Betaine and arginine supplementation of low protein diets improves plasma lipids but does not affect hepatic fatty acid composition and related gene expression profiling in pigs

The individual and combined effects of betaine and arginine supplemented to reduced protein diets were investigated on plasma metabolites, hepatic fatty acid composition and mRNA levels of lipid-sensitive factors in commercial pigs. Betaine has previously been shown to reduce carcass fat deposition and arginine improves meat quality of finishing pigs. Forty male crossbred pigs were randomly assigned to one of five diets (n = 8): 160 g kg-1 of crude protein (NPD), 130 g kg-1 of crude protein (RPD), RPD with 3.3 g kg-1 of betaine, RPD with 15 g kg-1 of arginine, and RPD with 3.3 g kg-1 of betaine and 15 g kg-1 of arginine.The restriction of dietary protein increased total lipids (P < 0.001), total cholesterol (P < 0.001), high-density lipoprotein-cholesterol (P < 0.001) and low-density lipoprotein cholesterol (P < 0.001). Betaine and arginine, individually or combined, reduced the majority of plasma lipids (P < 0.05) without affecting total fatty acids in the liver and the overall gene expression pattern.These findings suggest a positive effect of betaine and arginine, singly or combined, by reversing plasma lipids increase promoted by dietary protein restriction. © 2017 Society of Chemical Industry.