Performance, body and carcass composition and bone characteristics of pigs fed rapeseed and soyabean meal-cereal diets supplemented with microbial phytase

Abstract

Thirty-three female pigs from 25 to 70 kg body weight were fed isocaloric and isoprotein diets composed of rapeseed (RSM) or soyabean meal (SBM) and a wheat-barley mixture with high intrinsic phytase content (over 900 FTU/kg). Basal diets containing 0.19-0.20% of digestible P were unsupplemented or supplemented with either microbial phytase (1000 FTU/kg, Natuphos®) or dicalcium phosphate to the level of 0.25% recommended for growing pigs. Apparent digestibility of nutrients, growth performance, carcass value, physical properties of the femur, third metatarsal and metacarpal and chemical composition of the whole bodies of pigs were investigated. Microbial phytase supplementation increased (P>0.01) the content of digestible P to a higher degree in the diet with RSM (0.78 g) than with SBM (0.48 g/kg), and in the empty body increased ash, calcium and phosphorus contents by 1.55, 0.58 and 0.34 g/kg, respectively. The phytase-supplemented pigs had similar Ca:P ratios as unsupplemented ones and higher (P<0.01) ratios of ash and phosphorus to protein in their bodies. Growth performance, carcass characteristics, protein and energy content in the body and physico-mechanical properties of the femur and metatarsal were not changed by phytase or dicalcium supplementation, except the strength value in the third metacarpal which was higher in pigs receiving the diet supplemented with inorganic P. Utilisation of digestible P was significantly higher (85-87%) in pigs fed basal diets than in animals fed diets supplemented with microbial phytase or dicalcium phosphate (67-73%). Daily protein deposition in the body was not decreased by reducing the P content in the diet to 0.19%. RSM, as the high protein feed in the diet with barley and wheat, supplied a sufficient amount of P to cover the requirements of growing pigs. The results of the experiment indicated that cereal phytase has a beneficial effect on total phytic P utilisation.