AHWNI urges farmers to act now on BVD

Through ear tissue testing, the BVD Programme has already reduced the overall incidence of BVD in NI by more than 70 percent through early disclosure of Persistently Infected calves.

Maximising herd immunity to the BVD virus through vaccination and reducing the number of opportunities for the virus to enter and spread are key strategies for many farmers.

Vaccination

There is a need for BVD vaccination on certain farms, to produce a protective immunity in breeding cattle. The immunity gained means that the negative effects of the BVD virus on fertility and the birth of Persistently Infected calves can be avoided. While the incidence of the BVD virus in NI is decreasing, it is important to be aware that there is an accompanying decrease in natural immunity to the virus (due to reduced exposure). This reduction in immunity may leave herds more exposed to large outbreaks should an infected animal be introduced or in a high risk situation, such as an outbreak in a neighbouring or associated herd or herds with a greater than normal throughput of people, such as demonstration farms.

Unfortunately there have been recent examples of BVD Positive results emerging where the vaccine manufacturers’ recommendations have not been followed. If you are vaccinating your herd for BVD, ensure that all breeding stock including breeding heifers have been vaccinated, and that the vaccine and boosters are being given at the right time and in accordance with the manufacturer’s instructions. Discuss with your vet how to optimise vaccine use. Remember that stopping a BVD vaccination programme prematurely, where biosecurity risks still exist, could be a very expensive exercise.

Biosecurity

The key risk factors that have been identified at herd level which increase the probability of BVD entering a herd are: large herd size, a history of BVD in the herd, purchase of cattle, purchase of ‘Trojan’ cattle (in-calf animals carrying a PI calf) and an increased concentration of BVD-Positive animals in the vicinity of the herd. It’s important that the risks of spread including direct contact (eg at boundaries, shows and sales) and indirect contact (eg contaminated environments, equipment or clothing or hands of farmers, employees, or visitors) are considered. Any herd which has been or is exposed to some or all of these risks in the absence of appropriate control measures has an increased probability of experiencing the spread of BVD into their herd.

How to reduce the risk of a BVD breakdown

- Buy low risk animals from low risk BVD herds

- Quarantine animals on arrival

- Minimise contact of bought-in cattle with other animals, particularly animals in the first four months of pregnancy

- Isolate purchased pregnant animals until calved and the calves tested with negative results

- Step up biosecurity during the breeding season - this is a key period where infections can lead to the birth of PIs

- Keep boundaries in good condition to prevent contact with neighbouring animals

- Supply cleaning and disinfection for farm personnel and visitors

- Clean and disinfect shared equipment.

The BVD Implementation Group continues to work towards the eradication of BVD in NI.This is being achieved one herd at a time – the sooner action is taken at the farm level, the sooner we will achieve

our goal.

Further information is available in the BVD FAQ section of the AHWNI website: www.animalhealthni.com.