Effect of heat stress and feed type on trimethylamine concentration and fishy odor of duck eggs

Abstract

We investigated the effect of heat stress and feed type on the trimethylamine (TMA) concentration and the fishy odor of duck eggs (Study 1) and the relationship between the TMA level in serum and egg content (Study 2). In Study 1, pooled egg samples (n = 75) were divided by feed type (CP12, n = 24; CP18, n = 27; CP20, n = 24) and heat stress (no, n = 49; moderate, n = 15; severe, n = 11). The collected samples were obtained for TMA analysis and sensory testing. In Study 2, a total of 15 egg and 15 serum samples from no heat stress (n = 10) and moderate heat stress groups (n = 5) were included in the TMA analysis. In Study 1, the TMA concentration of egg yolk in the severe heat stress was higher than the moderate and no heat stress (P = 0.034), while the CP20 was higher than the CP18 and CP12 (P = 0.008). Heat stress and feed types did not affect the fishy odor rating score of egg yolk and egg white (P > 0.05). The TMA concentration of egg yolk positively correlated with the fishy odor score (P = 0.010). In study 2, the serum TMA concentration was positively correlated with egg yolk TMA (P < 0.05). In conclusion, the heat stress and feed type affected the TMA concentration of egg yolk but not egg white. An increased egg TMA concentration was found in the ducks exposed to severe heat stress or consumed feed containing high choline. There was no effect of heat stress and feed types on the fishy odor of duck eggs. Lastly, the TMA concentration in egg yolk was positively correlated with the TMA concentration in the serum.