Efeito de diferentes níveis de proteína bruta e balanço eletrolítico sobre o desempenho, parâmetros sanguíneos e características ósseas de frangos de corte na fase de 36 a 42 dias de idade

Abstract

The aim of this study was to evaluate the effect of different levels of crude protein (CP) and electrolyte balance (EB) of the feed of broilers. 480 male broiler of Cobb 500 strain were fed in the period 36 to 42 days of age with two basal diets, one with EB 200 and another with 240 mEq. kg -1 , combined with CP levels of 18.00, 17.28, 16.56 and 15.84%. The reduction in CP levels had growing linear effect (P <0.01) on feed conversion of birds (BE 200 and 240) even with the supplementation of industrial amino acids. For weight gain, reduced levels of CP had decreasing linear effect (P <0.01) to birds consuming diets with EB of 240 mEq. kg -1 and quadratic effect (P <0.05) for those who consumed ration with EB than 200 mEq. kg -1 being the level of 17.54%, which resulted in better weight gain of birds. There was linear effect (P <0.05) of reduction in CP levels on the plasmatic values of sodium (EB200) and chlorine (EB240) and quadratic effect (P <0.05) on plasmatic concentration of potassium (EB200) of birds, being the level of 17.05%, which provided the lower potassium values. For the plasma levels of uric acid, total protein and calcium, and bone development, reduction in the levels of CP had no effect on neither one of EB levels studied. Supplementation with bicarbonate salts of sodium and potassium chloride was not effective in improving the performance characteristics the birds, in the values of electrolyte balance studied, since there were no performance improvements with increase the electrolytic balance of the diets of 200 to 240 mEq.kg -1 .