Thermal comfort of cows and temperature humidity index in period of 2005-2016 in Vojvodina region (Serbia)

Abstract

The aim of this study is to determine value of temperature-humidity index (THI) in period of 2005-2016. in Vojvodina and their correlations with milk production and temperature of body surface of animals. THI index is calculated according to the following formula THI=(1,8×Temperature)-(1-Relative Humidity) × (Temperature- 14,3)+32. Temperature and humidity data were collected directly from Hydrometeorological Institute of Serbia. Average THI values were calculated for every month for every year from 2005 to 2016. Measuring spots were cities Vršac, Zrenjanin, Kikinda, Palić, Sombor, Rimski Šančevi and Sremska Mitrovica. Temperature and humidity are noted at 14h, so they represented maximal average values of THI index. Trend of THI values was represented for each day in every month in years from 2005. to 2016. Average production of drinking milk for year of 2016 was calculated. This year was chosen because is the last year of research and represents cumulative effect of heat stress in cows. Data were collected from Statistic Institute of R. Serbia. Thermo-vision camera was used for determining skin temperature of udder and skin in eye region. Results were showed that temperature ranged from 40.3 in January to 77.5 in July. Average maximal THI value in period of 2005-2016 showed that heat stress was presented in May, June, July and August. Drinking milk production was the greatest in January. After that it started dropping. The lowest production of drinking milk was noted in August with an increase afterwards till December. Body surface temperature was ranged from 34.1 to 38.5ºC. The highest body temperature was measured at August and the lowest in winter time. Significant negative correlation between ten-year average THI value and milk production was noted. Positive correlation was noted between THI and body temperature. From 2005 to 2016 positive linear trend of THI values that were measured in hottest period of day was noted. In every month statistically significant linear trend of rising THI value was founded, except in January, October and November. Extremely hot summers in Serbia appear in every five years when cows are affected the most. Showed data indicated global warming and climate changes which affect biological adaptation of cows.

Keywords

• THI
• heat stress
• cow
• trend