Influence of two rumen cannulation techniques on postoperative recovery in sheep

Objective To determine the influence of two methods of rumen cannulation on postoperative animal welfare. Study design Experimental study. Animals Twelve commercial wethers (n = 6 per group). Methods Group 1 wethers underwent a one-step procedure to place a cannula immediately after fistulation of the rumen to the skin. Group 2 wethers underwent a two-step procedure in which a portion of the rumen was externalized and held with a clamp for 9 days, after which the cannula was placed into the fistula created by removal of the clamped rumen tissue. Feed intake and vital signs were monitored daily for 24 days postoperatively. Plasma fibrinogen and serum cortisol were measured daily for 14 days postoperatively to estimate inflammatory and stress responses, respectively. Change in body weight was also assessed. Results Cannulation method did not affect (P > .05) body weight, temperature, heart rate, respiratory rate, fibrinogen level, or cumulative cortisol level. Feed intake was lower (0.82 vs 1.2 kg/d; P < .0001), and mean cortisol level was greater (124.2 vs 121.5 ng/mL; P = .038) in group 2 compared with group 1. Conclusion Although both cannulation methods mostly elicited similar physiological responses, animals seemed to experience more discomfort and stress when undergoing the two-step procedure. Clinical significance Rumen cannulation performed in one step is recommended to improve postoperative welfare.