During a ewe’s gestational and early lactational stages, she will have increasing nutrient requirements, particularly an increase in energy, protein and certain vitamins and minerals. If there is a shortage or an imbalance in her feed, she may develop pregnancy disorders.

Hypocalcaemia

Hypocalcemia is also referred to as milk fever, and is a disorder that is common among pregnant ewes. During pregnancy and early lactation, the ewe must provide the growing lamb with all of its calcium requirements, as the milk she produces is the only source of sustenance that it will receive.

During pregnancy a ewe’s bone calcium will be mobilised to ensure that the bones of the growing in-utero lamb is provided with enough calcium to develop strong bones. The demand on the bone stores may increase up to 70% during early lactation, and, should the ewe receive an inadequate supply of calcium, she will develop a higher risk of developing milk fever with the next pregnancy.

Signs:

Unlike pregnancy toxemia, this disorder progresses rapidly, and affected ewes may die within 6 – 24 hours after developing the disorder. Affected ewes will have a stiff-legged gait and display difficulty walking. Muscle tremors may be present, and the ewe will show signs of struggling when approached.

Affected ewes may be staggery and weak, often display signs of being unable to support their own bodyweight.

If left untreated, the ewe may lie down and show signs of depression and drowsiness. Watery discharge from the nose is not uncommon.

Cause:

This metabolic disorder is caused by a lack of calcium in the bloodstream, and will present itself in late gestation and early lactation, just like pregnancy toxemia. Ewes that graze on poor quality veld, or that are fed an unbalanced diet, are at risk of this disorder.

The risk of developing milk fever increases as the age of the ewe increases.

The risk of developing milk fever increases if the ewe is pregnant with twins or triplets.

Prevention:

Pregnant and lactating ewes should be fed a diet that contains an adequate amount of calcium. If the veld that pregnant ewes are being fed on does not contain enough calcium, then their diet should be supplemented with an effective calcium source.

Pregnant ewes should not be kept from feed for long periods of time, such as in a holding yard or during transportation.

The diets of these pregnant or lactating ewes should not be changed without an adequate adaptation period.

Ewes should be kept in an environment (such as out of extreme cold and rain) so that shivering and increased maintenance levels do not occur.

Treatment:

Affected ewes should be diagnosed and treated as fast as possible. A subcutaneous injection of a calcium solution should be administered by a vet or animal health technician, and the ewe closely monitored to check for signs of recovery. Ewes that are treated for hypocalcaemia tend to make fast recoveries, anywhere from a few minutes to about an hour after treatment.

This disorder is easy to avoid if the farm manager provides the proper level of nutrition and management.

Should you have any concern of your ewe developing this disorder, please contact your Technical Advisor.