Modern livestock genetics have created animals that grow so fast and produce so much that their bodies cannot support their own productivity, causing chronic welfare problems.
Intensive genetic selection has pushed livestock animals to biological extremes that their physiology cannot sustain. High-yielding dairy cows are in negative energy balance for months after calving, causing ketosis, liver disease, and reduced immune function. Fast-growing broilers develop cardiovascular problems and lameness. The welfare cost is baked into the genetic makeup of the animals, not just the production system. Breeding for balanced traits including health and longevity is an essential part of welfare reform.