Hypocalcaemia in sheep

Hypocalcaemia is a metabolic disease in sheep that is primarily due to a lack of available calcium. This is not usually a simple deficiency.

Sheep are most susceptible in late pregnancy, but hypocalcaemia may also occur during lactation or in young rapidly growing animals. The incidence is greatly increased when at-risk sheep are stressed through handling or changes in weather. There are numerous differences between sheep and cattle in susceptibility to deficiencies; peak timing of requirements; differences in the reproduction cycle and a greater variation in reproductive rates. Therefore while the sheep industry often looks to the dairy industry for solutions, recommendations on managing and preventing the disease should be considered separately.

Click here to read the full article about Hypocalcaemia in sheep

Current recommendations for prevention of hypocalcaemia

1. For sheep being fed cereal grain supplements (ewes and growing stock) in summer and autumn add 0.5% salt and 2% limestone (of the rations) to the diet. Mixing in the diet is preferable but an alternative is to provide limestone and salt ad lib as a loose lick.

Cereal grains are low in calcium (Ca) and sodium (Na). The purpose of this supplementation is to ensure bone reserves are not depleted prior to pregnancy and young growing sheep have adequate calcium for bone development. Salt provides sodium, but also is used to increase intake of the limestone.

2. For all pregnant ewes, from mid-pregnancy, keep stress events and time off feed to a minimum (i.e. yarding for shearing; crutching etc). Avoid yarding ewes during the last 4 weeks of pregnancy.

Stress can cause a redistribution of calcium and magnesium (Mg) in the body. It is likely stress can induce hypocalcaemia even in ewes that are otherwise managed to have an adequate calcium status. The higher the risk status of the ewes, the higher attention required.

3. For sheep grazing vegetative cereal crops, provide a mixture of causmag:limestone:salt (2:2:1) at an allowance of 30 g/head/day.

Young cereals are often low in magnesium, sodium and calcium but high in potassium (K). The risk of mineral imbalance is high.

4. Continue to provide calcium supplements to ewes grazing lush pastures post droughts (or after high rates of grain feeding).