Trimethylamine and Fishy Taint in Eggs

SummaryA “fishy” or “crabby” taint due to trimethylamine (TMA) occurs when the hen's capacity for metabolizing this substance is impaired and overloaded. Recently the causative factors were identified and their roles were determined.A strongly inherited genetic factor present in white and brown-egg breeds restricts the synthesis of TMA oxidase which is mainly responsible for the metabolism of TMA. This enzyme is inhibited by goitrin and soluble tannins supplied by both low and high glucosinolate rapeseed meals.TMA is released by the action of enteric bacteria on choline and TMA oxide. Both are present in fish meal and the former occurs in rapeseed meal in the form of sinapine. TMA derived from the choline in other commonly used dietary ingredients is sufficient to produce the taint when the inherent oxidation capacity of the hens is very low. The elimination of this defect by selective breeding is feasible and would provide the most effective solution to the problem.