Absorption and metabolism of benzoic acid in growing pigs1

Abstract

Dietary benzoic acid (BA) supplementation causes a pronounced reduction in urinary pH but only small changes in blood pH. The present study aimed to investigate the portal absorption profile, hepatic metabolism of BA, and renal excretion of hippuric acid (HA) underlying the relatively small impact of BA on systemic acid-base status. Eight growing pigs (BW = 63 +/- 1 kg at sampling) fitted with permanent indwelling catheters in the abdominal aorta, hepatic portal vein, hepatic vein, and mesenteric vein were allocated to 4 sampling blocks and randomly assigned to control (CON; nonsupplemented diet) or BA supplementation (B; control diet + 1% BA top-dressed). Feed intake was restricted to 3.6% of BW and the ration divided into 3 equally sized meals offered at 8-h intervals. Blood pH (7.465 and 7.486 +/- 0.004) and urinary pH (4.99 and 7.01 +/- 0.09) were less (P = 0.03 and P < 0.01) in B compared with CON. The arterial concentration, net portal flux, and net hepatic uptake of BA increased (P < 0.01) in B compared with CON. The net portal flux of BA increased (P < 0.01) after feeding with B, but remained positive (P < 0.01) at all sampling times (n = 8). Recovery of dietary BA as increased net portal flux and hepatic uptake of BA was 87 +/- 5% and 89 +/- 15%, respectively. The recovery of dietary BA as urinary excretion of BA and HA was 0.08 +/- 0.02% and 85 +/- 7%, respectively. It is concluded that the small impact of BA supplementation on systemic acid-base status was caused by a protracted BA absorption and efficient hepatic extraction and glycine conjugation in combination with efficient renal clearance of HA. Together, these physiological mechanisms prevented major BA and HA accumulation in body fluids.

Effects of benzoic acid on nitrogen, phosphorus and energy balance and on ammonia emission from slurries in the heavy pig

“…In a study of Kristensen et al (2009), adding 1% benzoic acid to a diet for growing pigs markedly acidified the urine pH (about 2 points), but only slightly reduced blood pH and no effects of benzoic acid supplementation were detected on inter-organ fluxes of O2, CO2, glucose, lactate and urea. Similarly, Kluge et al (2010) found a decrease in urine pH with the addition of 0.5% benzoic acid to the diet of sows.…”

Evaluation of in situ valine production by Bacillus subtilis in young pigs

“…The blood samples taken in Experiment 2 on day 18 were obtained 3 h after feeding to assure a steady Val absorption. This time point was set up based on our own data obtained in Experiment 1 and on measurements on absorption kinetics in pigs showing a maximum absorption of nutrients from 0.5 to 2 h after feeding whereafter it decreases until~6 h post-feeding (Rerat et al, 1993;van der Meulen et al, 1997;Kristensen et al, 2009). Although the AA in focus was Val, other AA and metabolites were also measured.…”

Effects of Acidifying Pig Diets on Emissions of Ammonia, Methane, and Sulfur from Slurry during Storage

“…The present experiment demonstrated that dietary interventions can decrease slurry pH to an extent that emissions of NH 3 are significantly reduced. The observed decrease in slurry pH may be explained by a decrease in the pH of urine (Kristensen et al, 2009;Nørgaard et al, 2010aNørgaard et al, , 2010b. The pH drop resulted in significant reductions in NH 3 emissions of 28 to 40%, least for +BA and most for the two treatments with CaCl 2 .…”

“…Benzoic acid (BA) is approved in the European Union as an ingredient in diets for fattening pigs at a level between 5 and 10 g kg -1 (European Commission, 2007), and BA is effective in decreasing urinary pH by voiding hippuric acid, which is produced in the liver from metabolism of BA (Kristensen et al, 2009;Nørgaard et al, 2010aNørgaard et al, , 2010b. The use of acids in diets for pigs elicits an antimicrobial effect and increases gain (Kluge et al, 2006).…”