The inclusion of synthetic amino acids and the protein level in two feeding systems for broilers

Two feeding systems (triphasic and monophasic) with three crude protein (CP ) levels (high, medium and low) with or without the addition of synthetic a mino acids (SAA) dl-methionine and 1-lysine in maize-soybean diets, were ev aluated using 2160 broilers of both sexes of the E-24 commercial hybrid, wh ich were distributed according to a completely randomized design with a 2 x 3 x 2 factorial arrangement. In both the triphasic and monophasic systems, the protein level worsened the feed intake/gain ratio (2.39, 2.44 and 2.46 ) throughout the fattening stage. However, the inclusion of SAA improved th is indicator at both the starting (1.93, 2.14 and 2.09 vs. 1.81, 1.79 and 1 .76) and growth stages (2.33, 2.50 and 2.39 vs. 2.22, 2.16 and 2.29), while this did nor occur in the finishing stage, in which it provoked an impairm ent in the main economical indicators. This suggests that the inclusion of SAA is not justified in the finishing stage. There was an interaction betwe en the feeding system used and the inclusion of SAA, where the triphasic sy stem proved to be the most efficient. Also, the cost per Cuban peso produce d decreases between 0.02-0.05, with respect to the monophasic system. It is Suggested that it is possible to attain better economical advantages with an adequate strategy from the use of SAA and the triphasic feeding system, taking into account not only the productive but also the economic benefits, thereby contributing to make broiler production more sustainable.