Milk composition traits in Jamunapari goats: Genetic parameters and effect of CSN1S1 gene variants

Milk protein polymorphism was analysed to improve the protein content in milk. The present study characterises the CSN1S1 gene and the effect of allelic combinations on milk composition traits in Jamunapari goats. The allelic variants obtained from sodium dodecyl sulfate polyacrylamide gel electrophoresis and polymerase chain reaction-restriction fragment length polymorphism were confirmed by cloning and sequencing. Genetic parameters were obtained from 518 records from 48 sires and 131 dams. The A, B and F alleles were observed in the population and the protein percentage in milk was significantly (P < 0.01) affected by allelic variants. The frequencies of A, B and F alleles were 0.456, 0.503 and 0.041, respectively. The protein content in milk was highest in the goats with AB genotype followed by AA > BB > BF > AF > FF. The goats with AB genotype had a significantly (P < 0.01) higher protein percentage in milk than goats with BF (t = 5.311, df = 113), AF (t = 8.13, df = 123) and FF (t = 9.55, df = 115) genotypes. The direct heritability for protein percentage was 0.441. Parity and season of birth had significant effects (P < 0.05) on the solids-not-fat percentage and lactose concentrations. The CSN1S1 AA, AB and BB genotypes should be selected for higher protein content and to improve milk quality and processing traits in Indian goats.