Alpha S1-casein genetic variations in Bulgarian sheep breeds and significance on milk casein fractions

Deyana Gencheva, Darina Pamukova, Nikolina Naydenova, Petya Veleva and Milena Tzanova

Abstract: Single nucleotide polymorphism (SNP) of the exon III at CSN1S1 gene encoding alpha S1-casein (αS1-CN) was investigated by means of the PCR-RFLP analysis in two sheep breeds – Bulgarian Dairy Synthetic Population (BDSP, n = 89) and Pleven Blackhead sheep (PLBH, n = 38) with an aim to establish the possible effect of a particular genotype on the casein content and distribution of milk fractions. The homozygous CC genotype was observed in 63.2% of the studied ewes, while the homozygous AA genotype was established in 4.5 % of the individuals. The calculated mean values of observed (Hо = 0.323) and expected (He = 0.321) heterozygosity at CSN1S1 locus indicated a moderate degree of genetic variability in the examined sheep populations. The estimated negative values of the coefficient (Fis = –0.001 ÷ –0.006) showed a low level of inbreeding.The results of the associative analysis indicated that CSN1S1 genotypes were significantly associated with the milk αS1-CN in the BDSP 2 population (P < 0.05). The highest casein percentage in this population (35.24 ± 3.96) was associated with ewes carrying the heterozygous AC genotype. No significant differences (P > 0.05) were established for CSN1S1 genotypes in terms of casein content in the studied PLBH sheep population.

Keywords: caseins; CSN1S1gene; PCR-RFLP; sheep milk; SNP

Date published: 2022-06-16