Environmental drivers of broiler carcass condemnation in humid subtropical regions: an exploratory study on the association of 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 remain 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 relevant case study for poultry production within Köppen Cfa and Cfb climate zones, were analyzed using Spearman rank correlation and robust 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 marginal predictor for inflammatory lesions. These findings suggest an association between environmental conditions during the initial stages of rearing and the final carcass quality. The established models offer insights for seasonal management across similar humid subtropical belts to mitigate economic losses and enhance production sustainability.