Effect of micronizing full fat canola seed on amino acid disappearance in the gastrointestinal tract of dairy cows

Abstract

Ruminal and total tract digestion of the amino acids (AA) in full fat canola seed was studied in two in situ experiments with three nonlactating, ruminally and duodenally fistulated dairy cows. Whole, full fat canola seed was hand-cracked or micronized (an infrared heat treatment) for 90 s and then studied in that form or after grinding to pass a 1.25-mm sieve. In the first experiment, the four sample types were ruminally incubated in nylon bags for up to 96 h. In the second experiment, they were sealed in mobile nylon bags, incubated ruminally for 16 h, placed in acidified pepsin for 1 h, and then inserted into duodenal cannulas for passage through the intestine. Amino acids in the canola seed and in the residues from in situ incubations were analyzed by HPLC. Micronization reduced ruminal disappearance of total AA and essential AA from full fat canola seed. Degradation kinetics from Experiment 1 indicated reduced soluble fraction and increased slowly degradable fraction of both total AA and essential AA following micronization. Micronization reduced disappearances of total AA and essential AA from whole canola seed in the total digestive tract but did not affect total tract digestion of total AA or essential AA in ground seed. Intestinal disappearance of total AA and essential AA from both whole and ground full fat canola seed were increased by micronization. Micronizing canola seed may be of value in improving AA utilization in ruminants.