Free Amino Acid–Enriched Diets Containing Rapidly but Not Slowly Digested Carbohydrate Promote Amino Acid Absorption from Intestine and Net Fluxes across Skeletal Muscle of Pigs

Abstract

Background The approach to matching appropriate carbohydrates alongside free amino acids to achieve optimal muscle growth remains unclear. Objectives We investigated whether the consumption of a diet containing rapidly digested carbohydrate and free amino acids can enhance intestinal absorption and muscular uptake of amino acids in pigs. Method Twelve barrows (28 kg; 11 wk old) with catheters installed in the portal vein, mesenteric vein, femoral artery, and femoral vein were randomly assigned to consume one of two free amino acid-enriched diets (3.34%) containing rapidly [waxy corn starch (WCS)] or slowly [pea starch (PS)] digested carbohydrate for 27 d. Blood was collected to determine the fluxes of plasma glucose and amino acids across the portal vein and the hindlimb muscle. Dietary in vitro carbohydrate digestive rates were also determined. Data were analyzed using repeated measures (Time × Group) ANOVA. Results Carbohydrate in vitro cumulative digestibility at 30 and 240 min was 69.00% and 95.25% for WCS and 23.25% and 81.15% for PS, respectively. The animal experiment presented WCS increased individual amino acids (Lys, 0.67 vs. 0.53 mmol/min; Thr, 0.40 vs. 0.29 mmol/min; Ile, 0.33 vs. 0.22 mmol/min; Glu, 0.51 vs. 0.35 mmol/min and Pro, 0.51 vs. 0.27 mmol/min), essential amino acid (EAA; 3.26 vs. 2.65 mmol/min), and branched-chain amino acid (BCAA; 0.86 vs. 0.65 mmol/min) fluxes across the portal vein during 8 h postprandial, as well as individual amino acids (Ile, 0.08 vs. 0.02 mmol/min; Leu, 0.06 vs. 0.02 mmol/min and Gln, 0.44 vs. 0.25 mmol/min), EAA (0.50 vs. 0.21 mmol/min), and BCAA (0.17 vs. 0.06 mmol/min) net fluxes across the hindlimb muscle during 8 h postprandial compared with PS (P < 0.05). Conclusions A diet containing rapidly digested carbohydrate and free amino acids can promote intestinal absorption and net fluxes across hindlimb muscle of amino acids in pigs.