Environmental Drivers of Broiler Carcass Condemnation in Humid Subtropical Regions: A Predictive Model Incorporating Lagged Climatic Effects

Intensive poultry production in humid subtropical agro-ecologies faces unique environmental challenges that compromise carcass quality, welfare, and food security. While climatic influences are recognized, the temporal dimensions of these effects remains largely underexplored. This study quantified the immediate and time-lagged (1–3 months) influences of climatic variables on 12 causes of broiler carcass condemnation in a representative subtropical hub. Longitudinal data (2021–2023) from federally inspected slaughterhouses in Santa Catarina, Brazil, a global sentinel for Köppen Cfa and Cfb climate zones, were analyzed using Spearman rank correlation and advanced regression models, including Generalized Linear Models (GLM) with a quasibinomial distribution. Total condemnation rates rose from 13.1% in 2021 to 15.5% in 2023, dominated by gastrointestinal contamination (5.0%) and skin lesions (3.5%). Regression analysis revealed that lagged precipitation was a significant predictor for arthritis and cellulitis (p < 0.05), whereas higher temperatures and heat index reduced rejections for ascites and skin lesions (p < 0.01). A quasibinomial GLM identified lagged heat index (β = − 0.096, p = 0.051) as a critical driver for inflammatory lesions. These findings demonstrate that avian health in intensive systems is governed by a temporal environmental paradigm where conditions during early rearing phases dictate final carcass quality. The established predictive models offer an extrapolatable blueprint for seasonal management across global humid subtropical belts to mitigate economic leakages and enhance production sustainability.