Potential use of guanidinoacetic acid to spare dietary energy and influence muscle myopathies in Ross 708 male broilers

An experiment was conducted to assess the potential for guanidinoacetic acid (GAA) to spare dietary energy and influence muscle myopathies when included in broiler diets. A total of 1,056 male Ross 708 broiler chicks were randomly assigned to 48 floor pens with 22 chicks per pen. Broilers were fed one of four experimental diets and reared to 50 days of age. Dietary treatments consisted of a control (T1), T2 (T1 – 110 kcal/kg apparent MEn), T3 (T2 + 0.08% GAA), and T4 (T1 – 55 kcal/kg apparent MEn + 0.08% GAA). Biweekly BW, BWG, FI, and mortality corrected FCR were calculated for the 49-day period. On day 50, 13 birds per pen were processed and deboned. Parts consisted of Pectoralis major and minor, whole legs, wings, and rack. Part weights were used to calculate relative yield in relation to final live weight. Following deboning, breast and tenders were collected and scored for the presence of myopathies and used to complete further meat quality analysis. Data were analyzed as a one-way ANOVA testing the main effect of diet. Means were considered significant at P ≤ 0.05 and separated using a Tukey’s HSD test when significance was met. No differences (P > 0.05) were noted in BW, BWG, and FI. At 0-28 days, FCR was highest (P < 0.05) in broilers fed the T2 diet, followed by broilers fed T4, while broilers fed T3 were intermediate of T2 and T4, and broilers fed T1 the lowest. At 0-49 days, FCR was highest in broilers fed the T2 diet, lowest for broilers fed T1 and T4, while broilers fed T3 were intermediate. For processing, no differences (P > 0.05) were noted in live, carcass, or most part characteristics. However, differences were present (P < 0.05) in fat pad percentage as birds fed the T1 diet had a higher fat pad percentage than birds fed other diets. Broilers administered T4 and T3 had a higher leg yield (P < 0.05) than that of broilers fed the T2 diet, while broilers provided T1 were intermediate. No differences (P > 0.05) were noted in breast or tender myopathy severity or prevalence. Broilers fed T1 and T2 diets expressed a higher breast pH (P < 0.05) than birds fed T4, while broilers given the T3 diet were intermediate. Broilers fed T3 and T4 expressed lighter fillets (P < 0.05) than broilers given the remaining diets. No other differences were noted in meat quality characteristics (P > 0.05). These results indicate that GAA may spare dietary energy.