Changing Practices

There has been a tendency lately to question familiar practices that have evolved over the years and take a fresh look at things. This is particularly relevant to the way we manage worm infestations in sheep. It has been shown that a single untreated lamb on a pasture in England will pass 74 million worm eggs in the course of a year. Consider that 98% of the worms on your farm at any one time are on your pastures, not in your stock. The challenge is to manage this parasite population in such a way that it does not have a significant impact on the production of your farm.

Worm Tolerance

There is a constant battle going on between the newly ingested worms and the immune system of your sheep. Well fed sheep are able to resist a moderate worm challenge, most of the larvae that they ingest are rejected before they can get fully established and will not progress to the adult forms that do the damage. Unfortunately you cannot rely on this when sheep are under stress, such as when they are carrying or feeding triplets or if they have been stressed by markets or transport.

Balancing the Benefits

Studies have shown that the overall production of most flocks will not suffer if you target the drugs to the animals that have the greatest need, single lambs that are doing well will continue to grow whether you worm them or not, it is the twins and triplets that will benefit most. It is an expensive business to worm a flock, it is not just the cost of the drug but the gathering and handling that has to be considered. Considerable savings can be made if you just dose the lighter animals in the group. Studies have shown that with the use of strategic worming on most farms reducing the numbers of worm treatments from five to three resulted in a 1.5% reduction in the weight of lambs when they were finished. This is not a loss of production that most farms would be aware of. Most of these studies have been done on experimental farms where the stock are weighed every week. The trick is to know how the lambs should be doing and take the risk of cutting out the blanket worming if things are going well. In dry summers worm larvae are trapped in the ground as they cannot survive on dry pasture, this is an opportunity to suspend worm treatments until the worm challenge returns with the autumn rains.

Egg Counts

All farms are different, there are not many farms that are able to effectively rotate their sheep pastures each year to the extent that there are many times when worm free pastures are available. There are still things that you can do to determine if worming is necessary. Take samples from six animals warm off the field. It is better to bag them separately, we will mix them together and look at them at the surgery to determine if worming is necessary, or can be delayed for a week or two. Each year it is better to use one of the three different classes of wormer in rotation. Levamasole is particularly helpful to add to the rota as it is reasonably priced and helps to stop the development of resistance to the white wormers.

Monitoring the Wormers

It is a good idea to take further samples at least once during the course of the year two weeks after a routine worming. Again we can pool the samples and get an idea as to how well it is working. If the expected reduction in egg counts are not achieved it is important to move on to a different class of wormer as nothing is gained by repeated drenching with a wormer that is not working.

Comparing Costs

It is difficult to work out the cost of using the different wormers and compare prices as there are different dose rates and spectrums of activity. You might be able to get some idea if you look at our online shop on the Minsterley Vets web site. Full details of the products can be found if you search for the manufacture’s sites on Google and look for details of the different drugs.

Help Needed

Bethan is a second year student at the Royal Veterinary College in London and she would like your help to complete a survey on how colostrum is fed to dairy calves. Various studies have been carried out in the past, but there are no definitive conclusion as to whether it is cost effective to tube feed colostrum and how soon after birth it should be done. This has the potential to be a useful survey that should not take very long to complete. If you can help Bethan please do. I will let you know what conclusions she comes to in due course.

Bluetongue Vaccine

The expiry date on the last batch of Bovilis BTV 8 vaccine ran out at the end of November. If you have any in your fridge it might be better to inject it into an animal now and not throw it away as it will work for a full year. The new supplies are not expected until the end of January. There may be some advantages to vaccinating stock if they are scheduled for sale as buyers are more likely to be interested in vaccinated stock if the rest of their herd or flock have been inoculated. DEFRA has undertaken a study on dairy farms throughout the country so we should know more when the results are declared as to whether it will be necessary to use the vaccine again next year.

Pre movement Certificates

Many of you buy in cattle over 42 days of age, mainly from farms that are on annual or bi annual testing, that have been pre movement tested. Ideally these cattle should not be tested again for at least another sixty days if your herd test is scheduled during that period. The pre movement test will count as part of your whole herd test. This is causing confusion as you will usually know when the animals arrived on the farm, but few of you have any certificates or test charts to say when the animals were actually tested. This may be days or weeks before the sale. If we go one day over you may find yourself under movement restrictions until we can come back again and retest the animals that have been missed. That is why we have always issued you with an individual certificate for each animal we pre movement test for you to pass onto the buyer. The certificates state the date of the test and the date the certificate expires so there should be no confusion.

Poisoned Pets

Take care if you have a rat problem on your farm. Most rat baits contain an anti coagulant and dogs and cats can readily become affected if they find small quantities of the bait or if they catch rats that have been affected by it.

There is an antidote, but it needs to be given promptly before there has been any significant internal bleeding. It can take several weeks to overcome the effects of this poison.

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