The objective of this study was to describe the association between thermal measures in the barn environment (pen temperature and humidity) and fecal shedding of Salmonella in dairy cattle. A repeated cross-sectional study was conducted within a commercial dairy herd located in the midwestern United States. Five pooled fecal samples were collected monthly from each pen for 9 mo and submitted for microbiological culture. Negative binomial regression methods were used to test the association [incidence rate ratio (IRR)] between Salmonella pen status (the count of Salmonella-positive pools) and thermal environmental parameters [average temperature and temperature humidity index (THI)] for 3 time periods (48 h, 72 h, and 1 wk) before fecal sampling. Salmonella was cultured from 10.8% [39/360; 95% confidence interval (CI): 7.8% to 14.5%] of pooled samples. The highest proportion of positive pools occurred in August. The IRR ranged from 1.26 (95% CI: 1.15 to 1.39, THI 1 wk) to 4.5 (95% CI: 2.13 to 9.51, heat exposure 1 wk) across all thermal parameters and lag time periods measured. For example, the incidence rate of Salmonella-positive pools increased by 54% for every 5°C increment in average temperature (IRR = 1.54; 95% CI: 1.29 to 1.85) and 29% for every 5-unit increase in THI (IRR = 1.29; 95% CI: 1.16 to 1.42) during the 72 h before sampling. The incidence rate ratio for pens exposed to higher temperatures (> 25°C) was 4.5 times (95% CI: 2.13 to 9.51) the incidence rate ratio for pens exposed to temperatures < 25°C in the 72 h before sampling. Likewise, the incidence rate ratio for pens exposed to THI > 70 was 4.23 times greater (95% CI: 2.1 to 8.28) than when the THI was < 70 in the 72 h before sampling. An association was found between the thermal environment and Salmonella shedding in dairy cattle. Further research is warranted in order to fully understand the component risks associated with the summer season and increased Salmonella shedding.

During the sanitary-hygienic evaluation of livestock-rearing farm building (cow kennel and calf pens) by means of industrial and traditional technology there were revealed the infringements of constructive and exploit matter in ventilation system which proved to be the reason for formation of dissatisfactory stable climate. In case of the appropriate estimation, adherence to specification of ventilation construction and rather attentive attitude to the problem of ventilation regulation there could be obtained the positive results in optimization of air medium in animal husbandry houses. Support of air physical properties in livestock houses at the optimum hygienic level was possible only by means of ventilation and a choice of construction materials corresponding to the veterinary and hygienic requirements. The necessity of heat accumulation in livestock houses unites all mentioned above requirements. In some animal husbandry farms in the Republic of Belarus there was applied the mechanical ventilation. However, it was a great mistake to install only the air-moving device without heat exchanger installation. Therefore, an important point for optimization of microclimate livestock houses should be the determination of building thermal balance

In the pig enterprises of Belarus the most widespread sources of heat for pigs heating proved to be the infrared radiation lamps. In recent years there was stated the wide application of electric heated rugs of various designs or the electric heated floors. The special brooders, equipped with various sources of heat, passed the experimental check possibility of use for heating of pig houses. Their advantage was in decreasing of heat losses in the sleeping areas of pigs that demanded lower expenses of energy for heating of stores. However, till the present the effective brooder design, which could be convenient in use, cheap, easily sanitized and providing an optimum microclimate for piglets, was not offered for the production yet. Agricultural enterprise Kadehks has developed a design and the pre-production model of a warmed den for pigs under the name Logovo Dlya Porosyat UKhL-4 (Logovo). Application of brooder Logovo in combination with the warming plate made it possible to design more favorable mode for sleeping areas of pigs, to reduce preheating time of plates up to 10 days, to save (in comparison with incandescent lamps) up to 155 kw/h of electric power used for heating of pig sleeping area without decreasing their growth rate and safety. Application of the presented device in combination with heating plates made it possible to reduce the expenses for pig production and for the equipment of heating plates temperature regulators. Application of the differentiated heating mode with the possibility to deactivate the heating plates from the electric power sources after 10 days of the suckling period made it possible to lower the expenses for production of female socket of pigs