Effects of Replacing Corn with an Aged Brown Rice-Wheat Mixture on Laying Performance, Egg Quality and Nutrient Digestibility in Laying Ducks.

This study examined the effects of replacing corn with an aged brown rice (ABR)-wheat mixture (ABR: wheat = 85%:15%) on laying performance, egg quality, yolk fatty acid profile, economic benefits, serum biochemistry, and nutrient digestibility in laying ducks. A 12-week trial with six hundred 32-week-old Jinding ducks were randomly divided into five groups, with 10 replicates per group, and each replicate contained 12 ducks. The levels of ABR-wheat mixture in the diet were 0%, 12.5%, 25%, 37.5%, and 50%, respectively, to replace equal amounts of corn. The basic diet of the control group was corn-soybean meal (corn accounted for 50%). The experimental period was 12 weeks (from 32 to 43 weeks old). No significant differences were observed in laying performances ( > 0.05). From a numerical perspective, the duck-housed laying rate and egg mass were highest in the 37.5% group and lowest in the 50% group. Yolk color declined linearly ( < 0.05) over 12 weeks. The albumen height and Haugh unit showed a quadratic increase in weeks 4 and 8 ( < 0.05). The relative content of monounsaturated fatty acids (MUFA) increased linearly ( < 0.05), while the relative content of polyunsaturated fatty acids (PUFA), ω-3 PUFA, ω-6 PUFA, and ω-6/ω-3 PUFA decreased linearly in egg yolks ( < 0.05). The triglycerides (TG) content in serum showed a significant secondary change ( < 0.05), with the 50% group significantly lower than the other treatment groups ( < 0.05). The apparent digestibility of ether extract (EE) in the diets decreased linearly ( < 0.05). The apparent digestibility of crude protein (CP) in the diets was significantly reduced with the 50% group ( < 0.05), while there was no significant difference between the 0% and 37.5% groups ( > 0.05). Compared with the control group, economic analysis revealed net gains of 0.04-0.10 USD/duck at ≤37.5% substitution, but a loss (-0.04 USD) at 50%. In conclusion, the ABR-wheat mixture could reduce the yolk color and yolk PUFA content, but it could improve albumen quality and increase yolk MUFA content. High-level ABR-wheat mixture (50%) significantly reduced the TG content in serum and nutrient digestibility of the diet and also showed a numerical decrease in laying rate and egg mass. Our findings suggest that up to a 37.5% ABR-wheat mixture can effectively replace corn in laying duck diets without negatively affecting laying performance, while improving albumen quality and altering yolk fatty acid composition.