Parâmetros químicos, bioquímicos e mecânicos de fêmures de frangos de corte submetidos a diferentes balanços eletrolíticos

The objective of this study was to evaluate bone characteristics of broilers treated with different levels EB in the diet. A total of 935 Cobb chicks of 1 day of age were distributed in a randomized blocks design with six treatments (EB: -50, 0, 50, 100, 150 and 200 mEq/kg), six replicates and 26 birds per experimental unit. The basal diet for the two phases - starter, from 1 to 21 days and growth, from 22 to 42 days of age - was composed of corn and soybean meal, with electrolytic balance of 200 mEq/kg. For the obtainment of the other EB levels, the basal diet was supplemented with ammonium chloride. Mineral and bone protein contents and geometric parameters of femurs at 7, 14, 21 and 42 days were evaluated. At 7 days of age, birds fed the diet with EB of 200 mEq/kg presented the highest magnesium content in the bone. The contents of calcium and phosphorus obtained with EB of 150 mEq/kg did not differ from that achieved with EB of 200 mEq/kg. The greatest calcium:phosphorus ratio was observed in bones of birds fed the diets containing EB of 0 and 50 mEq/kg and the lowest content of ash was in those consuming the diet whose EB was 200 mEq/kg. The electrolytic balance of 200 mEq/kg feed promoted the lowest content of calcium at 42 days of age, but at the evaluation of the calcium:phosphorus ratio, it did not differ from the balance of 150 mEq/kg. The content of collagenous proteins did not differ at 21 days between EB of 150 and 200 mEq/kg feed. At  the  evaluation  of  the  biomechanical  parameters  at 7  days,  the  highest  value  of  maximum  bending  strength  was  obtained  with  the  electrolytic  balance  of  200  mEq/kg  feed, demonstraiting  that at 7 days of age the birds were more sensitive to variations of EB of the diet. At 14, 21 and 42 days, wider variations, from 150 to 200 mEq/kg can be used in the EB levels, for they do not harm the bone properties of broilers.