Seasonal variations in rectal temperature of Yankasa sheep.

From measurements of rectal temperature (Tre) at 06:00h (06:00Tre) and at 14:00h (14:00Tre), meteorological stress was determined in six Yankasa ewes in terms of per cent rise of 14:00Tre over 06:00Tre reference values during the harmattan and hot-dry seasons. Absolute and mean Tre values were significantly higher (P less than 0.05) during the harmattan than the hot-dry season. In both seasons, mean 14:00Tre was significantly higher (P less than 0.01) than 06:00Tre. The mean diurnal difference between 14:00Tre and 06:00Tre, i.e. delta Tre was about 1 degrees C during the harmattan but ranged between 0.5 and 0.7 degrees C during the hot-dry season. All animals were observed to shiver during harmattan nights.