Creation of comfortable conditions for dairy cow housing ensures maximum realisation of their productive genetic potential; the temperature and the relative (absolute) humidity of the air are of primary importance in this respect. Russian and foreign researchers have established that temperature fluctuations in the range of +10 to +22 ºС and relative air humidity in the range of 50 to 90 % do not have any adverse effect on productivity of animals. According to Russian standards, the minimum inside air temperature should be from + 3 ºC to +10 ºC, with the relative humidity being 40 to 85 % depending on the animal housing technology. Our study showed that in winter in the barn with tied housing of dairy cows, the air temperature varied from +3.5 ºC to +12.3 ºC, with the outside air temperature being from-4.6 ºC to-10.5 ºC. An uneven distribution of air temperature across the barn was registered, with the difference reaching 5 to 7 ºC in some cases. This indicates an uneven and insufficient thermal insulation of the premises. The absolute air humidity in the barn was 5.42 to 9.98 g•m-3 and was also distributed unevenly, depending on the absolute humidity of the outside air, which was 1.46 to 3.28 g•m-3 , and the wind direction, which created additional conditions for active ventilation of the premises. To identify the conditions causing stress in animals, the Thermal Humidity Index was applied; its values were in the range of 45.6 to 57.8, with the recommended values being 65-68. So the housing conditions of cows were considered normal. The study results were used to create Excel graphical and regression models of temperature and humidity conditions and THI in the barn, depending on variation of external weather conditions, with the coefficient of determination R 2 being from 0.915 to 0.969.

Prolonged exposure of human and animal organisms to carbon dioxide can cause chronic poisoning, various diseases, and reduction in productivity. The normative permitted content of carbon dioxide in the indoor air of cattle premises is 0.25 %. Carbon dioxide emission from cattle manure when removed by a scraper-chain conveyor was studied in a typical barn for 200 head with the tied housing system, natural ventilation and 11 t•d-1 manure output. The study included continuous measurements of carbon dioxide concentration before, during and after manure removal. In the experiment, CO 2 concentration was measured just above the manure canal and in the opposite ends of the barn-near the milk collecting unit and manure accumulation tank with the unloading conveyor. For study purposes IEEP designed a mobile unit for microclimate monitoring. The study revealed that during manure removal, which lasted for 15-17 minutes, the CO 2 concentration increased 1.3 to 1.5 times in different parts of the barn. When manure removal was completed, the concentration of carbon dioxide decreased and after 6 to 10 minutes, returned to initial values. This short-term increase in CO 2 concentration, even in case the permissible values were slightly exceeded, was not dangerous for the animal care personnel and had no adverse effect on animals and their productivity. The study revealed the dependences of CO 2 emissions; relevant mathematical models were created.

One of the factors contributing to higher milk productivity and good health of cows is sufficient and reliable round-the-clock water supply. Scarce water consumption leads to irreversible processes in the animal body, up to its death. The aim of this study was to measure the drinking water consumption in the loose housing system of cows with consideration of the time of day, the milk yield and the indoor barn climate. The study was conducted in August-November 2019 in a cow barn with the loose housing system. The inside climate was maintained by a natural ventilation system through the light ridge on the roof and by adjustable systemsinflatable membranes on the windows and air blowers installed inside the barn. The group of animals consisted of 80 Holstein cows with the productivity of 10 000 to 12 000 kg of milk per head per lactation period. During the study, the average drinking water consumption was 1.99 ± 0.26 l•l -1 of milk. Near the waterers, the air temperature ranged from + 2.7 ºС to + 20.8 ºС, with the relative humidity being 78.4-100 %. The maximum average water consumption of 6.5 l•head -1 •hour -1 was registered after the evening milking, the minimum of 0.8 l•head -1 •hour -1 was observed during the morning feeding. The water consumption increased in the first hour after the afternoon and evening milkings by 40-45 % that was associated with the water balance restoration in the animals' body. The study revealed the dependences of the drinking water consumption on the milk yield and the temperature and humidity conditions in the barn; graphical and mathematical models were constructed. This study is required to create a comprehensive model for the optimal drinking water supply of cows on dairy farms under reasonable energy and water inputs.

The great concern of scientists is the rise in the average temperature of the Earth's atmosphere associated with the greenhouse effect caused by higher concentration of some gases, carbon dioxide included. Animals and their wastes are one of the carbon dioxide sources. Annually there is the growing need in livestock products. This leads to a bigger number of farm animals and consequent higher carbon dioxide emissions into the environment. Theoretical and experimental studies of 2015-2021 at the premises of the Institute for Engineering and Environmental Problems in Agricultural Production and agricultural enterprises in the Leningrad Region of the Russian Federation were aimed at identifying the main sources, intensity and patterns of carbon dioxide emissions in dairy cow barns with due account for the effect of animal housing conditions. The main carbon dioxide sources on a cattle dairy farm are the air exhaled by animals and manure. From the study results, a dairy cow exhales from 4.5 to 8.5 kg of carbon dioxide per day depending on its productivity and mass. The carbon dioxide emission from manure accumulated in a barn is below 1 % of the carbon dioxide exhaled by animals. Modern innovative technologies allow for more efficient use of genetic potential of animals and reduce the negative impact on the environment. The revealed patterns and modelling of carbon dioxide emissions showed that with an increase in cow milk yield from 10 to 30 kg/day, the carbon dioxide emission per 1 kg of milk can decrease 2.3 to 2.5 times.