Hypocalcaemia, or milk fever, occurs in cattle, sheep and goats. It is most common in high producing or dairy cross cows and in milking goats. Clinical signs develop when serum calcium levels fall below a critical level (hypocalcaemia).
Affected animals are initially excited or agitated with muscle tremors, then go down and are unable to rise.
Conditions when hypocalcaemia is likely to occur
- Property history of hypocalcaemia.
- In older cows (greater than five years old) or does (greater than four 4 years old) or ewes.
- Late pregnancy (also after calving in dairy cows).
- High producing and dairy-cross cows.
- Cows with a history of hypocalcaemia.
- Alkaline diets (high sodium and potassium and low sulphate and chloride).
- Low calcium intake after calving (and high intake before).
- Low roughage intake.
- Heavy grain feeding of sheep.
- Fat cows (ie fat score of 3.5 or greater).
Identifying and diagnosing hypocalcaemia
Clinical signs that would lead a producer to suspect hypocalcaemia include:
- Tetany, unable to rise, dry muzzle.
- Ewes cast after handling, often with hind legs behind.
- Responding to treatment with calcium borogluconate.
Blood samples can also be collected to determine serum calcium levels.
Prevention strategies for hypocalcaemia
- Avoid over-fat cows.
- Ensure constant access to feed during calving.
- Avoid grazing high-risk pastures (as for grass tetany)
- Feed hay before calving (consider cost-benefit).
- Keep calcium intake to less than 50g/day before calving.
- Feed as much calcium as possible after calving, for example clover-dominant pasture.
- Prevent hypomagnesemia.
- Avoid handling heavily pregnant ewes.
- Lower the herd/flock age structure as older cows, does and ewes are higher risk.
- Cattle Disease guide from MLA's More Beef from Pastures
- Module 6 from MLA's Going into Goats Guide: A profitable producers' best practice guide
- Agriculture Victoria: Milk fever (hypocalcaemia) in cows
- Biosecurity Tasmania: Milk Fever in sheep