Оценка типа стрессоустойчивости коров-матерей и их потомков

Abstract

Abstract. Resistance to stress in cows depends on factors such as age, gender, fatness, body type and heredity. The effects of long-term stress factors on the dairy herd cause hard-to-recover damage during production. The purpose of our research was to assess the types of stress resistance of mother cows and their offspring. Methods. The stress tolerance index of the studied animals was calculated according to the method of N. A. Safiullin and others. This method includes the impact on animals during machine milking of a stress factor and changes in milk production indicators, determining the stress resistance indicator of cows by the average value of the sum of estimated indicators: the ratio of 1 % milk, changes in the intensity and completeness of milk production, the duration of the latent milking period. Results. It was found that the most stress-resistant animals were less productive (8000 kg and less for maximum lactation). The stress tolerance index in the mother cows of this group is on average 0.137 (p < 0.001) higher than in other animals evaluated. At the same time, their descendants also had a stress tolerance index higher than in other evaluated groups by an average of 0.041 (p < 0.01). A high type of stress tolerance was determined in 75.0 % of heads in the group of cows-mothers with the lowest productivity for maximum lactation. Slightly less animals with a high type of stress resistance in the group of their descendants – 33.0 % of heads. At the same time, in these groups of mothers and daughters, cows with a low type of stress resistance were not found at all. Repeatability coefficients indicate that in low-yielding mother cows, the stress tolerance index is repeated in groups of daughter cows to a much lesser extent (at r = 0.26) compared to groups of high-yielding cows. The scientific novelty lies in the fact that the indicators of stress resistance of cows and their offspring are established depending on the highest productivity of mothers.