Trends in Necrotic Enteritis and Coccidiosis Control Practices in Canadian Poultry Flocks, 2018-2023

Necrotic enteritis (NE) and coccidiosis continue to be diagnosed in poultry in Canada. Since 2013, the Canadian Integrated Program for Antimicrobial Resistance Surveillance (CIPARS) has been collecting data on antimicrobial use (AMU) and antimicrobial resistance (AMR) in broiler chicken and turkey flocks, with layer flocks added to surveillance in 2021. This study describes enteric disease control strategies utilized in poultry production from 2018 to 2023, based on farm data reported to CIPARS. In broiler chickens, 85% (51.7 mg/kg broiler chicken biomass) of the total quantity of medically important antimicrobials was used for NE control, compared to 51% (28.1 mg/kg turkey biomass) in turkeys and 74% (16 mg/kg layer biomass) in layers. Since 2019, antimicrobial classes used for NE control have decreased following the voluntary elimination of preventive use of macrolides, penicillins, and streptogramins. Bacitracin remained the most frequently used antimicrobial for NE control across all poultry. For coccidiosis control, ionophores were used more frequently than chemical coccidiostats, with a 2.5:1 ratio in broiler chickens (ionophores: 2892.9 kg; chemical coccidiostats: 1126.6 kg) and a 2.4:1 ratio in turkeys (ionophores: 1840.2 kg; chemical coccidiostats: 749.9 kg). Layer flocks used exclusively monensin (39.3 kg) and amprolium (31.6 kg). Over the surveillance time frame, the diversity of coccidiostats used in broiler chickens and turkeys remained stable. Shuttle/dual-control programs (58%) were commonly used in broiler chickens, whereas continuous/straight programs (51%) were predominant in turkeys. Notably, alternative disease control strategies such as vaccination are emerging or continuing. Clostridium perfringens vaccine was used in 1% of broiler chickens, and coccidiosis vaccines were administered in 13% of broiler chicken flocks, 16% of turkey flocks, and 29% of layer flocks. These nonantimicrobial alternatives may reduce the reliance on AMU. Despite shifts in AMU practices, mortality and enteric disease diagnoses remained stable. The findings highlight the importance of preserving antimicrobial efficacy, including coccidiostats, for gut health. Ongoing surveillance is crucial for monitoring trends in disease control strategies and assessing their impact on poultry health and production.