Fitase, granulometria da fonte de cálcio e relação cálcio e fósforo em dietas para frangos de corte

Abstract

Resumo: O calcio (Ca) e o mineral de maior inclusao nas dietas baseadas em milho e farelo de soja, tem importante participacao no funcionamento de alguns sistemas no organismo, principalmente o osseo. Como grande parte do fosforo (P) do ingredientes vegetais, encontra-se como parte da molecula de fitato, nao esta disponivel para os animais nao ruminantes, a inclusao de fosfatos de rocha se fazem necessario para atingir a quantidade de P requerida pelas aves. A enzima fitase entra como estrategia para aproveitar o maximo dos nutrientes, principalmente de fosforo dos ingredientes vegetais. Foram realizados dois experimentos para avaliar a inclusao de fitase, relacao entre Ca e P e granulometria (DGM) da fonte de calcio (FC). Foram utilizados seis tratamentos, variando na inclusao de fitase (0 e 500 FTU/kg), relacao Ca e P total (1,34:1 e 1,70:1) e DGM da fonte de calcio (grossa com DGM de 1354 ƒÊm e fina 428 ƒÊm). Os animais de ambos experimentos foram criados juntos, recebendo a mesma dieta e manejo ate o 21o dia de vida, apos esse periodo os animais foram alojados nas instalacoes de cada experimento. No ensaio de desempenho foram utilizados 1200 frangos de corte, alojados de 22 a 42 das de idade. Foram seis tratamentos com dez repeticoes de 20 aves em cada unidade experimental, sendo dez macho e dez femeas. Foi avaliado consumo de racao medio (CRM), ganho de peso medio (GPM)e taxa de conversao alimentar (CA) de 22 a 42 dias de idade. Aos 42 dias de idade um de cada unidade experimental foi selecionado para coleta das duas tibias, foi realizado avaliacao de resistencia ossea (RO), porcentagem de residuo mineral (%RM), calcio (%Ca) e fosforo (%P). No ensaio de metabolismo foram utilizados 960 frangos, alojados de 22 a 28 dias de idade. Foram seis tratamentos com 16 repeticoes de dez aves em cada unidade experimental, sendo oito repeticoes de machos e oito de femeas. A coleta total de excretas foi de 25 a 28 dias de idade. Foi avaliado coeficiente de metabolizabilidade aparente da materia seca (CMAMS), calcio (CMACa) e fosforo (CMAP). As variaveis de desempenho e caracteristicas osseas foram comparadas por meio de analise de variancia. As variaveis de metabolizabilidade foram comparadas em esquema fatorial 6x2, sendo seis tratamentos e sexo das aves. Havendo diferenca significativa as medias foram comparadas por meio de Teste de Tukey a 5% de probabilidade. Nao houve diferenca significativa (p>0,05) de desempenho e RO. Para %RM no osso houve diferenca estatistica (p<0,05). O tratamento com relacao Ca e P de 1,34, FC fina e fitase apresentou menor concentracao de RM no osso comparado ao tratamento com relacao 1,70, FC grossa e com fitase. Para %Ca no osso houve diferenca estatistica (p<0,05). O tratamento com relacao 1,70, fitase e FC grossa apresentou maior concentracao de Ca comparado ao grupo com mesma relacao e fitase. Nao houve interacao significativa (p>0,05) entre os fatores para nenhuma das variaveis de metabolizabilidade. Nao houve diferenca significativa para CMAMS. Houve diferenca significativa (p<0,05) para a variavel CMACa, os tratamentos recebendo fitase foram iguais entre si, independendo da relacao Ca e P ou FC. O desempenho e RO dos frangos nao foram influenciados pela inclusao de fitase, relacao calcio e fosforo e granulometria da fonte de calcio. A dieta contendo fitase e relacao calcio e fosforo de 1,70 e fonte de calcio grossa (1354 ƒÊm) apresentou maior concentracao de residuo mineral no osso comparado a dieta com fonte de calcio fina (428 ƒÊm). Independente da relacao Ca e P e DGM da FC, os frangos alimentados com dietas contendo fitase apresentaram maior coeficiente de metabolizabilidade de Ca. Palavras-chave: enzima, metabolizabilidade, minerais, resistencia ossea

Abstract: Calcium is the mineral most of the diets based on corn and soybean meal, plays an important role in the functioning of some systems in the body, especially bone. Phosphorus is the second most mineral included in chicken diets, however, is the third most expensive dietary component. Because much of the phosphorus vegetable ingredients is not available for non-ruminants, the inclusion of rock phosphates are necessary to achieve the required amount by birds. The enzyme comes as a strategy to make the most of the nutrients, especially phosphorus, vegetables ingredients. Two experiments were conducted to evaluate the inclusion of phytase, ratio between calcium (Ca) and phosphorus (P) and particle size (PS) of the calcium source (CS). Treatments were varying the inclusion of phytase (0 and 500 FTU / kg), calcium and phosphorus ratio (1.34: 1 and 1.70: 1) and particle size of the calcium source. (thick with PS 1354 ìm and thin 428 ìm). The animals in both experiments were raised together, receiving the same diet and management until the 21st day of life. In the performance test were used in 1200 broilers housed 22-42 of age. There were six treatments with ten replicates of 20 birds in each experimental unit, ten male and ten female. Was rated average feed intake (FI), weight gain (WG) and feed conversion ratio (FC) 22-42 days old. At 42 days of age one of each experimental unit was selected for the collection of both tibias, was conducted evaluation of bone strength (BS), percentage of mineral residue (% MR), calcium (%Ca) and phosphorus (%P). In the metabolism assay were 960 chickens were housed 22 to 28 days of age. There were six treatments with 16 replicates of ten birds in each experimental unit, eight repetitions of males and eight females. The total excreta collection was 25-28 days old. Was evaluated coefficient of apparent metabolizable dry matter (CAMDM), calcium (CAMCa) and phosphorus (CAMP). The performance variables and bone characteristics were compared using analysis of variance. The metabolizability variables were compared in a factorial 6x2, with six treatments and sex of birds. A significant difference means were compared by Tukey test at 5% probability. There was no significant difference (p> 0.05) performance and BS. The %MR for the bone was statistical difference (p <0.05). Treatment with Ca and P 1.34, CS thin and inclusion of phytase showed lower concentration of MR in bone compared to treatment with ratio 1.70, thick CS and phytase. There was no interaction (p> 0.05) among the factors for any of metabolizability variables. Gender did not significantly different. There was no significant difference for CAMDM. There was a significant difference (p <0.05) for CAMCa variable, treatments receiving phytase were equal to each other, regardless of Ca and P or FC interface. There was a significant difference (p <0.05) for the CAMP variable, the control treatment, ratio 1.34 and thick FC got metabolizability lower values compared to all other treatments with phytase in the diet. The performance and RO of the chickens were not affected by the inclusion of phytase, calcium and phosphorus ratio and particle size of the calcium source. The diet containing phytase and calcium and phosphorus ratio of 1.70 and a source of thick calcium (1354 ìm) had a higher concentration of mineral residue in the bone compared the diet with fine source of calcium (428 ìm). Regardless of the calcium and phosphorus and particle size of the calcium source, the chickens fed diets containing phytase had higher coefficient of calcium metabolization. Key-words: bone strength, enzyme, metabolization, minerals