The Effect of Heat Stress on Milk Yield, Milk Fat Rate and Rectal Temperaturein Holstein-Friesian Dairy Cattle

Abstract

Heat stress is an environmental factor that negatively affects the morphological and physiological properties of dairy cattle. The aim of this study is to investigate the relationship between heat stress and milk yield, milk fat ratio and body temperature in Holstein-Friesian dairy cattle. The data of the study was obtained from a private Kurtalan Farm of Siirt province, the Southeastern Anatolia Region of Turkey. Milk yield and other traits of 13 head HolsteinFriesian dairy cattle were recorded in March, April, May, June, July, August and September. In addition, temperature and humidity records were recorded in the farm and in the parlor to be used for calculating the temperature humidity index value. In the analysis of data, correlation and regression methods were used. As a result of the study, the negative correlation (P<0.01) was found between milk yield and milk fat ratio and the positive correlation (P<0.001) were detected between heat stress and body temperature. In addition, a significant negative relationship was observed between rectal temperature and milk yield (P<0.01).