Analysis of antibiotic use, biosecurity and mortality in semi-intensive broiler farms in Kenya

The indiscriminate use of antibiotics in food-producing animals contributes to antimicrobial resistance (AMR), posing a global threat. Understanding the factors associated with antibiotic use is critical to combat resistance while maintaining animal health. This study examined antibiotic use practices, mortality rates, biosecurity levels, as well as the associations between biosecurity and antibiotic use, and between biosecurity and mortality, in semi-intensive broiler farms in Kenya.The study was conducted in 129 semi-intensive farms with total flock sizes between 200 and 2000 birds across three peri-urban counties in Kenya. Data were collected prospectively over one production cycle, with farms visited biweekly using questionnaires and a drug bin approach. Biosecurity levels were assessed by a panel of experts who weighted scores for various external and internal biosecurity subcategories. Directed acyclic graphs (DAG) described potential relationships between explanatory variables, confounders and outcome. Logistic regression analysis was conducted with antibiotic use as the outcome variable. Explanatory variables with P < 0.25 in the univariable logistic regression were included in the multivariable regression. Similarly, linear regression was conducted using mortality as the outcome.Overall, 72% of farms used antibiotics, primarily for prophylaxis (66%), with erythromycin and oxytetracycline being the most commonly used antibiotics. The median mortality rate across the production cycle was 6%. There was no significant difference in mortality between farms using antibiotics and those not using antibiotics. Biosecurity practices were low, with a median biosecurity score of 14.3/67.9. Univariable screening suggested potential associations between antibiotic use and vaccination of day-old chicks, flock size, cleaning protocol for chicken drinkers, resting period between batches, feed store cleaning, water source, distance from neighbouring farms, and age. However, these were not significant in multivariable logistic regression. Linear regression showed an association between mortality and biosecurity measures, specifically disease management and visitor entry regulation.This study highlights widespread antibiotic use, low biosecurity implementation, and variability in mortality rates in the farms surveyed. There is a gap in farmers' implementation of effective biosecurity measures and understanding of prudent antibiotic use. An urgent need exists to develop comprehensive data collection methodologies, education, and interventions to promote responsible antibiotic stewardship and cost-effective biosecurity practices among poultry farmers in Kenya.