DIETARY LEVEL AND SOURCE OF NEUTRAL DETERGENT FIBER AND ILEAL ENDOGENOUS NITROGEN FLOW IN PIGS

Two experiments were conducted to study the effect of dietary level an d source of neutral detergent fiber (NDF) on ileal dry matter flow and on total and endogenous N flow at the terminal ileum. Twenty-two cros sbred 6-wk-old castrated male pigs with an average BW of 9 kg were use d. The pigs were fitted with a post-valvular T-cecal cannula and two i ndwelling blood catheters. During the experimental period of 10 d, the pigs were 11 wk of age with an average BW of 14 kg. They were fed 2.6 times their maintenance requirement for energy of a corn starch-based , semisynthetic diet. The diets contained 178 g of soy isolate/kg as t he only source of nitrogen (N). In diets of Exp. 1, purified NDF was i ncluded at 0 and 200 g/kg of feed at the expense of glucose. The diets of Exp. 2 contained one of the three different NDF sources (purified NDF, wheat bran, or sunflower hulls) at a level of 144 g of NDF/kg of DM. The purified NDF (pNDF) was isolated from the same batch as the wh eat bran (WB) used in Exp. 2. The endogenous N flow at the terminal il eum of these pigs was determined with the N-15-isotope dilution method . The inclusion of NDF in the experimental diets increased (P < .05) t he daily DM flow at the terminal ileum. Dry matter flow was increased .697 g for every g/kg increase in NDF in the diet. The different sourc es of dietary NDF gave similar (P > .05) ileal DM flows. The inclusion of pNDF (Exp. I) increased (P < .05) the ileal flow of total N by 1.8 84 g/kg of dietary DM intake. This increase is composed of 59% endogen ous and 41% exogenous N. With the inclusion of various NDF sources (Ex p. 2), similar (P > .05) amounts of endogenous N passing the terminal ileum were obtained. Calculated from results of Exp. 1 and 2, endogeno us ileal N flow was increased .008 g for every gram/kilogram increase in NDF in the diet. The total ileal N flow, however, varied (P < .05) with the inclusion of various NDF sources in the diets (Exp. 2). The r esults show that increase in ileal N with dietary NDF depend on level and type of NDF.