Temperature regulation in the new-born lamb. I. Changes in rectal temperature within the first six hours of life

Abstract

Changes in rectal temperature during the first 6 hr of life of lambs born under adverse weather conditions are described. The rectal temperature of lambs at birth was slightly above that of the ewe (av. 0.35°C higher). The subsequent changes varied from zero to a fall of 11°C within 30 min of birth. Temperature usually fell by 2 or 3°C during the first hour after birth and commenced to rise again in many Iambs, even though the coat was still wet. It had returned to 39–40°C by 3 hr after birth in most lambs. In some lambs the temperature continued to fall until death. There was a significant inverse relationship between birth weight and rate of cooling. Cooling was more pronounced in twins than in single lambs, and in lambs that subsequently died than in lambs that survived. In two series of observations, under-nutrition of the pregnant ewe resulted in the birth of lambs that appeared to cool more rapidly than lambs from well-fed ewes. The possible mechanism of the changes observed is discussed, together with practical implications of the observations.