Selective breeding for feed efficiency in livestock improves economic and environmental performance but can create welfare trade-offs through metabolic stress and altered physiology.
Feed efficiency selection creates welfare trade-offs that breeding programmes have historically failed to adequately account for. Animals selected for maximum production efficiency - converting feed to meat, milk, or eggs most effectively - often do so at significant physiological cost. High-growth broilers suffer cardiovascular and skeletal problems. High-yield dairy cows experience chronic metabolic stress and elevated disease risk. Highly efficient pigs may have altered stress responses affecting welfare. Modern genetic evaluation is beginning to incorporate welfare traits alongside production traits in breeding objectives, but the economic dominance of efficiency selection creates persistent pressure toward welfare-compromising phenotypes.