Factors affecting the requirement of dietary sulphur-containing amino acids of young pigs.

Abstract

In the first of 3 experiments, requirement for total and digestible sulphur amino acids (SAA) was estimated in 240 pigs, 14 to 40 kg. A diet with low digestible amino acids content (digestible sulphur amino acids (SAA) 0.37%) was supplemented with all essential amino acids except methionine and 0, 0.05, 0.1, 0.1 or 0.2% synthetic DL-methionine added, providing diets with 0.42, 0.47, 0.52 and 0.57% digestible SAA. A control diet contained 0.52% digestible SAA. At similar levels of digestible SAA, there was no difference in performance between the experimental and the control diet, showing that optimum performance can be obtained with a less digestible diet supplemented with essential amino acids. Optimum performance was at 0.52% digestible SAA content in the diet, corresponding to about 0.65% total SAA. In experiment 2, 360 pigs 15 to 40 kg, were used to study SAA requirement at sub-optimal (0.60%) and optimal (0.70%) dietary threonine levels. Increasing threonine from 0.60 to 0.70%, increased (P