Individual and Group Euthanasia in Farmed Mink / Indywidualne i grupowe uśmiercanie norek z chowu fermowego

The study seeks to evaluate the effectiveness of euthanasia in mink (Neovison vison). The gases studied were filtered exhaust CO, and cylinder CO and CO₂. The experimental setups were as follows: (1) individual killing of mink in a small killing box (35 × 30 × 60 cm; H × W × L); (2) individual killing of mink in a small killing box, kept inside a killer (12.5 × 12.5 × 55 cm; H × W × L); (3) group killing of mink in a large killing box (75 × 75 × 150 cm; H × W × L); and (4) group killing of mink in a large killing box (70 × 70 × 125 cm; H × W × L). The results showed that filtered exhaust CO concentrations of 1.2-3% were too low. Concentrations of 4-6% were effective. With cylinder CO of 4% the killing time was the same as that with engine CO at 4%. A cylinder CO₂ concentration of ≥ 80% was effective. The shortest time interval after the end of all movements and respiration was with cylinder CO₂. No difference was found between cylinder and filtered exhaust CO. The time the animals were alive did not significantly differ between the groups (P>0.05). The first animal collapsed soonest among those inhaling CO₂ (CO₂ vs cylinder CO; P=0.0045; and CO₂ vs filtered exhaust CO; P=0.0009). No difference was found between cylinder CO and filtered exhaust CO (P=0.4654). There was also a significant difference in the time it took for the last animal to collapse. Here again the CO₂ animals collapsed the soonest (CO₂ vs cylinder CO, P=0.0062; CO2 vs exhaust CO, P=0.0012). No difference was found between cylinder and filtered exhaust CO (P=0.5660). It is concluded that concentrations of CO ≥4% and of CO₂ ≥80% in the euthanasia box are sufficient to kill effectively.