VARIABILITY OF APPARENT ILEAL AMINO-ACID DIGESTIBILITY IN CANOLA-MEALFOR GROWING-FINISHING PIGS

Studies were conducted with six barrows, average initial body weight 3 2.5 kg, fitted with a T-cannula at the distal ileum, to determine some of the factors responsible for the variability in apparent ileal dige stibility values of amino acids (AA) in canola meal. The barrows were fed six corn starch-based diets, formulated to contain 18.0% crude pro tein (CP) on a dry matter (DM) basis from six canola meal samples, acc ording to a 6 x 6 Latin square design. Chromic oxide (0.3%) was used a s a digestibility marker. The pigs were fed twice daily, at 08:00 and 20:00 h. The dietary allowance was 1600 g d(-1). Each experimental per iod consisted of 8 d. Ileal digesta were collected, at 2-h intervals, for a total of 24 h from 08:00 on day 6 to 08:00 h on day 8. With the exception of proline, there were differences (P < 0.05) in the apparen t ileal digestibility values of all AA among the six canola meal sampl es. Of the indispensable AA in canola meal, the digestibility values o f arginine, histidine, and methionine were relatively high, ranging fr om 79.4 to 84.4, from 76.5 to 81.0%, and from 77.3 to 82.4%, respectiv ely, while the digestibility values of threonine and tryptophan were r elatively low, ranging from 59.7 to 66.5 and from 61.7 to 67.5%, respe ctively. Furthermore, with the exception of arginine, the digestibilit y values of the indispensable PLA were negatively correlated (P < 0.05 ) with the neutral-detergent fiber (NDF) content in canola meal. In ad dition, with the exception of threonine, tryptophan and valine, the di gestibility values of the indispensable AA were positively correlated (P < 0.05) with their respective dietary levels. In conclusion, measur ed with the ileal analysis method, there were differences (P < 0.05) i n the digestibility values of the majority of AA among the canola meal samples. Differences in NDF content were mainly responsible for the v ariation. In addition, differences in the dietary levels of most AA al so contributed, in part, to the variation of AA digestibility values.