This study was undertaken for genetic polymorphisms of bovine milk proteins for 17 randomly selected young bulls which were produced with a view to progeny test in Korea. Semen samples form voung bulls were collected and analyzed by PCR-RFLP procedures. Genetic effects of milk proteins on production traits were also studied using daughter records from young bulls. The results obtained were as follows : 1. Amplified products of 310bp(as]-casein), 396bp(a,2-casein), 498bp(P-casein), 874bp( K-casein), 583bp( a-lactalbumin), and 961bp (P-lactoglobulin) were observed using the PCR procedure. 2. Amplified products were digested with Mae III(oc,,-casein), Mnl I( as,-casein), Hind III( K-casein), Msp I(a-lactalbumin), and Hph I ( p-lactoglobulin). 3. After digestion, cx ,-casein was detected by 214bp and 96bp for BB genotype, while a s,-casein was shown by 272bp and 124bp for AA genotype. Both K-casein and a-lactalbumin were characterized by 498bp, 259bp, 393bp, and 190bp for BB genotypes, respectively. 4. After PCR amplification with restriction enzymes, 11AA and 6AB genotypes for K-casein, 9AB and 8BB genotypes for p-lactoglobulin, as well as 1211 and 5ID genotypes for growth hormone were observed. 5. Genetic differences among genotypes (K-casein, p-LG, bGH) for production traits studied were significant. 6. When daughter yields were grouped by AA and AB genotypes of K-casein, means and standard deviations for all the traits studied, except milk fat percent, showed remarkable differences. Keywords : Milk protein, Genotypic effects, Young dairy bulls

K. J Lee, M. S Kang, Y. K Lee, K. W Chang

Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume 26: Quantitative genetic theory; selection theory and experiments; internationalisation of breeding programs; detection of quant, , 377–380, 1998
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