End to drought brings spring-type staggers
By Rebecca Austin
WHEN a reasonable amount of rain falls while the ground is still warm, lush grass growth could cause staggers in cows deficient in magnesium. So warns Dr Basil Lowman of the Scottish Agricultural College, Edinburgh.
He says that re-growths after drought with little or no grass are very lush and will be identical in terms of chemical composition and feed value to spring grass.
"Spring tetany is mainly caused by high levels of potash and ammonia in the soil, which suppress magnesium uptake," he says. "This autumn the problem could be more acute because some farmers applied compound fertilisers, which are part potash, earlier in the summer in an attempt to get the grass to grow."
Autumn-calvers and cows in poorer condition would be those most susceptible to grass staggers.
"Although cows are now in tremendous bloom and from a distance look well, they are losing condition so body reserves, which include magnesium, are dwindling," says Dr Lowman. "Even though milk doesnt contain a great deal of magnesium, the cow needs a lot to produce that milk."
To prevent risk of staggers he advises offering cows 56g (2oz) a day of calcined magnesite. But ensuring they receive it might not be easy.
"When there is lush grass about cows prefer the grass to any concentrates," he says. Ad-lib magnesium syrup/licks through wheel or ball feeders are therefore the best option.
"Providing the mineral as cobs or in a barley mixture, which is the more traditional approach, is not satisfactory as only a few cows will take them. The rest are still at risk. Once a cow has staggers she is dead within 10 minutes more often than not."
• Cattle grazing dead material for about two months in extreme cases of drought risk vitamin A and E deficiency, according to Dr Lowman.
But he advises against spending money blood sampling stock to check for the existance of such deficiencies.
"Vitamins A and E are cheap, and most producers supplementary feeding cattle would be best to ensure a good mineral mix in the ration," he says.
"Calves born from now on will not be taking in supplementary feed and it would make sense to seek vet advice about whether to give each calf a nutritional injection at birth."