Antibiotic use in livestock serves both treatment and historically growth-promotion purposes, with welfare implications for individual animals and human health from resistance development.
The welfare relationship to antibiotics is complex. From an individual animal welfare perspective, access to antibiotics for treating bacterial infections is essential - denying sick animals effective treatment to achieve 'antibiotic-free' certification causes genuine suffering. The welfare-conscious approach maintains therapeutic use for genuinely sick animals while eliminating routine prophylactic use that can mask poor husbandry. Systems that rely on antibiotics to make poor welfare conditions viable are doubly problematic - they cause suffering and contribute to resistance.