Comparison of the single dose and withdrawal method for measuring the rate of passage of two digestibility markers in digesta collected from the distal ileum and feces in growing pigs

Six growing pigs were fitted with a simple T-cannula at the distal ileum. The pigs were given 1 kg of feed twice daily. Three pigs received a grower diet containing 5 g kg−1 chromic oxide and 25 mg kg−1 dysprosium. The markers were withdrawn at the 08:00 h feeding on day 11 of the experimental period. The other three pigs received the diet without the markers. On day 11, at 08:00 h, they were given a single dose of both markers mixed in the diet. The treatments were crossed-over during the second experimental period. The experiment was repeated with the same pigs to measure the rate of passage of these markers in feces. The rate of chromic oxide passage, determined using rate constants, for digesta collected from the distal ileum were similar for the withdrawal and single dose methods. In contrast, the rate of dysprosium passage in digesta measured with the withdrawal method was higher (P < 0.05) than with the single dose method. The rates of passage of both markers, measured in feces, were similar with the two methods. In conclusion, either marker or method can be used to study the relative differences in rate of passage of digesta between diets, although chromic oxide provided more consistent results.