Graaff-Reinet veterinarian Dr Roland Larson’s research on the effects of trace minerals and vitamins in livestock, especially small stock, is showing the way forward for exciting improvements in condition, productivity and the treatment of disease.

In 2007 Graaff-Reinet veterinarian Dr Roland Larson got a call from sheep farmer Kayne Kingwill from the Murraysburg district in the Karoo to ask his advice about his Dorpers and Merinos.

“He explained that there had been good rain and the veld was good, yet his animals were losing condition,” explains Larson (55) from his veterinary clinic in Graaff-Reinet where he has practised for 26 years.

“We started to investigate the problem, first using drenches as the animals had serious worm infestations. After the first drench there was no improvement, so we re-drenched using another product, and within a short period of time the animals started gaining condition and doing well. The second drench happened to contain cobalt and selenium, and this was an eye-opener for me,” says Larson who, with the collaboration of Kingwill, started doing trials on the effects of trace minerals and vitamins on small stock.

They took a wide range of samples – water, blood and various organs – the most telling were the blood and liver.


The lab results for Kingwill’s farm, which can be applied to most farms in the district of Murraysburg, Graaff-Reinet, and also heading towards Aberdeen and Middelburg, showed that the area has notably low levels of the micro or trace minerals selenium, zinc and cobalt levels, combined with extremely high percentages of iron in the borehole water.

Trace or micro minerals are essential to healthy body function and are so-named because they are needed in such small amounts.

Historically, free-roaming animals would have roamed and sourced the lacking minerals from nature, but fenced-in animals need to be supplemented, especially if they are confined to cultivated, irrigated or fertilised pastures.


Larson diagnosed that the sheep on Kingwill’s farm needed to be treated for a deficiency of selenium as well as vitamins B12(cobalt) and E.

“We injected them with all three, and within a two-week period I could not believe it was the same flock of sheep,” says Kingwill. His lambing percentage went up to 97.8% in October 2008 from 30% in February 2008.

Larson and Kingwill were heartened by the result.

As a ‘back to basics’ man Larson is highly circumspect about the indiscriminate and often excessive use of drenches, doses, chemicals and antibiotics used to treat livestock diseases and condition problems.

“For me it’s trying to put an expensive plaster on a problem that starts with nutrition,” says Larson who believes that many livestock diseases can be eliminated by introducing the appropriate minerals and vitamins to the animals’ diet. The specific minerals and vitamins required will vary enormously across South Africa, from district to district, farm to farm and even camp to camp.

Let’s look at why he selected selenium, B12 (cobalt) and E for the sheep on Kingwill’s farm:


Vitamin E and selenium are major anti-oxidants, which have a positive or agonistic interaction with each other, improving the uptake of each other. An antagonistic interaction is where the uptake of a mineral or vitamin has a negative interaction with another mineral or vitamin, depressing the uptake. Antagonists of selenium are calcium, sulphur and iron; hence the high percentages of iron in the water on Kingwill’s farm can contribute to the selenium deficiency.

Selenium is essential for a strong immune system, Larson explains. Deficiencies in small stock result in weakness and ‘White Muscles Disease’ in lambs, often causing death, and young and adults alike don’t do well, lose weight and condition even with good food, the ewes and rams also suffer from fertility and their gums pull away from their molars.

“Sheep can tolerate far higher levels of selenium (five times higher) than previously anticipated,” continues Larson.

Two of the recommended injectable forms of selenium are Multimin and Deposel, while an oral formulation is Embamin.


As for B12…this brings us to Larson’s pet mineral subject, cobalt.

“Cobalt in ruminants is an essential component of Vitamin B12. It is utilized by rumen micro-organisms to produce Vitamin B12 and sheep need ten times more cobalt than cattle,” he explains. “As I explained there is a deficiency of cobalt in the Graaff-Reinet/Murraysburg area, exacerbated by the heavy liming of acid soils, which farmers often do. The heavy liming further reduces the availability of cobalt.

The best way to supplement for cobalt deficiency is with vitamin B12 injections. “I have been appealing to distributors to bring in a B12 product from New Zealand called SMARTShotB12 which lasts for six to eight months in small stock, as opposed to the current products in South Africa which last or a maximum of four weeks.”

