Digestibility Marker Type, but Not Inclusion Level Affects Apparent Digestibility of Gross Energy and Nitrogen and Marker Recovery in Growing Pigs

This study was conducted to investigate if the apparent ileal digestibility (AID) of GE or nitrogen (N) was influenced by digestibility marker (DMr) level and type, and oat bran (OB) level, and if the apparent total tract digestibility (ATTD) of GE or DMr recovery was influenced by the three aforementioned factors and duration of feces collection (3 or 5 d). Six diets were formulated as a 3 × 2 factorial arrangement with three DMr levels (2.5, 5.0, or 7.5 g/kg) and two OB levels (0 or 100 g/kg). Chromic oxide and titanium dioxide were used as DMr and the analyzed values in diets were 1.64, 3.09, 4.65, 1.66, 3.18, and 4.70 g/kg for Cr, and 1.49, 2.99, 4.41, 1.52, 3.04, and 4.48 g/kg for Ti. In Exp. 1, eighteen barrows fitted with T-cannulas at the distal ileum were used in a triplicate 6 × 2 incomplete Latin Square design with 6 dietary treatments and 2 periods. The ileal digesta were collected for 3 d after 5-d adaptation, and the AID of GE and N were determined. In Exp. 2, seventy-two barrows were assigned in a randomized complete block design with diets and duration of feces collection. Feces were quantitatively collected with the marker-to-marker method after 7-d adaptation. The ATTD of GE and DMr recovery were determined by measuring Cr or Ti. The data were analyzed as split-plot arrangement using the MIXED procedure of SAS. In both experiments, there was no interaction among factors. In Exp. 1, the AID of GE and N determined by Ti were greater (P < 0.05) than Cr regardless of the levels of DMr and OB. The AID of GE or N was not affected by DMr level or OB level. In Exp. 2, the DMr level and duration of feces collection had no effect on ATTD of GE and DMr recovery. The total collection method determined greater (P < 0.05) ATTD of GE than Ti, which was greater (P < 0.05) than Cr. The recovery of Ti was greater (P < 0.01) than Cr. Inclusion of OB decreased ATTD of GE. In conclusion, the AID of GE and N, ATTD of GE, and DMr recovery were affected by DMr type but not DMr level; the inclusion of OB did not affect AID of GE and N and DMr recovery; and the duration of feces collection had no effect on ATTD of GE and DMr recovery.