10.0 DISEASE CONTROL AND PREVENTION
10.1 Foot Lameness
There are several common causes of lameness in cattle. They cause a loss in milk production and body condition because of the pain involved, and also because they prevent the cattle from grazing freely and eating as much as they need. The feet conditions result mostly from bad management, and they can usually be prevented by attention to correct husbandry. Once they have already occurred, these conditions usually require expert attention if they are to be successfully treated
Cattle are particularly sensitive to foot lameness when they are raised in pastures with protruding stones and rocky outcrops, or if they are forced to walk along roughly surfaced roads in which small stones protrude from the surface. Rough and uneven surfaces are an
important cause of lameness, because they bruise the sole, particularly in the wet season when the feet of cattle are soft. Bruising therefore occurs to a lesser extent in the dry season when the feet of cattle are harder. The bruised areas often develop into dead and empty pockets under the sole, which become infected. An infected sole requires the animal to be restrained and an expert must use a foot knife to trim away the bottom of the foot over the bruised area and apply a foot dressing which remains until the sole has healed.
Foot overgrowth, where the foot grows long and the toe becomes upwardly curving, results from the foot not being able to wear enough too keep the horn short and correctly shaped. Cattle which are grazing and able to freely walk around on reasonably dry hard ground have no problems with overgrown feet. Cows which are always tethered or penned, or which are kept in wet, soft paddocks have feet which do not wear sufficiently. If overgrown feet are noticed before they are too bad, the problem can be corrected by releasing the cattle or shifting them to better drained, harder ground. The feet can also be corrected by a veterinarian with the right equipment and the knowledge of the correct way to trim the feet. If the problem is not corrected for some time however, the bones and joints in the lower foot become distorted and the condition can not be changed and the effected animals then become permanently lame.
Figure 9. Overgrown feet
Under muddy conditions usually, a large, wart-like growth takes root usually between the toes of the hind feet. The growth can become quite large and by causing pain and infection, interferes with walking. The growth is fairly easily removed if the leg of the cow is restrained, but will grow back unless the wound left by the removed growth is treated by a veterinarian, using a bandage pack of Copper Sulphate cream.
Figure 10. Interdigital Papilloma
This disease is an infection of the foot. It can be a seasonal disease, occurring mainly during the wet season but it can also occur when the season is very dry.
Sometimes only one cow in the herd will have it. Sometimes many will have the disease at one time. It is first observed in cattle when they develop:
·a lameness in one or more feet
·swelling of the foot or a spreading of the toes and a reddening of the tissues above the hoof,
·the foot abscesses where the nail joins the skin and the discharge smells quite bad
·the cow will have a temperature, loss of appetite and body weight and milk production will fall,
It is caused by wet, muddy conditions and when the ground is stony, causing bruising of the sole of the foot. Therefore it can be prevented by draining areas which remain wet and muddy for long periods, and removing stones from roadways and pastures where possible.
Treatment requires the cow to be restrained by a veterinarian and the foot thoroughly examined, cleaned and dressed. Antibiotics are usually necessary as part of treatment.
10.2 Calf Diarrhoea (Scours)
·this section draws the attention of the farmer to this problem,
·it shows how to recognise a calf with diarrhoea and call assistance,
·emphasises good management as the main method of prevention.
Under normal beef cattle management, diarrhoea (and pneumonia) is not too common in calves. But if farmers are practising dairying they will have to wean their calves. This changes the system and increases calf stress. Calf diseases then have a greater chance of occurring, therefore management must also improve or calf deaths will occur.
Calf diarrhoea is common in dairy calves which are badly raised. It can have many contributing causes:
·not enough colostrum,
·poor nutrition generally,
·feeding milk at the wrong temperature
·using dirty feeding equipment.
·poor shelter so that the calf becomes cold and wet (also causes pneumonia)
Most calf sickness begins with an upset stomach, and upset stomachs are usually preventable.
Under normal grazing conditions, calf scours should not occur much unless calves are weaned into unsuitable, dirty pens or the pastures are overgrazed and young stock are underfed
Figure 11. The scouring calf. It should be treated quickly
The main types of diarrhoea which can occur are,
1. Nutritional Scours
·caused more by indigestion than by bacteria,
·occurs during the first month of birth,
·the dung is liquid and soft.
