Livestock farmers who suffered flooded fields last winter are being urged to get a full mineral analysis of grazing grass and conserved forages.
Adam Clay, ruminant manager with Trouw Nutrition GB, says where land has been flooded the level of mineral leaching from the soil will be higher than usual, resulting in poorer soil mineralisation.
Results from grazing samples analysed this spring at the company’s laboratory show elevated levels of heavy metals such as iron and aluminium, which can be antagonists to some minerals.
“This is almost certainly due to the soiling caused by flooding,” explains Mr Clay.
“Grazed grass is at best a variable source of minerals with levels directly dependent on the mineral content of soils. Some minerals will be in short supply, giving rise to potential deficiencies, while others can be present at high levels and can be antagonistic to other minerals. These risks increase where land has been waterlogged and where grass has been under water for any length of time,” he adds.
At the same time damage to the soil structure will reduce the ability of the roots to absorb nutrients from the soil, further depressing the levels available to livestock at grazing.
“Combined, these problems may lead to lower minerals levels at grazing, which could result in a range of problems including suppressed immune system and lower fertility.”
As a result, Mr Clay advises farmers to analyse both grazing grass and conserved forages taken from flooded areas for mineral content to ensure a winter balance can be found.
He warns against just blanket increasing mineral supply, as he says this can result in feeding minerals above the requirement level, which can push up costs and potentially make issues with antagonism worse.
“A mineral assay is the only way to understand the actual mineral levels in your grazing and the risks your cows are exposed to. You need to to understand the specific problem and then target supplementation from the most cost-effective solution.
“For example, if iron and molybdenum are locking up copper then it will be more important to feed the correct form of copper than necessarily just to increase the level fed. It will also be vital to reduce the levels of antagonists in supplementary mineral sources to alleviate the problem and to ensure legal maximum levels are not being exceeded,” he concludes.