Do you know the mineral status of your grass silage? If you don’t, you could be shooting in the dark when it comes to dry cow feeding and putting your herd at greater risk of milk fever.

So says Mole Valley Feed Solutions Technical Manager, Dr Matt Witt who believes analysing grass silages and balancing with an appropriate mineral pack is essential to prevent both clinical and subclinical disease.

Milk fever occurs when a cow is unable to meet increased calcium demands around calving. Although the clinical disease is obvious as a cow will often go down, the nature of less severe or subclinical illness means it is “hidden” from sight.

High grass silage dry cow diets put cows at higher risk of developing disease due to a number of factors.

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  1. Grass silage is high in Dietary Cation Anion Balance (DCAB) and also hugely variable, ranging from +300 to +800mEq/kg DM. High DCAB negatively effects calcium metabolism, increasing the risk of milk fever when fed to dry cows.
  2. Grassland that’s had slurry applied will have high potash levels, which negatively impacts on calcium metabolism and increases the risk of milk fever – avoid feeding this silage to dry cows.
  3. For a partial DCAB ration, the diet should ideally have a DCAB of zero with an acceptable range of -40 to +70mEq/kg DM.
  4. Testing your grass silages so you know the mineral status of the crop you’re feeding your dry cows is vital. This enables the ration to be balanced appropriately.
  5. Choosing a specially formulated mineral pack to complement your dry cow diet can help minimise the risk of milk fever. For example, Mole Valley Farmers’ Transition Dry Cow (TDC) 600 is ideal for high grass diets as it has a strong negative DCAB to overcome high DCAB in grass.
  6. For over-conditioned cows that are at higher risk of metabolic disorders like fatty liver and ketosis, farmers can choose to feed TDC 650. This includes protected choline to help mitigate the risk of metabolic disease.
  7. Farmers feeding diets containing maize or whole crop silage can opt for Mole Valley Farmers’ TDC 400 mineral, which is designed for these types of ration.

The figures 50% of all dairy cows could be suffering from subclinical milk fever. £50 – the cost per cow of subclinical milk fever. Nearly £50m – the total cost of subclinical milk fever to the UK dairy industry. References 1. Reinhardt, 2011 2. Macrae, 2015. 3. Mole Valley Farmers calculations (1.8 million cows x 50% x £50)

 >> The Mole Valley Farmers team can assess the DCAB of your diet and balance rations accordingly using their Precision Nutrition rationing programme. They can also carry out forage mineral analysis. Call The Mineral Line, Tel: 01278 420481 for more information. Follow Mole Valley Farmers on Facebook

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