Effects of a reduced calcium, phosphorus and protein intake and of benzoic acid on calcium and phosphorus metabolism of growing pigs

Abstract In order to minimise environmental pollution, many pig feeds contain low phosphorus and protein concentrations as well as benzoic acid (BA), an additive which reduces ammonia formation in the slurry. Since both a low P intake and metabolic acidosis compromise bone mineralisation, the effect of a diet with a low concentration of calcium (Ca), phosphorus (P) and crude protein (CP) and the effect of BA on Ca and P metabolism were examined in a 2 × 2 two-factorial experiment using pigs from 13 to 64 kg body weight (BW). Compared to the control piglet and grower diets (8.7 and 6.9 g Ca; 6.9 and 5.3 g P; 172 and 156 g CP per kg, respectively), the intake of the low nutrient piglet and grower diets (5.3 g Ca; 4.3 and 4.0 g P; 154 and 147 g CP per kg, respectively, both supplemented with 1500 U/kg microbial phytase) reduced (P 0.05) the apparent digestibility of Ca, increased the apparent digestibility of P (P 0.05) on the proportion of ingested Ca and P which was retained. Furthermore, BA increased (P