Animal diseases are an unavoidable aspect of any livestock farming enterprise and require due attention. Yet it is often overlooked, leading to major economic losses.
According to Dr Chris van Dijk, chairperson of the National Animal Health Forum (NAHF), the health status of the national herd is currently in much better shape than in previous years. However, the health status of individual herds has a direct influence on the national health status of livestock.
Some regions of the country have a high health status due to the vigilance with which producers manage their herds, while in other parts the status is considerably lower as some producers fail to pay the necessary attention to their herds’ health status.
The incidence of an animal disease involves more than just the clinical cases in a herd. For every clinically ill animal, there is a group of infected animals showing no visible symptoms. Producers must therefore ensure that their herds build immunity against the most common diseases in that specific environment, so as to prevent production losses and mortality.
Health management on the farm
When assessing the health of their animals, producers must take into account mortalities on the farm as well as the general state of the animals’ immune systems. Administering the right vaccine at the right time can make a huge improvement to an animal’s immune system.
According to Dr Van Dijk, a hit-and-miss approach is sometimes taken with vaccines and only 15 to 20% of all livestock are vaccinated against some of the most common livestock diseases. The remaining unvaccinated 80% is partly to blame for certain animal diseases running rampant in South Africa. Herd immunity at farm as well as national level is crucial.
He also warns that vaccines are the last input on which producers should try to save money. Veterinarians must play a more involved role in the farming enterprise, and the producer and veterinarian need to have a solid work relationship. The veterinarian can give advice on the most important diseases in the area against which animals must be vaccinated, as well as other diseases livestock producers should take note of.
Health programme: Key factors
The herd health programme must consider three key factors, namely:
- The host of the disease.
- The pathogen or vector that transmits the disease.
- The natural environment in which the farming enterprise is operated.
These factors will reveal which diseases require vaccination and which are less threatening to the herd.
This article sets out the most important guidelines for general health practices, as put forward by Dr Van Dijk, and are applicable to dairy and beef cattle as well as sheep.
Diseases in dairy cattle
Given the low profit margins of dairy farms, dairy producers can ill afford any losses in milk production or quality. Equally important is maintaining the correct somatic cell count (SCC) in the milk. Illness can easily cause an imbalanced SCC. Uncomplicated, preventable diseases can also have a negative effect on lactation periods.
The most common and most costly diseases on dairy farms are the clostridium-related diseases. It causes diarrhoea in calves, blackleg in all animals, and can lead to botulism and tetanus. Infectious bovine rhinotracheitis (IBR) is a respiratory disease especially prevalent in calves on dairy farms. It is an immune-suppressing disease that may cause abortions.
The herd health programme must consider three key factors, namely the host of the disease, the pathogen or vector that transmits the disease, and the natural environment in which the farming enterprise is operated.
Although the outbreak of clostridial diseases may lead to large-scale losses, it is preventable by vaccinating animals against it. It is, after all, better to spend a planned amount of money on a vaccine than to lose thousands of rand to mortalities and production losses.
In addition to the aforementioned diseases, dairy producers should keep a close eye on tick-borne diseases. Redwater and gallsickness pose an ever-increasing threat to the viability of dairy herds and young animals should therefore be vaccinated timeously.
Following a good dip programme for livestock and applying remedies correctly is also imperative. If remedies against external and internal parasites are applied incorrectly, it may lead to parasites building up resistance against the agents. This will weaken the animal’s immunity.
Diseases in beef cattle
Venereal diseases play a major role and can have a considerable impact on the profitability of a beef cattle enterprise. Trichomonosis and vibriosis can enter and spread unnoticed in your herd if no set mating season or breeding programme is followed. These diseases can be detected sooner when a breeding programme is followed, as the low conception and calving percentages are a clear indicator of their presence.
It is advisable that the veterinarian tests for bulls’ fertility, which includes sheath scrapes, before each breeding season. This will allow for early detection of venereal diseases, enabling producers to intervene in time. The test results will show whether it is necessary to vaccinate or not.
Dr Van Dijk also emphasises the importance of cryptosporidium in beef cattle herds. This disease is becoming more common, especially in the presence of organisms such as rota- and coronavirus. These viruses create a favourable environment that promotes cryptosporidium infection in animals.
Malnutrition, for example lower levels of minerals and vitamins, contributes to the outbreak of cryptosporidium in herds. This re-emphasises the value of proper herd and nutrition management. Farming nowadays is also more intensive than in the past, contributing even further to the higher incidence of disease.
Additional herd losses due to diseases such as three-day stiffsickness, acute calf diarrhoea, rotavirus, coronavirus, and E. coli can be controlled through timeous vaccination of cattle. This will elicit an appropriate immune response, which is essential for building immunity in cattle. Hence calves should not be vaccinated too early and producers must adapt the vaccination programme to the cattle’s biological cycle.
Diseases in sheep
As with beef cattle, supporting the fertility of your rams and ewes need to take precedence. Subclinical cases of pizzle rot may initially not have a significant impact on the lambing percentage of your herd, but if left unchecked, it can bring the farming enterprise to a standstill. It causes discomfort in rams as well as ewes during the mating season, ultimately leading to a lower conception rate.
Sheep scab does not lead to mortalities among sheep, but can hamper wool production. As an immune-suppressing disease, it can lead to outbreaks of other diseases. Orf and footrot can also severely impair the production of your herd.
Dr Van Dijk advises sheep producers to thoroughly examine animals before buying them. By examining the wool, mouth and claws of new sheep, the producer can prevent the spread and exposure of these diseases on his or her farm.
Brucellosis – a deadly enemy
Brucellosis is a herd disease that poses a threat not only to livestock, but also to people who have contact with infected animals. This disease spreads easily in the herd and can lead to a large number of abortions, consequently lowering profits and leading to a poor herd growth rate.
During an online workshop held earlier this year, Dr Alicia Cloete, in collaboration with the NAHF, explained the new seven-point policy on brucellosis. The policy includes vaccination, training, testing, movement control, slaughter, reporting, and brucellosis control measures.
In order to effectively curb this disease, all role-players in the livestock industry must do their bit. Producers are legally obligated to vaccinate female animals between three and eight months of age against brucellosis and to only buy livestock from herds that have been certified as brucellosis negative.
A final thought
Livestock producers need to maximise the immunity of their herds and minimise the instances of disease. Animals must not be vaccinated randomly; instead, a strategic and effective vaccination programme must be followed against the most important diseases prevalent in a specific region.
Managing nutrition, grazing, mating seasons, and vectors is just as important as vaccine administration. Take note of vectors that transmit diseases, such as flies, mosquitoes, and ticks. Through the correct application of biosecurity at farm level, many diseases can be prevented and will ultimately benefit the health status of the national herd. – Mario van den Heever, Department of Agricultural Economics, University of the Free State
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For references, send an email to the author at VanDenHeeverMJJ@ufs.ac.za.