The Role of Minerals In Preventing and Treating Sheep Illnesses
Selenium Deficiency Can Present a Host of Problems, Including White Muscle Disease
By Alethea Kenney – You don’t usually think about sheep illnesses when you look at a flock of sheep to assess the overall health of the flock. The first thing that catches most people’s eye when they look at a flock of sheep on the sheep farm is the wool. Fuzzy looks and gentle eyes make sheep uniquely appealing. That look is more than skin deep: It starts with proper digestion, nutrition, and pasture management. Without those things, sheep quickly become ragged and unthrifty, experience poor reproduction, suffer difficult lambings, exhibit poor milk production, have weight loss and/or poor gain, and more prone to other common sheep illnesses. Worms move in (and invite all their friends). All of these problems can combine, making the life of the shepherd a nightmare of management chores.
Many shepherds assume these sheep illnesses are part of raising sheep, just par for the course and something that must be dealt with. Fortunately, that’s not the case. Issues like poor wool quality, hoof conditions, low lambing percentages, lambing problems, poor weight gain, poor milk production, and worms are all related very closely to the health of the animal and underlying nutritional issues.
To help flock managers struggling with these difficulties, I’ll briefly explain the importance of minerals in restoring and maintaining health in sheep and ways to get those minerals into the sheep in an easily digested form to prevent and treat sheep illnesses.
Since sheep are herbivores, their nutritional needs are met mostly with hay and forage. Like all living things, sheep also need minerals, the building blocks of the body. They can take in much of their mineral needs from their feed, yet almost all shepherds offer some type of mineral supplement to their sheep. In an ideal world, soils would provide most of the mineral needs for the flock through the pasture and hay, but many factors come into play in mineral availability in soils. Many farms have soils deficient in several key minerals, have used applications of certain fertilizers that inhibit trace minerals, making them unusable by plants (and therefore by grazing animals). Extremes in soil acidity or alkalinity cause some minerals to become less available. Weather may cause plants to take up more of (or less of) certain key minerals.
Problems in health can occur when the mineral supplements
• Don’t contain enough of a particular needed mineral
• Contain it in a form that is not very available to the body for digestion, or
• Don’t contain the needed mineral at all
On some farms, excesses of certain minerals in soils, water or feed may throw off the balance of related minerals or inhibit digestion of trace minerals. Supplemental mineral mixes may not contain enough of a needed mineral to offset those local conditions.
Minerals are generally divided into trace, or micro and macro minerals. Trace minerals are those that are needed in very small amounts. This is not to say they aren’t vital to health; they may be the critical factor in life or death! Macro minerals like calcium, magnesium, and phosphorus are needed in large amounts. They’re also critical to health and life; without proper amounts of these minerals in proper balance with each other, sheep will eventually die. Thankfully, many mineral imbalances don’t cause death, at least not immediately. Low-level deficiencies often lead to a variety of sheep illnesses and contribute to loss of production in a flock. Those types of deficiencies cost a shepherd a lot of time and money.
When Mineral Needs Increase
Situations that produce stress in a flock can change mineral needs and upset rumen balance. Stress increases need for minerals like selenium (and related vitamin E), magnesium and even copper. Heat and humidity, travel, and worms are all stressful and can increase mineral needs. Tetany (magnesium deficiency) may occur from the stress of travel, from grazings low in magnesium or due to heightened nutrient demands during lactation.
White muscle disease is due to selenium deficiency, which may show up as weak lambs and retained placentas at birth, or occur in heat-stressed adults.
Most mineral mixes can’t compensate for those types of situations: Shepherds need to be prepared to change their supplement strategies depending on weather, time of year and increases in stress.
Pregnancy and lactation increase need for minerals.
If a ewe is not getting what she needs for proper reproductive health before breeding, she won’t produce as many lambs (or may not cycle at all). Rams may produce inferior sperm.
Weight loss is an issue and is related not only to mineral intake but to the quality of feed. Once a ewe is bred, she needs enough minerals in proper ratio to meet not only her maintenance levels but to grow lambs and prepare for birth and lactation; her needs increase as the fetuses grow.
After lambing, the ewe’s need for some macro minerals (like calcium and magnesium) increase tremendously to meet the demands of lactation.
Lambs born deficient in some minerals may not thrive and may even die before reaching maturity.
Copper and selenium deficiency can lead to weak lambs for different reasons: Low selenium is associated with white muscle disease and weakness, while low copper is associated with poor nerve function and “swayback disease.” If lambs survive (usually after much intervention from the shepherd), they may grow poorly and can even die spontaneously from things like a copper deficiency.
Selenium also relates closely to immune function and fertility and acts as an antioxidant (important in protecting red blood cells) so it’s important during more than just lambing. For immune health, copper is important throughout life affecting the ability of the body to use iron (and therefore make hemoglobin in the blood) for preventing sheep illnesses, wool production, bone growth and reproductive health.
