Meta-analysisindependent cross-checkabstract checked I-RES-111 standard review

Antibiotics in feed do make broilers grow a little faster

Withdrawal of antibiotic growth promoters from broiler diets: performance indexes and economic impact.

Overview

Maria Cardinal K et al.. Poult Sci 2019 · PMID 31544941 · DOI 10.3382/ps/pez536

Across 183 experiments, antibiotic growth promoters increased weight gain and feed efficiency, mainly early in life.

Does the study support the specific claim? Yes · Methodological quality: moderate

Study explained simply

What did the researchers want to find out?: What are the performance and economic effects of withdrawing AGP from broiler diets?
How was the study done?: Meta-analysis of 183 experiments plus economic model (Brazil)
How many people, animals or samples were studied?: 174 articles, 183 experiments, 121,643 broilers
What was actually found?: AGP+ diets: higher feed intake, weight gain and lower feed conversion in the initial phase (1-21 d); no differences in the final phase (22-42 d); over the total period higher weight gain and better feed conversion. Economic impact $0.03 per bird.
How large was the observed effect?: AGP+ diets: higher feed intake, weight gain and lower feed conversion in the initial phase (1-21 d); no differences in the final phase (22-42 d); over the total period higher weight gain and better feed conversion. Economic impact $0.03 per bird.
What do the results mean in everyday life?: The growth effect is real but small.
What are the study's limitations?: Effect sizes not in abstract; Publication bias possible; Industry-economic framing
What does it say about Elawady's specific claim?: Supports the claim that antibiotics were used to make chickens grow faster.
Do the results apply to Germany and Europe?: Banned in the EU since 2006.
What can explicitly not be concluded from this study?: Does not show that modern fast growth is due to antibiotics.

What are the performance and economic effects of withdrawing AGP from broiler diets?

Study design: Meta-analysis – Meta-analysis of 183 experiments plus economic model (Brazil)
Population: Broilers in 183 published experiments (52% Ross)
Country: multinational; economic model Brazil
Period: literature to 2019
Sample size: 174 articles, 183 experiments, 121,643 broilers
Inclusion and exclusion criteria: as described in the abstract

Exposure / intervention: AGP in feed (avilamycin, flavomycin, virginiamycin, bacitracin)
Comparator: No AGP
Endpoints: Feed intake, weight gain, feed conversion, cost
Statistical methods: as reported in the abstract

Results: AGP+ diets: higher feed intake, weight gain and lower feed conversion in the initial phase (1-21 d); no differences in the final phase (22-42 d); over the total period higher weight gain and better feed conversion. Economic impact $0.03 per bird.
Absolute risks: not reported
Authors' conclusion: Broilers fed AGP have higher weight gain and better feed conversion; withdrawal increases production costs.

Statistically significant but economically small effect ($0.03 per bird).

Confirms that antibiotics in feed make broilers grow somewhat faster.

Across 183 experiments, antibiotic growth promoters increased weight gain and feed efficiency, mainly early in life.

Multidimensional assessment
Multidimensional assessment
Authenticity of the source	verified
Methodological quality	moderate
Risk of bias	some concerns
Precision of results	moderate
Directness	direct
Reproducibility	replicated
Consistency with the overall evidence	consistent
Regional transferability	moderate
Adequacy of the interpretation (by the archive)	not applicable