Effects of benzoic acid and inulin on ammonia–nitrogen excretion, plasma urea levels, and the pH in faeces and urine of weaner pigs

Halas, D., Hansen, C.F., Hampson, D.J., Kim, J.C., Mullan, B.P., Wilson, R.H. and Pluske, J.R. (2010) Effects of benzoic acid and inulin on ammonia–nitrogen excretion, plasma urea levels, and the pH in faeces and urine of weaner pigs. Livestock Science, 134 (1-3). pp. 243-245.

Abstract

The present experiment tested the hypothesis that dietary supplementation with BA and IN would reduce total ammonia-N (NH3-N) excretion. Ninety-six female pigs (Large White × Landrace) aged 21 ± 3 days and weighing 5.87 ± 0.077 kg (mean ± S.E.) were used in a 2 × 3 factorial experiment, with the respective factors being benzoic acid (BA; 0 and 5 g/kg) and inulin (IN; 0, 40 and 80 g/kg) in the diets. Pigs were housed individually and fed their respective diet for 3 weeks. Blood samples from 6 focus pigs per diet were collected on days 14 and 21, and digesta, urine and faecal samples were collected at slaughter on day 21. Feeding only BA decreased (P = 0.050) the combined faecal and urinary NH3-N concentration while IN increased (P = 0.001) the NH3-N proportion in faeces and proportionally decreased (P = 0.001) the NH3-N proportion in urine. Additionally, dietary BA reduced the pH level in urine (P = 0.001) and faeces (P = 0.033), and plasma urea levels were decreased with both BA (P = 0.010) and IN (P = 0.008). No significant BA × IN interactions were noted. These data suggest that BA and IN can reduce NH3-N excretion by different mechanisms, possibly by reducing excreta pH and bacterial populations (BA), as well as changing bacterial metabolic activities (BA and IN).