Comparison of different digesta collection methods to determine the apparent digestibilities of the nutrients at the terminal ileum in pigs

Three different cannulation techniques in pigs were tested with 15 crossbred castrates. Four pigs were fitted with a simple T-cannula, six pigs with a postvalve T-caecum cannula (PVTC cannula) and five pigs with ileocaecal reentrant cannulas. Four diets were tested: a conventional diet, a pectin-rich diet, a crude fibre-rich diet and a semisynthetic diet. For quantitative collection of ileal digesta the PVTC cannulation technique was tested for homogeneity of sampling. Cr₂O₃ and TiO₂ were used as solid phase markers and Co-EDTA as a liquid phase marker. The digestibilities of dry matter, nitrogen, crude fibre, ADF and NDF were determined. Digestibilities measured with re-entrant cannula as a quantitative collection method were sometimes significantly higher (P < 0.05) than with the other cannulas. After correction to 100 % Cr recovery the differences were reduced to less than 5%. Nitrogen digestibility measured with the re-entrant cannula was lower than with the PVTC cannula in the fibre-rich and semisynthetic diets. The Crrecovery was mostly lower than 100%, except with PVTC cannulas and the semisynthetic diet. The recovery rates of Co were higher than those of Cr. In the semisynthetic diet, recoveries of Co and Cr were similar. The recovery rate of TiO₂ with the semisynthetic diet was lower than that of the other two markers. The recovery rates of the markers depended on fibre contents of diets. With the pectin-rich and fibre-rich diets the Cr and Co recoveries were lower than with the control diet. In general, digestibility coefficients measured with the three different cannulation techniques were different. However, when corrections were made for marker recoveries there were only small differences.