Dietary starch sources affect net portal appearance of amino acids and glucose in growing pigs

Four male pigs (Duroc X Landrace X Yorkshire; average initial (mean +/- SEM) BW = 22.5 +/- 1.1 kg), fitted with permanent catheters in the portal vein, ileal vein and carotid artery, were used in a 4 X 4 Latin square experimental design to measure the effect of dietary starch sources on the net portal appearance of glucose and amino acids. Dietary starch sources were resistant starch (RS), maize, sticky rice and brown rice. Diets were provided at 0730, 1530 and 2330h during a 6-day adjustment period and 1-day collection period. On day 7 of each period, blood samples were collected from the portal vein and carotid artery at 0730h (prior to feeding) and hourly up to 8h after meal. Blood samples were used to determine glucose, amino acid, packed cell volume and partial pressure of oxygen (pO(2)). When calculated per 100g feed intake, cumulative portal glucose appearance was lower (P < 0.05) for resistant starch than for maize, sticky rice or brown rice up to 8 h after the meal. Cumulative portal glucose appearance was higher (P < 0.05) for sticky rice and brown rice than for other diets until 4 h after the meal, but maize had higher cumulative glucose appearance after 4 h. Net cumulative portal concentrations of most amino acids for resistant starch were also reduced (P < 0.05) than for the other starch sources. Cumulative portal appearance of amino acid represented 48.39%, 63.76%, 61.80% and 59.18% of dietary intake for resistant starch, maize, sticky rice and brown rice, respectively. Collectively, our results indicate that dietary starch sources substantially affect the appearance of amino acids and glucose in the portal circulation.