## 2 Materials and Methods  
### Farm, Microclimate and Animals Health Status  
The research was carried out in October-November 2021 in 2 stages:  
Stage 1 included measuring milk yield and udder surface skin temperature in a large group of healthy animals and classifying them according to the main features (lactation stage, average single milk yield, udder surface temperature). The selection of animals for research was carried out from one room, where the total number of kept cows is 250 heads of Yaroslavl breed. In total, the farm has a total livestock of 560 forage cows. The farm is located in the Yaroslavl region (Central Russia). The climate of Yaroslavl farm (location 57.701, 40.019) is temperate continental with short, relatively warm summers, long, moderately cold winters, and distinct spring and autumn seasons. The average monthly temperature of the coldest month of the year-January--varies from \(-10.5\)\({}^{\circ}\)C to \(-12\)\({}^{\circ}\)C, and the warmest-July--from +17.5 \({}^{\circ}\)C to +18.5 \({}^{\circ}\)C. The total amount of precipitation is 500-600 mm per year, with 70% of it during the growing season and about 30% in winter. When selecting the studied animals, only animals of the same breed were chosen. The breed of dairy cows was \"Purebred\" with the presence of animals of the \"4 th\" generation. The breed purity is 85% or more. The udder is cup-shaped, without abundant hair formation. The nipples are predominantly directly weighing, even and approximately cylindrical in shape. The shape of the teats provides the most efficient way to secure the teat cups to the cow's teats and eliminate the falsification of research data. All of the selected animals had strong sustainable lactation activity. In order to correctly compare two animals from different groups, it is necessary to take into account that the productivity of the two compared animals in a healthy state did not differ from each other by more than 5%. The body condition of the animals (body score condition) was in the range of 3-3.5 points and their weight were 500-550 kg. They were in their 3-4 th lactation and they had been on 5-6 th months of lactation, and the average service period on the farm was 137 days. The diet of cows on the farm (their weight is 500-550 kg) is as follows: 34 kg of feed per day, crude protein 1.45 kg, crude fiber 4.2 kg. One-time average milk yields of 9.5 kg, milk fat content 4-4.2%, protein 3.5-3.7%, the number of somatic cells up to 160,000 for healthy animals. The way of keeping was tethered. Feeding was done from the feed table. The water temperature for drinking was 15 \({}^{\circ}\)C. Animals were walked once a day from 12:00 to 16:00 in the walking yard. At this time, the premises were completely ventilated and cleaned, the bedding changed, and the water in the drinking bowls replaced. Morning milking was carried out from 5:00 to 8:00 a.m. Evening milking from 17:00 to 19:00. In the morning from 3:00 to 5:00 the cowhold was ventilated and cleaned. We used Testo 400 device and the corresponding probes in a 50 cm radius around the cows for the air velocity estimation. It was established that the concentration of the gaseous medium was normal and complied with the Russian veterinary requirements. The speed of air movement near the cow did not exceed 1 m/s. During the research, the temperature inside the cowhold ranged from 2 to 6 \({}^{\circ}\)C. During the research, the concentration of gases did not exceed the norms. Illumination was 50-75 lux. We made tests for mastitis for 250 selected animals to confirm the status of \"healthy\", then all animals underwent 4 control milikings within 2 days to determine the average single milk yield, and thermograms were made to determine udder health. At the second stage, 30 days later, knowing that on average 4-7% of animals get mastitis of varying severity within a month, we checked the herd again. At the end of the month, 12 animals were identified by veterinarians as sick and they were retested to confirm the presence of mastitis.