EFFECTS OF HIGH-COPPER FEEDING ON PORTAL AMMONIA ABSORPTION AND ON OXYGEN-CONSUMPTION BY PORTAL VEIN-DRAINED ORGANS AND BY THE WHOLE ANIMALIN GROWING PIGS

Growing gilts that had catheters inserted into the portal vein, ileal vein, and carotid artery and that were trained to consume 1.2 kg of a 16% CP corn-soybean meal basal diet once daily were used. In Trial 1, hourly simultaneous measurements of the 02 consumption by portal vein- drained organs (PVDO) and by the whole animal during the 24- to 30-h p ostprandial period were conducted in eight pigs (33.8 +/- .6 kg). Afte r initial measurements, four pigs continued to receive the basal diet and four pigs were fed a basal diet + 250 ppm of Cu. Following a 7-d a cclimation period, the second series of measurements were made. In pig s fed the diet supplemented with Cu, the PVDO and whole-animal O2 cons umptions and the fraction of whole-animal O2 consumption used by PVDO were not different (P > .05) between the initial and second series. In Trial 2, seven gilts (38.5 +/- .9 kg) were used for measurements of n et portal NH3 absorption and the O2 consumption by PVDO and by the who le animal during the 0- to 6-h postprandial period. The second series of measurements were made 7 d after four pigs were fed the diet supple mented with Cu. For pigs fed the diet supplemented with Cu, during the second series of measurements, the net portal NH3 absorption was lowe red (P < .05). No differences (P > .05) in PVDO and whole-animal O2 co nsumptions and the fraction of whole-animal O2 consumption used by PVD O were found between the initial and second series. These results indi cate that mechanisms other than reduced oxidative demand by PVDO may b e responsible for the growth-stimulating effect of high dietary Cu on pigs.