Campylobacteriosis, or vibriosis, is a venereal disease of cattle caused by a bacterium Campylobacter fetus subsp venerealis, which lives in the lining of the reproductive tract. Infection in a herd reduces reproduction and prolongs the calving period. Pregnancy rates may be reduced by up to 20 per cent in infected herds. Vibrio can cause problems in both dairy and beef herds.
There are no obvious outward signs of infection in infected cows or bulls. However, cows that cycle constantly and regularly but do not go in calf may be affected by this disease. Bulls will typically be working hard right through the breeding season. Some cows eventually recover from the infection and go in calf, resulting in a drawn out calving period with subsequent management problems, such as numerous brandings and uneven lines of weaners. Herds that use artificial insemination will often have higher pregnancy rates from AI than from the use of bulls (this should be the other way around).
The vibrio organism causes irritation of the lining of the reproductive tract in female cattle, leading to delays in conception and may lead to them becoming barren due to permanent damage to the reproductive tract. Most infected cows develop immunity and eventually go in calf. However, pregnancy rates are generally reduced, especially in herds with restricted joining periods. In herds where the infection is entrenched, heifers are most severely affected. If recently introduced to a herd, vibrio can cause a sudden, severe reduction in reproductive performance across the whole herd.
Infected cows or heifers may abort later in pregnancy and vibriosis should always be considered in cases of abortion.
The vibrio organism is transferred between infected cows by bulls, which can harbour the infection in their sheath. As bulls age, the lining of their sheath develops folds, which can effectively harbour the vibrio organism. Therefore, older bulls are more likely to harbour the organism and carry it between cows than young bulls.
Infection will establish quickly in herds with year round joining. The use of bulls in a number of different herds in a breeding season may also spread the infection, unless the bulls are vaccinated. Incursions of bulls from neighbouring properties may also be a source of infection. Putting young bulls in with older bulls may also result in them becoming infected.
The disease is confirmed by measuring antibodies in the vaginal mucus of infected cows and heifers. The sample is collected by a veterinarian and tested in a laboratory. Bulls can also be tested for the presence of infection, though this is not very reliable. A diagnosis may also be made by isolating the organism from aborted foetuses.
The vibrio organism is susceptible to particular antibiotics. The treatment must be flushed into the sheath of the bull to be effective. Treatment of bulls by veterinarians may be warranted in special cases. Giving young infected bulls 6-9 months sexual rest and vaccinating them against vibriosis will cause most, but not all, to clear the infection. Bulls over eight years of age should be culled.
|Prevention and control|
Sound reproductive management is essential. The use of a restricted breeding season or the annual culling of dry, empty cows in herds that join continuously is advised. This removes any cows or heifers from the herd that may be carrying the infection or that are barren as a result of chronic damage to their reproductive tract. Culling older bulls is also an essential part of reproductive management. Joining vaccinated young bulls to wet cows will control the infection.
Cows and heifers that have recovered from infection have a strong immunity that will prevent reinfection for a time.
An effective vaccine is available for Vibrio. Vaccination should be completed at least one month before intended joining time. Two injections, one month apart, are required for protection. In herds with confirmed infection, annual vaccination of the replacement heifer group and all bulls is recommended. Vaccination of cows may also be required. Once infection is eliminated from the herd and reproductive rates are at an acceptable level, heifer vaccination may be discontinued but annual bull vaccination should be continued.
Annual vaccination of all bulls in all herds is recommended as a precautionary measure. Whole herd artificial insemination will eliminate the disease. This is a practical control option in dairy herds. If the above control measures fail, then concurrent infection with Trichomoniasis should be considered.