Postprandial portal fluxes of essential amino acids, volatile fatty acids, and urea-nitrogen in growing pigs fed a high-fiber diet supplemented with a multi-enzyme cocktail

The present study investigated the effects of adding a multi-enzyme cocktail (MC) to a high-fiber diet on net portal-drained viscera (PDV) fluxes of essential AA (EAA), volatile fatty acids (VFA), and blood urea-N (BUN) in growing pigs. Five female pigs (22.8 +/- 1.6 kg BW), with catheters in the portal vein, ileal vein, and carotid artery, were fed 3 isocaloric-nitrogenous diets at 4% of their BW once daily at 0900 h for 7 d in a replicated 3 x 3 Latin square design. The diets contained corn and soybean meal with 0% (control) or 30% distillers' dried grains with solubles (DDGS; HF) produced from a 1:1 mixture of wheat and corn. The third diet was supplemented with MC in addition to the 30% DDGS (HF + MC). The MC supplied (analyzed values) 5,397 U of xylanase, 162 U of beta-glucanase, and 2,000 U of protease and guaranteed minimum activities of 1,000 U of alpha-amylase and 25 U of pectinase per kg of diet. On d 7, para-amino hippuric acid was infused into the ileal vein (to measure flow rate), and blood was sampled from the portal vein and carotid artery for 7 h after feeding to assay EAA, urea-N, and VFA. Portal absorption of nutrients was derived by multiplying the porto-arterial plasma concentration differences by portal vein blood flow. Diet had no effect on postprandial portal vein plasma flow rate and net BUN flux, but portal BUN tended to be lower (P = 0.070) and arterial BUN was lower (P < 0.05) over the 7 h in pigs fed control. Postprandial portal Arg, Ile, Leu, Trp, and Val or net fluxes were lower (P < 0.05) in HF-fed pigs from 30 to 240 min than control-fed pigs and MC supplementation tended (0.05 <= P <= 0.10) to or improved (P < 0.05) portal appearances of those AA, but not their fluxes. Control-fed pigs had higher (P < 0.05) net portal fluxes of most EAA and pigs fed HF + MC had higher (P < 0.05) Lys, and similar Met and Phe net portal fluxes were compared with control-fed pigs. Portal VFA was not affected by diet. However, total portal VFA flux was lower (P < 0.05) in the HF-fed pigs than in the control pigs. The MC supplementation improved the total portal VFA flux, although it did not improve arterial VFA concentration relative to the HF diet. In conclusion, supplementing the HF diet with MC improved net portal appearance of some EAA and fluxes of total VFA, whereas fluxes of EAA did not change. The HF diet increased EAA demand by the PDV, but MC addition was not able to reduce this demand.