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<0.05) performance. At 0.60% threonine, SAA requirement was 0.60%, whereas at 0.70% threonine, performance increased up to the highest dietary SAA level of 0.64%. In experiment 3, the replacement value of cystine for methionine was studied in 324 pigs 20 to 50 kg, using diets with 0.50, 0.55 and 0.60% dietary SAA. Results suggest that at least 50% of the SAA requirement should be met by methionine. (Abstract retrieved from CAB Abstracts by CABI’s permission)