Advancing metrics for animal welfare and antibiotic use in sustainability assessments of diets

Assessment of the sustainability of diets typically includes the diet's impact on the environment, including effect on greenhouse gas emissions, and the use of land and water. However, there are other crucial sustainability aspects including animal welfare and antibiotic use that sustainability assessments usually neglect due to methodological challenges and lack of available data. This study contributes to the improvement of sustainability assessments of food systems by advancing methods to include animal welfare and antibiotic use. The proposed animal welfare indices reflect the number of animals affected per kilogram of animal product, the animals' cognitive ability to experience negative effects, and the quality of the production system, including disease frequency and space limitations. The proposed antibiotic use indicator acts as a proxy for the risk of bacteria developing resistance to antibiotics that threatens health of humans and animals. It was developed based on national sales data, adjusted for species-specific differences. The animal welfare indices and the antibiotic use indicator were applied to a range of animal products commonly consumed in a set of European countries, revealing substantial variations in animal welfare loss and antibiotic use across species and production systems. For example, rabbit and chicken production showed high welfare loss per kilogram of meat due to the number of animals affected and the relatively poor conditions in intensive livestock systems. Meat from cattle and wild-caught species had lower welfare loss (i.e. favourable) per kilogram, attributed to the larger body mass of these animals and less suffering in production. The methodologies developed here offer a much needed tool for evaluating trade-offs between animal welfare, antibiotic use, and environmental sustainability in food production.