STUDY OF THE NEGATIVE EFFECT OF HEAT STRESS ON DAIRY PRODUCTIVITY OF COWS UNDER DIFFERENT HOUSING METHODS

摘要

A serious problem for cattle breeding in the warm season is the threat of heat stress in animals, which causes significant economic losses for the entire industry, while having a negative impact on the productivity of dairy cows, as well as the composition of the milk produced. Daily monitoring of temperature and humidity by special electronic sensors in livestock premises and further calculation of the temperature and humidity index (THI) were chosen as an indicator of thermal stress in dairy cows, after which a link was established between the microclimate of the farm and financial losses. Four farms with different herd management systems, ventilation systems, milking methods and manure disposal were selected as experimental agricultural enterprises. The lowest milk losses were recorded at a megafarm with loose maintenance, robotic milking and an innovative automatic ventilation system. The greatest losses, due to the effect of heat shock on dairy cows, were incurred by a farm with tethered housing, milking in a milk pipeline and not equipped with a ventilation system. At the same time, the indicator of the content of the mass fraction of fat in milk remained relatively stable, the decline was noted only after cases of sharp jumps in the temperature and humidity index in the livestock premises. Most often, such jumps, and the subsequent decline in productivity, occurred in the second half of June and the first half of July 2024. Stabilization of both the temperature and humidity conditions on farms and reduction of the negative effects of heat stress occurred at the end of August and the first half of September. On average, 57 days with critical indicators of the temperature and humidity index were registered for the entire season.