Salivary cortisol as an indicator of stress in sheep (Ovis ovis)

Abstract

Recent work^p(1)(2) has suggested that measuring salivary cortisol may provide a noninvasive measurement of stress-induced changes. A noninvasive collection technique is particularly useful in stress and welfare studies because the technique may not impose additional stress, as would a more invasive technique such as venepuncture.

We have developed a method that allows saliva collection from sheep for subsequent cortisol analysis and shows unambiguous stress related changes. Saliva was collected by use of an absorbent strip of cloth (Chux, Nationalpak Ltd, Auckland) attached to the end of a rod. A swab was cut from the cloth to the dimensions 260 x 40 mm. The rod dimensions were 1 mm diameter, 450 mm long with a 10 mm loop at one end for swab attachment. The sheep were manually restrained while the swab was placed in the mouth and the animal allowed to chew on it until the swab was saturated with saliva (generally 10–40 seconds). Saliva was expressed from the swab using a syringe (one per animal). If the saliva sample volume was less than 1 ml, the collection procedure was repeated using the same a to yield a greater sample volume. Saliva samples were stored at -20 °C within 1 hour of collection.