A triple enrichment of three bioactive nutrients in eggs of laying hens elicited moderate interactions on related gene expression

Background: Dietary intakes of docosahexaenoic acid (DHA), 25-hydroxyvitamin D3 (25-OH D3), and astaxanthin (AST) are associated with reduced risks of chronic diseases. Because the commonly consumed foods by the public do not provide adequate intakes of these three bioactive nutrients, chicken eggs have emerged as an economical and convenient carrier for such dietary supplementation. The objective of this study was to enrich poultry eggs with DHA, 25-OH D3, and AST and to explore the potential interactions from the enrichments. Methods: Fifty laying hens were individually housed and fed a corn-soybean meal basal diet (BD), BD + DHA, BD + DHA + 25-OH D3, BD + DHA + AST, or BD + DHA + 25-OH D3 + AST for 6 weeks (n = 10). Animal health and production status, fatty acid profiles, 25-OH D3 and AST levels, and gene expressions in eggs, plasma, and tissues were measured. Data were analyzed by one-way analysis of variance (ANOVA). Results: BD + DHA resulted in 16 mg DHA/g yolk, whereas the enrichment was decreased by the addition of AST (13%) but not 25-OH D3. DHA was also deposited into the liver and adipose tissue. Egg yolk and hepatic arachidonic acid (ARA) concentrations were lowered (34%) in BD + DHA in response to the DHA supplementation. Enrichments of 25-OH D3 and AST reached 160 ng/g yolk and 5.5 µg/g yolk, respectively. BD + DHA upregulated hepatic expressions of ELOVL5 and SRB1, but the addition of 25-OH D3 diminished the ELOVL5 upregulation and downregulated FABP2 and the addition of AST lowered CPT1A expressions. Conclusions: This study demonstrated a successful triple enrichment of DHA, 25-OH D3, and AST in the egg yolks to nutritionally relevant levels for human consumption. The additional 25-OH D3 and (or) AST supplementations prompted novel effects on the yolk DHA enrichment and lipid-related gene expressions in the liver and intestine. Our findings provided the scientific evidence and feasibility for the animal and food industry to produce a new-type of health-promoting eggs.