Botulism outbreak causes cattle deaths
AHVLA is notified about 20 cases of botulism in the UK each year.
A number of cows are said to have died following an outbreak of botulism at a farm in Carmarthenshire.
The Animal Health and Veterinary Laboratories Agency (AHVLA) said it is currently investigating the incident.
A spokesperson said: "Analysis has confirmed that the likely source of botulinum toxin, the cause of botulism, was from a decaying animal carcase present in the grass silage being fed."
BBC news has reported that more than 70 cows have died as a result of the outbreak.
AHVLA said it is notified of 20 incidents of botulism in the UK each year. However, as botulism is not a notifiable disease, the actual figure is likely to be higher.
Botulism is usually caused by animals coming into contact with the litter of broiler chickens, according to AHVLA. This litter is brought onto farmland as a source of fertiliser.
Farmers are advised to securely store litter well away from livestock and to block access to birds and other scavengers.
It is illegal to use poultry litter as bedding material for other livestock. In addition, litter containing visible carcase material must not be used as fertiliser.
Defra has published guidance for the vet sector ahead of a proposed UK-EU Sanitary and Phytosanitary agreement.
