Assessment of a Typical Greek Sheep Barn Based on Potential Heat-Stress of Dairy Ewes

Abstract

Abstract. This article studied the potential seasonal heat-stress of dairy ewes housed in a typical naturally ventilated sheep barn located close to the east coast of central Greece. Heat stress was assessed using the Temperature Humidity Index (THI) and the Seasonal THI-hrs index. Dairy ewes were exposed to potential heat-stress (THI ≥ 22.2) in 79%, 17%, and 11% of summer, autumn, and spring hours, respectively, whereas no heat-stress was present during winter. The monthly means of the daily maximum hourly THI values remained above the extreme severe heat-stress threshold (i.e. 25.6) during the summer months and above the severe heat-stress threshold (i.e., 23.3) during May and September. During all summer days the minimum daily maximum hourly THI value was 24.6 indicating that sheep experienced severe heat-stress (THI ≥ 23.3). THI levels remained very high (usually above the extreme severe heat-stress threshold) during daytime and dropped below the heat-stress threshold (i.e., 22.2) only for a few hours during night-time. The values of the Seasonal THI-hrs index under heat-stress conditions (THI ≥ 22.2) were 6596, 975, 0, and 516 during summer, autumn, winter, and spring, respectively. These findings suggest that under summer conditions in the east coast of central Greece, dairy ewes were exposed to severe or extremely severe heat-stress conditions, while they were also partially exposed to severe or extremely severe heat-stress conditions during autumn and spring.