Vitamin B12 is essential for basic metabolic function. It is required for DNA synthesis and red and white blood cell production. A deficiency results in lacrimation, pernicious anaemia, the animals become weak, they lose condition and they don’t show signs of improving. These symptoms are often confused with worm and internal parasite infestations, Johne’s disease, CLA and others.

“I have been amazed by the results achieved with correct mineral and vitamin supplementation. Severe lacrimation, for example, has cleared up with a shot of B12,” says Larson who cites vitamins B12, E and A as the most important for livestock.


Deficiencies in Vitamin A lead to lacrimation (excessive tear flow), blindness, diarrhoea, nasal discharge, abortions, poor reproduction and performance.


Deficiencies in zinc result in poor wound healing, poor reproduction and compromised wool growth in small stock. Angoras get a condition called parakeratosis where the mohair loses its typical crimping to become long and steely.

Over the past four years Larson has immersed himself in researching minerals and vitamins, their interaction with each other, and their effect on livestock metabolism and reproduction. It’s a neglected field of research, which has only received attention by a few South African veterinarians over the years, including Dr James Kitching who worked in the Western Province Provincial Veterinary Laboratory in Stellenbosch, now retired, and Dr Gareth Bath, formerly of Grootfontein followed by Onderstepoort, also now retired.


“The supplementation of minerals and vitamins has been ad hoc – a bit of this and a bit of that – with farmers often using the same ‘cocktails’ that their grandfathers gave their livestock,” Larson explains.

The problem with this is that trace minerals and vitamins can have either a very positive or very negative effect on animal health and reproduction. Which is why Larson emphasizes that farmers need to know precisely which deficiencies their animals have before simply administering this or that from a bottle.

“For example, an excess of copper in sheep is fatal, so you don’t want to be dosing an off-the-shelf product that contains copper if you have a high level of copper in your region. Excess copper in sheep causes diseases such as Enzooitic Icterus or ‘Geelsiekte’. A copper deficiency on the other hand, causes ‘swayback’ – a nerve-related condition in sheep, as well as bone fractures, anaemia and depigmented fibre, where, for example, the black fibre of black dorpers turns to an orange colour.”

If you look at a selenium, zinc and manganese injectable like Multimin, you will see that it comes in two options, with and without copper.

A deficiency in manganese leads to reproductive issues, infertility, abortions and a condition called brachygnathism in rams where the mandible protrudes beyond the maxilla – which often indicates a manganese deficiency.


Regarding the macro-mineral magnesium, Larson offers a strong answer to the question many farmers have asked him: why their small and large stock consume so much salt.

“Salt promotes the animals’ uptake of magnesium, without which they suffer from a loss of appetite and consequent weight loss, as well as all sorts of diseases, such as ‘grass staggers’ (acute convulsive seizures, trembling and rigidity) particularly on highly fertilized pastures with a high calcium, potassium, phosphate and nitrogen content and a low sodium content.

I know that many farmers worry about high levels of salt uptake, but I am a firm believer that animals will only take as much as they need, so make sure it is available to them at all times. The average salt intake for small stock is 1.6g per ewe per day or 48kg per 1000 ewes per month. For large stock you would times this by about four. But no absolutes can be applied.”


Each region, each farm and each camp has different deficiencies, and it is so important to work out what your animals’ specific mineral and vitamin needs might be.

“Farmers like a quick fix but there is no quick fix,” says Larson. “Fortunately nature also assists us and animals are remarkably adaptable in conditions where, for example, there is a high iron content. Animals thrive in areas where the statistics tell us the iron content should kill an animal. At the same time we need to know how to compensate for this with minerals and vitamins and whether to filter the water or at least dilute the mineral supplements with distilled water.”


“It is absolutely imperative to consult with your local veterinarian as he will know your area. I am happy for vets and farmers to contact me if they need advice or collaboration,” says Larson who recommends liver, blood and water samples as the best indicator of your animals’ deficiencies. All this can be done through your local vet who sends the samples to specific pathology laboratories.

The liver test costs approximately R400; the blood samples cost approximately R130 per sample and Larson recommends about five samples per flock. Your vet might well be able to negotiate the price for several samples with the laboratory.

“Your vet will advise you about the appropriate minerals and vitamins to dose once you have the results,” says Larson who advises that you repeat the test six months later as it will give you a good indication of what is happening on your farm.

“Once you are on top of the situation, keep monitoring your animals. Make sure you have a decent scale so that you can weigh them and keep records that will help you see whether you are on track.”