Ácido guanidinoacético e interação com outros nutrientes sobre o desempenho e ocorrência de miopatias em frangos de corte

Abstract

Two experiments were conducted to evaluate the effects of supplementation of nucleotides and guanidinoacetic acid (GAA) on broiler diets, in addition to the interaction effect of GAA, different inclusion levels of arginine (Arg) and glycine (Gly) were evaluated on broiler performance, blood parameters, leukocyte differential count, mitotic activity of satellite cells, absorption of embryonic attachment, organ and breast development, carcass yield, meat quality, incidence of breast myopathies and skin lesions in broilers. In the first experiment, 600 birds were randomly distributed among 3 treatments with 8 replicate/treatment and 25 birds per pen. Treatments consisted of a control diet (CD), CD + 1 g kg-1 of nucleotides (fed from 1 to 28 d, afterwards broilers were fed the CD) and CD + 0.6 kg-1 of GAA. In the second experiment, the birds were distributed in a central composite design rotated with double experimental mesh. Each experimental mesh, represented by the inclusion/ exclusion of 0.6 kg-1 of GAA, presented four factorial points (combination of levels 96.4 and 117.6% of Arg and 132.5 and 161.5% of Gly), four axial points (combination of levels 92 and 122% of Arg and 127 and 168% of Gly), and a central point, represented by the pair 107% of Arg and 147% of Gly, totaling 18 treatments. Each factorial and axial point had four repetitions and the two central points presented 24 repetitions each, all with 25 birds per pen. In the first experiment, broilers fed diet supplemented with GAA; improved FCR, and increased BWG and concentration of creatine kinase in the broiler serum from d 1-10, compared to the control treatment. GAA supplementation provided a reduction in; the occurrence of dermatosis, incidence of moderate and mean woody breast (WB) scores, proportions of severe and mean scores of white stripping (WS) at 42d, in comparison to broilers fed diets supplemented with nucleotide. In the second experiment, FCR from 1 to 10 days, presented a decreasing linear behavior for the Arg and quadratic levels as a function of the Gly levels. The birds supplemented with GAA, in periods from 1-10d and 1-42d, showed a better FCR when compared to birds fed diets without GAA. AST concentrations exhibited an increasing linear behavior and a decreasing linear effect as a function of Arg and Gly levels, respectively. GAA supplementation decreased AST blood concentrations. There was an increase in the occurrence of mild WB score and a reduction in the sum of the moderate+severe WB scores from broilers fed GAA diet. In addition, the proportion of occurrence of normal WB score increased while that of severe WS score was reduced with the supplementation of GAA. In conclusion, supplementation of nucleotides, increases the incidence of breast myopathies, having no effect on other parameters. The dietary supplementation of GAA improved broiler performance from 1-10d and 1-42d, as well as reducing the severity of WB, WS and the occurrence of dermatosis in broilers, at 42 d of age. The increased ratio of digestible Arg:Lys and Gly:Lys, in 10 and 16% of the recommendations, provide an improvement in FCR during the initial phase.