Net portal absorption of enterally fed alpha-ketoglutarate is limited in young pigs

Our aim was to quantify the intestinal metabolic fate of dietary alpha-ketoglutarate (AKG). Female pigs (n = 6; 21 d old) were implanted with arterial, venous, portal and gastric catheters and an ultrasonic portal flow probe and fed a corn and soybean meal-based diet. On the day of the experiment, the pigs received a 4-h intragastric infusion of sodium AKG at a rate equivalent to 0, 2.5, 5 or 10% of dietary intake. The net portal AKG balance of the control and 2.5% treatments did not differ and were not different from zero. However, the net portal AKG balance of both the 5 [163 micro mol/(kg. h)] and 10% [159 micro mol/(kg. h)] treatments were greater (P < 0.05) than the control. Despite significant net AKG absorption at the 5 and 10% levels, the net portal appearance represented only 10.8 and 6.7%, respectively, of the enteral input. The net portal appearances of glutamate, glutamine, ammonia and the branched-chain amino acids were not affected by dietary AKG level. We conclude that the absorption of dietary AKG is limited in young pigs and does not change the net portal balance of amino acids or ammonia.