Minimising poor fertility in beef herds
21 October 2015
North Coast Local Land Services District Veterinarians have reminded beef producers of ways to minimise the risk of vibriosis – a common cause of poor fertility in North Coast beef herds.
Despite a very effective vaccine being available to prevent vibriosis it remains a common cause of poor fertility in beef herds in this area. Vibrio, also known as bovine venereal campylobacteriosis, is a venereal disease of cattle caused by bacteria which does not survive outside the reproductive tract of cattle.
Bulls have the potential to remain infected persistently without showing any signs of infection. In cows and heifers, infection causes early loss of pregnancy, altered oestrous cycles, delayed conception and occasionally abortion. Aside from this there are no other signs of infection.
When vibrio is first introduced into a herd the earliest sign may be a large number of heifers and cows returning to the bull. These returns to service are usually longer than the normal oestrous interval of 18 to 21 days. Pregnancy rates in herds where infection has recently been introduced are usually very low. While in herds where the infection has been present for some time, pregnancy rates will be better, but still well below that expected in a non-infected herd.
Most cows eventually develop immunity to the disease and subsequently hold a pregnancy. However, a small percentage of cows, less than 1 or 2%, may remain permanently infertile. A small number of cows may also abort as a result of vibrio infection.
Swabs taken from the vagina of a sample of heifers and cows in the herd may be used to confirm a diagnosis of vibrio in a herd. Testing of bulls may also be used, using material collected from the prepuce of bulls. In cases where abortion has occurred, samples from the foetus can be used to confirm a diagnosis.
Ian Poe, District Veterinarian said "Factors which may increase the risk of vibrio in a herd include year round joining; use of hired or shared unvaccinated bulls; poor boundary fencing and introducing females from multiple sources."
To avoid vibrio ensure all bulls are vaccinated with Vibrovax. Previously unvaccinated bulls should receive two doses 4 to 6 weeks apart, preferably with the second dose given shortly before joining. Bulls should receive a booster every 12 months.
In herds where vibrio has been diagnosed, vaccination of bulls and females may be used to control the disease. Additional management practices such as a restricted joining period, culling empty cows and using young bulls may also help in control of vibrio.
For more information about the control of this bacteria in your beef or dairy herd contact your North Coast Local Land Services District Veterinarian.
Ian Poe, District Veterinarian, North Coast Local Land Services 0429 987 255
Photo caption: Vibriosis remains a common cause of poor fertility in North Coast beef herds