Selective breeding for feed efficiency in livestock has improved production economics but created welfare problems through extreme growth rates and metabolic stress.
The drive for feed efficiency has created breeds that are highly productive but physiologically compromised. Broilers that reach market weight in 35 days frequently cannot walk properly by the end of their lives. High-yielding dairy cows are in perpetual negative energy balance during peak lactation, causing body condition loss and metabolic disease. Breeding programs that include welfare traits alongside productivity are beginning to emerge, but industry uptake is slow. Consumer and regulatory pressure is essential to accelerate the transition to welfare-inclusive selection criteria.