Title page for ETD etd-01172009-063407
|Type of Document
||Hoffman, Rhonda Michelle
||Pre-weaning diet and stall weaning method influences on stress response in foals
||Master of Science
||Animal and Poultry Sciences
|Kronfeld, David S.
|Jack, Nancy E.
|Lawrence, Larry A.
|Date of Defense
The response of foals to the stress of weaning was examined in terms of
a behavioral protocol and the responses of plasma ascorbate, serun1 cortisol,
and the serum cortisol response to an ACTH challenge. Behavior scores (1 to
10) as an index of stress were assigned to each foal daily, with high scores
indicating less stress and better adjustment. The experimental plan was a 2 X 2
factorial of pre-weaning diet and stall weaning method. Foals were raised on
pasture supplemented with hay and a pelleted concentrate (PHC) or pasture
supplemented with hay only (PH). Foals were placed in stalls singly or in pairs
for weaning. Gender influences were also examined. The foals exhibited
characteristic behavioral and physiological responses to the social dislocative
stress of weaning. Behavior scores were lower in paired than in single foals (p =
.008) and tended to be lower in PH than PHC foals (p = .15). No differences in
post-weaning plasma ascorbate concentrations were found among treatments.
Responses of serum cortisol to an ACTH challenge were lower in PH than PHC
foals (p = .001) and in paired than single foals (p = .058), and lower responses
were taken to represent adrenal depletion arising from stress. Behavior scores
were positively correlated with the response of serum cortisol to ACTH. Both
behavioral data and the serum cortisol response to ACTH indicate that foals
were better able to cope with weaning stress when supplemented with
concentrate prior to weaning and when weaned singly.
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