Grass staggers (hypomagnesaemia) is caused by Magnesium deficiency. Dairy cows are often deficient in Magnesium (Mg) in early lactation. This is because immature spring pasture has low levels of Mg, especially when urea is applied or the soil is high in potassium. Combine this with the high Mg demand by cows during calving and early lactation and your herd is likely to have problems with grass staggers this spring.
Mg supplementation also provides up to 15% extra milk production, even in cows not showing clinical signs of disease. With extra Mg your herd will have reduced animal health problems, lower mortality, and be less nervous during milking. So for most NZ dairy herds, it’s not if, but how to supplement Magnesium?
Many dairy farmers struggle to administer the right amount of Mg to all cows in the herd. Some farming operations have a workable system so cows can be drenched at each milking. Others cannot afford the extra labour, have a shed design ill-suited to drenching, or would prefer to avoid drenching.
Common magnesium supplementation methods
Drenching
Common magnesium drenching supplements are Mg Chloride, Mg Sulphate, or Mg Oxide. Each cow is dosed at same rate, but this method can labour intensive. Requires right drenching system & product to be effective.
Pasture dusting
Mg Oxide rate of intake variable and absorption is low. High Mg Oxide wastage, & can reduce grass intake. This method may be useful pre-calving.
Hay/silage slurry
Mg Oxide rate of intake can be variable and absorption low. Uneven dosage and can be unpalatable.
Water trough
Mg Chloride or Mg Sulphate in water requires accurate dispenser and monitoring of concentration. Take cares with palatability, used if grass is too short for dusting.
Magnesium capsules
Elemental Magnesium is released at 1-3grams per day for 9-12 weeks. High effective Mg absorption and convenient.