Dietary Schizochytrium algal powder is an effective strategy to develop docosahexaenoic acid-enriched eggs in Chinese yellow-feathered laying quails.

Although docosahexaenoic acid (DHA) enrichment in eggs has been extensively studied in laying hens, research on DHA-fortified eggs in quails remains limited. This study evaluated the effects of graded levels of Schizochytrium algae powder (SAP) on production performance, egg quality, egg DHA enrichment and fatty acid composition, and related gene expression responsible for DHA absorption and transport in yellow-feathered laying quails. A total of 960 birds were randomly assigned to four dietary groups (0%, 0.4%, 0.8%, or 1.2% SAP) for an eight-week trial, with each group consisting of six replicates of forty quails each. A quadratic response was observed for egg production and egg mass (P < 0.05), with the 0.4% SAP group higher than the control group (P < 0.05). A significant decreasing linear trend in mortality was observed with increasing SAP levels (P < 0.05). Egg yolk color responded linearly and quadratically to dietary SAP at both 4 and 8 weeks (P < 0.05), with all supplemented groups exhibiting higher values than the control (P < 0.05). DHA content in whole egg and yolk exhibited linear and quadratic increases with SAP supplementation at all timepoints (P < 0.05), resulting in higher levels than the control in all SAP-treated groups (P < 0.05) and plateauing at the 0.8% inclusion level. Moreover, SAP supplementation linearly elevated total omega-3 polyunsaturated fatty acid content and the omega-3/omega-6 ratio, while linearly reducing γ-linolenic acid and arachidonic acid concentrations in yolk (P < 0.05). Transcriptional analysis revealed linear upregulation of key genes involved in DHA absorption and transport in the duodenum, jejunum, and liver in response to SAP supplementation (P < 0.05). These findings demonstrate that dietary supplementation with SAP quadratically increased production performance, improved yolk color, enriched egg DHA content, elevated the omega-3/omega-6 ratio, and modulated the expression of genes involved in DHA absorption and transport. Collectively, this study provides an effective strategy for developing DHA-enriched quail eggs, with an optimal dietary SAP inclusion range of 0.4%-0.8%.