Stress Hormone Responses of Sheep to Food and Water Deprivation at High and Low Ambient Temperatures.
Publication Type: |
Journal Article |
Year of Publication: |
1996 |
Authors: |
R.F. Parrott, D.M. Lloyd, J.A. Goode |
Publication/Journal: |
Animal Welfare |
Keywords: |
animal welfare, cortisol, dehydration, food deprivation, prolactin, sheep, temperature |
Abstract:
The effects of food and/or water deprivation at different ambient temperatures (7 or 35 ·C)
on stress hormone release in sheep (n = 8), were studied to provide background data for
research into the effects of road transport. Blood samples were taken from catheterized
animals at the start and, at 6h intervals, during 48h tests in an environmental chamber.
Cortisol release was unaffected by temperature or deprivation state but was stimulated by
introduction to the chamber. Prolactin secretion showed a similar tendency and levels of this
hormone were generally higher in the first test, whichever chamber was used. Heat exposure
also had a prolonged stimulatory effect on prolactin release, especially in the first test.
Growth hormone concentrations were rather variable but tended to be greatest when the
animals were deprived of food. Measurements of plasma osmolality indicated that sheep
remained in water balance, even when water was withheld for 48h, unless they had access
tofood. The results suggest that under laboratory conditions, and over a wide thermal range,
withholding food and water for 48h does not induce cortisol or prolactin release in sheep.
However, exposure to novel situations seems to have a stimulatory effect.