BVD causes large losses on dairy and beef farms
As well as causing sporadic deaths, poor production and a few unthrifty young cattle on chronically infected farms, the bovine virus diarrhoea virus (BVDv) can have a significant negative impact on fertility and kill large numbers of young animals. The examples that follow occurred in Southland and are just as likely to be happening in our patch.
Deaths began at calf marking in November on a large sheep farm running 3000 ewes, 50 mixed-aged cattle and 20 heifers. At pregnancy-testing in March, half the heifers were found to be empty. By weaning in May, seven weaners had died after a short illness. After weaning, 28 calves died with similar signs over the next few months while some of the surviving calves looked poor. The source of this BVDv infection may have been a yearling from the dairy farm next door found in with the cows while they were early in calf.
Deaths occurred among newborn calves from a group of 70 home-bred heifers on a 600-cow dairy farm. Calves started dying from severe diarrhoea that developed within 12 hours of birth. Unusually, most calves born from mature cows in this herd, calving at the same time and afterwards, and reared in the same sheds, were unaffected. About half the calves from the heifers had died by weaning. Of the 150 ‘healthy' heifer replacements from both heifers and cows, 25 were persistently infected with BVDv. The source of this BVDv infection is thought to be cows bought in to build herd numbers.
Identify the risks of BVDv getting onto your farm. Then set up a plan to mitigate these risks. If farmer and vet work well together as a team and the plan is implemented properly, BVDv can be controlled on most farms.
