A meta-analysis of the effects and relationship between guanidinoacetic acid and the growth performance of broiler chickens

Regulating dietary Arginine (Arg) levels in the diet of broilers has been a focus of researchers due to the potential economic benefit to the industry. This meta-analysis evaluated the effects of dietary guanidinoacetic acid (GAA) supplementation on the production performance of broiler chickens fed diets that were either adequate or deficient in Arg or energy. Through studies, the basal diet generally met standard requirements for broilers, with deficiencies in Arg or energy being experientially induced. The meta-analysis using weighted random-effects models revealed that dietary GAA improved average daily gain (ADG; P < 0.001) by 2.17% and 1.08% during starter and finisher periods, respectively. Concomitantly, the feed conversion ratio (FCR; P < 0.001) also improved by 2.37% and 2.41% in the starter and finisher periods, respectively, with minimal evidence of publication bias for these key traits. However, significant heterogeneity (I² > 90%) indicated strong between-study variances. In broilers fed Arg-deficient diets, GAA supplementation only showed minimal effect to reduce the detrimental effect of an Arg-deficient diet (-4.75 vs. -3.64% ADG reduction), suggesting its limited Arg-sparing function. Under low energy diet, GAA restored ADG to levels equivalent to those of energy-sufficient diets. In the finisher phase, comparable but less pronounced effects were observed, suggesting reduced responsiveness with age. Dose-response evaluation suggested no difference in ADG or FCR between low and high GAA inclusion, suggesting low GAA level is more effective. Meta-regression models identified feed intake and arginine intake as the dominant predictors of ADG, and including GAA consistently improved model accuracy and increased ADG compared to the control diet. The meta-refgression suggested that 0.06% GAA supplementation increased final body weight by approximately 2.11% (60 g) in Ross 308 broilers. Collectively, the results confirm that GAA exerts a robust, dose-limited benefit of growth efficiency in broiler chickens, thereby supporting its incorporation into Arg or energy deficient diets that would have potential economic benefit.