Fósforo disponível em ração para frangos de corte dos 8 aos 21 dias de idade mantidos na termoneutralidade utilizando duas metodologias / Available phosphorus forbroiler chickens from 8 to21 days of age maintained at thermoneutrality using two methodologies

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

18/07/2011

RESUMO

Two experiments were conducted to determine the nutritional requirement of available phosphorus (aP) for broilers, from 8 to 21 days old. Were used 896 chickens, Cobb, kept in a thermoneutral environment, with an average temperature of 28.92 0.86 C and calculated WBGT of 78.08 0.47 and 27.05 0,61 C and 75.74 0.53 for WBGT, respectively, for phases 8 to 15 and 16 to 21 days old. In both experiments the birds were distributed in a completely randomized experimental design in 4 x 2 factorial scheme (four levels of aP x two methodologies: settling Ca at 0.899% and supplementing P CaF and supplementing Ca and P, keeping 2:1 ratio - CAV). The aP levels of the experimental diets were: 0.25, 0.35, 0.45 and 0.55%. In the first experiment, conducted to evaluate the performance and bone parameters, were used 576 chickens, divided into eight repetitions with nine birds per repetition. The aP levels influenced the feed intake (FI) only for birds receiving diets with CaF which increased linearly, however, the linear response plateau model (LRP) was the best fit to the data, estimating at 0.356% the level of aP from which the plateau occurred. Increasing levels of aP influenced weight gain (WG) and feed conversion (FC), which increased in a quadratic form to the estimated levels of, respectively, 0.446 and 0.438% for diets with CaF and in a linearly form for diets with CaV. However, the LRP model was the best fit to the WG data for birds feddiets with CaV, estimating the level of 0.450% aP from which the plateau occurred. The protein (PD) and fat deposition (FD) in the carcass increased in a quadratic form to the estimated levels of 0.492 and 0.429%, respectively, for diets with CaF and in a linear form for diets with CaV. When subjected to diets with CaF, the variables in bone calcium (BCa), bone phosphorus (BP) and bone ash (BA), in both percentage (%) and quantity (g), increased in a quadratic form to the estimated levels of, respectively, 0.478 and 0.469% for BCa, 0.495 and 0.481% for BP and 0.459% Pd and 0.474 for BA. However, the LRP model was the best fit to the CaO (%), CaO (g) and PO (%) data, estimating at, respectively, 0.347, 0.357 and 0.437% aP levels from which there was a plateau. For diets with CaV, while BCa (%) and BP (%) increased in a quadratic form to the estimated levels of, respectively, 0.418 and 0.444% aP, the CaO (g) and BP (g) increased in a linear form. However, the LRP model was the best fit to the BP (g) to diets with CaV, estimating the level of 0.464% aP from which the plateau occurred. The % and g of BA increased in a linear form for diets with CaV. In the second experiment, conducted to determine the phosphorus (P) balance, were used 320 broilers, divided into eight repetitions with five birds per repetition. The aP levels of diets influenced in a linear form increasing phosphorus intake (PI) and phosphorus excreted (PE) and decreasing phosphorus retention (PR). The P retention coefficient (PRC) was influenced by the levels of aP in diets with CaF which increased in a quadratic form up to the level of 0.351%. In the diets with CaV the PRC decreased in a linear form, depending on the levels of aP. It was concluded that diets in which the level of Ca was kept fixed and on those where the level of Ca varied in proportion to the P levels, the levels of, respectively, 0.446 and 0.550% provided the best performance results for broilers maintained in a thermoneutral environment from 8 to 21 days old.

ASSUNTO(S)

nutricao e alimentacao animal aminoácido fósforo disponível termoneutralidade amino acid available phosphorus thermoneutrality

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