Pests in Cattle – External Parasites
Livestock production practices, when intensified, create a conducive environment for the multiplication of different pests that reduce animal productivity through competition for food, especially blood feeders, while others act as disease vectors. Some pests are present throughout the production periods and are major challenges to livestock farmers. Some control measures and practices have often resulted in harder-to-control pests due to repeated applications of the same formulation remedy and pest resistance results.
There are two categories of these pests based on the location of their harm to the livestock and they are classified as either internal or external pests. The correct diagnosis is essential. Livestock keepers should be well versed in these various challenges affecting their investments to use the best and economically viable control mechanism to ensure optimal livestock production.
Major losses have been reported in livestock production systems resulting from tick-borne diseases, especially in warm tropical regions. The cattle tick is a significant ectoparasite of cattle and a vector for important diseases such as East Coast Fever, babesiosis and anaplasmosis. Ticks cause physical damage to the animal by feeding on it by sucking blood. The cattle tick is widely distributed, and climatic factors largely determine the distribution. Ticks require high humidity and ambient temperatures of at least 15-20 °C for egg laying and hatching.
Cattle tick infestation causes:
- Damage to hides;
- Loss of production;
- Anaemia and death,
- Weakness during droughts.
The life cycle involves free-living stages. After feeding on cattle, engorged female ticks drop to the ground and lay eggs (up to 5000). After hatching, the larvae survive on pasture for several months. The larvae then become active, climb up grass, and transfer to animals as they brush past. The larvae attach and feed from the host. A potential risk for introduction to new areas might be transportation through dogs, although egg production is much reduced in this species, and the risk is considered low.
There are four methods available for controlling ticks:
- Treatment with acaricides
- Pasture spelling
- The use of resistant cattle
Tick control by acaricide dipping has been widely used in endemic areas. Acaricide used for this purpose includes various synthetic pyrethroids, amitraz, and organophosphates. Dipping may have to be done every 4-6 weeks in heavily infested areas.
Cattle are the main hosts for cattle ticks although they may be found on horses, goats, sheep, deer, camel and buffaloes. Heavy infestation of cattle ticks causes loss of condition and even death because of blood loss. Thicks can also carry and transmit tick fever which cause death and sickness in cattle. If cattle are heavily infested, ticks can be found anywhere on their body. The main places to look on a lightly infected animal are the neck, tail, belly, shoulder, dewlap and ears. Tick bites damage the hides of heavily infested animals. In severe cases hides may become unsaleable.\
Cattle are particularly vulnerable when they first encounter cattle ticks but develop a degree of resistance after repeated exposure. Indigenous breeds (tropical breeds) and their crosses develop better resistance than exotic breeds. Horses, goats and sheep also suffer tick problems but after some time, they develop strong resistance. The best time to identify the cattle tick is at the adult stage.
Adult females feed for a week, then lay eggs and die. They can lay up to 3000 eggs, and then they die. The eggs hatch into larvae, which can survive on pastures for 2 (warm weather) to 7 (cold weather) months until they find a host. The cattle tick spends about 21 days on one host, during which it goes from a larvae to a nymph and then an adult. Males feed occasionally, but they don’t fill with blood. Cattle ticks can be controlled with resistant cattle, chemical treatments, the cattle tick vaccine, pasture spelling, or a combination of methods. However, resistance to chemicals is a growing problem. Hand dressing is effective but labor-intensive. Using a combination of methods is usually necessary to control tick infestations.
To ensure that dipping is both safe and effective, the following principles should be observed:
- The bath should be roofed to prevent dilution of the acaricide by rain or evaporation hot during the weather
- The bath must be long, wide, and deep enough to ensure complete animal immersion without injury. These should be access along its whole length to enable help to be brought to any animal in difficulty and to enable an operator, stationed at the side of the bath to duck the head of each animal by means of a dipping crutch.
- When the required amount of acaricide has been measured out it must be evenly distributed over the bath surface. The animal should have a second dipping
- The full dip-tank volume should be accurately measured. This should be done at the time of filling (for example, by counting the number of 200 litres drum-full of water it takes to fill the dip-tank
- The dip tank should be accurately calibrated
- To mix it, 20 cattle should be passed through the dip at the beginning of dipping. After these cattle should drained and pass through the dip again
- Each animal should be totally submerged at least once
- The dipped cattle should be allowed to drain for only 2-3 minutes in the drainage race before releasing them. This results in a wash consumption of 2-21/2 litres per head
- Ear fringes and trail brushes must be clipped once every six weeks
- A sample of the dip wash should be taken for analysis once a month. This should be taken while the dip wash is still very agitated after the passage of at least 50 heads or immediately after the last animal has been dipped.
