Influence of repeated restraint and isolation stress and electrolyte administration on pituitary-adrenal secretions, electrolytes, and other blood constituents of sheep.

Crossbred lambs (n = 24) were blocked by weight and assigned within blocks to four treatments applied in two replications of a 2 x 2 factorial arrangement. Main effects included no stress (NS) or three consecutive days of restraint and isolation stress (RIS) and treatment with either water (W) or an electrolyte (E) solution. Each lamb in the RIS treatment group was moved from its home stanchion to another room, isolated from visual and tactile contact with other lambs, and restrained for 6 h on three consecutive days. Lambs received either distilled W or E (320 mL) on each of the 3 d of stressor treatment. On the morning of the 3rd d of stressor treatment, blood samples were collected at 1-h intervals for 6 h for determination of concentrations of ACTH, cortisol, and lactate. Also, blood was collected at the conclusion of, and 18 h after, the termination of stressor treatment (at slaughter) to measure serum electrolyte concentrations and other blood constituents. Polynomial curves fit to plasma concentrations of ACTH, cortisol, and lactate data differed (P < .005) between RIS and NS lambs during the last 6-h stressor bout. Stressed lambs had lower (P < .05) serum calcium and alkaline phosphatase concentrations than did NS lambs. Serum glutamic oxaloacetic transaminase was increased (P < .05) 20- to 30-fold in RIS lambs. Restraint and isolation stress caused clear increases in plasma concentrations of ACTH, cortisol, lactate, and glutamic oxaloacetic transaminase but had minimal effects on serum electrolytes. Electrolyte treatment had no appreciable effect on pituitary-adrenal secretions or any other measured component of blood.