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

Abstract

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.

An optimal dietary non-phytate phosphorus level of broilers fed a conventional corn–soybean meal diet from 4 to 6 weeks of age

“…Bone ash percentage is another commonly used criterion for estimating dietary NPP requirements of broilers. In the present study, the optimal dietary NPP level required to obtain the optimal tibia ash percentage was estimated to be 0.29% based on the broken-line model, which was lower than those reported by Yan et al (2001), Dhandu and Angel (2003), Karimi et al (2011) and also recommended by NRC (1994). Although tibia ash percentage is a sensitive criterion for NPP requirement evaluation (Dhandu and Angel, 2003), it is inevitable to slaughter birds for tibia sample collection.…”

“…In recent years, broken-line models have been often used for estimating dietary NPP requirements of broilers (Waldroup et al, 2000;Yan et al, 2001;Karimi et al, 2011). Therefore, in the present study, dietary NPP requirements of broilers have been evaluated by broken-line models.…”

“…However, excessive quantities of inorganic P are commonly added into broiler diets for maximum growth and bone development, partly because the P requirement of broilers has not been well evaluated (Yan et al, 2001;Dhandu and Angel, 2003;Karimi et al, 2011). The P is an expensive mineral, and dietary supplementations with excessive quantities of P would increase the feed cost of broilers (Woyengo and Nyachoti, 2010).…”

“…Growth performance, bone ash and tibia bone strength of broilers are commonly used indices for evaluating P requirements of broilers in previous studies (Yan et al, 2001;Dhandu and Angel, 2003;Karimi et al, 2011;Liu, 2012). A recent study from our laboratory indicated that tibia bone mineral content (BMC) and density (BMD), and middle toe ash content were sensitive criteria for estimating the NPP requirement of broiler chickens from 1 to 3 weeks of age, and the optimal dietary NPP level based on these sensitive criteria is 0.39% (Liu, 2012), which is lower than the current recommendation (0.45%) of dietary NPP by NRC (1994).…”

“…Few studies have been done to evaluate dietary NPP requirement of broilers in the later growth stages, and the reported results are inconsistent, ranging from 0.16% to 0.36% (Yan et al, 2001;Dhandu and Angel, 2003;Karimi et al, 2011), maybe due to the differences in breeds, indices for evaluating NPP requirements and experimental duration. Therefore, the present experiment was conducted to further study the optimal dietary NPP requirement of broilers fed a conventional corn-soybean meal diet from 4 to 6 weeks of age by investigating the impact of dietary NPP level on the growth performance, serum parameters, bone characteristics and P metabolism-related gene expressions of birds.…”