The effect of heat stress on some reproductive traits in jersey cows under semi-humid conditions in Turkey

Abstract

This study was aimed to evaluate reproductive losses of Jersey cattle attributed to heat stress. Reproductive traits such as frst calving age, days open, gestation length, and frst calving interval of 253 Jersey cows raised in The Karakoy State Farm of Samsun province in Turkey, from 1995 to 2005, were used as retrospective data. In addition, heat stress terms were calculated with temperature humidity index (THI) for successive seasons and data were arranged appropriately to THI values of seasons. The mean values for temperature, humidity and THI were 25.30°C, % 73.83 and 74.67 in summer, respectively. Regarding to weather parameters, signs and symptoms of heat exhaustion was only observed during summer season. The overall means for frst calving age, days open, gestation length, and frst calving interval were 525.37; 813.34; 69.73; 283.55; and 365.98 days, respectively. From these traits, only frst breeding age was signifcantly affected (P < 0.05) from heat stress. In addition, it was detected that summer calves reached frst breeding age later than those born in other seasons did. As a result, maintenance cost increased at least $ 123-164 per cow because of the delay of first breeding age.