Different Proportions of Branched-Chain Amino Acids Modulate Lipid Metabolism in a Finishing Pig Model

This study aimed to investigate the effect of the supplementation of branched-chain amino acids (BCAAs) at different ratios in protein restriction diets on lipid metabolism in a finishing pig model. The BCAA supplementation (leucine/isoleucine/valine = 2:1:1 and 2:1:2) ameliorated the poor growth performance and carcass characteristics, particularly high fat mass caused by a protein-restricted diet. Serum adiponectin increased while leptin decreased in BCAA diets in comparison to the 12% CP group. BCAA supplementation also increased the low-protein expression of AMPK and SIRT1 caused by protein restriction. The mRNA and protein levels of peroxisome proliferation-activated receptor-γ (PPARγ) and acetyl-CoA carboxylase (ACC) were highest in the protein-restricted group and lowered in the 2:1:1 or 2:1:2 group. In conclusion, BCAAs supplemented in an adequate ratio range of 2:1:1 to 2:1:2 (2:1:2 is recommended) in reduced protein diets could modulate lipid metabolism by accelerating the secretion of adipokines and fatty acid oxidation.