Smart Milk Samples

National Milk Records will now do individual tests on milk for Johnes disease. This may be a useful test to monitor how many of your cows have been exposed to this infection. Johnes disease can be a particular problem if you buy in cattle for dairy replacements. Calves become infected at birth either through the placenta if the cow is carrying the infection or by sucking teats that have been contaminated by faeces from infected animals. Johnes disease takes a long time to develop in most cattle, more than five years sometimes, so you will have opportunities to cull known positive animals before they show any symptoms.

Making Decisions

The milk test does have its limitations. Some cows will give a reading if the test is done within two weeks of calving. Johnes disease is caused by an organism that is similar to Bovine Tuberculosis and a recent tuberculin skin test can also affect the results. If cows have a high titre they can pass the infection to their off spring by the placenta. A more common way of disease transmission if for young calves to ingest the bacteria when they suck teats contaminated with infected faeces. If you have cows that have a medium or high reading at least twice it might be wise to confirm the result with a blood sample. If positive animals are clinically well you will probably want to hold on to them until that situation changes. It would be better if you can feed any heifer calves with stored colostrums and not allow then to suck the tests of the cow as it is difficult to avoid any contamination when this occurs. Even if you take precautions there is a strong possibility that calves born to cows suffering from Johnes disease will eventually succumb to the infection and it should always be assumed that they are carrying the disease.

Scouring Lambs

So much of what we do and what we see depends on the weather. The winter started off mild and now there has been a cold spell which, if the warmer weather returns, is the worst possible conditions for nematodirus. This is the parasite that affects young lambs and occasionally calves. Unlike most strongyl worms that start their development as soon as they are passed onto the field nematodirus just sits there through the heat of the summer and the cold of the winter waiting for the temperature to rise in the spring before they develop into infectious larvae. This is particularly triggered after a period of frost. All of the larvae that have been passed onto the pastures in the past twelve months will become active at the same time. That is how it can be so damaging to your growing lambs.

Frequent Treatments

Nematodirus is a problem for young animals. Logic suggests that it can be avoided if you could put your lambs out onto clean fields each year. Unfortunately not many farms have the fencing or pastures to do this. It is unusual as it is the young worms that do the damage before they mature and shed eggs. Lambs with the infection develop a severe scour, but they will have few if any strongyl eggs in the faeces. The disease is also unusual because it is not a resistant worm so any, usually a white, drench will treat it. If the lambs cannot be moved to fresh pastures they may need to be treated every three weeks until they have a chance to build up an immunity against the parasite. Be prepared for nematodirus and treat it as soon as you think you might have it as losses can be significant if there is a delay.

Get ready for the Grass

The problem for cattle in March, and sometimes April, is staggers brought on by a shortage of magnesium in the spring grass. At this time of the year extra magnesium will be incorporated in the concentrate ration that you buy for your dairy cows so most of your herd will be covered and it might just be any dry cows that are on restricted rations that you will need to supplement. Although cattle cannot store magnesium to any significant degree it is often a good idea if you are using the magnesium buckets mixed with molasses to let them start on it two or three weeks before they go out to grass. That way they will be used to the buckets and know to look for them in the field to get their daily allowance. Hereford cows and their crosses are particularly prone to a shortage of magnesium. The soil association has relaxed its rules now. Organic farmers must feed organic molasses if you can find any but there are no restrictions if you are using it to get a drug into your cattle so they are no more expensive to treat than cattle kept in a conventional system.

Horses with Sore Feet

With the recent wet weather there are a lot of horses with mud fever. This is a common problem that occurs when continual wetting of the skin results in a breakdown of the protective barrier of the skin epidermis. This allows bacteria to enter and infection to take hold. Equine skin provides an excellent medium for bacteria which normally live on healthy skin and cause no harm. If the skin becomes injured or damaged the balance between bacteria and horse is disturbed. The bacteria enter the body through the broken skin and multiply in the damp, warm epidermis starting an active infection.

Although some cases need veterinary intervention there are ways in which it can be managed as well. Clip the skin from the affected area Wash legs thoroughly in warm water with a very small amount of hibiscrub added. Soak off any scabs particularly at the back of the pasterns Dry legs after washing Apply a barrier cream such as Sudocrem to protect the skin. Keep your horse in out of the wet at night on clean bedding.

If the legs swell up or there is any degree of lameness then we would advise your horse is seen. We will come out and may prescribe a course of antibiotics or anti-inflammatory drugs to bring the situation back under control. Mud fever is easier to control when the ground dries up in the spring.

Cattle with Sore Feet

There seems to be a number of farms that are having problems with digital dermatitis at the moment. In many ways this is the bovine equivalent of mud fever, but because it is caused by a spirochete it is a lot more aggressive and difficult to treat if you are trying to avoid antibiotics. The infection thrives in stagnant water and is able to get established when skin has been saturated. The challenge is to keep the bedding dry and drain any areas around troughs and feed passages were water accumulates.

Treating the Infection

If you just have a small number of cows that are lame it might be possible to separate them from the rest of the herd, keep them on a dry bed and spray all four feet with terramycin every day. Often there will be more and more cases each day and you will need to think about treating all of your stock. This is when it gets difficult not to use antibiotics. Of all the products available lincospectin in a standard size foot bath will give the best results. If you can it helps to get the feet as clean as possible before they use the footbath. It is not always possible to pressure wash the feet particularly of beef cattle and you might end up stirring the cattle up too much and making things worse.

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