Food intake of sheep exposed to hot-humid, hot-dry, and cool-humid environments.

Water intake, food intake (wet and dry weight), rectal temperature, and food digestibility were determined in 6 sheep exposed to 4 weeks each of hot-humid, hot-dry, and cool-humid environments, alternated with 3 weeks each of cool-dry exposure. Compared with values determined during the cool-dry environments, wet-weight food intake decreased between 5% and 33% and between 3% and 9% during hot-humid and hot-dry exposures, respectively. During the week of cool-humid exposure, wet-weight food intake decreased by 11%. During hot-humid, hot-dry, and cool-humid environments, dry-weight food intake decreased between 5% and 17%. The effect of high ambient temperatures on wet-weight food intake was significant (P less than 0.01), whereas dry-weight food intake was not related to ambient temperature. During hot-humid exposure, water intake decreased 4% and the increased 7%. During hot-dry exposure, water intake increased between 37% and 45%. During the first 2 weeks of cool-humid environment, water intake decreased between 13% and 15%. From the 4th week of hot-humid exposure until the 3rd week of the following cool-dry period, food digestibility increased between 18% and 32%. During hot-dry exposure, food digestibility increased between 6% and 14%. The digestibility of food was significantly increased (P less than 0.005) when dry-weight food intake increased; therefore, decreased digestibility was related to water content of the feed. Increased ambient humidity was associated with decreased dry-weight food intake (P less than 0.05).