Differential impacts of dietary distillers' dried grains with solubles levels on Cherry Valley ducks: Insights into meat quality and intestinal health

This study evaluated the effects of dietary distillers' dried grains with solubles (DDGS) levels on nutrient digestibility, meat quality, and intestinal health in meat ducks. In a 28-d feeding trial (Exp. 1), 400 Cherry Valley ducks (average body weight [BW] = 658.73 ± 3.79 g, age = 14 d old) were randomly assigned to five groups receiving 0 (CON), 5%, 10%, 15%, or 20% DDGS. Each treatment had eight replicates (cages) with ten ducks per replicate. A subsequent metabolism trial (Exp. 2) was conducted using the same diets. At 42 d of age, two ducks per replicate were randomly selected and fed diets supplemented with 0.5% titanium dioxide for digestibility determination. Results showed that 20% DDGS significantly reduced the digestibility of gross energy (GE; <i>P</i> = 0.010) and crude protein (CP; <i>P</i> = 0.026) compared to the CON group. As DDGS increased, CP digestibility decreased linearly (<i>P</i> = 0.001) and quadratically (<i>P</i> = 0.049). Serum triglyceride levels were significantly increased in the 20% DDGS group (<i>P</i> = 0.034). For meat quality, DDGS decreased breast muscle lightness (<i>L</i>∗_{45 min}, <i>P</i> = 0.031) and increased yellowness (<i>b</i>∗_{45 min}, <i>P</i> = 0.028). Shear force of breast muscle increased significantly in the 20% DDGS group (<i>P</i> = 0.009) and increased linearly with DDGS (<i>P</i> = 0.015). Histologically, DDGS supplementation decreased muscle fiber density (<i>P</i> = 0.005) and jejunal villus height (<i>P</i> = 0.001), but increased muscle fiber diameter (<i>P</i> = 0.027). Both muscle fiber diameter and density showed significant linear relationships with increasing DDGS levels (<i>P</i> = 0.003 and <i>P</i> < 0.001, respectively). Cecal butyric acid level decreased at 15% and 20% inclusion (<i>P</i> < 0.05), and valeric acid level decreased at 20% inclusion (<i>P</i> < 0.001). Notably, 10% DDGS increased cecal microbial diversity and the abundance of beneficial Prevotellaceae (<i>P</i> < 0.05). In summary, dietary inclusion of 5%-20% DDGS did not adversely affect growth performance, carcass traits, and organ indices in ducks. While higher levels impaired some meat quality traits, 10% DDGS was identified as the optimal level, improving intestinal microbiota without compromising overall production performance. These findings support the partial replacement of corn-soybean meal with DDGS in duck diets.