Breeding and genetic parameters of signs of own productivity of sires in different age periods

Abstract

Based on the calculation of the selection and genetic parameters of the main indicators of sperm production of Holstein bulls in different age periods, an assessment of their own productivity under the influence of various factors was carried out. The factors "year" and "year of birth" have a significant effect on the volume of ejaculate (n=2.4-4.0%***), the total number of spermatozoa in the ejaculate (?=3.7-2.8%***), the concentration of spermatozoa (?=1.4-2.4%***). The factor "age of the bull" also significantly affects the quantitative indicators of sperm production. There are significant differences in the volume of ejaculate (P?0.001, R²=0.93), the total number of spermatozoa (P?0.001, R²=0.85). The concentration of spermatozoa in 1 ml decreases with age (R²=0.63), at the age of 1-2 years, the indicator value is higher than in all other age periods up to 12 years (P?0.001). The volume of ejaculate and the concentration of spermatozoa had relatively high heritability coefficients – 0.51 and 0.65, respectively. The genetic and phenotypic correlations between the volume and the number of spermatozoa of 0.68 and 0.52 are determined by the average relationship. In all age periods, the relationship between the indicators of the own productivity of producing bulls was mainly linear. A significantly high correlation between the volume and the number of sperms in the ejaculate was at the level of +0.59(P?0.001)...+0.66 (P?0.001); between the number and concentration of sperms at the level of +0.31(P?0.001)...+0.49 (P?0.001) in all age periods.