Energy Balance during Heat Stress in Sheep

Abstract
Shorn unanesthetized sheep were acutely exposed to ambient temperatures ranging from thermoneutral (25 C) to severe heat stress (45 C). Oxygen consumption, rectal temperature respiration rate and respiratory and cutaneous water loss were measured. Oxygen consumption increased significantly (P<.05) during severe heat stress (45 C). This increase was partitioned into somatic-humoral and Q10 portions assuming Q1O=2.O with the Q10 effect accounting for as high as 41% of increased metabolic rate during heat stress. Both respiratory and cutaneous water loss are avenues of heat loss in shorn sheep with increased respiratory losses more apparent during mild heat stress (30 and 35 C) and cutaneous water loss more important during severe heat stress (40 and 45 C). Panting indices implied that panting is not a thermal liability in shorn sheep in the range of ambient temperatures studied. Copyright © 1971. American Society of Animal Science . Copyright 1971 by American Society of Animal Science.

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