RESUMEN
One experiment was conducted to evaluate the effects of guanidinoacetic acid (GAA) supplementation in broilers fed corn or sorghum-based diets on live performance, carcass and cut up yields, meat quality, and pectoral myopathies. The treatments consisted of corn or sorghum-based diets with or without the addition of GAA (600 g/ton). A total of 800 one-d-old male Ross 708 broiler chicks were randomly placed in 40 floor pens with 10 replicates (20 birds per pen) per each of the four treatments. At hatch, 14, 35, and 50 d, BW and feed intake were recorded. BW gain and FCR were calculated at the end of each phase. Four broilers per pen were selected and slaughtered at 51d and 55d of age to determine carcass and cut up yields, meat quality and myopathies (spaghetti muscle, white striping, and wooden breast) severity in the Pectoralis major. Data were analyzed as a randomized complete block design in a 2 × 2 factorial arrangement with grain type and GAA supplementation as main effects. At 50 d, diets containing GAA improved (P < 0.01) FCR (1.682 vs. 1.724 g: g) independently of grain type. At 55 d, broilers fed corn diets with GAA had higher breast meat yield (P < 0.05) compared to corn without GAA. Drip and cook loss, and shear force (Warner-Bratzler) were not affected (P > 0.05) by GAA supplementation at any slaughter ages. However, GAA decreased (P < 0.05) the ultimate pH at 51 and 55 d in breast meat samples compared to unsupplemented diets. At 51 d, broilers supplemented with GAA had double (P < 0.05) breast meat fillets without wooden breast (score 1) compared with broilers fed non-supplemented diets, therefore reducing the severity of this myopathy. In conclusion, GAA supplementation improved broiler live performance in broilers raised up to 50 d independently of grain source, increased breast meat yield in corn-based diets and reduced the severity of wooden breast myopathy.