as P<0.1 in Brown Swiss. T allele for C1180T polymorphism resulted in increasing milk yield in early lactation period without causing a change in the milk composition. The effects of C2059T/A2584G and C3100T polymorphisms on milk yield and composition were not found significant but T allele for C3100T polymorphisms and C allele for C2059T/A2584G polymorphisms appeared to have a tendency in increasing milk yield.In conclusion, the effect of C1180T polymorphism on milk yield was found significant in early lactation period (P<0.05). The association between C1180T polymorphism and milk yield suggests that C1180T polymorphism might be a useful marker for genotypic selection such as marker assisted selection. Selection of T allele for C1180T polymorphism could provide considerable economic advantage for increasing milk yield.