HYGIENIC ASSESSMENT OF DAIRY COWS UNDER TIE-STALL HOUSING

In modern dairy farming, the microclimate parameters of livestock premises are considered one of the leading factors determining the physiological state, productivity and welfare of dairy cows. Air temperature, relative humidity, speed of its movement and concentration of harmful gases form a thermoregulatory load on the animal body and directly affect feed consumption, milk production, immune status and reproductive function. According to modern research, deviation of microclimate parameters from the thermoneutral zone causes heat or cold stress, which is accompanied by a decrease in milk yield, a change in the composition of milk and an increase in morbidity. The problem becomes particularly relevant in conditions of tethered and stalled housing, where the motor activity of cows is limited, and the animals are in direct contact with the litter and the stall microclimate for a long time. In such systems, it is the parameters of the air environment and the sanitary condition of the stalls that determine the level of body contamination, udder cleanliness and the risk of mastitis, which is considered an effective indicator of welfare outcome. Modern climate changes and the tendency to increase the ambient temperature lead to an increase in the frequency of heat stress in cowsheds, which requires systematic monitoring of the microclimate and assessment of its impact on the productivity and health of cows. The paper investigates the parameters of the microclimate of the premises for keeping dairy cows in different seasons of the year and their impact on the hygienic condition of the animals. A pronounced seasonal variability of temperature, humidity, air velocity and gas composition of the cowshed air with deviations from the standards of NTP-APK 01.05, most significant in the winter and summer periods, was established. In the winter period, the air temperature was 2±1 °C with increased concentrations of NH₃ and CO₂, which indicates insufficient efficiency of the ventilation system. In summer, the temperature reached a maximum value of +32 °C, forming a risk of heat stress, while the gas composition of the air improved. In the autumn-spring period, according to the results of the multi-zone assessment of cleanliness, 83% of cows had 3 points and 17% - 4 points, the hygiene assessment index was 3.17 points, which corresponds to an unsatisfactory sanitary condition. In the summer period, the index decreased to 2.88 points, which indicates a relative improvement in animal hygiene. It was established that the deterioration of microclimate parameters is accompanied by an increase in the contamination of the cows' bodies and microbial contamination of the air. The results obtained confirm the decisive role of the indoor microclimate in the formation of the hygienic status of the dairy herd and the need to optimize ventilation systems, manure removal and management of maintenance.