Cow Health: Sodium deficiency

Sodium is an essential element for animals. Dairy cows routinely expel Na from the body in urine, faeces, saliva and milk which has to be replaced. It is essential to maintain an animal's water balance and for nerve and muscle function.

Regions likely to be Sodium deficient

Inland soils, such as the Central Plateau pumice soils, associated volcanic soils of the Waikato/ King Country, and soils of inland Marlborough, Canterbury, Otago and Southland, are more likely to be low in Na.

Sodium is lost from the soil via leaching (30-80 kg Na/ha/yr), while significant amounts of Na is present in rainfall. About 30 kg Na/ha/yr has been measured in the Waikato from rainfall, leaving a deficit and coursing Na levels to fall. Areas close to the coast will get more Na in the rain and areas further inland less.

Sodium (Na) is essential for animals:

• Sodium is not essential for pasture growth, but most plants will take up sodium from the soil
• Sodium is leached from the soil but most soils have inputs of sodium via rainfall, the amount in the rain being higher the closer the land is to the coast
• Pasture (herbage) tests are the most simple and reliable means of diagnosing Na deficiency
• Supplementing dairy cattle that are low in Na with salt (sodium chloride - NaCl) can give a significant lift in milk production
• Drenching is the most effective means of supplementing dairy cattle. But adding salt to the fertiliser, dusting with salt or adding salt to supplementary feed can also be effective.

For more information refer to:

DairyNZ Farmfact: Sodium deficiency in dairy cattle (3-2)