The concentration of livestock production around a handful of highly productive breeds has dramatically reduced genetic diversity in farm animals, with welfare consequences including reduced disease resistance and heightened susceptibility to emerging pathogens.
Genetic concentration causes direct welfare harm through inbreeding depression - reduced immune function, fertility problems, and physical traits selected for production that compromise welfare (as seen in fast-growing broilers and high-yield dairy cows). Highly inbred populations have reduced capacity to mount effective immune responses, meaning more frequent disease outbreaks and greater antibiotic dependence. Traditional and native breeds often have welfare-relevant adaptations developed over centuries that have been lost in the race for productivity. Preserving genetic diversity is both a conservation and welfare priority.