Risk factors

Traditionally cases of grass staggers occur following spring turn out and often during wet weather when dietary intakes of grass drop for short periods. Staggers is also seen in the autumn months when we get a late rapid growth of grass. Despite this apparent seasonality, the risk is ever present and for herds that rely predominantly on grazed grass, staggers should be considered throughout the grazing season and preventative measures put in place in order to manage high risk times or to ensure that cows are receiving adequate magnesium in order to prevent problems from arising.

Risk factors for development of staggers

• Decreased dry matter intake (often during cold wet weather)
• Cows around calving and early lactation
• High levels of potassium (potash) in grass
• High levels of crude protein in grass
• Ryegrass or young rapidly growing grass lays

Prevention

In terms of prevention there are several options which can be used; with the preferred choice dependent on the particular farming systems. If concentrates are being fed in the parlour or cows are being buffer fed then adding calcined magnesite (magnesium oxide) typically at a rate of 25-30g per cow per day can be used, thorough mixing should take place and all cows should have access at the same time to ensure submissive cows get adequate access. Magnesium chloride crystals can be added to water troughs, however excessive levels can lead to the water becoming bitter and cows will reduce their water intakes which we should try to avoid. It is important for this to be effective that all available water sources are treated, so if there is access to streams etc this option is not recommended. If magnesium chloride is added to water troughs then levels around 40g/cow/day are typically recommended. Water troughs should have a volume of at least 20L/cow for this option to be used successfully. Cows can be bolused with magnesium bullets to give a slow release of magnesium, however they vary in terms of daily amounts of magnesium released and how long they last for. Often multiple boluses need to be given as they typically do not release a large quantity of magnesium and hypomagnesemia can still occur in these animals if single boluses are given.