The reported effects of dietary supplemented microbial phytase on the utilization of phytate phosphorus (pP) differ widely by investigators. In order to clarify the differences, the contents of total phosphorus (P) and pP in commonly used five plant feedstuffs, corn (C), soybean meal (SM), defatted rice bran (RB), wheat bran (WB) and high level flour wheat bran (FWB) were determined, and the effect of microbial phytase on utilization of pP in these feedstuffs was studied using male broiler chicks.
The contents of total P in plant feedstuffs were determined to be 0.25, 0.67, 2.81, 1.04 and 0.54%, and those of pP to be 0.15, 0.31, 2.02, 0.71 and 0.32% in C, SM, RB, WB and FWB, respectively. The ratios of pP to total P ranged from 47.2% (for SM) to 71.8% (for RB). The experimental diets were formulated using C, SM, RB, WB or FWB as a sole source of pP. Male broiler chicks were fed the diets supplemented by 0 or 500 phytase units/kg of diet microbial phytase for 10 days from 7 to 17 days of age. There were large differences in pP retention among plant feedstuffs without microbial phytase. Especially the retention was low (5.4%) in the C and high (73.4%) in the WB. The pP retention in SM, RB and FWB were 52.3, 42.5 and 51.1%, respectively. On the other hand, with the addition of microbial phytase, pP retention in C, SM, RB, WB and FWB increased to 69.9, 75.0, 78.6, 86.6 and 84.1%, respectively.