Table 6.

Prioritization of importance (decreasing order) of the different initial sources and vehicles of C. botulinum contamination (spore, vegetative form and toxins) in a cattle farm (Anses, 2021).

Initial source of contamination	Source of contamination	Argumentation for prioritization
Asymptomatic (or symptomatic) carriage by poultry and excretion in effluents	Poultry manure	Quantitative importance of this source of contamination in France with (direct or indirect) link between the cattle farm and a nearby poultry farm
Carcasses of dead animals	Contaminated silage or wrapping	Inclusion of an animal during harvest
Equipment		Dual role of equipment: - Contamination of silage if not cleaned. - Homogeneous distribution of the contamination throughout the ration (e.g., with a silo mixer)
Animal feces, operators, airborne contamination		Lesser importance than dead animals and equipment
Spreading of poultry manure	Pasture	Contamination of cattle if contaminated poultry manure is spread on pasture (direct ingestion) or if a dead animal is present
Carcasses of dead animals
Carcasses of dead animals	Other forages/ On-farm feed fabrication	Contamination of the feed if a dead animal or contaminated raw material is present
Contaminated raw materials