Hypocalcaemia in sheep
Following the long dry summer and extensive grain feeding of sheep, we are seeing numerous cases of hypocalcaemia (milk fever) in Autumn lambing ewes. Hypocalcaemia (a metabolic disorder) in sheep occurs when there is insufficient intake and absorption of calcium and insufficient resorption from skeletal reserves to meet foetal demands. The condition develops with the approach of lambing and is characterised by ewes that appear staggery and unable to stand and death can follow if left untreated. Hypocalcaemia in sheep resembles pregnancy toxaemia (twin lamb disease caused by energy deficit) being more likely to occur in twin bearing ewes that are losing condition, are stressed by transportation or movement (i.e running ewes in pre-lambing for crutching or vaccinating/drenching) or have been exposed to a sudden change in or shortage of feed. In one recent example, a farmer in north west Victoria moved ewes (2 weeks from lambing) from a lucerne paddock (high in calcium) to a Veldt grass paddock (low in calcium) and within 1 day of moving them, suffered 45 cases of hypocalcaemia, including 18 dead. It is possible that pregnancy toxaemia can develop in conjunction with hypocalcaemia because loss of appetite is common with this disease, thus reducing energy intake.