The number of herds in Northern Ireland retaining BVD PI animals has "fallen dramatically" since toughened eradication measures were introduced to the region's Farm Quality Assurance Scheme earlier this year.

Bovine viral diarrhoea (BVD) is a highly contagious viral disease of cattle that can be transmitted as easily as the common cold.

Dr. Sam Strain, programme manager for Animal Health and Welfare Northern Ireland (AHWNI), current estimates put the cost to the region at between £25 million and £30 million a year (a figure which is based on comparative estimates in the Republic of Ireland).

Action over the summer saw AHWNI partner with the Livestock and Meat Commission to enforce requirements for farmers to remove PI animals from their farm or face losing their Farm Quality Assurance.

Letters were sent to farms found to have retained PI animals, explaining that if they did not cull the animals within a set period of days further action would be taken.

Eradication efforts

BVD eradication has proved challenging as the virus can be spread directly by infected animals, or indirectly, for example through contaminated visitors or equipment.

It means keeping persistently infected (PI) animals on-farm substantially increases the risk to other animals.

Infected animals can look entirely normal, particularly at birth, but may become stunted and fail to thrive, making it a costly disease in terms of agricultural production.

PI animals often develop a severe, and always fatal, wasting condition with diarrhoea and ulceration of the gut and feet, called mucosal disease - typically occurs between six and 18 months of age. The majority of PI animals die before reaching breeding age or slaughter weight.

Dr. Strain explained: "As a result of the letters, we saw a substantial reduction in the number of retained positive animals. Since we started recording in early 2018 until November 2020, the figure has dropped by 80%.

The most recent snapshot - on November 2 - shows the number of herds with a living BVD positive animal recorded on-farm that day at 173. That could change slightly day-to-day but, when you compare it with the peak of 785, it's quite a significant difference.

"The result of this has led to an in the overall number of PIs born. That, in turn, will protect more pregnancies in the next few months."