Bovine beta-lactoglobulin (β-LG) and kappa-casein (κ-CN) genic variants are associated with productivity, quality and processing features of milk. The objective of this study was to analyze through the PCR-RFLP technique, the frequency of AA, AB and BB genotypes of bovine β-LG and κ-CN, and their association to milk production (kg milk/day) in Girolanda, Holstein and Jersey cattle. For κ-CN, the frequency of the AA genotype was higher in Holstein (37%) and Girolanda (63%), while there was a predominance of the BB genotype in Jersey (60%). For β-LG, the BB genotype was the most found in Girolanda (54%) and Holstein (58%), while there was a predominance of the BB genotype (45%) in Jersey. There was a positive association between B allele of κ-CN and milk production in the Girolanda and Holstein cattle and between A allele of β-LG and milk production in the Jersey cattle. Genetic variants of κ-CN could be used as markers for the selection for productivity in Girolanda and Holstein cattle. The genetic variants of β-LG would be more appropriate for this selection in the Jersey breed.
milk; whey proteins; caseins; frequency of genotypes