·the calf will still eat but it loses weight rapidly and may become dehydrated.
2. White Scours
·often caused by a lack of colostrum and dirty conditions,
·occurs mainly during the first week and only during the first month of life,
·droppings are liquid and white or yellow,
·calf has no appetite and is dull and weak.
3. Blood Scours
·often can sed by dirty conditions where several calves are kept together,
·droppings are liquid, bloodstained and smell badly,
·the calf strains when passing dung.
4. Worm Scours
·caused by internal parasites,
·green, brown or black scours
·rough coat, pot belly, dehydration.
The important points to remember are to:
·ensure good hygiene and a clean environment,
·separate young and adult stock,
·protect calves from stress with good housing and management
·clean grass from a protected area
·rotational grazing with calves first and adults following
·observe all stock frequently.
With the exception of worm scours which can be prevented by management and treated with anthelmintics, calf diarrhoea requires treatment which should be left to the veterinarian and paravet.
10.3 Calf Pneumonia
Pneumonia is an infection of the lungs. It occurs in calves:
·in cold and wet conditions (which is why good calf housing is important),
·where several calves are penned together,
and when there is overcrowding - several calves in a pen which is too small for them.
Calves have pneumonia when:
·there is a discharge from the nose,
·loud and painful breathing, often with diarrhoea,
·poor appetite, sometimes followed by death.
Some pneumonia can not be treated
Prevention is the best cure:
·don't overcrowd calves in a pen,
·keep pens clean,
·protect calves from becoming wet and cold.
10.4 Internal Parasites
Worms may cause animals to become sick or die. The signs of worms depend mainly on
·the type of parasite/s
·tapeworms cause little problems
·blood sucking worms cause anaemia and weakness
·worms which move around can cause coughing and pneumonia,
·the number of parasites an animal has,
·the age and health of the animal itself:
·young animals are more susceptible
·a few worms in a sick animal can be a problem, the same worms in the same animal which is healthy may be no problem at all
Parasitic infestations can be recognised by e loss of body weight,
·slow rates of weight gain in young stock,
·obvious sickness, lack of appetite, thinness of the body,
· sometimes death - particularly in young animals if the worms are untreated
Figure 12. The wormy calf. Note the rough coat and pot belly
These points are important:
·worms are mostly a problem of young stock
·adults (older than two years) are usually resistant to them,
·worms are most important during the several months after a calf is weaned, because at that age it is becoming dependent on grazing, adult cattle are the main source of infection for the younger animals Therefore young and old age groups should be separated
Control and Prevention
Most cattle older than two years have few parasite problems, so farmers should concentrate on
preventing worm problems in calves and other young stock
Parasite prevention in young stock involves
·cutting and carrying pasture grass to preweaning calves,
·grass areas for calves should be fenced from the normal grazing areas of older cattle,
·if possible, use fences to subdivide grazing areas to permit rotational grazing.
·where farms are fenced and electric fences are used, young stock should be weaned onto pasture areas which have been "spelled", i.e. not grazed for say 3 weeks.
·move the young stock every three weeks with adult cattle following ten days behind them,
·use broad-spectrum dewormers. Deworm young stock:
·first at weaning and,
·on two or three occasions 3-5 weeks apart with the first deworming at the onset of the main rams.
You should get the information on the correct type of anthelmintic to use from the veterinarian or local paravet. But, any farmer can deworm his own animals using a coke or long neck beer bottle, provided he/she knows the right dose and method
·deworming calves requires only a long necked bottle.
·with the dose for the calf in the bottle, and the bottle in the right hand, push the calf up against a wall, (or tree if the calf is small),
·by pushing the fingers of the left hand into the left side of the calf's mouth between its front and back teeth, open its mouth just wide enough to put the neck of the bottle over its tongue and pointing down the throat.
·slowly lift the bottle to pour the dose into the mouth and allowing time for the calf to swallow.
·lower the head immediately if the calf begins coughing.
·add a little water to the bottle to rinse the remaining medicine and give it to the calf in die same way.
