Characteristics of population genetic and breeding parameters of the traits of milk productivity of black-and-white and Holstein cows of the Republic of Kazakhstan
Authors: Kharzhau A. , Shamshidin A. , Sermyagin A. , Zhumanov K. 
Published: January 2022

Purpose: determination of the selection and genetic parameters of the daily milk productivity of black-and-white and Holstein cows to characterize the population.

Materials and methods. The studies were carried out using a database formed on the basis of the information and analytical management system of animal husbandry in the Republic of Kazakhstan (RK) for daily control milking of Holstein and black-and-white cows. The sample included indicators of milk productivity for three lactations of animals bred in 43 herds: I lactation - 14 482 records (3130 cows and 391 bull fathers), II lactation - 13 656 records (2734 cows and 537 bull fathers), III lactation - 4,911 records (886 cows and 260 bull fathers).

Results. Phenotypic variability indices (CvP) by lactation varied: daily milk yield - 34.1 ... 38.8%, MJ - 9.8 ... 11.6%, BMD - 6.7 ... 8.6%, SCS - 32.5 ... 37.8%. The additive genetic variability (CvA) was lower and ranged for: daily milk yield - 22.9 ... 27.0%, MJ - 3.8 ... 4.7%, BMD - 2.6 ... 3.1%, SCS - 13 , 8 ... 14.7%. The heritability of indicators of milk productivity on average for three lactations was: in terms of milk yield - h2 = 0.440, percentage of fat - h2 = 0.155, percentage of protein - h2 = 0.121, SCS - h2 = 0.161. Evaluation of the dynamics of changes in daily milk yield and SCS showed the standard nature of the shape of lactation curves with the values ​​of the determination coefficient of the phenotypic trend equation, respectively, R2 = 69.9 ... 86.4% and R2 = 11.8 ... 20.5%. An increase in the number of recorded days of control milking from 1 to 10 increased the accuracy of the forecast of the breeding value (EBV) of animals for signs of milk production by 1.7-2.4 times. Evaluation of cows by their own productivity for milk yield with optimal values ​​of forecast reliability over 70% can be carried out on the basis of 4 control milking units. At the same time, for the percentage of fat and protein, SCS, the number of observations to achieve reliable EBV results ranged from 8 to 10. Based on the average values ​​of the breeding value of cows, the population genetic characteristics of the farmed cattle in the Republic of Kazakhstan were determined in the context of breeds, country and region (population) origin. Holstein animals (+54.3 kg of milk) were characterized by the highest EBV values. Among imported cows, the best breeding value forecast was obtained for cows imported from Germany (+63.3 kg of milk). For the Kazakh population of cattle, leading positions in terms of genetic prognosis were achieved in East Kazakhstan region (KZF, +334.4 kg of milk). A principal component analysis based on an assessment of the breeding value of cows showed clear differentiation by breed level, country and region of origin of the livestock. The most significant differences were found for animals originated in the Kostanay region (KZP).

Conclusion. Analysis of the results of population-genetic and breeding parameters of the characteristics of milk productivity of black-and-white and Holstein cattle showed that there are necessary prerequisites for the development of their own breeding base, increasing the efficiency of selection of animals for breeding groups.