Preliminary findings on seasonal heat stress of sheep

Abstract

This paper studies the heat stress conditions imposed onto sheep housed in a naturally ventilated sheep barn during the four seasons of a year. The barn is located near the east coast of central Greece. Heat stress is assessed by means of the hourly temperature-humidity index (THI). The analysis shows that animals were exposed to heat stress in 11%, 80% and 17% of spring, summer and autumn hours, respectively, whereas no heat stress was identified during winter. As expected, animals are more prone to severe heat stress during summer, as the daily maximum hourly values of THI remained higher than the extreme severe heat stress threshold (i.e. THI = 25.6) in 90% of the summer days. Additionally, THI remained higher than 25.6 during the vast majority of the summer daytime hours. Measures have to be taken so as to improve the indoor climate conditions and to alleviate animal's heat stress.