FMO3 is a genetic defect found in RDM/SRB/FAY cattle. The mutation gives a fishy off-flavour/ smell  in the milk. The defect is due to lack of degradation of the TMA (trimethylamin) protein in the milk. The defect is inherited recessively, i.e. a cow must inherit the defect from both parents for the fishy off-flavour to be present in its milk. Animals with the defect, or carriers, are viable and have no visible signs of the defect.

Carriers of FMO3 can be identified by a DNA test.

Information about multiple birth