Evaluation of ME predictions and the impact of feeding maize distillers dried grains with solubles with variable oil content on growth performance, carcass composition, and pork fat quality of growing-finishing pigs

Abstract

A total of 432 pigs (initial BW: 25.8±5.1kg) were used to evaluate growth performance, carcass characteristics, and pork fat quality of growing-finishing pigs fed maize–soybean meal diets containing 40% distillers dried grains with solubles (DDGS) with variable ether extract (EE) content, but similar predicted ME concentration (3232 to 3315kcal/kg predicted by a commercial service). Pigs were blocked by initial BW, and within blocks, pens were allotted randomly to 1 of 4 dietary treatments (9 pigs/pen, 12 replicates/treatment) in a 4-phase feeding program (26–50kg, 50–75kg, 75–100kg, and 100–120kg BW). Dietary treatments consisted of: (1) maize–soybean meal (CON); (2) 40% low-oil DDGS (59g/kg EE; LOW); (3) 40% medium-oil DDGS (99g/kg EE; MED); and (4) 40% high-oil DDGS (142g/kg EE; HIGH). Diets contained similar concentrations of standardized ileal digestible amino acids and standardized total tract digestible P within each phase. Overall, ADFI of pigs fed CON was greater (P<0.05) than those fed MED and HIGH, resulting in pigs fed CON having greater (P<0.05) overall ADG than pigs fed LOW, MED, and HIGH diets. However, ADFI and ADG did not differ among DDGS treatments, but pigs fed LOW had reduced (P<0.05) G:F compared with the other treatments. Pigs fed CON had greater (P<0.05) HCW, carcass yield, and LM area than those fed the DDGS diets, but there were no differences among DDGS treatments. No treatment differences were observed for backfat depth and percentage of carcass fat-free lean. Back, belly, and jowl fat iodine value of pigs fed LOW and MED were less (P<0.01) than in pigs fed HIGH but greater (P<0.01) than in pigs fed CON. Based on the observed overall G:F responses, dietary ME content of LOW was less than MED, HIGH, and CON diets, indicating a slight overestimation of predicted ME concentration for the low-oil DDGS source using either the commercial service estimates or the Anderson et al. (2012) equations. In conclusion, including 40% DDGS in maize–soybean meal-based diets negatively impacted the growth performance of growing-finishing pigs. However, reduced EE content of DDGS sources did not affect ADG, ADFI, and carcass composition, and led to improvements in pork fat quality. These results suggest that current ME predictions need to be refined for more accurate estimation of ME content for low-oil DDGS sources for swine.