The cold weather has arrived in most parts of the country and in the next few months we shall notice further effects of the dry winter weather which should be followed by warm, wet conditions.

Managing the health of your herd is a critical step towards profitable cattle production. Waiting until you experience a loss on your farm may cost you dearly. It is therefore important to invest in the prevention of diseases in your herd.

Why vaccinate?

The three main reasons to vaccinate are to increase immunity, reduce the spread of disease and eliminate diseases. Vaccination programmes should always be customised according to your farming operation. Items to consider while establishing a vaccination programme include geographic region, and the type of cattle on your farm. A vaccination programme is an important element in a comprehensive, well planned herd health control strategy.

External parasites

External parasites include horn flies, face flies, stable flies, ticks, and lice. The largest health problem comes from the additional stress caused to animals by these insects. When infested, cattle spend more time in the shade and do not graze, which leads to poor performance.

Eliminating the areas where pests reproduce also helps to reduce the severity of external parasites. Pour-on and dips are effective in treating animals infested by ticks. It is important to understand the life cycle of ticks and recognise the stage and species of ticks infesting cattle when treating for tick infestation.

The blue tick, which is easy recognisable by its blue-grey colour, is a one-host tick, and newly hatched larvae feed and moult on the cattle for about 3 weeks until the fully engorged adult female blue tick drops off to lay her eggs on the ground. They often appear in June/July and may infest cattle into the spring. The tick is easy to recognise on the back, sides, neck, and upper legs of the cattle.

All farmers know this tick species, which transmits redwater and gallsickness mostly during wet summer months. Larvae are very small, and farmers must look carefully for these parasites when deciding when to dip. The enzootic areas of the disease correspond to the distribution of the vector species in southern, eastern, and western African countries.

Avoid dipping calves to control blue tick for up to 4 to 6 months of age during cooler months as 4 to 5 month old calves are resistant to redwater and gallsickness. Allowing them to be exposed during this period will induce a resistance to these two tick transmitted diseases.

Brown ear ticks are well known to farmers. The life cycle is yearlong with larvae and nymphs active in winter, and adults active in summer around January, February, and March. The adults can cause severe damage to the ears, head, neck, and areas under the tail, leading to skin damage and screw worm infestation. The adult tick also transmits theileriosis causing high mortality in cattle. Tactical dipping during the winter months reduces larval and nymphal numbers, thereby reducing the challenge posed by adult brown ear ticks and the risk of theileriosis. Be aware that calves are very susceptible to theileriosis and cattle of all ages must be free of adult brown ear ticks during the critical hot, wet months.

Internal parasites

Internal parasites such as roundworms, lungworms, and liver flukes commonly occur in cattle. These hidden parasites cause poor performance and occasionally kill young animals. Invasion of the stomach or intestinal wall by a parasite leads to poor digestion of nutrients and damage to organs. Signs of parasite infestation include scouring, rough hair coat, poor weight gain, and a potbelly appearance.

Deworming at strategic times during the year reduces the numbers of internal parasites. Use faecal sampling to determine the severity of the infestation and the type of dewormer that will be effective. Treat animals with a long acting flukicide such as Fluconix which also controls wireworm, and an anthelmintic such as Intermectin as we enter the cooler autumn months. Thereafter it is not necessary to deworm stock until warmer temperatures are experienced from September onwards.

Calves

Dose at 6 weeks against tapeworm with Niclosamide or a Benzimidasole. Thereafter, a Benzimidasole may be used to dose calves up to 7 months of age every 4 to 8 weeks (depending on the type of pasture and the rainfall). Dose again at 12 months and thereafter at 18 months. An Ivermectin such as Dectomax can be used as a substitute for Benzimidasole.

Cattle

Healthy cattle over the age of 20 months build up immunity against internal parasites. Dosing of mature cattle is thus usually unnecessary unless they have been under stress because of disease, drought, or a difficult calving.

Disease control

Vaccinations and parasite controls are available for many of the diseases affecting cattle. Vaccinate all animals against botulism before the winter months, even if additional feed and lick is not fed to animals, as a lack of phosphorus causes pica in animals (appetite for strange objects such as plastics, decaying carcasses, faeces, et cetera). Eating decaying carcasses and contaminated vegetation causes botulism in cattle.

A lack of green fibre in winter leads to a vitamin ADE deficiency which affects the immune system, leading to other diseases such as keratitis and bone deficiencies. Supplementing all stock with injectable Vit ADE improves response of animals to vaccines.

Safety

Do not vaccinate shortly before or after transporting, dipping, castration, and dehorning. Stress neutralises vaccination. Some vaccines must be administered in winter, well before the onset of wet weather that heralds the arrival of flies, mosquitoes, and midges. In cattle, these diseases include lumpy skin disease (LSD), rift valley fever (RVF) and three-day stiff sickness (ephemeral fever). Do not wait for the rains to begin before you vaccinate. Be aware that LSD and RVF can cause abortions if not treated correctly. Bulls can be rendered unable to service cows for weeks and sometimes months after contracting three-day stiff sickness. It is notable that although anthrax can infect livestock any time of the year, most outbreaks of disease occur in the early winter as water levels in dams drop. Vaccinate against anthrax well before the winter months, especially in the lowveld of Zimbabwe. Do not be afraid of vaccinating in winter three months before breeding as the vaccine can last for up to two years.

Summary of vaccinations required by cattle:

• Breeding cows and heifers QE (quarter evil), anthrax, RVF, LSD, vibrio, and BVD/IBR.

• Bulls require all the above as boosters, and young breeding bulls require two vibrio vaccinations six weeks apart before the breeding season starts.

• Do not omit three day stiff sickness vaccination in bulls before the wet weather. Cows optional.

• Weaners QE, LSD, RVF, anthrax, botulism, tetanus.

• Weaner heifers require CA (contagious abortion) vaccination additionally between three and eight months of age.

General vaccination programme for beef cattle (by Dr Ariena Shepherd)

We thank the following sources for the material used in this article:

MSD Animal Health -https://www.msd-animal-health.co.za/

The Agricultural Research Council -https://www.arc.agric.za/

Vet360- https://vet360.vetlink.co.za/

Fivet Animal Health -www.fivetanimalhealth.com