engleski

The influence of mastitis risk on response to heat stress in dairy Simmental cows

Aiming determination of the influence of mastitis risk (defined accordingly to daily somatic cell count) on response to heat stress (defined as relationship between daily milk traits and microclimate parameters) in dairy Simmental cows over two million test-day records were analysed. The relationship between daily milk traits and microclimate parameters (ambient temperature, relative humidity, and THI) as well as variation in daily milk traits due to heat stress was tested for each mastitis risk class using PROC GLM/SAS. Based on the performed analysis, the negative effect of the increase of microclimate parameters on daily milk production in all cows was determined. Also, the highest decrease of daily production due to temperature and THI increase was determined in healthy cows, while high humidity had the highest effect on cows in high mastitis risk. Furthermore, the difference between the milk production in normal condition comparing to heat stress vary depending of THI threshold value and mastitis risk that is the highest decline in performance could be expected in cows in high mastitis risk in environment characterized by highly pronounced heat stress.

daily milk traits; dairy Simmentals; microclimate parameters; mastitis risk

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