The role of riboflavin refeeding in reversing deficiency effects on duck reproductive performance and embryonic development.

Riboflavin (vitamin B2) is essential for poultry reproduction and embryonic development. Riboflavin deficiency adversely affects egg hatchability and embryonic survival, but whether these effects are reversible remains unclear. This study aimed to assess the effect of riboflavin refeeding (RR) on reproductive performance, embryonic development, riboflavin status, antioxidant capacity, and hepatic metabolism in duck breeders and embryos. A total of 60 duck breeders (40 weeks, 3.45 ± 0.90 kg) were randomly assigned to two groups: a riboflavin-deficient (RD) group (n = 40) and a control (CON) group (n = 20). The RD group received a riboflavin-deficient diet (1.48 mg/kg), while the CON group was fed a riboflavin-sufficient (RF) diet (16.48 mg/kg) for 9 weeks. Following this period, the pigeons previously fed the riboflavin-deficient diet were randomly divided into two subgroups: one continued receiving the RD diet, and the other was refed a riboflavin-sufficient diet (RR) group. The RR and CON groups were maintained on the RF diet for an additional 5 weeks. Riboflavin deficiency reduced egg hatchability (P < 0.001), but hatchability was restored to near-normal levels within 1 week of refeeding (P > 0.05). Plasma and tissue riboflavin concentrations, along with hepatic flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) levels, were restored to CON levels after 5 weeks of refeeding (P > 0.05). RR improved hepatic antioxidant capacity (P < 0.05) including glutathione peroxidase (GPX), reduced glutathione (GSH) and glutathione reductase (GR), reduced lipid accumulation (P < 0.001) including total lipid (TL), triglycerides (TG), and free fatty acids (FFA), and restored liver histomorphology. Embryonic growth and development were also restored to levels comparable to those in riboflavin-sufficient conditions (P > 0.05). Metabolomic analysis revealed that RR partially restored metabolic balance related to protein, vitamin, and lipid metabolism. These findings indicated that RR over a 5-week period can effectively reverse the adverse effects of a 9-week deficiency. However, full restoration of antioxidant capacity and metabolic balance may require longer refeeding periods or higher doses. These findings highlight the crucial role of riboflavin in poultry health and provide insights for preventing and treating riboflavin deficiency.