Prediction of fecundity of livestock by the level of adaptability in the ecological and climatic conditions of the Southern Urals

Abstract

Abstract The article presents the results of studies on the natural resistance of castrated bull calves of Simmental breed in the Southern Urals and half-blood Holstein crossbreeds. The aim of the present study was to determine the adaptability of purebred and cross-breeding animals to a sharply continental climate when keeping them in an open feeding area. Assessment of the body’s response to the influence of negative air temperatures was carried out according to the indicators of the natural resistance of the humoral and cellular parts of the immune system and hair condition – regularity of its shift, length, density and fractional composition. Significant differences in the determined indicators were revealed both depending on the genotype and on the season of the year. Simmentals exceeded their cross-breed peers in hair density from 1 cm2 of skin, weight, and hair length. These differences are most pronounced in winter. Assessment of the humoral link of natural resistance showed significant intergroup differences. Simmental bull calves exceeded cross-breed peers in bactericidal blood activity depending on the season of the year by 1.28–2.87 %, in terms of lysozyme content – by 2.9–7.1 %. Intergroup differences were also revealed in the assessment of cellular factors of natural resistance. In spring, the activity of neutrophils increased in comparison with autumn and winter months in Simmental bull calves 6.4 and 7.3 times. The highest value of the phagocytic index was noted in winter period – 11.4–11.9 %. In summer, it decreases slightly. Intergroup differences in these indicators are slightly expressed.