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

## TL;DR

Replacing up to 37.5% of corn with an aged brown rice–wheat mixture in duck feed improves egg white quality and changes yolk fat content without harming duck productivity.

## Contribution

This study is the first to evaluate the effects of replacing corn with an aged brown rice–wheat mixture in laying duck diets.

## Key findings

- Replacing corn with 12.5% to 37.5% aged brown rice–wheat mixture did not harm laying performance but improved egg white quality and altered yolk fatty acids.
- A 50% substitution reduced nutrient digestibility and serum triglycerides while lowering laying rate and economic benefits.
- The optimal substitution level for productivity and economics was 37.5%.

## Abstract

Brown rice and wheat are common energy feed substitutes for corn in poultry diets. But there are few reports on the replacement of corn with a mixture of brown rice and wheat. This study aimed to explore the application effect of replacing equal amounts of corn with an aged brown rice–wheat mixture. The results showed that substitution levels of 12.5% to 37.5% did not negatively impact laying performance and economic benefits, but it reduced yolk color and yolk polyunsaturated fatty acids, improved egg white quality, and increased yolk monounsaturated fatty acids. At 50% substitution, nutrient digestibility declined significantly. The highest laying performance and economic benefits could be achieved at a level of 37.5%. Therefore, it is feasible to use a suitable proportion of ABR–wheat mixture as a substitute for corn in egg duck production, which is significant for scientifically destocking aged rice and alleviating corn shortages.

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 (p > 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 (p < 0.05) over 12 weeks. The albumen height and Haugh unit showed a quadratic increase in weeks 4 and 8 (p < 0.05). The relative content of monounsaturated fatty acids (MUFA) increased linearly (p < 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 (p < 0.05). The triglycerides (TG) content in serum showed a significant secondary change (p < 0.05), with the 50% group significantly lower than the other treatment groups (p < 0.05). The apparent digestibility of ether extract (EE) in the diets decreased linearly (p < 0.05). The apparent digestibility of crude protein (CP) in the diets was significantly reduced with the 50% group (p < 0.05), while there was no significant difference between the 0% and 37.5% groups (p > 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.