Failure of 25-hydroxycholecalciferol to prevent milk fever in dairy cows

Abstract An intramuscular injection of 4 mg of 25-hydroxycholecalciferol [25(OH)D3] in corn oil was administered 3–10 days before calving to 123 cows of third or subsequent lactation on 6 dairy farms. There were no significant differences in the prevalence and severity of milk fever or in the level of plasma calcium within 24 h of calving between the injected cows and paired control animals. Cows with milk fever were significantly older than those without, but were no different in circulating 25(OH)D3 levels or in condition score. The prevalence of milk fever in the selected cows in each herd ranged from 0 to 26% and was correlated with the calcium content of the hay supplement fed prior to parturition.