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Interpretive Summary: Improving performance of finishing pigs with added valine, isoleucine, and tryptophan: validating a meta-analysis model

By: Anne Kamiya, MS

Branched-chain amino acids (BCAA) include the amino acids (AA) isoleucine (Iso), leucine (Leu) and valine (Val). All of the BCCA are essential AA used for protein building, however an excess of any one BCAA will cause an undesired breakdown of all BCAA, as well as tryptophan (Trp), which is not a BCAA (but uses the same transporters). Trp is especially crucial to growth performance because it is an AA used to create serotonin, a neurotransmitter that impacts appetite. So anything that increases the breakdown of Trp potentially reduces feed intake. Corn protein-based feed contains excess Leu so a scenario of AA imbalance becomes especially problematic here. The authors of this recent Journal of Animal Science study did a meta-analysis of existing studies and then hypothesized that adding the lacking AA (such as Iso, Val or Trp) would ameliorate any AA imbalance issues. 

Dried distiller’s grains with solubles (DDGS) is a high corn protein diet containing an excess of Leu. In this study, pigs were fed one of six different diets for 103 days with varying amounts of added Ile, Val and Trp, ranging from low to high. Results indicated that pigs fed the diets with added Ile, Val and Trp had improved average daily gain over pigs that were not fed excesses of these AA, however the ratio of each AA needed to optimize performance was not determined. Results were overall consistent with the meta-analysis reports the authors had referenced when creating their hypothesis. Overall, more studies to determine the proper ratios of BCAA and Trp that should be added to corn protein-based diets with excess Leu are needed. 

The full paper can be found on the Journal of Animal Science website.