SEPARATION AND GENE FREQUENCIES OF BLOOD SERUM TRANSFERRIN, CASEIN AND BETA-LACTOGLOBULIN LOCI OF DAIRY CATTLE AND THEIR EFFECTS ON CERTAIN PRODUCTION TRAITS

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Abstract
A procedure was developed for the simultaneous phenotyping of β-casein and β-lactoglobulin at acid pH. The population structure of the transferrin, αs1-casein, β-casein, κ-casein and β-lactoglobulin loci as well as their relationship with different production traits was studied for some herds of Ayrshire, Canadian, Holstein-Friesian, Jersey and Milking Shorthorn breeds representing approximately 1300 animals. The transferrin alleles, Tf A, D1, D2 and E were found in the Ayrshire and Holstein-Friesian breeds. The αs1-casein alleles A, B and C were observed; the A allele was present in the Holstein-Friesian cattle only. The A1 and A2 alleles of β-casein were found in all the breeds, while the C allele was present in the Milking Shorthorn and the A3 allele in the Holstein-Friesian breed. The B allele was absent only from the Milking Shorthorn breed. Both A and B alleles were present at the κ-casein locus in all breeds. Both β-lactoglobulin alleles A and B were observed in all breeds. Some relationships were found between the different loci (alone and in combination) and the percentage butterfat, percentage protein and percentage lactose. Differences between breeds with regard to superior genotypes were observed.