Calcium, often regarded as a forgotten nutrient, was the topic of discussion at a conference held recently in Nantwich, Cheshire, and organised by Calcifert. Katie Jones reports.
Calcium plays a vital roll in livestock systems and is the fifth most abundant element in an animal, with 99 per cent of this found in bones.
David Atherton, owner of pharmaceutical company Thomson and Joseph, explained the element played an important role in the health and immune system of the dairy cow, particularly around calving.
“The amount of calcium a dairy cow needs before and after calving is very important and is strictly controlled in an animal’s system.”
Problems with calcium levels around this time can lead to hypocalcaemia, or ‘milk fever’, which is a gateway for other diseases including ketosis, metritis, retained cleansings, and mastits.
Dr Atherton said for every cow showing signs of hypocalcaemia there were probably another 10-12 cows also suffering at a lower level.
He explained the extra 20-30g of calcium required in the 24 hours after calving was made available by the parathyroid hormone, which helps the bone to release calcium.
However, Dr Atherton explained an excess of potassium in the cow’s diet can interfere with the release of calcium from the bone and its absorption.
“It is important to keep a close eye on potassium levels and there are various strategies to help cope with this.”
For instance, replacing grass silage, which is high in potassium, with alternative forages may be an option, but care needed to be taken when re-introducing grass silage into the diet post-calving.
Therefore, it was important to keep some grass silage in the diet, said Dr Atherton.
Dietary strategies to prevent hypocalcaemia
The importance of testing soils for calcium
When it comes to soil health, calcium is often overlooked, despite being the one of the largest elements required by a plant.
This was the message from soil health experts who told conference delegates calcium levels were not being measured often enough in soils.
Ian Robertson, managing director of Sustainable Soil Management, said while most people used pH as an indicator of calcium levels, this on its own was not enough.
“Calcium is important for cell walls in plant and animal health, but do we know how much calcium is required and how much calcium is in the plant?
“Calcium is the third or fourth largest element in most plants, so why are we not testing for it more.”
Mr Robertson said more testing for soil calcium levels would help when making decisions about nutrient application.
He said just looking at pH on its own was misleading and it was important to understand what was driving these pH levels.
“When we are testing we need to be looking for how much calcium is readily available in the soil, and then this needs to be matched to crop demand.”