I’ve had a few conversations with farmers who have found dead cows or cases of sudden death over the last week. There are many potential causes for sudden death at this time of year. The top five are:

1 Grass tetany.

2 Frothy bloat.

3 Clostridial diseases.

4 Lead poisoning.

5 Nitrate poisoning.

The first two are the most common causes in cows grazing at this time of year. We see less clostridial disease now, with most farmers choosing to vaccinate. Lead poisoning is often caused by old batteries discarded in fields. Nitrate poisoning can occur with recent nitrogen application and rapid plant uptake.

Diseases such as grass tetany become a greater risk around peak grass growth. Variable weather can also increase the risk. With variable intakes, cows and ewes need daily intakes of magnesium.

I would encourage all farmers to have a source of magnesium going into stock this spring and to understand where your farm risk is? The easiest way to supplement magnesium is through a nut or meal, with the option of in water, licks, boluses or pasture dusting.

Cows being left into lush pastures with leafy grass can always be at risk of bloat when you have a sudden change in diet.

When making introductions to new paddocks or big changes, some farmers will put up a strip wire to start or limit intakes with something like calmag dusted on the pasture.

Post-mortems should be carried out on any animals found dead. They can be sent to your regional vet lab or some samples can be taken including eye fluid for tetany by your vet. I always took the opportunity during post-mortems to check for liver or rumen fluke and check lungs etc.

If you’ve lost cows or sheep suddenly, get post-mortems carried out and check magnesium supplementation. Check clostridial vaccination status and walk the field checking for car batteries, especially if beside a public road.

If bloat is suspected, look at supplementing or adding fibre such as silage or hay to the diet. Bloat oil is available to go through water if needed. Look at strategies to control intakes when changing cows into new pastures with lots of leafy sward.