Windhoek-Government and private veterinarians are working around the clock to identify the cause of hundreds of reported incidents of cattle abortions in the Windhoek district. The reports originate from various farms, with losses ranging from five to 45 and even 128 on certain farms. It is suspected the incidents of abortion are occuring more widely than reported.
Numerous samples have been submitted to the Windhoek Central Veterinary Laboratory (CVL), as well as to Onderstepoort and Path Care in the Western Cape. Thus far only the bacterium enterococcus casseliflavus has been identified, which according to literature, is not known to cause abortions. Tests for other known venereal diseases have also been negative so far.
Although most of the abortions reported took place between the stages of three to six months, there were also reports of older calves aborted. It seems that symptoms vary, but one is a high fever of the cow shortly before aborting.
As much information as possible is needed and it is crucial to report any incidents of cattle abortions to the CVL or veterinarians. A form is available from DVS offices to report the abortions.
Veterinarians told Farmers Forum that the basis of all abortion prevention programmes is sound herd health management. They say biosecurity is key. Their advice is to minimise the risk of introducing diseases on the farm. If the disease can enter the herd it can spread within the herd. Either effectively quarantine cattle for a minimum of 14 days, or maintain a completely ‘closed’ herd.
Special attention must also be given to the health status of bulls. Purchased bulls can introduce disease and spread it. Farmers are thus advised to get their veterinarians to assess the health status of their bulls and to only buy bulls from farms with a proven high health status.
Farmers must further ensure that farm visitors and their equipment are clean before entering the farm. Disinfection must be used if necessary. Boundaries must be stock proof, as cattle jumping fences often carry disease with them. Isolating aborting cows and immediately removing aborted materials can reduce spread within the herd.
Provide a sufficient quantity of a properly formulated and delivered ration. Cows under stress are more likely to become infected and to abort. Feed good quality feed to pregnant cows. Food which is contaminated with moulds should not be fed to such cows.
It is not good removing the visibly affected portion, as toxins and fungus will be present in the apparently normal portion too. Store feed properly – keep vermin out as they can spread bacteria and viruses, particularly salmonella.
Vaccination is an integral component of a complete herd health programme. It is not a remedy for poor management. Many of the infectious diseases that cause abortions in cattle have vaccines available, which are safe and effective.
Thus farmers are advised to work closely with their vets to develop vaccination programmes targeting diseases, which their farms are at risk from. Vaccines will not work if they are not properly handled and administered.
Abortion is the production of a dead calf within 270 days of insemination. Most abortions go undetected for up to about 120 days. Most herds have an abortion rate of 2 percent per year. A rate of 5 percent per year indicates a significant problem.
Abortion can be divided into non-infectious and infectious causes. Infectious causes are the most important and the ones for which there are specific control measures. Abortion due to infection can occur as a secondary complication of severe infection in the dam, but often occurs without clinical signs.
The diagnostic rate of abortion submissions is low. It can be increased with good recording and maximising the amount of material submitted. All abortions in cattle need to be reported to the local animal health officer, who will decide if a statutory abortion investigation is needed.