Abstract / Summary
Over the past decade, phytotherapy such as licorice has attracted research as an alternative to antibiotic growth promoters in broiler production, driven by rising concerns over antimicrobial resistance. However, the consistency of its effects across productive, physiological, and health outcomes remains inconsistent. This meta-analysis quantitatively synthesized published experimental evidence on the effects of dietary licorice on growth performance, carcass yield, blood indices, visceral organs, oxidative status, intestinal morphology, and cecal bacterial balance in broiler chickens. A systematic literature search identified studies published between 2010 and 2025, and effect sizes were computed (Hedges' g ; 95% confidence interval). Pooled estimates were derived under the random-effects model using the restricted maximum likelihood estimator, with between-study heterogeneity characterized by I² and the Q -statistic. Univariable mixed-effects meta-regression was conducted to identify study-level moderators of treatment response, and publication bias was assessed using a funnel plot and the Rosenberg fail-safe N criterion. Dietary licorice did not affect feed intake or the feed conversion ratio, but it did increase body weight gain (BWG; SMD = 0.289; P = 0.002), breast, thigh, gizzard, and bursa weights ( P < 0.05). Gut integrity also improved with the villus height/crypt depth ratio (SMD = 0.931; P = 0.041), and Lactobacillus spp. counts (SMD = 0.266; P = 0.003) increased, while Escherichia coli populations were suppressed (SMD = −1.737; P < 0.001). Overall, the findings support that licorice enhances body weight gain, with route, duration, sex, and strain moderating efficacy.