Animal-welfare-promoting housing and management reduces the stress experienced by the animals, improving their immune competence and reducing the need for antimicrobials. This is particularly important during the early life of the animals, when appropriate maturation of the immune system determines the susceptibility to pathogens circulating in the herd. In ISAP stress, welfare and immune functions of pigs and broilers are evaluated with state-of-the-art methods. Animals are studied in field studies, intervention studies and experimental setups and followed from birth to slaughter.