A Note on Copper
Sheep have a copper requirement but the line between toxicity and deficiency in sheep is much closer than it is in other livestock. Copper may be available in soils and forage, bought-in hay or other supplements and may, therefore, provide what sheep need without additional input. To complicate matters, some breeds of sheep are more sensitive to copper, may store copper more easily or may require and tolerate higher amounts of copper. This makes a shepherd’s job more difficult unless some testing is done to know where copper levels are on the farm and in the animals. Liver analysis for trace minerals is the best way to evaluate how an individual sheep is making use of available copper and other minerals. Until a shepherd knows for sure how high the copper levels are in the flock, copper should not be offered.
The form in which copper is supplied also plays a role in how available the copper is for digestion and absorption by the rumen. Copper oxide isn’t well-absorbed at all. Copper sulfate is somewhat better absorbed and chelated copper is the form best absorbed. Toxicity can be diagnosed by a veterinarian. A copper-toxic sheep will be depressed, not eat, have red urine and may be jaundiced. At this point when sick sheep symptoms are apparent, with treatment, the sheep may recover, but without treatment, it will almost certainly die.
Conventional copper treatments include molybdates, which bind with copper. Additional therapies like high doses of vitamin C, liver and kidney-supporting herbs and homeopathic remedies and dolomitic limestone (high in calcium and magnesium) can help reduce toxic effects and support healing.
Parasites & Minerals
Many shepherds consider worms of various types part of raising sheep and attack them as the enemy. While worms can certainly be detrimental (and in some cases, deadly), it’s not reasonable to try and eliminate all worms. Healthy sheep won’t maintain high levels of worms, making the shepherd’s job much easier. Restoring and maintaining health is a top priority when dealing with worms, and minerals play a huge roll.
Copper is one of the first minerals to be considered when talking about parasites because of its use as copper oxide wire particles (COWP) to kill some types of worms (usually Haemonchus contortus, or “barber pole” worm). However, the sheep’s copper needs must be carefully evaluated before supplementing additional copper.
Selenium’s role in immune health is important in building up immunity to worms and recovering from worm infections. Studies done on cobalt show that lambs getting adequate cobalt had lower levels of worms and better weight gain than those lambs getting no cobalt but regular wormings. These three are not the only minerals important to health but their lack can definitely increase susceptibility to worm damage.
Disadvantages of Blocks When Preventing Sheep Illnesses
Sheep have different needs than other animals even though all mammals require essentially the same minerals for proper health. Because sheep don’t have upper and lower front teeth, they don’t make good use of mineral blocks. Mineral blocks also have the disadvantage of containing salt. Sheep self-limit salt intake, keeping sheep from overeating the block. But it also means they won’t make use of the mineral or trace minerals in the blocks, even if they have severe deficiencies.
Minerals in blocks also aren’t in a form that is readily absorbed. Blocks often contain elemental forms of minerals, which aren’t easily digested. Mineral blocks (and many loose supplements) contain mostly salt, but also flavor-enhancing additives and preservatives. The flavor enhancers ensure sheep eat the mineral-enhanced salt, but the overall mix doesn’t provide needed nutrients, and an excess of the ones it does provide could be detrimental and lead to increased sheep illnesses. Molasses, for example, adds sweetness but may increase the susceptibility of the sheep to internal and external parasites, attract insects and disrupt proper rumen function.
The form in which minerals are supplied is important. Elemental forms of minerals (sometimes called “rock salt” forms) are not as easy for animals to digest in many cases. In nature, soil bacteria and fungi assist plants in taking the elemental minerals and changing the form to something useful for growth and much more digestible for sheep. Knowing this, mineral supplement manufacturers create minerals that are bound to amino acids and therefore more available for digestion. These minerals are called chelated.
Chelated minerals have several advantages, such as better availability for digestion and palatability (better tasting). Because chelated minerals are so easily digested (sometimes close to 100 percent usable by the body), they can help offset situations where other minerals interfere with absorption of the needed mineral. This interplay occurs for all minerals and is a problem when one mineral becomes completely unavailable due to the extreme excess of another antagonistic mineral. Examples are molybdenum completely binding up copper or iron causing the elimination of selenium.
Other mineral interactions become a problem if minerals are out of balance with one another. Excess salt will deplete potassium (or the reverse) and excess calcium not only interferes with trace minerals, it throws off the balance with magnesium and phosphorus. Several of the more common trace minerals (and some macro minerals) are now available in a chelated form for supplementation, making it easier to get a proper amount of those minerals into a sheep.
The Importance of Natural When Treating Sheep Illnesses
I am always surprised to hear from shepherds who spend a lot of time giving injections, particularly when those injections are to try and meet mineral needs (or compensate for a mineral deficiency that leads to vitamin deficiencies). BoSe, Bovine Selenium injectable is used to treat selenium deficiency in pregnant ewes (an extra-label drug usage or ELDU), to prevent white muscle disease or weakness in newborn lambs and treat low-level signs of white muscle disease in adults.
