Bovine Leukocyte Adhesion Deficiency: Genetic Welfare

BLAD is a genetic immunodeficiency in Holstein-Friesian cattle causing recurrent infections and early death. This guide covers welfare and breeding implications.

Key Facts

BLAD is caused by an autosomal recessive mutation in the CD18 gene
Affected calves cannot mount normal immune responses to bacterial infections
Calves develop recurrent infections from birth and die within months
Carrier Holstein-Friesians spread the mutation through AI bulls
Genetic testing identifies carriers enabling their removal from breeding programmes
The frequency has dramatically decreased through mandatory testing of AI bulls

Welfare Considerations and Management

BLAD welfare management requires preventing the birth of affected calves through genetic testing and selective breeding. Affected calves suffer significant welfare impacts from recurrent infections (pneumonia, enteritis, skin infections) throughout their short lives. Palliative care can extend survival but cannot address the fundamental immune deficiency. Genetic testing of bulls before AI use has nearly eliminated the disease in managed Holstein populations. Continued vigilance in breeding programmes prevents recurrence.

What You Can Do

Test breeding bulls for BLAD carrier status before using in AI programmes
Avoid breeding from known BLAD carriers to prevent producing affected calves
Provide intensive supportive care for any affected calves while they survive
Contribute to breed-level genetic improvement by reporting and testing carrier animals