Microbial Fermented Feed Affects Flavor Amino Acids and Yolk Trimethylamine of Duck Eggs Via Cecal Microbiota–Yolk Metabolites Crosstalk

Microbial fermented feed (MFF) is an integral part of the feed industry. It has been demonstrated to improve nutritional status as well as promote animal health. However, only a few studies have focused on its effect on the flavor of animal products and the potential underlying mechanisms. This study suggested that dietary supplementation of MFF significantly increased the content of flavor amino acids in duck eggs, along with reducing the concentration of yolk trimethylamine. MFF improved the jejunal histomorphology, caused an increase in beneficial bacteria and a decrease in harmful bacteria in the cecum, and regulated the flora involved in nutrient metabolism. Moreover, MFF regulated 34 annotated metabolites markedly enriched in three metabolic pathways. Correlation analysis showed that cecal microbiota and yolk metabolites were closely related to flavor-related indicators of duck eggs. Our study therefore provides a theoretical basis for improving avian egg flavor starting from the feed.