Formation of economically useful traits in cows of ukrainian black-and-white dairy breed of different genotypes by kappa-casein
Authors: Ladyka V. , Pavlenko Y. , Sklyarenko Y. , Drevytska T. , Dosenko V. 
Published: October 2022

The influence of kappa casein genotype on the formation of economically useful traits of Ukrainian black-and-white dairy cattle has been studied. Genotyping of 25 heads of cattle of the Ukrainian black-and white dairy breed belonging to the Breeding Plant of the State Enterprise "Research Farm of the Institute of Agriculture of Northern East of NAAS" was carried out. Determination of polymorphism of the kappa-casein gene was performed in the genetic laboratory of the Bogomolets Institute of Physiology of NAS using molecular biological analysis of allele recognition by polymerase chain reaction (PCR) in real time. To assess the economically useful features used an electronic database of SUMS "Orsek". The content of milk components was determined in the laboratory of Sumy National Agrarian University on the equipment Ultrasonic milk analyzer Master Classic. It was found that the animals met the breed standard in almost all indicators of milk productivity. Between animals of different genotypes the difference on separate economically useful signs is revealed. However, in different periods and on different grounds, it varied greatly, and in some cases it was statistically significant. The genotype for kappa-casein did not have a significant effect on live weight in all study periods. Animals with the AA genotype predominated on this trait of animals of other genotypes. At the same time, animals of all studied genotypes in almost all age periods exceeded the breed standard. According to the results of the assessment of the reproductive capacity of animals, it was found that the youngest age of the first insemination is characteristic of animals with genotype AA, and the highest - with genotype BB. The age of first insemination in animals with genotype AA was less than the average for the herd. The live weight of these animals was the largest and was higher than the average for the herd. The average duration of the service period for the herd was 130 days. It was lowest in animals with homozygous BB genotype (P <0.05). Accordingly, the duration of the period between calving and the value of the reproductive capacity were the lowest in homozygous (BB) animals (P <0.05). The level of average milk yield of an animal with the desired genotype (BB) was lower than the average yield of animals with other studied genotypes. They were also inferior to the average indicator of the herd. The level of milk yield of animals of all genotypes was higher than the breed standard. It was found that the average fat content in the milk of animals of homozygous genotypes AA and BB slightly prevailed over animals with heterozygous genotype AB. Animals with the BB genotype (p <0.05) were statistically significantly superior in protein content. Compliance with the breed standard in terms of fat content in milk is positive, and only homozygous (BB) animals met the standard in terms of protein content. In terms of dry matter content, dry nonfat milk residue, casein, animals with homozygous BB genotype were preferred. In terms of lactose content, animals with the AA genotype were preferred. It is proved that the formation of herds with BB genotype for kappa-casein will not have a negative impact on the economically useful characteristics of animals. Key words: genotype, kappa-casein, live weight, reproductive capacity, milk productivity.