Wales Farmer 14 HEALTH ADVICE APRIL 2014


Grass staggers on the increase in Wales HEALTHYadvice


GRASS staggers (Hypo- magnesaemia) in cattle is increasing in Wales in the spring, despite the aver- age annual incidence of acute hypomagnesaemia in the UK being less than 1%.


Most cases occur in recently-


calved suckler cows, but disease can also occur in dairy cows, par- ticularly if they are un-supple- mented during the dry period. One possible reason for this


increase could be land improve- ment and therefore more fertiliser use. High levels of potassium (application of potash fertilisers) disrupt the absorption of magne- sium, while high levels of ammo- nia (from nitrogenous fertilisers) inhibit absorption. Lush pas- tures, as found in the spring and late autumn, are low in fibre and increase the rate of passage of foodmaterial through the rumen, reducing time for the absorption.


Clinical signs SUDDEN death is encountered


In her regular column for Wales Farmer, SALLY HARMER, animal health manager for Clynderwen and Cardiganshire Farmers (CCF) highlights seasonal health management issues and solutions in the livestock sectors.


most commonly in older lactat- ing beef cows four to eight weeks after calving, if they are at pas- ture without appropriate supple- mentary feeding. The cow is often found dead with disturbed soil around its feet indicating paddling, often after stressful weather such as heavy rain and high winds. Where there is acute disease there is initial excitability with


high head carriage, twitching of muscles (especially around the head) and un-coordination known as ‘staggering gait’. Affected cows become separat-


ed from the group and have a startled expression, show an exaggerated blink reflex and fre- quent grinding of the teeth. There is rapid progression to periods of seizure activity with frenzied paddling of the limbs,


sudden eye movements, rapid pounding heart, and teeth grind- ing with frothy salivation. Death can happen at any stage. It is important to note that sub-clinical/chronic disease often goes unrecognised, but investiga- tions have revealed an annual rate of 3-4% in lactating dairy cows. Cows may appear slightly


nervous, are reluctant to be milked or herded, and have depressed dry matter intake and poor milk yield. Dairy cows with sub-clinical


hypomagnesaemia in the dry period are predisposed to hypocalcaemia (Milk Fever).


Treatment


IT IS best to call a veterinary sur- geon immediately to administer a sedative drug to control the cow’s seizure activity, to prevent a fatal convulsion, and to facilitate intravenous treatment. The veterinary surgeon will


probably administer 400ml of 40% calcium borogluconate plus 50ml of 25% magnesium sul- phate by slow intravenous injec-


tion once seizure activity has been controlled. The remainder of the 400ml bottle of 25% mag- nesium sulphate is given by sub- cutaneous injection. The cow should then be sat up and left quietly. The administration of magne-


sium sulphate by injection will only increase plasma levels for six to 12 hours, therefore it is essen- tial to offer concentrates/hay to ensure adequate dietary intake to prevent relapse. The remaining cows are very


likely to have sub-clinical hypo- magnesaemia, and will be at risk from acute grass staggers, so it would be prudent to put in place preventive measures straight away.


Prevention and


control MAGNESIUM salts


are


unpalatable therefore it is diffi- cult to ensure sufficient intake with individual animals using mineral supplements. There are high magnesium


blocks and compounds available, with compounds the best as you can ensure every animal is getting sufficient


supplementation.


Blocks or buckets can be useful, but need to be monitored careful- ly to ensure the animals are con- suming enough to give them the levels they require. If a trough is the sole water


supply it can be medicated with soluble magnesium flakes. Pas- tures may be dusted during high- risk periods with finely ground calcined magnesite every 10-14 days.


Intra-ruminal boluses give a


slow release of relatively small amounts of magnesium into the rumen over a period of four weeks, so can be useful at the peak risk times of the year. Forage supplementation with something like straw can also be useful if the grass is very wet or lush as it increases the fibre in the diet and will increase the absorp- tion rate of both minerals and nutrients.


Thanks to NADIS for the information used in this article.


Tracing deficiency has positive effect on herd


TESTING for trace element deficiency has helped improve a suckler herd’s calving percentage and interval at a north Wales


farm. Following a difficult calving


season in 2012, Arwyn Williams decided to have a detailed look at the health of his suckler herd at Hendre Nantcyll, Garndolben- maen,Gwynedd. As there were no specific disease problems on the farm, it was decided to look at trace elements in the blood, and after testing five cows, it became apparent that Iodine was fairly lowin the herd. Of the five samples taken, two


were lower than the target level of 26-84nmol/l of thyroid hormone, Thyroxine (T4),which denotes the Iodine status in the body. All the results were towards the bottom of the scale, with the average just 25 nmol/l. At his vet’s suggestion, Arwyn


Williams gave the cows an Iodine bolus three months before calving in 2013, and he saw a significant change. “The calving season was much


less difficult than previous years, there was no comparison, the calves were much livelier when born, and each cowgave birth to a live calfwithout difficulty,” said Arwyn, whose farm is a Farming


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Connect demonstration farm. Last year all the cows were


pregnancy scanned, and the results were very pleasing, with every cow impregnated and all except one likely to calve in the first nine weeks. “If I can get one additional calf


to sell, I will have paid far in excess of the cost of testing and treating them,”said Arwyn. The calving period is set to be


much tighter this year, which is very valuable when it comes to selling them on as store cattle and Arwyn says the testing has proved worthwhile. “I have given the cows a bolus


again this year - for £4.50 a head it is certainly worth every penny,”he added.


Gethin Davies, regional Farm-


ing Connect facilitator said: “This experiment has been very valuable for Arwyn and it has obviously been worth investing in the tests and the iodine boluses.” This year Arwyn is comparing


cross-bred ewes with Welsh Mountain ewes to seewhich breed is most profitable for his system. This will give a good basis to inform business decisions for the future of the farm. More information on trace ele-


ments in cattle is available on the Farming Connect website at www.menterabusnes.co.uk/cyswllt ffermio.


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