Stress responses in lambs castrated with three different methods

Abstract

The present work was conducted to evaluate the animal response to stress in lambs caused by three different castration techniques. Forty-six male lambs aged 4-5 months were randomly allocated to one of four groups including Burdizzo (B), scrotal ablation (SA), orchiectomy (OR) and control handling (H). Local anaesthesia (lidocaine 2%) was administered in both spermatic cords and the scrotal neck of lambs before each treatment. Blood samples were collected at -30, -10, +1, +20, +40, +60, +120, and +180 minutes. Serum cortisol concentrations were determined using a competitive immunoassay and the area under the curve (AUC) was calculated for each lamb. The following biochemical parameters were assayed for each animal at each time point: alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), creatine kinase (CK) and glucose (GLU). The time needed for total lesion resolution and weight gain of each animal was recorded. Orchiectomy elicits the greatest cortisol response, significantly greater than that seen in similarly handled controls (P≤0.01), Burdizzo and scrotal ablation groups (P≤0.05). The serum cortisol AUC was higher in the scrotal ablation group (P≤0.05) than controls, but lower than in the orchiectomy group (P≤0.05). The Burdizzo group didn't differ from controls. Serum glucose levels of the castrated lambs differed significantly from the control group, following a trend similar to cortisol. No change was seen in ALT, AST, LDH or CK. No difference in weight gain was seen among the groups. Our results suggest that use of the Burdizzo is the preferable castration technique for adult lambs, while scrotal ablation is a valid surgical alternative to orchiectomy and permits more rapid wound healing that is ideal for extensive management where flocks are not under close observation.