The narrowing of genetic diversity in commercial livestock breeds creates welfare vulnerabilities through reduced disease resistance and increased metabolic disease risk.
The intensive selection of commercial livestock breeds for production traits has created populations with narrow genetic bases and associated welfare vulnerabilities. Holstein dairy cattle selected over decades for peak milk production carry genetic risk factors for metabolic diseases that cause significant suffering in high-producing cows. The genetic uniformity also creates systemic vulnerability — a disease capable of affecting one animal in a genetically uniform herd can potentially affect all. Rare and heritage breeds that have not been subjected to the same intensive selection often retain robustness, disease resistance, and longevity traits that have been eroded in commercial lines. Maintaining genetic diversity — both within commercial breeds and through conservation of rare breeds — is a welfare investment that reduces future disease burden and improves resilience.