Níveis de proteína e aminoácidos para frangos de corte em estresse térmico por calor

Abstract

ABSTRACT An experiment was conducted to evaluate the effects of crude protein (CP) and amino acid standards (AA) on performance, digestibility of nutrient and energy, economic efficiency index, as well as physiological and immunological responses, biochemical and hematological parameters in broiler chickens reared under cyclic heat stress. A total of 336 Cobb male broilers from 23 to 42 days old were distributed in a completely randomized design in a 2 x 2 factorial arrangement (2 protein levels: 19 and 21%, and 2 amino acid standards: high and low) and the broilers were exposed at 30 ± 1 ° C for 8 hours daily. Broilers receiving 19% CP had better dry matter digestibility than broilers that received 21% CP. The best weight gain was obtained from broilers that received high AA. The highest viability was obtained when they received low AA. Broilers fed with 19% CP and high AA had higher H: L ratios than those fed with 19% CP and low AA. For Broilers that received low AA, the H: L ratio was lower when fed with 19% CP than those fed with 21% CP. In the economic analysis, the high AA determined the highest cost. It was concluded that, although broilers that received diets with the lowest protein level and low amino acid standard had lower H:L ratios and this is indicative of lower physiological stress, the diet with 21% CP and low AA was the most economic and productively viable. Keywords: broilers, economic efficiency index, hot environment, physiological and immunological responses productive performance