Allele and genotype frequencies of β-lactoglobulin gene using PCR-RFLP in Algerian local cattle populations.

Milk protein genetic polymorphisms are associated with economically important traits in dairy cattle. The objective of this study is to genotype a single nucleotide polymorphism (SNP) responsible for the amino acid changes in the beta-lactoglobulin (β-Lg) variants A and B on 85 unrelated DNA representing Algerian cattle populations: Chelifienne (28), Cheurfa (31) and Guelmoise (26). The method used is the PCR-RFLP (Polymerase Chain Reaction-Restriction Fragment Length Polymorphism). Genetic polymorphism was detected by digestion of PCR products amplified of exon II of β-Lg gene by with the endonuclease HaeIII enzyme. The results revealed that the amplified product was observed as 247 bp. Restriction digestion with HaeIII revealed three genotypes: AA, AB and BB. The genotypic frequencies of AA, AB and BB genotypes were 0.08, 0.41, 0.50; 0.08, 0.41, 0.50 and 0.01, 0.19, 0.56 in Chelifienne, Cheurfa and Guelmoise and respectively. Frequency of AA genotype was absent in Guelmoise population. Frequencies of A and B alleles were 0.29 and 0.71 in both Chelifienne and Cheurfa and 0.25 and 0.75 Guelmoise population. These results further confirm that Bos torus cattle are predominantly of β-Lactoglobulin B type. The Chi-square test at p-value < 0.05 results revealed that the Chelifienne and Cheurfa populations were in Hardy-Weinberg equilibrium and the results are not significant for the Guelmoise. This genetic information could be useful to estimate the effect of polymorphism on different milk production of Algerian bovine populations.