Níveis de fitase e redução de cálcio em dietas de frangos

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Universidade Federal de Goiás


Two experiments were conducted at the Poultry Department of the Federal University of Goias to evaluate the inclusion of different phytase doses and reduction of calcium levels in diets of broiler chickens from 1 to 42 days old. In the first experiment the experimental design was completely randomized with six treatments, eight replications and 18 birds in each plot. In the second experiment the experimental design was completely randomized with six treatments, six replications and 10 birds in each plot. The treatments consisted of three levels of Ca (100%, 82% and 64%) and two phytase inclusions 750FTU / kg and 1500FTU / kg of feed. The 1.011% level was considered as 100% of the calcium recommendations for the pre-initial phase, 0.907% for the initial, 0.822% for growth and 0.661 for the final phase. For the phosphorus (P) requirement in the diet, the requirement of each phase was reduced by 0.150% for the treatments. Phytase overdose improved feed intake weight gain (P <0.05). In the first experiment, at 21 days of age, 36% calcium reduction and phytase supplementation of 1500FTU provided higher final weight, weight gain and feed intake (P <0.05). At 42 days, 1500FTU phytase supplementation improved final weight, weight gain and feed conversion. Reducing calcium inclusion improved feed conversion (P <0.05). Phytase supplementation of 1500FTU and calcium reduction by 18% showed higher carcass yield (P <0.05). In the first experiment, phytase overdose (1500FTU / kg of feed) increased the length, diameter, weight and bone strength of 21-day-old chicken (P <0.05). Regarding bone quality of broilers at 42 days of age, there was only effect of phytase factor for bone length and diameter (P <0.05). When birds were supplemented with 1500FTU phytase / kg feed, there was no effect of calcium levels on bone breaking strength (P <0.05). In the first experiment, reducing calcium inclusion in diets reduced cooking fluid loss and increased shear force of chicken breast meat (P <0.05). The inclusion of 1500FTU of phytase provided less liquid loss by thawing (P <0.05). The reduction in calcium inclusion associated with phytase supplementation decreased shear strength (P <0.05). In the second experiment, there was no effect of calcium levels and phytase enzyme supplementation on the incidence of woody breast at 42 days of age (P> 0.05). Regarding the histopathological evaluations, in the second experiment, the treatments were not effective in the action on meat quality (P> 0.05). Up to 36% reduction in calcium supplementation with inclusion of 1500 FTU / kg phytase can be used without adverse effects on performance, bone quality and meat quality of 42-day-old broilers.



COSTA, M. A. Níveis de fitase e redução de cálcio em dietas de frangos. 2019. 88 f. Tese (Doutorado em Zootecnia) - Universidade Federal de Goiás, Goiânia, 2019.