I can't speak for animal welfare organizations. Maceration is quicker than CO2 asphyxiation. Animals (including humans) can detect high levels of CO2 but mos

I can't speak for animal welfare organizations. Maceration is quicker than CO2 asphyxiation. Animals (including humans) can detect high levels of CO2 but most (rodents are an exception) can't detect low levels of oxygen. I found these articles: https://www.upc-online.org/slaughter/report.html https://www.upc-online.org/slaughter/report.html (scroll down to Gas Stunning). https://www.hsa.org.uk/downloads/technical-notes/TN12-gas-killing-of-chickens-and-turkeys.pdf https://www.hsa.org.uk/downloads/technical-notes/TN12-gas-ki... Both recommend inert gas asphyxiation but in the context of adult birds. Scientists are looking into in ovo sexing: https://link.springer.com/article/10.1007/s00216-016-0116-6 https://link.springer.com/article/10.1007/s00216-016-0116-6