Modulation of Egg Elemental Metabolomics by Dietary Supplementation with Flavonoids and Orange Pulp (Citrus sinensis)

Dried orange pulp (Citrus sinensis) is known for its antioxidant properties. This study aimed to examine the effects of adding dried orange pulp (OP) to the layers' diets on the concentration of selected elements in the egg. The present work was part of a bigger project aiming to investigate the effect of orange pulp in layers' diets on the performance of birds and egg quality. There were three dietary treatments and 63 layers per treatment, with 189 layers in total. Cages were the experimental units, and seven cages were allocated per treatment (n = 7). The dietary treatments were (1) a control treatment (C) that involved a basal diet without orange pulp addition, (2) an OP treatment with the addition of 9% dried orange pulp, and (3) a hesperidin-naringin (EN) treatment with 0.767 g hesperidin and 0.002 g naringin added per kg of diet; these levels of hesperidin and naringin represent those present in dried orange pulp for the OP treatment. Birds were fed the diets for 30 days. The diets had similar energy and protein levels and contained the same vitamin and mineral premixes. The analyzed egg (yolk, albumen, shell) elemental profile consisted of As, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Ni, Sb, Se, Sr, V, and Zn and was determined via Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Dried orange pulp supplementation significantly altered the elemental profile. OP largely altered the element concentrations in albumen and egg yolk. Most notably, it decreased the concentrations of Co (p < 0.001), Fe (p < 0.001), Mn (p < 0.001), Ni (p = 0.046), and Se (p = 0.035) in egg yolk and those of Co (p = 0.011), Fe (p = 0.025), Cr (p = 0.049), Cu (p = 0.001), and Se (p = 0.014) in albumen. In addition, it decreased the concentrations of As (p = 0.025) and Ca (p = 0.025) in the eggshell. Principal component analysis was applied to the concentrations of the examined elements in all egg parts to explore the relationships between the elements and detect those capable of distinguishing samples, resulting in the apparent separation of yolk, albumen, and eggshell samples. Further analysis revealed that all samples were clustered into the three dietary treatments, resulting in 100% correct classification. The chelating and antioxidant capacities of flavonoids are intricate and rely on a variety of factors. OP supplementation modulated the deposition of specific elements in egg parts in comparison to those from layers fed a typical diet. Thus, this study indicated that eggs with specialized elemental profiles could be created.