Аңдатпа
This research work compares the physiological and morphological characteristics of different genotypes and selection groups of Holsteins in summer and winter. The main objective of the study was to determine the physiological parameters of different genotypes, such as the time of rest, activity of rest and movement, and indicators of the development of the coat, and to study their interseasonal differences. The results of the study showed that for all genotypes, the time of rest was most active in the second half of the night and increased with age. For example, in purebred black-and-white cows of group I, the time of rest was 7.5 minutes, in Holstein cows of group II – 11.5 minutes, in group III – 10.1 minutes, in groups IV and V – 11.5 and 9.9 minutes. In addition, the activity of rest and movement of animals varied depending on the season. In summer, animals moved a lot in a short time, while in winter their rest time was longer. Cows in groups II and III had a higher resting time, and their duration was higher both in summer and winter. In particular, in summer they rested for a shorter time, and in winter for a longer time. The development indicators of the hair coat also changed depending on the season. In winter, the volume, length and thickness of the hair increased in all genotypes, which indicated good thermal insulation properties. In summer, the mass, length and thickness of the hair decreased, which indicated the effect of seasonal changes. The hair coat indicators of purebred black-and-white cows and Holsteins of foreign selection were higher, which confirms the observed selection effect. In general, the results of the study provide important information in assessing the physiological characteristics of different genotypes. They allow increasing productivity in the field of animal husbandry by correctly selecting genotypes and selection groups. In addition, they contribute to the development of practical recommendations for the correct assessment and effective use of livestock, taking into account inter-seasonal differences.