Last updated 22:07, Tuesday, 17 June 2008

Farmers frequently have to take risks that have an impact on the health and wellbeing of livestock.

Risks are involved when we decide what food types we feed them – from excess human food such as bread and biscuits and brewery and distillers’ byproducts to, at the other extreme, grass grown and fertilised by manure produced by the stock on that farm.

Although there are risks in feeding byproducts, these can be minimised by correct storage. Storing feed with air-tight covers and a narrow face, ensures it is not spoiled by bacteria and fungi that can lead to mycotoxicosis. Discard any mouldy food, or that from the edges of the pit.

Homegrown feeds need to be handled and stored with the same care. Poorly ensiled silage with a high pH can increase the risks of literiosis abortion and neurological disease.

By emptying out silage bunkers regularly and feeding only fresh, unspoilt silage these risks can be minimised.

Botulism is caused by ingestion of the clostridium botulinum toxin, which is produced by the decay of plant or animal tissue. This disease has a high mortality rate and is often associated with dead bird carcasses coming into contact with cattle or sheep feed.

Vets see this most commonly when farmers use hen/chicken shed manure and bedding for fertiliser. There is no denying that this is an excellent and cost-effective way of fertilising the ground, but it can come at a price. If used, the risk can be minimised by not allowing animals to graze the land fertilised, but machinery can also carry the manure back to the farmyard.

Rodents, rabbits and birds accidentally killed, baled and then ensiled into bales can also cause botulism. Reducing the risk of this, unfortunately, is almost impossible.

Risks are taken when we buy in stock; disease can be carried in animals.

A herd’s immunity (either natural or by vaccination) to diseases such as IBR and BVD may differ from one farm to the next. A carrier animal being bought in poses a high risk to a naive or clear herd. A naive animal is itself at risk if it enters a herd with active yet partially natural immunity.

These risks need to be discussed with your vet. They can be minimised by understanding what diseases and immunity your own animals have, and by assessing the immunity and disease status of the purchased stock.

Having an isolation facility on a farm for purchased animals and keeping them in it for three to four weeks will allow testing for diseases such as BVD, leptospirosis, IBR and Johne’s disease. This also allows for other diseases such as foot and mouth disease or blue tongue to develop and make themselves known.

You can be proactive in terms of the prevention of disease caused by worms and fluke; and remember, by sheath-washing bulls, you reduce the risk of infection from campylobacter to the bull and those he mounts.

Bulls and tups pose a high risk to a herd as they tend to come into close contact with a high proportion of a farm’s livestock in a short period of time. Isolating and monitoring these animals initially are good starting points to reducing disease risks.

As part of your disease prevention programme, look at how to reduce the spread of disease within your herds and flocks. Often, a simple solution of short-term isolation to monitor the animals for signs of emerging disease is all that is needed. As a compromise, you could take a moderate risk by running with only a few sentinel animals of your own herd at first.

We spend a lot of time and effort trying to prevent the introduction of diseases. Cattle imported from abroad undergo testing for diseases such as brucellosis and EBL that we have worked hard to eradicate from the national herd.

It now appears that blue tongue virus, transmitted by infected midges, is a new and real threat to our animals. Its introduction into this country was entirely beyond the control of farmers and vets, and no preventative measure could have easily reduced the risk of this disease’s introduction. Imported animals were being tested to prevent them bringing the disease in, but nothing could have prevented infected midge immigration.