Fishy taint / Fish Milk / Trimethylaminuria (FMO3-related) - Cattle

Fishy taint and Fish Milk in cattle

This DNA test examines the FMO3 variant c.712C>T that can cause fishy taint in milk. The trait is also known as Fish Milk, trimethylaminuria or TMAU. Reduced FMO3 function limits the conversion of trimethylamine, which can produce a fish-like smell or taste in milk.

What does this mean for milk and breeding?

• Milk quality: affected cows can produce milk with a clear fishy odour or flavour.
• Genetic cause: FMO3 is involved in breaking down trimethylamine, a compound with a strong smell.
• Breed context: the variant has mainly been described in Swedish Red and White cattle.

Practical value of this test

The result helps distinguish clear animals, carriers and genetically affected animals. For dairy breeders this supports prevention of milk quality problems, targeted carrier management and avoidance of risk matings. The trait is inherited as autosomal recessive.