What Is Milk Fever?
Milk fever—also known as parturient paresis or clinical hypocalcaemia—is a serious metabolic disorder that typically occurs within 72 hours after calving. It develops when a cow’s demand for calcium to produce colostrum and milk exceeds her ability to mobilize calcium from bone reserves or absorb it from her diet. Calcium plays a critical role in muscle function, so when levels drop too low, cows experience weakness, paralysis, and, if untreated, death.
Clinical Signs
Recognizing the stages of milk fever is vital for early intervention:
· Stage 1 (Early signs): Restlessness, muscle tremors, ear twitching, and head bobbing. Cows may appear unsteady or hypersensitive.
· Stage 2 (Moderate signs): Inability to stand, cold ears and legs, rapid heart rate, dry muzzle, bloating, and decreased rumen contractions. Without treatment, cows may lie down and be unable to rise.
· Stage 3 (Severe signs): Complete paralysis, unresponsiveness, coma, and eventual death if calcium is not restored.
Prompt recognition and treatment at Stage 1 or 2 dramatically improve survival rates.
Why It Happens
At calving, calcium demand can rise sharply to over 50 g/day - compared to around 30 g/day during the dry period. This sudden increase is needed for colostrum and early milk production. If the cow cannot absorb enough calcium from the diet or mobilize it quickly enough from skeletal stores, blood calcium levels fall.
Certain groups are at higher risk:
· Older cows – bone resorption mechanisms become less efficient with age.
· High-yielding cows – produce more colostrum and milk, creating higher calcium demand.
· Over-conditioned cows – excess body fat can interfere with metabolic balance.
Prevention Strategies
Preventing milk fever is far more effective than treating it after onset. Key strategies include:
· Dry Cow Diet: Provide a low-calcium diet (10–30 g/day) before calving to stimulate natural calcium mobilization.
· Dietary Cation-Anion Difference (DCAD): Implement acidifying diets or feed anionic salts pre-calving to enhance calcium absorption and mobilization.
· Magnesium Supplementation: Maintain magnesium intake at 40–50 g/day, as magnesium is essential for effective calcium metabolism. If this is overlooked during the pre-calving period the animals ability to absorb calcium is much lower when calcium requirements are high.
· Body Condition & Exercise: Keep cows in moderate condition (Body Condition Score 2.5–3.0) and encourage adequate movement to support metabolic health.
· Close Monitoring: Pay particular attention to older, high-yielding cows and those with a history of milk fever.
Supporting Cow Health with Animal Farmacy Products
Animal Farmacy provides effective solutions to help prevent and manage milk fever while supporting recovery around calving:
· Drench-Mate Drench Powder (7.5 kg) – A versatile post- and pre-calving drench formulated with six sources of calcium plus magnesium, potassium, niacin, and vitamins. It helps combat milk fever, supports hydration and appetite, improves liver function, and ensures cows recover quickly after calving.
· Superphos 5% Pre Calver – A balanced mineral block with calcium, phosphorus, and magnesium to help prevent milk fever. High levels of zinc and selenium aid in reducing mastitis and somatic cell counts, while essential trace elements support both cow and calf health. Selenium helps reduce retained cleanings, and calves are quicker on their feet. Convenient 10kg blocks fit any standard holder.
· BoviBoost Bolus – A long-acting trace element bolus delivering copper, iodine, zinc, selenium, and cobalt for 180 days from a single application. It enhances growth in youngstock, supports smoother calvings, boosts fertility, and improves overall herd vitality. With zero withdrawal period and proven trial results worldwide, BoviBoost ensures continuous mineral supply and better herd performance.
· PharCal + D3 Calcium Bolus – A rapid, fast-acting calcium supplement enriched with Vitamin D3 for superior absorption. Ideal at calving or after calcium injections, it helps stabilize calcium levels, supports muscle function, and reduces the risk of hypocalcaemia in vulnerable cows.
By incorporating these products into herd management, farmers can reduce milk fever risks, support smooth calving, and keep cows productive and healthy.