Influence of dietary non-phytate phosphorous levels and phytase supplementation on the performance and bone characteristics of broilers

precise phosphorus nutrition is important for significant reductions in both p pollution and ration costs. the influence of different levels (%) of dietary npp fed from 0 to 20 d (0.45, 0.40, 0.35, 0.30, 0.25, compared with feeding 0.20 npp with and without 500 f.t.u. of phytase per kg of diet) and from 21 to 36 d of age (0.414, 0.364, 0.314, 0.264, 0.214, compared with 0.164 npp with and without 500 f.t.u. of phytase per kg of diet) were evaluate using a total of 588 day-old commercial broiler chicks. each treatment was replicated four times in a completely randomized design. body weight (bw), daily gain (dg), feed intake (dfi), feed conversion ratio, plasma p level and bone characteristics were determined, and from these data the p equivalency of the phytase was estimated. feeding diets containing less than 0.40% of npp to birds between 0 and 20d resulted in inferior bw, dfi, plasma p level and bone characteristics compared with the control. however, optimum fcr and mortality was supported at lower levels of npp (0.25%). between 21 and 36 d, 0.364% was enough to optimise bw, dfi, and femur ash (%); whilst only 0.314% or greater was needed to support optimum dg, toe and tibia ash and only 0.214 to 0.264% was required to optimise shank, femur and tibia lengths; fcr and survivability. a broken line analysis also showed that the npp (%) requirement ranged from 0.267 to 0.410 and 0.272 to 0.380% during 0 to 20 and 21 to 36 d, respectively. phytase supplementation improved performance and bone criterion and its p equivalency, depending upon the response of interest and birds age, ranged from 0.00 to 0.110%. in conclusion, the results showed that the combination of a lower level of npp and phytase may be used to increase dietary p utilization, without severe changes in performance and bone quality.