PSIV-13 Cell Wall Bound Ferulic and Coumaric Acids in Diets Based on Corn and Soybean Meal or Corn, Soybean Meal, and Distiller Dried Grains with Solubles Are Poorly Fermented in the Intestinal Tract of Pigs

Abstract

Abstract Phenolic acids are bound to cell wall polymers in corn and distillers dried grains with solubles (DDGS) and contribute to the low digestibility of fiber in corn-based ingredients. Phenolic acids link arabinoxylans to lignin and may substitute sidechains of arabinoxylans, which precludes fermentation. To develop enzymes to aid in separating phenolic acids from arabinoxylans, the natural fermentation of phenolic acid in the intestinal tract of pigs needs to be known. Therefore, an experiment was conducted to test the hypothesis that phenolic acids are poorly fermented by pigs. A corn-soybean meal (SBM) diet and a corn-SBM-DDGS diet were fed to 24 pigs (initial body weight: 61.71 ± 5.39 kg) in a randomized complete block design with 4 blocks and a total of 12 pigs per diet. Diets were fed for 22 d; feces were collected during the last 5d. Concentrations of phenolic acids were analyzed in diets and feces using reversed phase ultrahigh-performance liquid chromatography coupled with mass spectrometry. Data were analyzed using the PROC MIXED of SAS with pig as the experimental unit. Results indicated that concentrations of bound phenolic acids were greater (P < 0.05) in feces from pigs fed the corn-SBM-DDGS diet than from pigs fed the corn-SBM diet (Table 1). Disappearance (%) of free coumaric acid and bound ferulic acid in the intestinal tract of pigs was not different between the 2 diets. In contrast, disappearance of bound coumaric acid was greater (P < 0.05) from the corn-SBM diet than from the corn-SBM-DDGS diet, but disappearance of bound ferulic acid and bound coumaric acid was less than 50% confirming that phenolic acids may hinder fermentation. In conclusion, ferulic acid and coumaric acid appear to be barriers for fermentation of arabinoxylans in pigs and enzymes that release phenolic acids may be needed to increase fermentation of corn fiber.