Pork fat quality of pigs fed distillers dried grains with solubles with variable oil content and evaluation of iodine value prediction equations.

Back, belly, and jowl fat samples of pigs fed control corn-soybean meal-based diets and diets containing 4 sources of distillers dried grains with solubles (DDGS) were used to determine the impact of feeding DDGS with variable oil content on pork fat quality and to evaluate the precision and accuracy of published iodine value (IV) prediction equations. Dietary treatments consisted of 4 corn-soybean meal diets containing 40% DDGS from different sources with 10.7, 5.6, 14.2, or 16.0% ether extract (EE; as-fed) content. Diets did not contain any other supplemental lipid sources. Regardless of fat depot, SFA content (g/100 g fat) of pigs fed 5.6% EE DDGS (35.4) was greater ( < 0.05) than that of pigs fed 14.2 or 16.0% EE DDGS sources (34.4 and 30.2, respectively) and tended to be greater ( < 0.10) than that of pigs fed 10.7% EE DDGS (34.6). Pigs fed 10.7 and 14.2% EE DDGS had greater ( < 0.01) SFA concentration than pigs fed 16.0% EE DDGS. Regardless of fat depot, MUFA content (g/100 g fat) of pigs fed 10.7, 5.6, and 14.2% DDGS sources were similar (43.7, 43.1, and 43.0, respectively) but were greater ( < 0.01) than that of pigs fed 16.0% EE DDGS (40.0). A dietary treatment × fat depot interaction was observed for PUFA ( < 0.05) and IV ( = 0.079). Pigs fed 10.7, 5.6, and 14.2% DDGS sources had reduced ( < 0.01) PUFA concentration and IV compared with pigs fed 16.0% EE DDGS, but the magnitude of responses in PUFA and IV to the variable oil content of DDGS was greater in backfat than in belly and jowl fat. Carcass fat IV data were used to evaluate prediction error (PE) and bias of published carcass fat IV prediction equations. Equations using dietary C18:2 content or IV product as a single predictor resulted in highly variable PE (g/100 g) ranging from 3.43 to 8.36 and bias (g/100 g) ranging from -5.05 to 5.66. Using equations that included additional diet composition information and pig growth performance factors decreased PE (3.27 to 4.73) and bias (-3.37 to 1.73) of prediction for backfat compared with equations only based on the characteristics of dietary lipid, but this improvement was limited in the prediction for belly and jowl fat. Predictions based on percentage of DDGS in diets had the greatest PE (6.66 to 9.19) and bias (5.53 to 8.00).