Features of herd formation based on betaand kappa-casein of different dairy cattle breeds

Abstract

In dairy cattle breeding, much attention is paid to indicators of the milk quality and technological properties. These indicators are significantly influenced by milk proteins. Therefore, the goal of our research is to evaluate the effectiveness of creating dairy herds of domestic dairy cattle breeds that are characterized by the desired beta- and kappa-casein genotypes. To fulfill these tasks, the genotyping of cows of the Ukrainian Brown dairy, Sumy intrabreed type of the Ukrainian Black-and-White dairy, Simmental and Lebedyn breeds was carried out. The beta- and kappa-casein gene polymorphism was determined in the genetic laboratory of the Bogomoletz Institute of Physiology of the National Academy of Sciences of Ukraine using real-time molecular biological analysis of allele recognition by polymerase chain reaction (PCR). As a result of the conducted studies, it is found that cattle of Lebedyn and Ukrainian Brown dairy breeds have a higher frequency of the desired kappa-casein BB genotype. As a result, they are also characterized by a higher frequency of the B allele. More than 50 % of cattle of Simmental breed have a heterozygous AB genotype. Cattle of the Sumy intrabreed type of the Ukrainian Black-and-White dairy breed have a higher frequency of the homozygous AA genotype and the A allele. Cattle of the Ukrainian Brown dairy breed are characterized by the highest frequency of the A2A2 genotype and the A2 allele of beta-casein. Cattle of the Simmental breed, which are also characterized by the highest frequency of the A1A2 heterozygous genotype, have a slightly lower frequency. Homozygous A1A1genotype is more common in cattle of the Sumy intrabreed type of the Ukrainian Black-and-White dairy breed. Using the principles of the model for creating a herd with the desired genotype, which is proposed by Mencarini IR et all, it is found that when testing the entire breeding stock, inseminating it with semen of homozygous stud bulls with the A2A2 genotype, random cow disposal at the level of 22 %, it takes 9–10 years to create herds with the desired genotypes of the Ukrainian Brown dairy, Simmental and Lebedyn breeds, respectively. To reduce the period for creating herds, it is essential to increase the percentage of cow disposal and simultaneously disposecattle with undesirable genotypes. Key words: genotype, casein, stud bull, breeding, allele.