Feeding Increasing Levels of Reduced-oil Distillers Dried Grains with Solubles from Two Ethanol Fermentation Methods Impacts Finishing Pig Growth Performance and Belly Quality
Reduced-oil distillers dried grains with solubles (DDGS) are an affordable source of energy in finishing pig diets, but differences in DDGS fermentation method on finishing pig growth performance and belly quality is relatively unknown. The objectives of this study were: 1) determine the influence of increasing dietary inclusion rate of hot fermentation (HF) and cold fermentation (CF) DDGS on growth performance, carcass characteristics and belly quality, and 2) compare the effect of HF and CF DDGS on finishing pig growth performance, carcass characteristics, and belly quality. Crossbred pigs (n = 200) were used in a randomized complete block design and assigned to one of eight treatments with varying inclusion rates of HF and CF DDGS (0, 20, 40, or 60%) and a diet with 40% inclusion of CF DDGS and withdrawal period. A 5-phase feeding program was utilized with diets formulated to be isocaloric and isolysinic. Pigs were harvested at a commercial abattoir when the average pen weight reached 122.5 kg. Two bellies per pen were collected for analyses. Orthogonal polynomial contrasts were used to determine linear and curvilinear effects. As inclusion rate of CF DDGS increased, overall average daily gain (ADG) and gain to feed ratio (G:F) decreased linearly (P < 0.0001), but HF DDGS did not influence ADG (P >0.24) or G:F (P >0.25). Pigs fed CF DDGS had decreased ADG (P < 0.001) and ADFI (P = 0.03) compared to HF DDGS. As inclusion rate of CF DDGS increased, hot carcass weight decreased linearly (P = 0.02), however, as inclusion rate of HF DDGS increased a quadratic effect was observed (P = 0.04). Carcass yield linearly decreased (P = 0.01) as HF DDGS inclusion increased and tended to decrease linearly (P = 0.08) as CF DDGS inclusion rate increased. Carcass yield was not different between CF and HF DDGS (P = 0.12). As DDGS inclusion rate increased, regardless of fermentation method, belly quality decreased, evidenced by a linear decrease in belly flop scores (P < 0.0001) and percentage of saturated fatty acids (P < 0.0001). Iodine values (P < 0.0001) and percentage of polyunsaturated fatty acids (P < 0.0001) increased linearly with inclusion rate regardless of fermentation method. Increasing the inclusion rate of HF DDGS did not affect growth performance, but decreased belly quality, however, feeding increasing levels of CF DDGS decreased growth performance and belly quality. Furthermore, pigs fed HF DDGS displayed improved growth performance compared to CF DDGS.