Bovine citrullinemia / BC (ASS1-related) - Cattle

About bovine citrullinemia

Bovine citrullinemia, also called BC, is an inherited metabolic disorder in cattle. This analysis detects the ASS1 c.256C>T variant. The variant disrupts argininosuccinate synthase, an enzyme in the urea cycle that is needed to remove ammonia safely.

Affected calves often appear normal at birth, but rapidly develop severe neurological signs because ammonia and related compounds accumulate in the blood. Typical signs include depression, inability to rise, tremors, seizures, apparent blindness, head pressing, coma and rapid death.

Practical value of this test

The test clarifies whether an animal is clear, a carrier, or carries two copies of the tested BC variant. This is especially relevant in breeding programmes involving Holstein Friesian, Brown Swiss/Braunvieh and Blanco Orejinegro cattle, where the variant has been described.

• Clear: the tested ASS1 variant was not detected.
• Carrier: the animal is usually not clinically affected, but can pass the variant to offspring.
• Affected: two copies cause bovine citrullinemia with a severe, usually fatal course in calves.

Targeted carrier identification helps avoid risk matings while preserving valuable breeding animals in the herd.