Objective: An experiment was conducted, using the ileal-cannulated animal model, to determine the nutrient value of fiber from corn and its co-products, and the effect of its increase in the diet on the pig’s ability to digest and utilize both fiber and the non-fiber portions of the diet when different nutritional strategies to supply energy (e.g. added fat) are implemented.

How research was conducted: For this experiment 18 growing pigs (BW = 33.8 ± 2.2 kg) were surgically fitted with a T-cannula in the distal ileum and allocated to 1 of 6 dietary treatment groups. Six dietary treatments were obtained by adding 0, 20, and 40% low-fat DDGS to corn-casein diets formulated with 2 and 6% SBO. Ileal digesta and fecal samples were collected and the apparent ileal and total tract digestibility of fat, fiber, and amino acids were determined.

Research findings: Results from the present experiment showed that the apparent digestibility of fat increased with dietary addition of extracted and intact fat from soybean oil and low-fat DDGS, respectively, but no increase was observed with addition of intact fat from low-fat DDGS to diets with high concentrations of extracted dietary fat from SBO. Low values of apparent digestibility of fat observed in diets with low dietary fat concentrations are possibly the result of the weigh of endogenous microbial fat losses on the fat output of these diets. Addition of low-fat DDGS to diets with high concentrations of extracted fat from soybean oil resulted in a quadratic response of the AID of NDF, and in a reduction of the ATTD of NDF. The high concentration of extracted fat in these diets may increase the transit time of digesta, resulting in the increase of fermentation time of fiber in the gastrointestinal tract. At low concentrations of dietary fat from soybean oil, the apparent digestibility of fiber at the terminal ileum and over the entire tract was not affected by the dietary increase of low-fat DDGS.

Results also showed that the apparent digestibility of amino acids was not affected by the dietary increase of fat, but was negatively associated with the concentration of low-fat DDGS, The decrease in the apparent digestibility of amino acids may be attributed to the effects of manufacture processes during the production of DDGS rather than the concentration of fiber in DDGS.

Importance to the industry: The present work suggests that the current panorama of high fiber diets is not as dire as previously thought since fiber from corn co-products can be fed to pigs without negative effects on the digestibility of fat and amino acids. We have also demonstrated that, if the diets are correctly formulated, quite high levels can be fed without impairment of performance. However the challenge of a new generation of co-products with a lower fat content means that digestibility of dietary fiber needs to be improved (e.g. using exogenous enzymes, further processing) to maximize the energy supply to avoid the extra-cost of adding additional fat to the diet. Even then, we have shown that fat added to diets high in reduced oil DDGS is well utilized by the pig. This provides confidence to pork producers and to nutritionists that classical approaches to diet formulation will be successful, allowing them the greatest flexibility in using corn c-products in practical diets when economics makes their use financially advantageous.

Contact information:
John F. Patience, Ph.D.
[email protected]
Professor, Dept. of Animal Science
201B Kildee Hall
Iowa State University
Ames, IA 50011-3150
Phone: (515) 294-5132""