Untargeted UHPLC-MS metabolic profiling as a valuable tool for the evaluation of eggs quality parameters after dietary supplementation with oregano, thyme, sideritis tea and chamomile on brown laying hens

Introduction Bioactive constituents of medicinal-aromatic plants used as feed additives may affect the metabolic profile and oxidative stability of hen eggs. Objectives To determine the effects of dietary supplementation with a mixture of dried oregano, thyme, sideritis tea and chamomile on laying hen performance, egg quality parameters, and oxidative stability in the egg yolk were monitored. Methods In this trial 432 hens were allocated in two treatments (unsupplemented vs. supplemented with the mixture) and fed for 42 days. Eggs were collected at the end of the trial period, egg yolk was separated, extracted, and the total phenolic content (TPC) and oxidative stability was measured. Furthermore, LC-MS metabolic profile of eggs was studied and pathway analysis was elaborated in MetaboAnalyst to facilitate annotation of features. Results Overall, egg production and feed conversion ratio were not affected by the supplementation. However, eggs from the supplemented treatment showed improved shell thickness and strength, and yolk resistance to oxidation. Moreover, LC-MS metabolomic analysis of egg yolk of supplemented and unsupplemented layers showed significant variations and tight clustering in unsupervised principal component analysis due to different chemical profiling of egg yolk. LC-MS study showed that secondary metabolites of aromatic plants did not transfer into yolk, nevertheless the feed supplementation impacted the pathway metabolism of tyrosine, phenylalanine, propanate, and the biosynthesis of aminoacyl-tRNA, phenylalanine, tyrosine and tryptophan. Conclusions The dietary supplementation of layers with a mixture of dried medicinal aromatic plants affected shell thickness and strength, the lipid and protein oxidative stability and increased tyrosine and phenylalanine content in eggs.