The effect of high temperatures on the technological milk properties of cows different breeds

Currently, interbreeding has become quite widely used in global dairy farming, which improves reproductive characteristics, resistance and health indicators, duration of productive use, and quality composition of milk in individuals of the first generation. The purpose of this work was to compare the qualitative composition of milk and its suitability for processing into cheese in cows of the Ukrainian red-spotted dairy breed and their crossbreeds with the Montbeliarde breed. The research was carried out at the enterprise “Azorel” LLC, Vinnytsia District, Vinnytsia Region (49°57′01″N, 28°47′09″E). The farm keeps cows of the Ukrainian red-spotted dairy breed and crossbreeds of the first generation obtained as a result of crossing with the Montbeliarde breed. Two groups of (pure-bred and cross-breed) analogue cows were formed with the number of 17 cows each in the 2nd-3rd months of lactation. Research was conducted during July 2021 during the period of high temperature load (average daily air temperature was +23.2 °C). It was established that during the study, the temperature-humidity index (THI) was in the acceptable range (70.5) during the period from 08.00 to 10.00, and 71.6–78.8 from 10.00 to 22.00, which is a sign of moderate heat stress The average daily temperature and relative humidity during these hours were 23–32 °С and 37–64 %, respectively. In general, long-term high-temperature loads became a significant stress factor, which affected both the productive characteristics of animals of both groups, as well as the syrupability and physicochemical properties of milk. The interbreeding of the Ukrainian red-spotted breed with the Montbeliarde breed had a positive effect on the indicators of nutrients in milk, such as the content of fat, protein, lactose, as well as on the suitability of milk for processing into cheese. Local first-born cows had higher indicators of the theoretically possible output of rennet cheese and the energy value of milk. In addition, milk samples from crossbreeds were characterized by a shorter coagulation phase and a higher class of rennet clot characteristics.