BEHAVIORAL AND CORTISOL RESPONSES OF LAMBS TO CASTRATION AND TAILING USING DIFFERENT METHODS

Lambs at 4-5 weeks of age were studied during the first 4 hours after castration and/or tailing using three methods in various commonly used combinations. The methods were: cutting with a knife, application of constricting rubber rings and using a heated docking iron (tailing onl y). Behaviour was monitored by quantifying the incidences of restlessn ess (during the first hour only), normal and abnormal standing/walking , and normal and abnormal lying. Plasma cortisol concentrations were a lso measured in samples taken at intervals during the 4 hours after tr eatment. With the knife, abnormal standing/walking predominated throug hout the first 4 hours and beyond, and restlessness was virtually abse nt. Plasma cortisol concentrations in knife-treated lambs remained abo ve pretreatment values for at least 4 hours. With rings, high restless ness was invariably present during the first 30-45 minutes, and much o f the associated standing/walking and lying was abnormal, but all beha viours had returned to control values within 4 hours of treatment, as had the plasma cortisol concentrations. There were no correlations bet ween the incidences of abnormal behaviours and the plasma cortisol con centrations during the first 4 hours after any treatment, except that when abnormal behaviour was present the cortisol concentrations were g reater than pretreatment values, and vice versa. Thus, the presence/ab sence of the abnormal behaviours reported here allowed an assessment o f the duration of distress after castration and/or tailing. However, a s the behavioural responses to castration and/or tailing were broadly procedure-specific, so that the responses to the knife and rings were not apparently part of the one behavioural continuum, it is argued tha t the relative intensities of distress caused by the two procedures ca nnot be assessed from behaviour alone. Rather, reference must also be made to established physiological indices of distress such as plasma c ortisol concentration. On that basis, the knife treatments apparently caused greater and more protracted distress responses than did the rin g or docking iron treatments, and should therefore be avoided. However , ring-treated lambs, especially those castrated or castrated and tail ed, apparently experienced distress, so that more benign alternatives to the use of rings should also be sought.