Enzymatic efficiency of plant and microbial phytase in cereal-rapeseed diets for growing pigs

Abstract

The experiment was carried out on 24 growing Polish Landrace pigs. The apparent digestibility of P from cereal grains (maize, barley, wheat, triticale, rye or mixture of barley with rye) and from diets containing cereals and 25% rapeseed meal (RSM) or 40% soyabean meal (SBM) was determined. The diets were unsupplemented or supplemented with microbial phytase (1000 FTU/kg), The digestibility of P was measured by an indirect method (with Cr2O3 as an indicator) in 129 individual collections. The activity of intrinsic phytase in maize and oil meals was low (no more than 180 FTU/kg DM) and was considerably higher in other cereals (from 750 FTU in barley to 2077 FTU/kg DM in rye). The apparent digestibility of P in barley, wheat, triticale and rye did not differ between species (average 37.1%) and was about 17% percentage points higher (P<0.01) than in maize. Although it was estimated that the effect of intrinsic and microbial phytase on digestibility of P was additive, plant phytase was 32 and 41% less effective than microbial phytase in diets with RSM and SBM, respectively. The intrinsic phytase content in cereal improved P digestibility in diets with RSM or SBM by 9.3-9.6% per 1000 FTU. Supplementation of diets with microbial phytase (1000 FTU) increased P digestibility by 13.7 and 16.3% in RSM and SBM diets, respectively. However, the increase in the content of digestible P by microbial phytase was similar (about 1 g/kg) in diets with both protein sources.