Trace Element Deficiencies
Often present as poorly grown lambs during late summer/early autumn. Important interplay between parasitic gastroenteritis and trace element deficiency states. Generally the elements considered are Cobalt, Copper, Selenium and Vitamin E.
Cobalt Deficiency (Pine)
· Cobalt has an important metabolic role as a constituent of Vitamin B12 which is manufactured by micro-organisms in the rumen (first stomach). The deficiency occurs when there is a low cobalt concentration in the soil; which may be further complicated by PGE (which causes diarrhoea, thereby comprising absorption of Vitamin B12).
· Clinical signs are most commonly seen in weaned lambs during late summer/autumn. Signs include lethargy, reduced appetite, and poor quality wool with open fleece, small size and poor body condition despite normal nutrition. Sometimes pale mucous membranes (eyes) develop after a few months. Also show failure to respond to vaccinations.
· Severe conditions (known as ovine white liver syndrome) show lambs present with nervous signs; such as depression, head pressing and aimless wandering.
· Much less common in adults but reported to cause reduced fertility and mothering ability.
· Differential diagnoses: there is interaction between chronic parasitism and TED, making it hard to pin-point the active problem. Other diagnoses are poor nutrition/overstocked pasture, poor grazing, coccidiosis and/or nematodirosis can cause a serious growth check around 6-8 weeks with protracted convalescence and PGE is a very common cause of poor lamb growth.
· Clinical diagnosis is based on veterinary examination; taking into account known Cobalt-deficient soil areas and low concentrations of Vitamin B12 in the liver or plasma.
· Treatment is most effective when intramuscular injections of Vitamin B12 and drenching with Cobalt Sulphate. Followed by monthly drenches, combined with anthelmintic preparation.
· Common when sheep graze pastures with low copper, high iron, molybdenum and sulphur. These 3 elements will act synergistically to bind copper out from a diet. Clinical manifestation varies worldwide. Swayback in UK, anaemia and poor wool in AUS and poor bone mineralization in NZ. Moreover, sheep can also suffer from copper accumulation and toxicity. There is breed variation when it comes to copper absorption; therefore differences in toxicity and deficiency of copper.
· Clinical presentation: in mid-pregnant ewes, may lead to swayback in lambs. In growing lambs, may result in poor fleece known as “steely wool”. Poor growth, anaemia and increased susceptibility to bacterial infections have been reported, but are less common.
· Prevention is more effective than treatment; as irreversible changes may be made to the lambs fleece and growth. Treatment of swayback is hopeless. Copper supplementation should be carefully measured, in order to prevent toxicity. Generally, copper is administered by an injection of copper heptonate.
Selenium and Vitamin E Deficiency
· Known as white muscle disease, nutritional muscular dystrophy and stiff lamb disease.
· Associated with risk factors such as feeding home grown cereals and root crops, along with incorrectly mineralised rations; however, prevalence is generally low. Selenium deficiency occurs in soils, leading to pasture/crop deficiency. Vitamin E conc. is high in green crop, but falls rapidly with drought. Certain crops are known to be low in both. Grain treated with propionic acid will increase the risk of the disease.
· Typically affects rapidly-growing, 2-6 week old lambs; often ram lambs of meat breeds (eg. Suffolk and Texel). Characterised by sudden onset of stiffness, lambs are reluctant to move (and so easily caught). Often unable to rise after 1-2 days. Early embryonic problems have also been attributed to this deficiency.
· Differential diagnosis: stiffness in lambs is mainly caused by bacterial infection of a joint in the neck. Poor growth is also attributed to cobalt deficiency, poor pasture management and PGE. Likewise, the association with embryonic failure can be caused by infertile ram, toxoplasmosis and Border disease.
· Diagnosis is based on clinical signs of rapidly growing lambs, which are in contact with the risk factors shown above. Muscle enzyme conc. will be measured by a vet. Gluthione peroxidase as the main indicator.