During recent conversations with clients on WhatsApp and Zoom there has been regular mention of bloat being an issue in dairy cows this spring. One of the less talked about reasons for bloat is the Potassium (K); Sodium (Na) ratio, otherwise known as the Bloat Index.

The reason this is important is that research has shown that K levels rise in the animal and Na levels fall immediately after consuming legumes, e.g. clover and Lucerne. The drop in Na impacts on the ability of the animal to digest the fibre from the pasture or silage in the rumen. This reduced digestibility leads to higher levels of gas production in the rumen causing bloat.

Increasing the sodium levels in the cow will improve the ability to digest the high protein pasture of silage by increasing water-soluble carbohydrates, sugar = energy for the rumen bugs to enable digestion.

Experiments have shown that applying sodium fertiliser NaCl at between 35 and 75 kgs/ha can reduce the amount of gas production in the rumen when feeding high legume content grazing. Sources of sodium fertiliser are shown in the table below from the PDA leaflet No6 Potash, Magnesium and Sodium Fertilisers for Grass.

The fertilisers with higher levels of K should be avoided as they will not help improve the K:Na ratio and can also increase problems with grass staggers.


• Avoid fields that have had large quantities of slurry as they will be high in K.
• Make sure salt licks are available both during milking and whilst grazing or housed.
• Apply sodium to high legume content leys, e.g. Cheshire Rock salt.

To discuss this or other fertiliser matters, contact Phil at or your local FCG Office.

Posted in Business Management, Dairy & Forage, Sherborne.