Effects of Dietary Organic Acid Supplementation in Coccidiosis-Challenged Broilers: A Meta-Analysis

This meta-analysis aimed to systematically assess the effects of organic acid supplementation on growth performance and disease-related parameters in broiler chickens challenged with coccidiosis. Following PRISMA guidelines, a systematic literature search was conducted across PubMed, Scopus, and Web of Science, yielding 11 controlled experimental studies for quantitative analysis. The outcomes measured were BWG, feed conversion ratio (FCR), lesion score, and oocyst count (OPG). No overall significant effect of organic acid supplementation was detected on body weight gain (BWG) (MD = 49.88 g; 95% CI: -156.94 to 256.70; p = 0.64) and FCR (MD = -0.12 g/g; 95% CI: -0.25 to 0.01; p = 0.08), with high heterogeneity across investigations (I² = 100%) as identified through random-effects meta-analysis. Organic acid supplementation was associated with lower lesion scores (MD = -1.08 score units; 95% CI: -1.39 to -0.77; p < 0.00001; I² = 57%) and reduced oocyst shedding (SMD = -1.25; 95% CI: -2.25 to -0.25; p = 0.01; I² = 93%). Exploratory subgroup analyses suggested possible differences according to study duration, organic acid type, Eimeria species, and measurement time point. However, several subgroup estimates were based on a small number of studies and should therefore be interpreted cautiously rather than as confirmatory evidence of differential efficacy. Leave-one-out sensitivity analyses showed stable conclusions for BWG, FCR, and lesion score, whereas the statistical significance of the OPG effect was sensitive to omission of some studies. Exploratory assessments suggested possible small-study effects for BWG and OPG, but these analyses were underpowered because fewer than 10 studies contributed to each outcome. Using the GRADE framework, the certainty of evidence was rated as very low for BWG, FCR, lesion score, and OPG because of risk-of-bias concerns, inconsistency, and imprecision. Overall, very low-certainty evidence suggests that organic acids may reduce intestinal lesion severity and oocyst shedding, whereas their effects on growth performance remain uncertain. Further well-designed and standardized studies are required to clarify treatment effects and optimal supplementation strategies.