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The Farm Fridge
Vaccines are expensive drugs and it is important that they are stored and used in the exact way that the manufacturers have intended. There are two different types of vaccine. Most of the ones that you will use are termed Dead Vaccines where part of the cell wall of the Virus or Bacteria has been modified so that it will still generate an immune response. Most dead vaccines require two doses to give a lasting protection. Some of the vaccines that you use are modified parts of live bacteria or viruses that grow inside your animals to mimic the disease that we protect them against. They cannot give them the actual disease because they have been treated to make them safe. These live vaccines are far more delicate and it is important that they are stored and used with care to make sure you get the maximum benefit from the time and money you invest in vaccinating your stock. Live vaccines are things like Toxovac and Enzovac that you use to prevent abortions in sheep and Bovela the new BVD vaccine for cattle. Live vaccines need just one injection for year long protection, some vaccines last for the rest of the animal’s life from a single dose if you are able to do it properly. Monitoring Temperatures
All of the vaccines have to be stored between 2 and 8 degrees centigrade. The ones we buy come in a refrigerated van and are transferred straight into our fridge. The only thing that goes into our fridge that does not come that way is tuberculin. Tuberculin comes in the normal post and spends most of its time in our fridge. It can be transported for up to fourteen days up to 37 degrees centigrade. We tend to take out only the amount we will need on a farm so mostly it will be out of our fridge on at most two occasions before it is used. None the less because we have tuberculin in our fridge we have to record the current fridge temperature every day as well as the maximum and minimum temperatures that the fridge had been at in the past twenty four hours. As well as this once each month we have to verify the thermometer we are using is working correctly by using a different one for a day at least.
Don’t Turn it Off
On some farms there is a tendency to use an old fridge out of your kitchen to store farm vaccines. This is OK as long as it is working properly, so you will need to get a maximum / minimum fridge thermometer to check it can cope with your vaccines. If in doubt it is better to buy a new one as the cost will be far less than the vaccine you damage. You probably will not use your farm fridge as much as we use ours, so it is a good idea to have it somewhere where it cannot be accidentally turned off un noticed. Store the vaccine at the bottom of the fridge away from the sides and monitor the temperature on the same shelf as the vaccine. Also make sure the door closes properly and cannot be left open. Vaccines are expensive, and they cost a lot to replace if they get too warm. Care with Live Vaccines
At this time of the year the air temperature will not be much more than that of the vaccine that you are going to inject. In the summer it is better to get everything ready first before you go looking for the vaccine. If the vaccine needs to be mixed do that on a level surface and invert the bottle several times to make sure it is thoroughly mixed before you use it. It is best to get one bottle ready then use it so it is not left for too long before it goes into an animal. Dead vaccines contain an adjuvant which attracts blood cells for maximum take up of the vaccine. They do not contain anything to limit the growth of bacteria so it is unwise to use any bottle that has been open for more than a day as the risk of infection is too high. Live BVD Vaccine
Bovela the live BVD vaccine from Boehringer contains both strains of the virus and is designed to be used as a single dose for cattle from three months of age before they have full contact with the adult animals in the herd. Animals need a booster injection every twelve months to maintain their immunity. Ideally this should be given at least three weeks before they first become pregnant. Bovela comes in various bottle sizes as small as five doses and it cannot be stored when mixed so it must all be used in a single day. Too Much Copper
This is the time of year when fattening lambs succumb to copper poisoning. Texel and Texel Cross lambs are particularly prone to this. It usually happens when they are given concentrates for a prolonged period if they are taking a long time to fatten and have not been allowed access to pasture. Copper accumulates in the liver and affected animals become jaundiced. This affects the whole carcass so it is often difficult to salvage even the fit ones in the group as carcasses will not pass meat inspection. Take particular care if you have Texels, as they are sensitive to even the small amount of minerals that are put into concentrate rations. Prevent Abortions Improve Fertility
Letospirosis is a common disease affecting both dairy and beef herds. An outbreak within your herd will carry significant economic implications; as well as being a common cause of abortion, it can also negatively impact fertility and milk yields. Leptospirosis is caused by the bacteria Leptospira hardjo. These bacteria can survive well for up to 6 months in the environment so long as the temperature remains over 10°C and conditions aren’t too dry. As a consequence in the UK spread of infection will be at its highest from late winter to spring. It may be particularly severe this year as the mild temperatures and wet conditions this winter will have done little to kill off the infection. Once infected, the bacteria will settle within the kidneys and reproductive tract of cattle, resulting in animals that can go on to spread the disease for months, if not years. The main route of transmission is though contact with infected urine or aborted material but it can also be transmitted venereally via an infected bull. When a cow becomes infected clinical signs are often non-specific, such as a transient fever, and so can often go unnoticed. Generally the severity of symptoms will depend on whether or not the herd is naïve to the disease. Monitoring Disease Status
If leptospirosis is suspected we can submit a blood sample for the ELISA test to look for bacterial antibodies. In dairy cattle we often run a bulk milk ELISA to monitor disease status of the milking cows and this gives a general idea of whether the infection is active in your herd. Vaccinations
Control of leptospirosis relies on a combination of management decisions to reduce risk of infection. Maintaining a closed herd will reduce the risk of introducing new infection into the herd, but replacements can be isolated and tested where necessary if it is difficult for you to farm without buying in adult dairy animals. Vaccinating your herd against leptospirosis is highly recommended; the primary course will require two injections four weeks apart, followed by a single annual booster. Vaccination will protect against milk drop and abortion, as well as limiting the bacterial shedding following exposure thus reducing the spread of disease, but it won’t be able to clear the infection from your cows completely.
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