Serum Calcium and Phosphorus Profiles in Dairy Cows with Clinical Hypocalcaemia in Kaduna State, North West Nigeria

Hypocalcaemia, commonly manifesting as milk fever in periparturient dairy cattle, is a metabolic disorder of significant economic importance in intensive dairy operations. This study characterised serum calcium and phosphorus profiles in Friesian-Zebu crossbred dairy cows presenting with clinical hypocalcaemia at a commercial dairy enterprise in Kaduna State, North West Nigeria. Fifty cows comprising twenty-five clinical cases and twenty-five healthy age-parity-matched controls were enrolled over a twelve-month period spanning two calving seasons. Blood samples collected at the time of clinical presentation were analysed for total calcium, ionised calcium, inorganic phosphorus, magnesium, and parathyroid hormone using automated biochemical analysis and radioimmunoassay. Clinical cases exhibited severe hypocalcaemia with mean total calcium of 1.4 mmol/L compared to 2.3 mmol/L in controls, accompanied by concurrent hypophosphataemia and mild hypomagnesaemia. Parathyroid hormone was significantly elevated in clinical cases, confirming appropriate endocrine response with impaired end-organ responsiveness. Parity and body condition score at dry-off were identified as significant risk predictors. The study recommends preventive dietary anion-cation balance management in the close-up dry period and enhanced calcium monitoring protocols for high-risk cows at the Kaduna dairy enterprise. Keywords: hypocalcaemia, milk fever, dairy cattle, serum calcium, Kaduna.