The voluntary phase of a Northern Irish BVD eradication programme became available to herd owners on 1st January 2013. It is estimated that around 0.5 to 0.75% of calves born each year in NI are persistently infected (PI) with BVDV. Calves can only become PI prior to birth, following infection of their dam during early pregnancy (around 30-120 days). Most commonly this happens when the dam becomes infected for the first time during this critical period of pregnancy, the alternative being that the dam is also PI. These PI calves have a very poor survival rate relative to their non-PI comrades, with the majority being dead with 24 months of birth. However during this time they are the main source of infection for other animals, contributing to scours and pneumonias in young stock and reproductive problems, including the creation of another generation of PI calves, in older animals.
The key goal of the programme, which it is planned to complete within a six year period, is the identification and removal of PI animals in a systematic, co-ordinated way. The programme will be based around the testing of ear punch samples collected as part of the official identity tagging process. This allows PI animals to be identified as soon as possible after birth. Prompt removal at this stage minimizes the cost of inputs they have received and their opportunity to spread infection within and between herds. In addition, testing of calves offers a two-for-one test result, since a direct negative result for a calf also gives an indirect negative result for its dam. On the other hand, a positive result for a calf raises a requirement to determine the status of its dam, which may be PI. Where breeding animals are shown to be PI, all of their offspring and descendents in turn are considered to be PI.
This highlights the importance to the programme of correctly recording the dam of each calf at registration.
For further information contact 028 8778 9126 or your own veterinary practice.
AHWNI will also be at this years Balmoral Show, see us on stand AP52.