Trimethylamine Production in the Caeca and Small Intestine as a Cause of Fishy Taints in Eggs

The caeca and small intestine of chickens consistently contain trimethylamine (TMA). The caecal contents in the birds studied ranged from 4 to 55 μg TMA/g and contained the higher concentrations when the diet contained rapeseed meal or supplementary choline. The amounts of TMA in the small intestine were lower (1 to 21 μg/g) and were less influenced by dietary composition. Supplementary choline in the diet of laying birds induced the production of tainted eggs by some birds. The yolks of tainted eggs contained concentrations of TMA which were consistent for each bird. TMA was also present in the follicular yolks of all sizes in the ovaries of birds which laid tainted eggs. It is postulated that, in birds laying tainted eggs, failure of the liver to oxidize TMA is responsible for deposition of TMA in egg yolk.