Production rates on farm are largely influenced by fertility and growth rates, both of which we can maximise in working alongside farmers. Common problems we encounter on farm which compromise these rates are inadequate nutrition for the stage of life, parasitism and disease. Trace elements, more specifically selenium, iodine, copper and cobalt, also play a role and may often go unnoticed due to their subclinical nature.
Animals may have single or combined deficiencies in their trace elements and may be affected at any point in life, although there are higher risk periods and groups for certain deficiencies. Even if the diet supplies enough of the essential minerals, interactions with the environment, disease or meds can affect the uptake or use of these elements. We can establish if your livestock are receiving adequate levels and detect deficiency before it presents itself clinically.
Clinical trace element deficiencies present in a number of ways. One example, an approach to poor weight gain, is depicted below. If you can rule out insufficient energy intake and disease as causes for reduced growth rates, you should consider trace element deficiencies. Other clinical signs may lead you to think one element deficiency is more likely than the others.
Selenium plays a major role in the immune system and resistance to infectious diseases. It is found in pasture, plants and forage and these levels can vary greatly between regions and seasons. Subclinical consequences are reduced submission and conception rates, early embryonic deaths, increased retained foetal membranes and the birth of weak or stillborn neonates. A general ill-thrift may suggest an issue with selenium, with slow growth and poor production proving costly. Supplementation is necessary in these animals, whether injectable or oral. A clinical consequence of selenium deficiency is White Muscle Disease, typically seen in young lambs, which affects the skeletal, cardiac and respiratory muscles. Unfortunately, this condition results in death as does Mulberry heart disease in piglets.
Iodine deficiency may be due to deficient soils or ingestion of legumes and brassicas. Just like a selenium deficiency, a lack can result in fertility issues because iodine is crucial to ovarian function. You may experience high perinatal mortality rates or still-borns on farm in addition to retained foetal membranes. Clinically an individual may have an enlarged thyroid gland. Supplying minerals, boluses or treating the water or pasture may be suggested to those who experience iodine deficiencies in their livestock.
A copper deficiency can present itself clinically in a variety of ways. It may be caused by deficient pastures or the antagonising effect of sulphur or molybdenum in the soil. An important role of copper is in the formation of nerves as well as collagen, therefore insufficient levels of this trace element can lead to a condition called Swayback, with animals displaying weak or paralysed hindlimbs and a poor prognosis. Coat discolouration, the appearance of spectacles around the eyes and diarrhoea may also result. Sub-clinically, reduced fertility rates can be experienced and anaemia in untreated animals. Copper supplementation is widely available.
Cobalt is essential to glucose production and energy, and therefore is required for any process in the body. A deficiency can lead to a whole host of clinical signs involving the hair, skin, nervous and musculoskeletal system. Clinically affected animals may be small in stature with poor appetite, lethargic and general ill-thrift, with nervous signs in severe cases. Sub-clinically they may develop an anaemia and be more susceptible to parasitism. Cobalt is a component of vitamin B12, so treatment with this can help kickstart glucose production. Boluses or drenches can provide cobalt too.
What can we do?
We can help to assess the likelihood of a trace element deficiency on farm and run blood tests to confirm this. The advantage of this is that you can assess the levels of multiple trace elements in one hit, which is useful as deficiencies can be linked. For example, a selenium deficiency can lead to an iodine deficiency, as well as being associated with lack of storage and retention of copper.
The same bloods can be used to screen for diseases such as Leptospirosis, Johnes, IBR and BVD. We can liaise with laboratories to advise you on the best course of action and direct you to the best treatment. It is important to prevent these issues occurring further down the line if we want to improve production rates and avoid unnecessary treatments or inappropriate overdosing.
Written by Olivia Casey Bsc (Hons) BVetMed MRCVS