INFLUENZA DEL POLIMORFISMO GENETICO DELLE FRAZIONI CASEINICHE E DELLA BETA-LATTOGLOBULINA SULLA PRODUZIONE QUANTI-QUALITATIVA DI LATTE DI BOVINE DI RAZZA FRISONA

Individual milk samples of 56 Fresian cows were subjected to electroforetic analysis by isoelectro focusing to determine the genetic polymorphism of some casein fractions (as1, b and k) and b-lactoglobulin. As regards as1 fraction, only BB genotype was detected; about b-Cn more diffuse genotype is A1A2 (57%), as regard k-Cn a higher diffusion of A allel makes this milk more suitable for direct consumption than for cheesemaking; at last, genotype AA of b-Lg has the highest presence (55%). Comparing the observed genetic frequencies with the ones expected, the tested population results in Hardy Weinberg equilibrium. Genotypes b-Cn A2B and k-Cn BB are related to higher percentage of fat and protein, while milk production is positively connected with b-Cn A2B genotype