Mastitis is a disease of the milk gland of the cow. It is the most costly disease of dairy cattle, causing loss of milk production and sometimes causing death. It is mostly caused by a bacterial infection which effects one or more quarters of the udder,
·without good management it can be spread by the process of milking, from one infected cow to all cows in a milking herd,
·places with much manure where cows are allowed to calve, contain many of the bacteria which cause mastitis,
·cows which have been dry for more than 60 days have a greater chance of getting mastitis than those with a shorter dry period,
·the risk of a cow getting mastitis increases as her milk production increases. Therefore good producers get more mastitis.
There are two main ways a cow can become infected:
·the udder of calves can be infected soon after birth by calves suckling each other, particularly if they are stickling cows which already have mastitis, or calves can pick up the infection from the environment of a dirty calf pen. Calves which are infected develop into heifers with mastitis from the first day they are milked.
·the infection may be transmitted from an infected cow to an uninfected cow on the hands of the milker.
Depending on the bacteria which causes it and how long the cow has had the disease, mastitis shows up in different ways:
New mastitis infections should be suspected if:
·one or several quarters is hot, hard and painful and the milk from that quarter may be thin and watery,
·a thick, yellow or white clotted discharge comes from the teat when it is milked,
·the milk may contain a few small clots when it is squirted onto the floor or the side of the milking bucket.
Old mastitis infections are suspected when:
·the milk contains a few small clots when it is squirted onto the floor or the side of a bucket, and
·when the udder is felt, it may contain large, hard lumps deep within the tissues.
·sometimes a thick, greenish-yellow pus may discharge from holes in the skin of the udder,
Mastitis can be treated if it is detected early enough. Every day the first two streams of milk from each cow in a small herd should be directed onto the side of the milking bucket to show up the clots of mastitis.
Using an RMT kit Simplifies the detection and treatment of Mastitis
The use of the RMT kit makes mastitis identification easier and more reliable, cows with a low level of mastitis can be diagnosed and treated early. By doing this, the cow suffers less, there will be less loss of milk production and treatment will generally be cheaper, because the infection is treated at a less advanced stage.
Use the RMT kit if you suspect mastitis, also use it to test each cow as she is first milked after calving [after colostrum is finished]. Regular RMT testing [say every 2 weeks] will help to mastitis early.
How to detect mastitis with the RMT kit
Always ensure that the paddle is clean and dry when used
1. Squeeze a small amount of milk out of each teat into the corresponding quarter of the paddle. Avoid frothing the milk.
2. Tip surplus milk Out of the paddle leaving only 2m1 milk in each segment [use the 2m1 line as a guide]
3. Press 3 ml CMT-Test liquid into each segment of the paddle. One press of the pump is equal to 3m1. Detergent can also be used, it is a matter of finding the right type and concentration of shop bought detergent.
4. Mix well by gently moving in a circular motion. [Change in consistency indicates an increase in the cell content of the milk = mastitis]
If mastitis is detected but you have never encountered mastitis before, you should call the veterinarian or paravet for the correct antibiotics and advise on treatment. The cow would normally be milked out and treated with antibiotics into the infected quarter for a number of treatments over several days according to the advise given. The milk of the quarters which are under treatment should always be discarded.
If the cow is not treated or the treatment is not effective, the infected tissue is eventually replaced by dead scar tissue and that part of the udder will no longer produce milk. Quite often, these old cases of mastitis act as a source of infection for other cows in the herd. Cows which are badly infected with old mastitis will often produce very little milk at all and they should be culled. The udders of cows which you may consider buying to add to your herd should always be examined. Those cows with signs of mastitis should be rejected.
Mastitis can be prevented by good management which begins with the birth of the calf.
·calves should not be permitted to suckle each other's udders, particularly if they are feeding from cows which already have mastitis. The infection is transmitted to the calf and develops in the udder of the calf from the first day the heifer comes into milk.
·calf pens should be kept clean.
·cows known to have mastitis should be milked after all of the other cows, their milk should be tested by squirting into a separate cup, not onto the floor as this milk has a higher chance of being infective. Once treated, they should be used only to suckle foster calves for the remainder of that lactation,
·the hands of the milker should be thoroughly washed between finishing milking one cow and beginning the milking of the next. This will prevent mastitis being transmitted to uninfected cows from mastitis cows which have not yet been detected.