Effect of β-casein, -casein and β-lactoglobulin genotypes on concentration of milk protein variants
Individual mid-lactation milk samples were collected from 116 cows of the Swedish Red and Swedish Holstein breeds with known genotypes of β-casein, -casein and β-lactoglobulin. Detailed milk protein composition and allele-specific expression of β-casein, -casein and β-lactoglobulin proteins in milk were analysed using reversed-phase high-performance liquid chromatography. Aggregate β-/-casein genotype was significantly associated with the -casein concentration in milk. The lowest -casein concentration was found in milk of cows with genotypes including -casein E (A1A2/AE, A1A1/AE) and also A2A2/AA milk, whereas highest levels were associated with genotypes including -casein B. Casein number was positively and concentration of β-lactoglobulin negatively associated with the β-lactoglobulin BB genotype. In heterozygote cows, β-casein A1 and β-lactoglobulin A proteins were found at higher concentrations in milk compared with the protein variant encoded by the alternative allele at these loci, whereas -casein A and B variants were found at similar concentrations in heterozygote AB cows.
Document Type: Research Article
Affiliations: 1: Department of Food Science, Swedish University of Agricultural Sciences, Box 7051, 750 07 Uppsala, Sweden 2: Department of Animal Breeding & Genetics, Swedish University of Agricultural Sciences, Box 7023, 750 07 Uppsala, Sweden
Publication date: April 1, 2008