350 - Meta-analysis of the Effects of Dietary Inclusion of Dry Distillers Grains with Solubles (DDGS) on Performance, Fermentation, Carcass Characteristics, and Nitrogen Efficiency in Sheep

Abstract: We conducted a meta-analysis to evaluate the effects of dietary supplementation of dry distillers grains with solubles (DDGS) on performance, fermentation, carcass characteristics, and nitrogen efficiency in meat sheep. A total of 36 peer-reviewed manuscripts from 1997 to 2021 met the inclusion criteria for the analysis. Data from 940 sheep (29.1±11.5 kg) were used to estimate the magnitude of the effect between DDGS and control (No DDGS) treatments weighted by inverse variance using a robust variance estimation. Categorical and continuous covariates, like breed (pure or crossbreed), CP, NDF, and DDGS inclusion rate (0 to 100%) were adjusted to a mixed model to perform a meta-regression and subset analysis. Dietary DDGS increased (P < 0.05) dry matter digestibility (75.9 vs.74.9 %), neutral detergent fiber digestibility (55.9 vs. 53.8%) with respect to the control. Compared with the control, dietary DDGS increased (P < 0.01) final body weight (51.4 vs. 50.4 kg) and tended to increase (P = 0.06) average daily gain (254.1 vs. 247.6 g/d) in sheep. Similarly, dietary DDGS tended to increase (P < 0.10) hot and cold carcass weight (25.5 vs. 24.6 kg; 21.1 vs. 19.8 kg), and meat redness (16.3 vs. 16.6) compared with the control. Dietary DDGS reduced acetate molar proportions (50.1 vs. 52.0%) and acetate: propionate ratio (1.63 vs. 1.87; P = 0.02). The subset analysis revealed that breed and DDGS levels in the diet influenced yield grade and carcass weight. Dietary inclusion of DDGS linearly increased (P < 0.05) nitrogen intake and rumen NH3-N, but also urinary nitrogen. The inclusion rate of DDGS should not exceed 30% in the diet to prevent negative effects on nitrogen metabolism, rumen fermentation, and carcass characteristics in meat sheep. Collectively, this study supports the inclusion of DDGS in meat sheep diets to increase performance and meat quality.