Local sheep farmers in the district are experiencing calcium deficient ewes known as Hypocalcaemia. This is a common calcium disorder for ewes that becomes more frequent at lambing time.
This disorder is common during this period, as the lamb is entirely dependent on the ewe to provide calcium to build strong bones for the first few weeks. The peak demand for calcium for a lamb is at 10 days of age, but that demand on the ewe steadily increases from midway through pregnancy, as the lamb’s bones begin to calcify.
Inadequate calcium supply by a ewe to her lamb means the lamb has lower bone calcium stores, and as an adult will be more at risk of hypocalcaemia when lambing, perpetuating the risk into the next generation.
The disorder is more common in transported sheep and those in stressful situations, such as when yarded for shearing in winter.
Fortunately, if recognised early, a simple treatment with a calcium solution injected under the skin and oral supplements will affect a recovery in most sheep.
Farmers can influence the risk of hypocalcaemia by ensuring the ewes get fed a balanced diet, which contains at least 3 gm/kg DM calcium, and up to 5 gm/kg in ewes with multiple lambs. Legume forages are great sources of calcium, and cereal grains are poor.
As pasture and fodder tops up the supply of calcium to the lamb during pregnancy and early lactation, anything that disrupts the supply or absorption of calcium from the feed puts ewes at risk of hypocalcaemia. This is where mustering or transport have their ef- fects, through disruption to the supply of calcium.
Diseases such as ‘worms’, which affect the absorption of nutrients, or copper deficiency, which interferes with calcium metabolism, can produce osteomalacia (‘soft bones’, or rickets) in lambs. Some pas- tures lack calcium or contain chemicals that interfere with calcium metabolism. Examples include oxalate containing weeds, green cereal crops, and rye grasses, which may contain compounds that have an anti-vitamin D effect. Vitamin D is a hormone formed in the body through exposure to sunlight and is important in assisting the uptake of calcium from the diet.
Sourced from agriculture.vic.gov.au