Development of a novel concept (Calcigard) for activation of calcium absorption capacity and prevention of milk fever.

The background to the development of a novel concept for the prepartal activation of calcium absorption capacity as a means of preventing parturient hypocalcaemia and milk fever in grazing ruminants is described. It was hypothesised that this objective could be achieved by decreasing the bio-availability of calcium from pasture for a 3 week period. Soya bean oil was chosen as a supplement, from a number of potential binding agents, to form poorly digestible calcium soaps in the gastrointestinal tract. 28 mature twin-pregnant ewes in late pregnancy were used as assay animals to test the hypothesis, and they proved to be a sensitive experimental model for dairy cows. Following the treatment period, overnight starvation was used to challenge calcium homeostasis. Calcium absorption capacity was assessed indirectly by measuring strontium concentrations in plasma following oral dosing with strontium chloride. Strong support for the hypothesis was obtained as the 14 Treated ewes were protected from severe fasting-induced hypocalcaemia (P = 0.002), and this was associated with a greatly increased capacity of the ewes to absorb calcium. The feeding strategy developed in this experiment led to the production of a Calcigard concentrate supplement which was subsequently shown to protect cows from hypocalcaemia and milk fever, and stimulate production.