The Effect of the Duration of the Time Interval Between Assays on True Metabolizable Energy Values Measured with Adult Roosters

Two experiments were made to study the effect of the duration of time between true metabolizable energy (TME) bioassays on the values obtained. Each experiment involved 6 birds assigned to each of 16 treatments. When soybean meal was assayed following a bioassay of corn, the TME values were not affected by the duration of rest. Birds force-fed soybean meal 24 hr after receiving corn yielded TME values no different from those of birds rested for 21 days. When wheat was assayed following a bioassay of rapeseed meal, a 48 hr delay was required because some of the rapeseed meal failed to clear the digestive tract within 24 hr. While a bird may be used for a second bioassay 24 hr after completion of the first assay, this does not permit recovery of body weight loss. It is recommended that rest periods be planned between groups of assays to permit recovery of body weight.