Euthanasia of meat rabbits with carbon dioxide: Behavioral and physiologic responses to gas chamber gradual- and fast-fill rates.

The use of CO2 inhalation with different gas chamber fill rates has not been evaluated for euthanasia in commercial meat rabbits. Our objectives were to evaluate the behavioral and physiologic responses of rabbits (pre-weaned to adult) when exposed to gradual- and fast-fill rates of CO2, and to determine the time to onset of insensibility and death. Cull rabbits (n = 81) were randomly assigned to either a gradual-fill chamber displacement rate of 28% volume change/min (n = 42) or a fast-fill chamber displacement rate of 58% volume change/min (n = 39). The fast-fill rate resulted in a more rapid loss of sensibility at a lower CO2 chamber concentration and in a faster death than for gradual-fill. There were minimal differences in behavioral responses between fill rates with no clear signs of distress. These findings indicate that CO2 at the studied displacement rates is suitable for commercial meat rabbit euthanasia.

Euthanasie des lapins de boucherie au gaz carbonique : comportement et réponses physiologiques aux taux de remplissage graduels et rapides. L'usage de l'inhalation du CO2 avec différents taux de remplissage de la chambre à gaz n'a pas été évalué pour l'euthanasie des lapins de boucherie commerciaux. Nos objectifs consistaient à évaluer les réponses comportementales et physiologiques des lapins (des lapins pré-sevrés à des lapins adultes) lors de l'exposition à des taux de remplissage graduels et rapides de CO2, et à déterminer le moment de l'insensibilité et de la mort. Les lapins de réforme (n = 81) ont été assignés au hasard soit à un taux de déplacement graduel du volume de la chambre de 28 % changement/min. (n = 42) ou à un taux de déplacement rapide du volume de la chambre de 58 % changement/min (n = 39). Le taux de remplacement rapide a produit une perte de sensibilité plus rapide à une concentration inférieure de CO2 dans la chambre et une mort plus rapide que le remplissage graduel. Il y avait des différentes minimales dans les réponses comportementales entre les taux de remplissage sans signes clairs de détresse. Ces résultats indiquent que le CO2 aux taux de déplacement étudiés est approprié pour l'euthanasie des lapins de boucherie commerciaux.(Traduit par Isabelle Vallières).

Efficacy of Blunt Force Trauma, a Novel Mechanical Cervical Dislocation Device, and a Non-Penetrating Captive Bolt Device for On-Farm Euthanasia of Pre-Weaned Kits, Growers, and Adult Commercial Meat Rabbits.

The commercial meat rabbit industry is without validated on-farm euthanasia methods, potentially resulting in inadequate euthanasia protocols. We evaluated blunt force trauma (BFT), a mechanical cervical dislocation device (MCD), and a non-penetrating captive bolt device (NPCB) for euthanasia of pre-weaned kits, growers, and adult rabbits. Trials were conducted on three commercial meat rabbit farms using 170 cull rabbits. Insensibility was assessed by evaluating absence of brainstem and spinal reflexes, rhythmic breathing, and vocalizations. Survey radiographs on a subsample of rabbits (n = 12) confirmed tissue damage prior to gross dissection and microscopic evaluation. All 63 rabbits euthanized by the NPCB device were rendered immediately and irreversibly insensible. The MCD device was effective in 46 of 49 (94%) rabbits. Method failure was highest for BFT with euthanasia failures in 13 of 58 (22%) rabbits. Microscopically, brain sections from rabbits killed with the NPCB device had significantly more damage than those from rabbits killed with BFT (p = 0.001). We conclude that BFT is neither consistently humane nor effective as a euthanasia method. MCD is an accurate and reliable euthanasia method generally causing clean dislocation and immediate and irreversible insensibility, and the NPCB device was 100% effective and reliable in rabbits >150 g.