EFFECT OF ELEVATED HEAT AND HUMIDITY ON CHEWING ACTIVITY, YIELD AND CHEMICAL COMPOSITION OF MILK IN LACTATING COWS 1ST INTERNATIONAL SYMPOSIUM ON BIOTECHNOLOGY (2023)202353ЗБОРНИЦИ

The objective of this study was to investigate the influence of surrounding temperature and humidity in different periods of the year on eating and rumination time on ilk yield and chemical composition in Simmental cows at late lactation (over 150 days in milk, DIM). Ambient temperature and relative humidity were registered every hoursing data logger Testo 174H. Rumination time and eating time data were collected using an automatic system – GEA CowScout Neck. It was noticed that different values of THI temperature and humidity index) affect eating time (p<0.01), rumination time (p<0.01), milk yield (p<0.05) as well as milk fat content (p<0.05). The average value of THI1 (52.55) had a positive effect on eating time (307.2 min/day), rumination time (384 min/day), milk yield (28.97 kg/day), and milk fat content (4.25%), compared to the average value of THI2 (72.88), where the observed eating time was 259.2 min/day, rumination time 343 min/day, milk yield 26.21 kg/day and milk fat content 4.11%. An increased chewing time was achieved at lower value of THI, as well as higher milk yield and improved milk composition.