#15-115

Complete

Date Full Report Received

06/27/2016

Date Abstract Report Received

06/27/2016

Investigation

Institution:
Primary Investigator:

Distillers dried grains with solubles (DDGS), wheat middlings, and soybean hulls are cost-effective co-products that may replace some corn in swine diets. However, these co-products contain more dietary fiber and less starch compared with corn. The amount of energy obtained by pigs consuming dietary fiber is less compared with pigs consuming starch. The digestibility of dietary fiber varies among sources of dietary fiber and, therefore, energy absorbed also varies. Water binding capacity and bulk density are two physical characteristics of dietary fiber that were hypothesized to be related to digestibility of dietary fiber by pigs and, therefore, the energy obtained by the pig from consuming dietary fiber. Therefore, this experiment was conducted to test the hypothesis that dietary physical characteristics of dietary fiber are correlated with the digestibility of dietary fiber fractions and energy and may be used to predict the disappearance of dietary fiber fractions and energy along the gastrointestinal tract of the pig. Results indicated that water binding capacity and bulk density were not correlated with ileal or total tract digestibility of dietary fiber fractions or energy. However, bulk density was positively correlated with the apparent cecal digestibility of gross energy and this implies that as the bulk density of diets decreases; the apparent digestibility of gross energy in the cecum of pigs but this does not contribute a great amount of energy supply to the pig because DDGS, wheat middlings, and soybean hulls contain only small quantities of soluble dietary fiber. Insoluble dietary fiber, on the other hand, is mostly fermented in the colon of pigs and contributes a significant amount of energy to pigs fed diets containing DDGS, wheat middlings, or soybean hulls because the concentration of insoluble dietary fiber is greater when these co-products are added to a corn-soybean meal diet. Wheat middlings contains more fermentable dietary fiber fractions compared with DDGS and soybean hulls, but the digestible energy (DE) in DDGS is similar to that of wheat middlings because of the greater concentration of fat in DDGS compared with wheat middlings. The DE in soybean hulls is mostly attributed to insoluble dietary fiber fermentation in the colon, and this is the reason the DE in soybean hulls is less than in DDGS or wheat middlings.
Key Findings:
• The physical characteristics of dietary fiber in experimental diets were not correlated with the digestibility of energy or dietary fiber fractions in experimental diets.
• Soluble dietary fiber is mostly fermented in the cecum of pigs, but this does not contribute a great amount of energy supply to the pig due to the low concentration of soluble dietary fiber in most swine diets.
• Insoluble dietary fiber is mostly fermented in the colon of pigs and contributes a significant energy supply to pigs fed diets containing DDGS, wheat middlings, or soybean hulls.
• Dietary fiber fractions in wheat middlings are more fermentable compared with the dietary fiber fractions in DDGS and soybean hulls.
• The digestible energy in soybean hulls is mostly attributed to insoluble dietary fiber fermentation in the colon, and this is the reason the DE in soybean hulls is less than in DDGS or wheat middlings.