Níveis de fósforo disponível em rações para frangos de corte suplementadas ou não com fitase

• Autor(a) principal: Martin, John Armando Parra
• Data de Publicação: 2013
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1860
• topic: Enzima; Desempenho; Minerais; Cinza; Enzima; Rendimiento; Minerales; Gris; CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA

Were performed two experiments at the Universidade Federal de Viçosa for assessing levels of available phosphorus (Pd) supplemented from dicalcium phosphate (experiment 1) and dicalcium phosphate and phytase (500FTU&#8729;kg-1) (experiment 2) maintaining the calci- um:phosphorus available ratio in 2,13:1. A number of 480 eight-day-old Cobb ® broilers were distributed into 24 floor pens and reared for 45 days. An isoenergetic and isonitrogenous maize-soja-bean-meal basal diet was formulated according to the Brazilian Tables for Poultry and Swine (ROSTAGNO et al., 2011) recommendations for starter (8-21 d), grower (21-33 d) and finisher (33-45 d) periods. The birds were distributed in a completely randomized se- quence with three levels and eight replicates of 20 birds each. Available phosphorus levels were: 90%; 100% (requirement to standard performance broiler according with Rostagno et al. (2011); and 110%. Based on bird performance the estimated available phosphorus levels, were 0,352, 0,391 (100%) and 0,430 percent for the starter; 0,308, 0,342 (100%) and 0,376 percent for growing; and 0,268, 0,298 (100%) and 0,328 percent for finishing phases, respec- tively. Each group of animals was kept at the same level ratio (90-100-110%) throughout the experiments. The parameters evaluated were final weight, weight gain, feed intake, feed con- version, and quantified ash, phosphorus and calcium in the tibia (at 22 and 33 days) and fe- murs (45 days). Experiment 1: There were no differences in performance values at 21 days or 33 days. At 45 days there was an increase in feed conversion as Pd levels increased (P<0,05). Regarding bone parameters, at 21 days were observed significant differences (P<0,05) only for phosphorus (% and g). At 33 days were not detected differences (P>0,05) for any of the bone parameters. At 45 days there were significant differences (P<0,05) weight of femur ash (% and g) in addition to amount of Ca and P. Consider decreasing the levels of Pd in 10% of 8 to 33 days old. Experiment 2: in relation to the performance of eight to 21 days-old were only significant differences (P<0,05) for food intake being less variable in the 110% level; the lev- els 90% and 100% were similar (P>0,05). At 33 days-old or at 45 days-old was no difference (P>0,05). Regarding bone parameters: at 21 days-old available phosphorus levels below the ixrequirement (90%), reported lower values (P<0,05) when compared with levels of 100% for the variables: ash (%), calcium (% and g) and phosphorus (% and g). At 33 days-old there was no significant difference (P>0,05). At 45 days-old the levels of Pd under the requirement (90%) reported lower values (P<0.05) for femur weight, ash (% and g) and phosphorus (g). For calcium there was no differences (P>0,05) being that as Pd levels increased the percent- age of calcium decreased numerically. It is recommended to assess levels of Pd less restricted to 10% for the period from eight to 21 days-old. From eight to 33 days-old the level of Pd under the requirement (90%) showed similar results for both performance and bone variables.