Antimicrobial Growth Promotion in Food-Producing Animals

Antimicrobial growth promoters (AGPs) have been employed in livestock and poultry production for over half a century to enhance feed efficiency, accelerate weight gain and maintain animal health. At subtherapeutic doses, AGPs modulate the composition and activity of the intestinal microbiota, dampen inflammatory responses and influence nutrient absorption. These multifaceted effects spare nutrients for growth and improve metabolic efficiency. However, routine AGP use has been implicated in the emergence of antimicrobial resistance, alteration of microbial ecosystems and the persistence of drug residues in animal‐derived foods. Consequently, regulatory bodies worldwide have restricted non-therapeutic antibiotic use and promoted the development of evidence-based alternatives. Contemporary research spans molecular mechanisms of host–microbe interactions, surveillance of drug residues, risk assessment of resistance transmission and innovation of feed additives that replicate the benefits of AGPs without undermining public health. This global endeavour seeks to balance productive animal husbandry with the imperative to safeguard human and animal well-being.

Research from Nature Portfolio

Foundational work using defined-microbiota mouse models has revealed that AGPs directly influence host immune pathways. Administration of chlortetracycline or tylosin phosphate reduced expression of pro-inflammatory cytokines in the intestine and acute-phase proteins in the liver, thereby mitigating weight loss during bacterial challenge. These findings demonstrate that AGPs act not only on microbial populations but also on host physiology to promote resilience. In pigs, combined use of antibiotics and zinc oxide was shown to shift gut microbial metabolism towards increased bile acid production. The altered bile acid profile activated signalling networks in the gut, liver and adipose tissue, reinforcing barrier function, attenuating inflammation and modulating lipid and protein metabolism. This tissue-specific remodelling of bile acid signalling offers a mechanistic framework for the growth-promoting effects of AGPs and identifies targets for development of non-antibiotic interventions.

Antimicrobial Growth Promotion in Food-Producing Animals publication trend

The graph below shows the total number of articles in antimicrobial growth promotion in food-producing animals across all publications each year (not limited to Nature Index journals).

Technical terms

Antimicrobial growth promoters (AGPs): Subtherapeutic compounds added to animal feed to enhance growth and feed efficiency through interactions with host physiology and microbial communities.

Microbiota: The community of microorganisms inhabiting the gastrointestinal tract, influencing digestion, immunity and overall host health.

Bile acid signalling: Communication pathways activated by bile acid molecules that regulate metabolic, immunological and barrier functions in host tissues.

Antimicrobial resistance: The ability of microorganisms to survive exposure to antimicrobial agents, undermining therapeutic efficacy and posing risks to animal and human health.

Dysbiosis: An imbalance in microbial community structure in the gut, which can impair intestinal function and contribute to disease or reduced growth performance.

References

1. Veterinary Drug Residues in the Food Chain as an Emerging Public Health Threat: Sources, Analytical Methods, Health Impacts, and Preventive Measures. Foods (2024).
2. Solutions to the Dilemma of Antibiotics Use in Livestock and Poultry Farming: Regulation Policy and Alternatives. Toxics (2025).
3. Alternatives to Antibiotics: A Symposium on the Challenges and Solutions for Animal Health and Production. Antibiotics (2021).
4. Antimicrobial growth promoters modulate host responses in mice with a defined intestinal microbiota. Scientific Reports (2016).
5. Antimicrobial promotion of pig growth is associated with tissue-specific remodeling of bile acid signature and signaling. Scientific Reports (2018).