[Detection of the kappa-casein genotype in bulls using restriction fragment length polymorphisms]

Genetic analysis of RFLP was used for detection of genotype and allele frequencies of kappa-casein in Slovakian Spotted (60 bulls) and Slovakian Pinzgau (22 bulls) cattle breeds, according to the method of Medrano et al. (1990). DNA was prepared from the semen of animals. In the Slovakian Spotted breed the frequencies of alleles were as follows: kappa-CnA = 0.666, kappa-CnB = 0.333. The frequencies of kappa-Cn A/A, A/B and B/B genotypes were 45.00, 43.33 and 11.66, respectively. In the 22 tested Pinzgau bulls, the frequencies of the A and B alleles were 0.682 and 0.318, respectively. The percentual occurrence of genotypes was also determined: 54.54 (kappa-Cn A/A), 27.27 (kappa-Cn A/B) and 18.18 (kappa-Cn B/B). Comparing our own results with those of Mácha et al. (1968), who carried out the analysis of distribution of the kappa-casein genetic variants in the same cattle breeds by starch gel electrophoresis of the milk samples of 170 cows (Tab. I), the 16 p.c. decrease of the allele B in the Slovakian Spotted cattle, lasting about 30 years, is very remarkable. The occurrence of homozygous genotype BB decreased by 35 p.c. In addition, the homozygous genotype AA increased by about 18 p.c. and the occurrence of heterozygous genotype is also higher by nearly 17 p.c. In the same comparison of the Slovakian Pinzgau breed, no difference was estimated in the allele frequencies of kappa-Cn (Tab. I).(ABSTRACT TRUNCATED AT 250 WORDS)