Preliminary investigation of some physiological responses of Bos indicus heifers to surgical spaying

Objective To determine the value of peripheral blood concentrations of cortisol, creatine phosphokinase (CPK), aspartate aminotransferase (AST), non‐esterified fatty acids (NEFAs) and haptoglobin as indicators of welfare in Brahman heifers spayed by either the Willis dropped ovary technique (WDOT) or the flank laparotomy method. Design A total of 24, 2‐year‐old Brahman heifers were allocated to: crush (head‐bail) restraint alone (Control, n = 5); crush restraint and ear‐punch (Ear‐punch, n = 5); crush restraint, WDOT spay and ear‐punch (WDOT, n = 9); or crush restraint, elecrtoimmobilisation, flank spay and ear‐punch (Flank; n = 5). Cattle were blood sampled frequently to 8 h, and then daily to day 4 and were monitored to 42 days post‐procedure. Peripheral blood concentrations of bound and unbound cortisol, CPK, AST, NEFAs and haptoglobin were determined. Results Concentrations of plasma bound cortisol peaked in the spayed heifers 3–4 h post‐procedure; values in the Flank (1603 nmol/L) and WDOT (1290 nmol/L) groups were similar and significantly greater (P < 0.05) than in the Controls (519 nmol/L). Flank heifers had elevated plasma haptoglobin levels to day 4 postprocedure. Liveweights were significantly lower in the spayed compared with the Control heifers at 21 and 42 days post‐procedure, with liveweight gains also significantly reduced at day 21. Conclusions Bound cortisol responses in spayed heifers were elevated to 6 h post‐procedure and similar in WDOT‐ and flank‐spayed animals, indicating comparable levels of pain and stress. An inflammatory response, indicated by haptoglobin concentrations, was sustained for longer in Flank than in WDOT spayed heifers, suggesting longer‐lasting adverse effects on welfare from flank spaying than WDOT spaying.