Grass Staggers
The late spring and sudden showers has caused all sorts of problems on some farms. We have seen cases of grass staggers in dairy cows for the first time in several years. Usually grass staggers is something you do not have to think about too much as extra magnesium is mixed into the dairy ration before you buy it. Sometimes when the weather conditions are against us and if cows have been let out earlier than you would have planned because stocks of silage have run out this will not be enough to maintain magnesium levels in the blood stream. It is a good insurance policy to allow access to magnesium buckets when cows first go out to grass. Individuals that are vulnerable will actively seek out the mineral or eat soil until their blood levels have stabilised. Once the consumption of magnesium has dropped off it will be safe to withdraw the buckets. Low yielding cows and cows that have recently been dried off are particularly prone to developing grass staggers.
Heightened Risk of Nematodirus
Yesterday I had a fax headed Urgent Nematodirus Warning.’ Nematodirus is a particularly nasty disease in lambs causing high mortality and stunting growth in flocks where it is not adequately controlled. This is a gut parasite of young lambs that was passed onto pastures last year, it is unusual as the development of the larvae is delayed until they have all over wintered. It is further complicated by the way the larvae need high temperatures to complete their development. What tends to happen when we have a late spring is that there is an overwhelming infection on the grass that the lambs will not be able to cope with. Last year the larvae started to hatch when most lambs were young and not eating much grass. This year the development has been delayed, and most lambs are taking quantities of grass now and will be exposed to ingesting large numbers of immature nematodirus larvae.
The risk Factors
Lambs grazing pastures that carried lambs last year.
A sudden late cold snap followed by warm weather
Lambs six to twelve weeks of age eating significant quantities of grass
Groups where coccidiosis is not adequately under control
Lambs that are under stress.
Triplets and fostered lambs are particularly vulnerable.
Vigilance and Treatment
Watch out for the warning signs and drench the whole group as soon as you see any individuals starting to scour. There are no resistance problems with nematodirus, it will always respond to one of the white wormers. Doses will need to be repeated every three weeks until the moisture goes out of the grass or the lambs can be moved to a clean pasture.
Bovilis BTV8 Vaccine
Intervet are well on schedule with their Bluetongue Vaccine production. The batch they are processing at the moments has given a better than expected yield and they have already delivered the first one million doses to farmers in the south east of the country. They hope that they will be able to dispatch a further two million doses before the end of next week. There are all sorts of rumours going around about the vaccine. There has been some confusion because live Bluetongue Vaccines are sometimes used in parts of Africa and these have been known to cause abortions and ill health. That cannot happen with the vaccine we have here. It is a dead vaccine with two adjutants added to get it to be taken into the recipient as rapidly as possible. You can expect a small swelling where the vaccine has been given, but this will disappear after three to six weeks. As far as I can tell that is the only side effect you will see.
How to use it
Bovilis BTV8 will be available in 50 dose vials or 20 dose vials. It is a small volume one ml dose under the skin. A single dose is required for sheep and two doses for cattle given three weeks apart. Immunity takes three weeks to develop from the last dose of the vaccine. We will be fighting against time to get the vaccine working before the first infected midges arrive.
Goats
The company are quite confident that the vaccine will work on goats. The situation is that it would have delayed the development if they tried to get a product license for goats so they have not done that yet. The immune system of goats is not so well developed as in other animals so it would be better to give two doses three weeks apart to get the vaccine to last for the length of the summer.
Rampant Moles
I understand that for many of you this will be the first year that you will not be able get help controlling moles, as the poisons the mole catchers use are no longer available. At the moment moles seem to be particularly active and it is alarming how much soil they will push up to the surface each night. This is going to cause all sorts of problems with Listeria in silage. It is not always recognised if a cow or a ewe aborts because of this infection. It is a regular thing for us to treat animals that have become blind because of listeria some of these patients respond poorly to treatments and will not survive. If you do know of any sensible effective ways of getting rid of moles please let me know and I will pass the information on.