Update on amino acid requirements for piglets fed with low crude protein diets

Abstract

The current context is favorable for a further reduction in the crude protein content in piglet diets. Knowledge of amino acid requirements and the use of free amino acids in diets allow reducing the dietary crude protein content and improving nitrogen utilization while maintaining performance of piglets. In low-protein diets, the branched chained amino acids (valine, isoleucine, and leucine) and histidine have been identified as limiting amino acids for growth. Therefore, the estimation of their requirements is necessary to balance the dietary amino acid supply. Dose-response experiments are usually carried out to estimate amino acid requirements. The experimental design, the response criteria used and the statistical analysis method contribute to the variability in reported requirement estimates. The average valine, isoleucine, leucine and, histidine requirements, based on empirical data and expressed relative to lysine on a standardized ileal digestible basis, are estimated to be 70, 52, 101, and 31% respectively. Excess amino acids can reduce growth due to competition for catabolism and transport. The use of blood cells in the diet increases the isoleucine requirement and an excess leucine supply aggravates the effect of a valine deficiency. A better adequacy should be sought between the supply and requirements of amino acids to reduce the dietary crude protein content and to ensure the production objective.