Milk fever (hypocalcaemia)
Conditions when likely to occur:
Previous history on property.
Usually older cows (>5 years old).
Usually late pregnancy (also after calving in dairy cows).
Usually high producing and dairy cross cows.
Previous history of cow with hypocalcaemia.
Alkaline diets (high Na+, K+ and low SO4 = C1-).
Low calcium intake after calving (and high intake before).
Low roughage intake.
Fat cows > FS3.5
Clinical signs: inability to rise, dry muzzle, either just about to calve or recently calved.
Management strategy to prevent disease:
Avoid over-fat cows: FS<3.5
Ensure constant access to feed during calving and avoid grazing high-risk pastures (as for grass tetany).
Feed hay after calving (consider cost benefit) avoid hay before calving. Keep calcium intake less than 50g/day before calving.
Lower herd age structure as older cows are higher risk.
Respond to treatment with calcium borogluconate with a dose of 8–14g of calcium.