Agronomy Advice
March 08, 2023

Selenium management throughout the year

Grass doesn’t need selenium to grow, but cows do. Selenium is essential to protect herd health and fertility

two cows in an open field
two cows in an open field

for more information, take a look at our blog entitled ‘What about selenium?’.

There are various ways farmers will try to prevent selenium deficiencies and one of the most popular is adding it as a mineral mix to diets when cows are housed. But there are two issues with this approach:

  1. Concentrates provide an inorganic form of selenium which you need a lot of to make a difference to selenium levels in the cow, so it can quickly get expensive.
  2. When your cows are out grazing, you’ll not be able to boost their selenium intake in this way, because lower levels of feed are fed. So you’ll inevitably see a decline in selenium levels in stock over this period if you’re not careful.

We also need to consider that we’re trying to keep cows out grazing for as long as possible to minimise winter housing costs, but in doing so we could be creating a selenium deficiency in the herd and inadvertently risking health issues that could lead to hefty veterinary bills.

Turn Grass into a Good Source of Selenium Nutrition

This approach leaves cows open to a lack of selenium from February until October (depending upon the weather and ground conditions), when they’re out grazing.

To preserve selenium levels in cows, we can turn grass into a good source of selenium by fertilizing it with a selenium enriched fertilizer. This will allow the grass to absorb the selenium ready for the cows to ingest when grazing.