Non-phytate phosphorus requirement for broilers from 8 to 21 days of age under heat stress conditions
Two trials were conducted to determine the non-phytate phosphorus (nPP) requirement for broiler under heat stress. In both trials, birds were distributed in a completely randomized 4 × 2 factorial design with four nPP concentrations: 0.25, 0.35, 0.45, and 0.55%, and two Ca supply techniques: Ca fixed at 0.899% (CaF) or varying along with nPP aiming a 2:1 Ca to nPP ratio (CaV). Both trials had eight pens/treatment, with nine and five birds/pen for exp. 1 and exp. 2, respectively. nPP concentration had no effect on feed intake (FI), body weight gain (BWG), feed conversion ratio (FCR), nor fat deposition ratio (FDR). nPP levels showed a linear effect on protein deposition ratio (PDR) only for CaF diets. The nPP levels had a significant effect, regardless the technique adopted, on tibia phosphorus (TibP), which varied quadratically, on tibia calcium (TibCa) that increased quadratically and linearly, respectively, on CaF and CaV diets, and on tibia ash (TibAsh) that showed a quadratic effect for both. No effect was observed on Ca to P ratio in the tibia (TibCa:TibP). The nPP levels showed a linear increase effect over phosphorus intake (PI), phosphorus excreted (PE), and phosphorus retained (PR), and a linear decrease effect on phosphorus retention coefficient (PRC). Therefore, the nPP requirement for broilers from 8 to 21 days of age that provided better performance and bone variables were 0.250 and 0.484%, respectively, for CaF diets and 0.250 and 0.511%, respectively, for CaV diets.
Keywords: Bone mineralization, Ca to nPP ratio, Heat stress, Mineral excretion, Thermal environment.
Abstract published in Tropical Animal Health and Production, February 2018, Volume 50, Issue 2, pp 317–325. DOI: 10.1007/s11250-017-1434-1.
Valeriy Kryukov, with his considerations on this subject, reinforces what I think about his vision and preference for basic research. In the specific case of this work, this preference is evident in his considerations about FITIN and about the activity of FITASE in the gastrointestinal tract, which are not essential parameters for the conclusion of this study. And how much your suggestion to evaluate the effect of temperature is not consistent with this work proposal. This is because the clearly established objective was to evaluate the influence of the calcium to non-phytic phosphorus ratio on the demand for non-phytic phosphorus by broilers from 8 to 21 days under heat stress, there was no proposal to evaluate the effect of high temperature. If that were the objective, experimental units with chickens subjected to thermoneutral temperatures receiving the same treatments would have been included in the experiment. . I understand that only in this case would it be possible to also evaluate the influence of high temperature, as has been suggested. Finally, I consider that the performance parameters, protein and fat deposition rate, bone characteristics and phosphorus balance, are sufficient to fully achieve the objectives.
Oluitan Oladiran, for the experimental period, the climatic chambers were set to remain with a constant air temperature of 29°C from 8 to 15 d of age and 27ºC from 16 to 21 d of age and relative air humidity between 55-65%, featuring a thermoneutral environment condition, according to Cobb Vantress (2012).
Dear sirs!
From an economic point of view, increasing the availability of phosphorus phytates is important, but there is another position. The lower esters of phytic acid in the body play the role of messengers. Their role is not actually studied. Let me remind you that there is a drug in medicine: fitin. This is no accident.
Natural intestinal phytases + raw materials phytases play an important role in the digestion of phytates. Therefore, in terms of the discussed problem, it is necessary to establish the age-related change in the activity of phytase in the gastrointestinal tract and the influence of temperature
