Check mineral levels in flooded grassland

1 February 2016

Livestock farmers in areas affected by flooding and waterlogging this winter are being advised to check mineral levels in forages, to avoid problems with deficiencies or imbalances when feeding these forages this year.

Following a record-breaking wet winter, farmers in many parts of the country are struggling to get to grips with the financial cost of flooding, especially as getting animals out to grazing early will be essential to help reduce production costs. While problems such as increased poaching risks are highly visible, Rosie Miller, Ruminant Nutritionist with Trouw Nutrition GB warns of a hidden problem.

“Flooding can have a significant impact on the mineral content and balance of pasture,” she warns. “Grazed grass is at best a variable source of minerals, with levels directly dependent on the mineral content of soils.

“Typically, some minerals will be in short supply giving rise to potential deficiencies while some can be present at high levels and be antagonistic to other minerals.”

Minerals and vitamins are involved in all the core functions of the body including metabolism, enzyme function, nutrient utilisation, reproduction and cellular repair. A deficiency or toxic level of any mineral will potentially compromise a number of metabolic functions and reduce performance from grazing so she says it is vital to ensure the correct levels are fed.

She explains that in waterlogged or flooded fields the levels of mineral leaching can be higher, resulting in poorer soil mineralisation. At the same time, damage to the soil structure will reduce the ability of the roots to absorb nutrients from the soil. Combined these may lead to lower forage mineral levels in grazed or conserved forages.

“In addition, farms may suffer the effects of increased level of heavy metals which are antagonists to more favourable metals. Many fresh grass samples analysed from pastures which were flooded in previous years show elevated levels of mineral elements such as iron, molybdenum and aluminium. This is almost certainly due to the soiling of grassland caused by flooding and soil run off.”

Ms Miller believes if farmers take prompt action it will be possible to identify any problems and take action to prevent performance, health and production being affected.

She advises farmers to having grazed grass analysed for mineral content as soon as possible, explaining that a mineral assay is the only way to understand mineral levels in grazing and the precise risks stock may be exposed to. The aim must be to understand the specific problem and then to target supplementation from the most cost-effective solution.

“Using the analysis it will be possible to supplement diets precisely to supply the right minerals in the most appropriate form. Furthermore, it is essential to ensure legal maximum levels are not being exceeded.”

She particularly urges dairy farmers to pay close attention to mineral nutrition at grazing as she believes deficiencies may not be adequately rectified due to a desire to reduce costs of production.

“While cutting back on buffer feeds and parlour concentrates will reduce costs, this also reduces the opportunities to provide effective mineral supplementation. A short term gain in reduced costs will soon be wiped out if fertility suffers or conditions such as mastitis and lameness, both of which are related to mineral deficiencies, increase.

“However, farmers should avoid blanket increases in mineral levels as this can result in feeding minerals above the required level which can just push up costs and can make issues with antagonism worse. The most cost-effective approach will be accurate supplementation based on the analysis of forage mineral levels.”