Study tests GAA in reduced-energy broiler diets

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A newly indexed 2026 paper in Animals examines a question poultry producers keep revisiting as feed costs stay tight: can guanidinoacetic acid help broilers hold performance when dietary energy is reduced? The study, led by Patrícia Tomazini Medeiros and colleagues, tested GAA alongside three metabolizable energy levels in Ross AP95 male broilers through 35 days of age, with a separate nutrient-metabolism analysis in additional birds. (alice.cnptia.embrapa.br)

The premise is familiar, but the timing matters. Nutrition programs across broiler production have increasingly focused on “matrix” strategies that lower formulated energy while leaning on additives to preserve feed conversion and nutrient utilization. GAA has drawn attention because it is the direct precursor to creatine, a central component of cellular energy buffering. In poultry, that biology has made it a candidate additive for supporting ATP regeneration, muscle energetics, and potentially sparing arginine under practical corn-soy formulations. (pmc.ncbi.nlm.nih.gov)

In the new study, 1,944 day-old Ross AP95 males were randomly assigned to six treatments, with 12 replicates per treatment, across standard-energy, minus 50 kcal/kg, and minus 100 kcal/kg diets, each with or without GAA. A separate metabolism trial used 960 male broilers distributed across the same six treatments with 16 replicates each. According to the study record, the investigators evaluated performance and nutrient digestibility from day 1 to 35 and analyzed the data with ANOVA and Tukey’s test at p≤0.05. (alice.cnptia.embrapa.br)

While the indexed abstract available through Embrapa’s Alice repository summarizes the design more clearly than the journal listing currently surfaced in search, the broader literature helps frame what the authors were testing. A 2025 review in Veterinary Sciences concluded that GAA can improve broiler feed conversion, with the most consistent responses often showing up in FCR rather than body weight gain alone. That review also noted that benefits may be more apparent in low-energy diets and that excessive inclusion can be counterproductive, reinforcing that dose and diet context matter. (mdpi.com)

Regulatory background also gives the study practical relevance. EFSA previously assessed guanidinoacetic acid for use in feed and described intended inclusion ranges of 600 to 1,200 mg/kg complete feed, including poultry applications. EFSA’s review characterized GAA as an endogenous compound in creatine biosynthesis and summarized evidence that it is highly digestible in chickens, while also highlighting the metabolic pathway through methylation to creatine. (pmc.ncbi.nlm.nih.gov)

Industry interest in GAA has been building for several years, especially as formulators look for tools that can support lower-cost, lower-energy diets. A 2023 paper in Revista Brasileira de Zootecnia described GAA as a feed additive already associated with improved growth performance, breast meat yield, and feed conversion ratio in broilers, and specifically explored its metabolizable energy equivalence in corn-soybean meal diets. Taken together with the new Animals paper, that suggests the field is moving beyond asking whether GAA works at all and toward a more operational question: how much dietary energy can be safely pulled back when GAA is included, and under what formulation constraints? (rbz.org.br)

Another recent Animals study adds useful biological context from a different angle: the role of early gut development in setting growth potential. In a brooding-stage comparison between Liangshan Yanying chickens and Arbor Acres broilers, researchers found that by 28 days of age, Arbor Acres birds had body weights 3.24 times higher, average daily gain 3.11 times higher, and average daily feed intake 2.36 times higher, while feed conversion ratio was 24.10% lower. The faster-growing Arbor Acres birds also showed significantly greater intestinal segment density, higher villus height in the duodenum and ileum at hatch, and villus-to-crypt ratios that were 78.27% to 91.05% higher in most intestinal segments across ages. Correlation analysis linked higher body weight at 14 and 28 days with stronger average daily gain and lower FCR, supporting the idea that intestinal morphological development is not just a background trait but a likely contributor to performance differences. That does not test GAA directly, but it sharpens the broader point that feed-efficiency interventions may work best when they are understood alongside gut-development biology.

Why it matters: For veterinarians working with poultry integrators, this is less about a single additive and more about ration resilience. If GAA can reliably help preserve feed efficiency or nutrient utilization in reduced-energy diets, it becomes part of a broader health-and-performance conversation that includes gut integrity, amino acid balance, carcass outcomes, and cost control. The comparative gut-morphology data from Animals also reinforce that early intestinal development can be a major determinant of later growth and feed efficiency, which matters when interpreting why nutritional tools perform differently across breeds, strains, or production systems. But the literature also argues against a one-size-fits-all approach. Responses appear strongest when diets are marginal in energy or arginine supply, and there are signals that higher doses may reduce performance rather than improve it. That means veterinary and nutrition teams will still need to assess ingredient quality, amino acid ratios, methyl-donor supply, baseline gut health, and flock-specific performance goals before treating GAA as a straightforward energy replacement. (pmc.ncbi.nlm.nih.gov)

What to watch: The next step is likely more commercially oriented validation, including cost-per-ton and return-over-feed analyses, plus confirmation of how GAA performs across strains, housing systems, and ingredient variability. For veterinary professionals, the useful signal will be whether future studies translate these controlled-trial findings into consistent field performance, not just statistical improvements on paper. It will also be worth watching for studies that pair performance outcomes with intestinal morphology or other gut-function markers, especially in slower-growing or local breeds where early developmental constraints may limit how much any feed additive can deliver on its own. (mdpi.com)