Effects of Holsteinization on Productive Lifespan of Black-and-White Cows in Smolensk Oblast

Abstract

The aspects of Black-and-White holsteinized cow’s productive lifespan were the objectives of the survey carried out with 9270 Black-and-White cows and their crosses with Holstein bulls that were culled in 1990–2020 for different reasons at the end of their productive lifespan. The survey was performed based on pedigree and commercial cattle farms in Smolensk oblast with the grouping method. Phenotypic correlations between the analyzed production traits were estimated. Holsteinization of the Black-and-White breed in the Smolensk oblast resulted in its absorption through crossing the cows with Holstein sires to have a Holstein blood percentage of 90.0%. The survey outcomes have revealed a regularity indicating that the higher the percentage of Holstein blood is, the shorter longevity of cows is observed. The difference in lifespan of cows with Holstein blood percentage from 17.6 to 87.1% comprised 4.36 lactation cycles. The productive lifespan of cows can reach 12–13 lactation cycles. However, 50.9% of these animals are culled between the second and fourth lactation cycles. The ratio of days in milk to days dry in dairy cows tends to change with aging. Thus, the longer the productive lifespan in cows is, the higher the number of days in milk per each year of life, on average, is recorded. The major proportion of cows is productive within the ratio of days in milk to lifetime days, varying in the range of 50.1 to 75.0%. Their lifespan is measured by 4.3 lactation cycles. The lifetime milk yield usually varies from 10 000 to 30 000 kg (for 56.7% of the analyzed livestock). The parameter for lifetime daily yield is reasonable to use as an indicator of cow productive lifespan due to its strong positive correlations (r = 0.44–0.90) relative to age-related and productivity performance. The Black-and-White cattle inventory in the Smolensk oblast has proven that it is reasonable to replace this breed with the Holstein breed for its subsequent pure breeding.