Apparent digestibility (ileal and overall) of nutrients and endogenous nitrogen losses in growing pigs fed wheat (var. Soissons) or its by-products without or with xylanase supplementation

The main aims of this experiment were: 1) to study the sites and extent of digestion of the nutrients in wheat (var. Soissons) and its by-products (br an, middlings) and in recombined wheat (flour + bran + middlings); 2) the c ontribution of microbial action (VFA apparent production) and endogenous se cretion of N in the small intestine; and 3) interactions with an exogenous non-starch polysaccharide (NSP) degrading enzyme (xylanase). The post valve "T" caecal cannulae (PVTC, 12 pigs) and end-to-end ileo-rectal anastomosis (IRA, 30 pigs) ileal digesta collection methods with TiO2 and Cr2O3 as the indigestible markers, and the N-15-isotope dilution technique were used in this study. Four diets, based on wheat (W), recombined wheat (WR), wheat p lus bran (WB) or wheat plus middlings (WM) were used without or with xylana se addition. NSP content was highest in the diet based on wheat bran and lo west in the W and WR diets. Recombination of the milled fractions had no ef fect on digestibility values relative to the ground wheat. Negative correla tions (P < 0.001) occurred for apparent overall and ileal digestibility of dry matter (DM), energy, crude protein (CP) and amino acids with NSP conten t, As shown in some previous studies, NSP contributed to a higher ileal flo w of endogenous nitrogen (P ( 0.001) and volatile fatty acids (VFA) (P = 0. 021) and the proportion of DM fermented in the large intestine was increase d (P (0.001). Although statistically significant (P < 0.05), the improvemen ts associated with enzyme addition in overall apparent digestibility of DM, CP and gross energy were only of the order of 1% and those at the ileal le vel were less than 2% (P > 0.05). However, with the WE diet the improvement s for all three parameters were approximately 2% for overall apparent diges tibility and 4% for ileal apparent digestibility. (C) 2000 Elsevier Science BN. All rights reserved.