Genetic characterisation of CSN2 gene in Girgentana goat breed

Abstract

Among the calcium sensitive caseins, the B-casein is the most abundant in milk, representing up to 50% of total casein content. The goat B-casein locus has been widely investigated and at least ten alleles have been identified in different goat breeds. The aim of this work was to investigate the genetic polymorphisms of the B-casein gene in the Girgentana dairy goat breed, in order to assess the genotype distribution and to evaluate how the frequencies have changed during the last 10 years, as it is known genotype influences technological and nutritional milk properties. Sequencing analysis and alignment of the obtained sequences of B-casein exon 7, showed the presence of A, C, and C1 strong alleles, and 0' null allele, with frequencies of 0.597, 0.326, 0.023, and 0.054, respectively. Seven genotypic classes were found in Girgentana goat breed and the most frequent genotype was CC1 (0.423) followed by CC (0.327), C1C1 (0.107), and C0' (0.097). No AA and 0'0' homozygous individuals were found. The presence of strong alleles at CSN2 gene in Girgentana goat breed could be useful for the production of milk with high protein content and good cheese-making properties. Moreover, food business operators should consider the possibility of reviving interest in Girgentana goat milk using weak and null genotypes at CSN2 locus to make peculiar food products, such as drinking milk.