0986 Investigations of marker and fiber effects on energy and nutrient utilization in growing pigs.

An experiment was conducted to investigate whether the apparent ileal and total tract digestibility of nitrogen and energy, and excretion patterns of indigestible markers were influenced by the type of marker and dietary fiber. Twenty barrows surgically fitted with T-cannula at the end of ileum were used in two experimental periods consisting of a 7-d adjustment period followed by a 3-d total fecal collection period and a 3-d ileal digesta collection period. Three diets were identically formulated except for 10% of the cornstarch (CS), corn bran (CB) or oat bran (OB). All three diets contained three index markers (5 g/kg chromic oxide [Cr2O3], 5 g/kg titanium dioxide [TiO2], and 20 g/kg acid-insoluble ash [AIA]). Pigs were fed at 0800 h and 1600 h with 2 equally sized meals during the experimental period. The ileal digesta were collected every 3 h from 0900 h to 1700 h with 4 time periods (TP) on ileal digesta collection days. For all 3 markers, the marker concentration of CS diet was greater than OB diet, which had greater marker concentration than CB diet (P < 0.001). The marker concentration of the first ileal collection day (Day1) was significantly lower than the third day (Day3) for Cr2O3 (P = 0.05), TiO2 (P < 0.001) and AIA (P < 0.01), respectively. The 3 markers were excreted in a similar pattern over 4 TPs for ileal digesta. The highest marker concentration appeared at the second TP (1200 h to 1500 h). The apparent ileal digestibility of energy (AIDE) and nitrogen (AIDN) of CB and OB diets was not affected by markers. For all 3 diets, the apparent total tract digestibility of energy (ATTDE) and nitrogen (ATTDN) determined by total collection method was greater (P < 0.05) than those determined by using inert digestibility markers. The ATTDE and ATTDN of CB diet calculated based on Cr2O3 were lower (P < 0.05) than those determined by TiO2, but for OB diet, the ATTDE and ATTDN determined by AIA were greater (P < 0.05) than those determined by TiO2. In conclusion, the marker distribution varied over time periods and was affected by fiber type, and the marker type may affect the estimate of total tract but not ileal digestibility of energy and nitrogen.