- The dip tank should be emptied and cleaned once every year
- Cattle that are hot, tired and thirsty should not be allowed to rest and drink before the treatment
- Dipping should be carried out early morning
- Calves should be treated after the treatment of adult cattle
- Calves under one month of age should be treated with care and attention
The mechanical spray race
- The spray race should be built across a slight slope and at right angles to the prevailing winds
- The spray race, the sump housing and the power source should be roofed
- The sump should be filled with water regarding the number of animals which will be treated – allow 2.5 litres per animal and an additional 300-500 litres, depending upon the race, for the sump.
- It is essential that the spray race carries a pressure gauge and that the recommended pressure is maintained (1-1.4bar)
- The spray race should be checked before any animal is treated to ensure that there is sufficient pressure, the nozzles are clear and that the spraying works correctly.
- The sump should be cleaned out between treatments.
- The sump tank should be accurately calibrated by pouring water into the sump from 200litre and/ or 20litres drums and making off the various levels on a dipstick.
- The prepared spray wash should be allowed to circulate for 5 minutes through the entire spray race system before spraying commences
- Two-foot baths must be filled with clean water before the animals start going through the spray race. The footbaths should be cleaned out after the spraying
- The sprayed animal should drain for 2-3 minutes before being released. This results in a wash consumption of 2-21/2litres per head
- Ear fringes and tail brushes of cattle should be clipped every six weeks
- Cattle that are hot, tired or thirsty should not go through the spray race. They should rest and drink before.
- Spraying should be carried out early morning
- The animals should be rushed through the spray race
- Calves should not be sprayed along with adult cattle. The calves should be allowed to go through the spray race after the adults
- Calves under one month of age should be sprayed with due care and attention
- The wash is delivered via one or two lances either manually or by a motor-operated pump
- Depending on the number of cattle to be sprayed, they may be restrained in a race in single file or a single animal crush
- The recommended operating pressure for hand spraying is 3 bar with each lance delivering 3.5-4.5litres of wash per minute as a fine spray
- The wash can be placed in a bucket. ( for each animal, 9-13 litres of wash is used normally)
The following routine should be followed to achieve adequate wetting of the whole animal:-
- Spray the hind legs, under the scrotum and the tail. The tail should be laid along the back while being sprayed to prevent unnecessary wastage of wash
- Spray the belly of the animal, followed by the flanks and backline
- Spray the front legs, brisket, neck, head and ears
- Spray the inside of the ears last
Mange is a condition caused by mites, which look like small arachnids similar to spiders, mites, can infect and harm the skin of both domestic animals and humans. Problems can occur all year round. Three main species of mite affect cattle, the surface mite, the burrowing mite and the sheep scab mite. The surface mite is the most commonly seen.
Usually, the mites are found on the neck, legs, and tail head. It can cause limited hair loss, which increases slowly. However, the lesions are very itchy, resulting in hide damage as the cattle try to rub the affected areas.
The scab mite in sheep is found on the flanks and around the tail head, and anus. Although this mite feeds on the skin’s surface, its mouthparts pierce the skin, producing blisters, which can be very irritating.
The burrowing mite prefers the neck and the loin area next to the tail (leading to the description of the ‘neck and tail’ mange). As the mites burrow into and out of the skin, they produce a much more intense irritating reaction causing skin damage rapidly. In much larger areas, the skin becomes very thickened and crusty. Infection of the damaged areas often develops and affected animals have reduced production.
The surface mite and the sheep scab mite spend their entire life cycle on the skin’s surface. Females lay around 90 eggs which, once hatched, take about ten days to develop into mature adults.
The burrowing mites’ lifecycle is more complex. The female mite tunnels into the animal’s skin and lays around 50 eggs. These hatch in four or five days, each releasing a larva. Some of these tunnel to the surface to become adults, while others develop in the tunnels; this process takes around two weeks. More tunnels are often formed during the mating process.
Infection is spread mainly by direct contact between cattle for all three species. The burrowing mite can survive for some time off the host. Therefore for this species, bedding and other objects that come into contact with the infected animals may become contaminated and help spread the infection.
A range of products is available to treat mange in cattle. The choice is between pour-on products and injections. The first ones are easier and quicker, and cheaper to use. However, in severely infected animals (as is often seen in burrowing mite problems), the skin reaction can mean that contact between the product and the mite is limited. In such cases, scabs may have to be removed before treatment. If very severe situations, injectable products are better. For very severe surface mite problems, the injection should be followed up by a pour-on treatment when the skin has recovered. This happens because in these species (unlike the burrowing mite), injections can control but do not eliminate.
Read more in the book of the author “Success in agribusiness: Profitable milk production”, by James Mwangi Ndiritu.
Pests in Cattle- External Parasites
Pests in Cattle- Internal Parasites
Serious Cattle Diseases caused by Pathogenes
Mastitis in Cattle – Causes, Symptoms and Management