Influence of carbadox on fasting oxygen consumption by portal vein-drained organs and by the whole animal in growing pigs
1992
Yen, J.T. | Nienaber, J.A.
Fasting O2 consumption by the whole animal (W) and by portal vein-drained organs (PVDO) during the 24- to 30-h postprandial period were measured in seven growing pigs (36.1 +/- 2.3 kg) with catheters chronically placed in the hepatic portal vein, ileal vein, and carotid artery trained to consume 1.2 kg of a 16% CP corn-soybean meal basal diet (B) once daily. The pigs were placed individually into an open-circuit, indirect calorimeter and connected to an arteriovenous (A-V) O2 difference analyzer for hourly simultaneous measurements of O2 consumption by W and PVDO. The PVDO O2 consumption was calculated by multiplying the A-V O2 difference by the portal vein blood flow rate derived from constant infusion of a p-aminohippuric acid solution into the Heal vein. After the initial series of hourly measurements, four pigs remained on the B diet and three pigs were fed a B + 55 ppm carbadox diet. Seven days later, the second series of measurements was made. In pigs fed the diet with carbadox added, the hourly W O2 consumptions were not different (P > .05) between the initial and second series and averaged 7.5 mL-min-1-kg of BW-1. However, the A-V O2 differences (mL/dL) were reduced (P < .05) from 4.6 to 4.0 at 24 h, 4.8 to 4.0 at 25 h, and 4.6 to 4.0 at 29 h postprandial and the fractions of W O2 consumption used by PVDO (percentage) were reduced (P < .05) from 28.6 to 21.6 at 26 h and 25.2 to 18.2 at 27 h postprandial. These results suggest that the growth-promoting effect of carbadox, a synthetic antimicrobial agent, in growing pigs may be associated with reduced oxidative demand by the PVDO, which includes digestive tract, pancreas, and spleen.
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