Effects of feeding corn distillers dried grains with solubles diets without or with supplemental enzymes on growth performance of pigs: a meta-analysis

A meta-analysis was conducted to determine the effects of the dietary energy system (net energy or metabolizable energy), oil content of corn distillers dried grains with solubles (cDDGS), diet inclusion levels, and pig age on growth performance of pigs fed cDDGS-based diets. Mean differences of average daily gain (ADG), average daily feed intake (ADFI), and gain:feed (G:F) were calculated and expressed as a percentage change relative to feeding corn–soybean meal (SBM)- and cDDGS-based diets to nursery [body weight (BW) < 25 kg] and growing-finishing (BW > 25 kg) pigs, and to compare the effects of supplementing various types of exogenous enzymes without or with phytase on growth performance. A total of 27 studies with 106 growth performance observations were included in the cDDGS dataset, and 34 studies with 84 observations for enzyme responses in cDDGS diets were used in the enzyme dataset. Approximately, 64.7% of the observations showed no change, and 26.7% of observations showed a reduction in ADG, ADFI, and G:F when feeding cDDGS-based diets to the nursery and growing-finishing pigs compared with feeding corn–SBM-based diets. Furthermore, feeding cDDGS diets resulted in decreased (P < 0.01) mean difference of ADG (–4.27%) and G:F (–1.99%) for nursery pigs, and decreased (P < 0.01) mean difference of ADG (–1.68%) and G:F (–1.06%) for growing–finishing pigs. Every percentage unit increase in the inclusion level of cDDGS in growing–finishing pig diet was associated with a decrease (P < 0.01) in ADG (–0.10%) and ADFI (–0.09%). Feeding high oil (≥10% ether extract) cDDGS-based diets to pigs resulted in a 2.96% reduction in ADFI whereas feeding reduced-oil (<10% ether extract) cDDGS-based diets reduced G:F by 1.56% compared with pigs fed corn–SBM-based diets. Supplementation of exogenous enzymes improved (P < 0.05) the mean difference of ADG and G:F by 1.94% and 2.65%, respectively, in corn–SBM-based diets, and by 2.67% and 1.87%, respectively, in cDDGS diets. Supplementation of exogenous protease, enzyme cocktail, or xylanase improved (P < 0.05) ADG by 7.29%, 2.64%, and 2.48% in pigs fed corn–SBM-based diets, respectively. There were no differences between the dietary addition of single enzymes and enzyme combinations for any growth performance parameters in corn–SBM- or cDDGS-based diets. In conclusion, feeding cDDGS-based diets slightly reduces the growth performance of nursery and growing–finishing pigs, but supplementation of xylanase or enzyme cocktail can improve G:F of pigs fed cDDGS-based diets.