Cattle consuming low feed with low magnesium are susceptible to grass tetany especially during lactation periods.
Grass tetany is caused by low levels of magnesium in the blood but more common in older cows with calves, along with Angus and Angus cross cattle.Grass tetany is quite serious and fatal. It can quite often occur when you move cattle from indoor feeding to outdoor grazing.
Low magnesium levels are caused by low magnesium levels in pasture are low, for example grazing cattle on pasture that’s recently been fertilised with a high nitrogen fertiliser.
Magnesium levels in grass are lower in winter because of winter rainfall, bad weather conditions, cool temperatures which all limit the uptake of magnesium from the soil into the plant which is consumed by the cattle. Also grazing animals on young pastures with low roughage contents. Symptoms may include increased muscle twitches, and abnormally aggressive behaviour.
Prevent grass tetany is best done by preventing low magnesium levels in animals by providing salt lick with magnesium, mixing magnesium oxide into feed, increasing roughages in the diet. Soil and leaf testing to make sure the soils the pasture is grown on has the right nutritional balance and correcting deficiency through good fertilising programs, to produce a healthy pasture and animals.
