Technical note: Construction of a CO2 supply system for depopulation of pigs in a container

TY - JOUR

T1 - Technical note

T2 - Construction of a CO2 supply system for depopulation of pigs in a container

AU - Kaiser, Marianne

AU - Kristensen, Jens Kr

AU - Thomsen, Peter T.

PY - 2025/3/11

Y1 - 2025/3/11

N2 - Situations may arise where authorities need to depopulate large quantities of pigs in a short time. This must be done in an animal welfare-responsible manner. This paper describes in detail a technical mobile container system for CO2 depopulation of pigs. The system consists of simple and easily accessible materials and can be replicated and scaled for multiple container systems for CO2 depopulation. The container system was tested at 4 depopulation events where the pigs’ behavior was filmed (1 event) and the duration of the various procedures was recorded. The results showed that the system’s capacity met AVMA’s recommendations for a CO2 supply rate of 10% to 30% of the chamber volume per min. On average, the containers were supplied with CO2 for 7 min, and it was possible to maintain a CO2 concentration of 80% for at least 10 min after stopping the CO2 admission. By maintaining the tarpaulin on the container during transport, this “extending effect period” can be utilized for additional CO2 exposure and acts as an extra safeguard for successful depopulation. Target CO2 concentration of 80% occurred after a mean of 7 min. Pig escape attempts were first observed 2 min:26 s after the start of CO2 exposure. Presumably due to the stocking density (a mean of 0.52 m2 per pig), no loss of posture (indicating loss of consciousness) could be observed. On the other hand, the last escape attempts were observed after 3 min:04 s, and the last atactic movements after 3 min:13 s. It is therefore reasonable to assume that all pigs have lost consciousness around that time. No pigs survived the procedure, and the described CO2 depopulation system therefore lived up to expectations. We recommend that users are given the opportunity to practice thoroughly before an authentic emergency. Lay Summary This paper describes a CO2 depopulation system for large numbers of pigs. The system consists of a movable container to which heated CO2 from gas batteries is added. The method can be continuously monitored and complies with the American Veterinary Medical Association’s recommendations on CO2 supply rate for depopulation of animals. The materials used can be easily acquired and are relatively cheap, making it affordable for authorities to establish multiple systems which can shorten the process on farms. The method was tested on finishers at 4 events where no pigs survived. The paper reports on the technical design of the movable container system, practical data observed during depopulation as well as pig behavior observed from video surveillance in one container.

AB - Situations may arise where authorities need to depopulate large quantities of pigs in a short time. This must be done in an animal welfare-responsible manner. This paper describes in detail a technical mobile container system for CO2 depopulation of pigs. The system consists of simple and easily accessible materials and can be replicated and scaled for multiple container systems for CO2 depopulation. The container system was tested at 4 depopulation events where the pigs’ behavior was filmed (1 event) and the duration of the various procedures was recorded. The results showed that the system’s capacity met AVMA’s recommendations for a CO2 supply rate of 10% to 30% of the chamber volume per min. On average, the containers were supplied with CO2 for 7 min, and it was possible to maintain a CO2 concentration of 80% for at least 10 min after stopping the CO2 admission. By maintaining the tarpaulin on the container during transport, this “extending effect period” can be utilized for additional CO2 exposure and acts as an extra safeguard for successful depopulation. Target CO2 concentration of 80% occurred after a mean of 7 min. Pig escape attempts were first observed 2 min:26 s after the start of CO2 exposure. Presumably due to the stocking density (a mean of 0.52 m2 per pig), no loss of posture (indicating loss of consciousness) could be observed. On the other hand, the last escape attempts were observed after 3 min:04 s, and the last atactic movements after 3 min:13 s. It is therefore reasonable to assume that all pigs have lost consciousness around that time. No pigs survived the procedure, and the described CO2 depopulation system therefore lived up to expectations. We recommend that users are given the opportunity to practice thoroughly before an authentic emergency. Lay Summary This paper describes a CO2 depopulation system for large numbers of pigs. The system consists of a movable container to which heated CO2 from gas batteries is added. The method can be continuously monitored and complies with the American Veterinary Medical Association’s recommendations on CO2 supply rate for depopulation of animals. The materials used can be easily acquired and are relatively cheap, making it affordable for authorities to establish multiple systems which can shorten the process on farms. The method was tested on finishers at 4 events where no pigs survived. The paper reports on the technical design of the movable container system, practical data observed during depopulation as well as pig behavior observed from video surveillance in one container.

KW - carbon dioxide

KW - disease control

KW - emergency

KW - gas

KW - killing

KW - livestock

UR - http://www.scopus.com/inward/record.url?scp=105003631310&partnerID=8YFLogxK

U2 - 10.1093/tas/txaf034

DO - 10.1093/tas/txaf034

M3 - Journal article

C2 - 40264540

SN - 2573-2102

VL - 9

JO - Translational Animal Science

JF - Translational Animal Science

M1 - txaf034

ER -