THE EFFECT OF HEAT STRESS ON SOME REPRODUCTIVE TRAITS IN JERSEY COWS UNDER SEMI-HUMID CONDITIONS IN TURKEY

摘要

This study was aimed to evaluate reproductive losses of Jersey cattle attributed toheat stress. Reproductive traits such as first calving age, days open, gestation length, and first 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 first calving age, days open, gestation length, and first calving interval were 525.37, 813.34, 69.73, 283.55, and 365.98 days, respectively. From these traits, only first breeding age was significantly affected(P < 0.05) from heat stress. In addition, it was detected that summer calves reached first 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 breedingage.