Estimation of neutral detergent fibre degradation in pigs by an in vitro method

In vitro neutral detergent fibre (NDF) degradation kinetics was determined using caecum-colon and rectal inocula from pigs fed three different diets. The test feeds included in the diets were rice bran, tofu residue and water spinach (Ipomaea aquatica). Data, consisting of a total of 864 observations, were fitted to an exponential function for estimating rate and potential degradability of NDF. The NDF degradation was similar for caecum-colon and rectum inocula and very little disappearance of NDF occurred after 36 h. Diet affected rate of NDF degradation (P<0.05), but not potential degradation. Rice bran and water spinach had higher NDF degradation rates than tofu residue. However, rice bran had a lower potential degradation of NDF than both water spinach and tofu residue. Rectal contents can replace caecum-colon contents as inocula sources to measure NDF degradation with no impact on estimations of NDF degradation kinetics.