Use of enzymes and inoculants to manipulate the feeding value of liquid fed DDGS for young pigs
Corn distiller’s dried grains with solubles (DDGS) is an alternative nutrient and energy source in swine diets. It has been suggested as a functional ingredient in weanling pig diets via decreasing digesta viscosity, and inhibition of enteric pathogen growth due to high insoluble fiber content. DDGS feeding value may be enhanced through fiber hydrolysis promotion, probiotic growth (e.g. Lactobacilli), production of organic acids (particularly lactic acid), and prebiotic formation (e.g. arabinoxylan oligosaccharides) in liquid feed. Micro-scale fermentations were initially conducted to establish effective conditions for manipulating DDGS feeding value. Three studies were then performed to determine the effects of (1) including untreated DDGS in a conventional diet, (2) steeping DDGS with enzymes (xylanase and β-glucanase) for inclusion in liquid feed, and (3) partially fermenting DDGS with a silage inoculant and enzymes for inclusion in liquid feed on growth performance and gut function of weanling pigs. In micro-scale fermentations partially fermented DDGS was produced via incubation at 40°C (16% dry matter) between 1 and 7 days with silage inoculant and enzymes, yielding >100 mM lactic acid, pH <4.5, and acetic acid <40 mM. However, in macro-scale fermentations, variability in acetic acid and lactic acid concentrations was observed. Liquid feeding partially fermented DDGS improved average daily gain in piglets weaned at low body weight (5.8 ± 0.6 kg) in week 7 post-weaning compared to pigs fed unfermented DDGS (P<0.05). Intestinal weights and digesta organic acid profiles were influenced by dietary treatments throughout the nursery period (P<0.10). Liquid feeding partially fermented DDGS reduced Chao 1 alpha-diversity measures in the ileal mucosa and feces of pigs on day 42 post-weaning (P<0.05) and resulted in the establishment of an abundant ileal mucosa Lactobacillus proportion. Liquid feeding partially fermented DDGS with silage inoculants and enzymes was shown to positively impact growth of pigs under challenge and result in probiotic colonization of the ileal mucosa. Efforts must be taken to improve consistency in fermentation conditions, identify relevant quality markers, and elucidate optimal DDGS inclusion levels and inclusion timing in order to establish a viable feeding program for practical application.