From my point of view, injecting minerals to compensate for the lack of available minerals in a supplement (or soils and forage) is not the best way to tackle the problem. Not only is this an unnatural way to get a mineral into a sheep, it’s costly, time-consuming and can have side effects: In the extreme case, death from anaphylactic shock. A better way to meet selenium needs would be to use a chelated product like Selplex (made by Alltech). This product has three advantages:
• It crosses the placenta—lambs are born strong and running
• It crosses into the milk—lambs continue to get selenium from their mother after birth
• Bio-availability—it’s easily digested and not going to interfere with antagonistic minerals. An ounce of prevention really is worth a pound of cure when working with minerals.
In addition to chelated mineral products, things like kelp contain needed minerals (both trace and macro) in an easily digested form that is palatable.
Herbs, brush, and trees can provide minerals in individual cases and as part of a grazing program. Since tree roots reach deep into the subsoil and bring up trace minerals otherwise not available in the pasture, sheep may eat bark to try and meet trace mineral needs otherwise lacking in the supplementation program.
Improving soil health by reducing the use of chemicals that can kill off beneficial bacteria, fungi and insects improves availability of minerals and nutrient content of forage.
Restoring minerals through applications of compost and fertilizers (preferably natural) also improve mineral availability.
It’s important to remember everything needs to work together for a sheep to be healthy and one of the first steps is proper digestion. Without this, a sheep cannot make use of any nutrient that it takes in. All minerals interact with one another, in soils, in plants, and in the body. While minerals are discussed separately, in reality, they can’t be so easily divided.
No matter how much quality feed is provided, if a sheep is unable to digest it, the nutrients are worthless. Herbivores—ruminants in particular—have very elaborate digestive systems, designed to take plant material and use it to meet the nutritional needs of the animal. Ruminants can make use of roughage completely indigestible to other mammals, as long as their rumens are fully functional. Minerals play a huge role in maintaining the health of the bacteria in the rumen that are the basis for digestion and assimilation of nutrients.
Cobalt is a mineral I consider the base of the pyramid. Although it’s a trace mineral, it’s vital to the rumen bacteria health and ability to assimilate nutrients. It’s also used to make vitamin B12 (cobalamin) and is important in folate metabolism. Lack of cobalt results in rumen bacteria dying, associated lack of appetite and weight loss (referred to as chronic wasting disease). Other symptoms include coldness, poor wool production or loss, and pernicious anemia, which is indistinguishable by sight from iron-deficient anemia. Iron-deficient anemia can be related either to low iron or low copper, making iron unusable.
Low cobalt also can cause tearing from the eyes.
Sheep can pull cobalt from stores in the liver to make vitamin B12 but they can’t use cobalt stored in the liver to put back into the rumen to support bacteria health. Cobalt must be taken in orally on a regular basis for sheep to survive. Cobalt toxicity is much less a concern in ruminants than other mammals. Sheep tolerate high levels compared to needs, although lambs that don’t yet have fully functioning rumens should not be fed extremely high amounts of cobalt.
Sulfur is also critical to digestion, a macro mineral needed for amino acid and protein production. It’s important for wool, skin and nervous system health.
Without proper amounts of sulfur, sheep lose appetite and have poor quality wool growth. They may become more susceptible to external parasites (like lice), salivate and have tears from the eyes.
Excess sulfur will interfere with trace minerals like copper, reduce rumen function and result in breath that smells like sulfur.
Many other minerals are important in digestion, including salt. Deficiencies and excesses will disrupt rumen bacteria and lead to poor health and possibly death.
Vitamins and Sheep Illnesses
Walk into any pharmacy or big discount store and you will see aisles of vitamin supplement products. The array is dizzying and leads one to believe we would never survive without some bottle or liquid product. In both sheep and humans, there are certainly cases where supplementing vitamins is critical, such as when digestion gets disrupted and the ability to make and absorb vitamins is diminished, which can lead to a number of sheep illnesses.
In times of stress or illness, increased need for vitamins makes supplementation a wise choice. However, restoring digestive function is the first step and reducing underlying causes of deficiencies should be next.
Sheep make and absorb their own B vitamins and vitamin C if they’re healthy, with properly functioning digestive systems. The amount they make should meet their nutritional needs unless something changes substantially. During situations where digestion is poor (disease, parasites, stress), working on digestion while injecting vitamins is the quickest way to restore health and treat sheep illnesses. This is one of the only times I use injections; since the animal isn’t digesting properly, feeding the vitamins is a waste of time.
Vitamins A, D and E are fat soluble, meaning they’re stored in the body, unlike vitamins B complex and C, which are easily flushed from the body and needed on a daily basis.
Vitamin E, while fat soluble, is often considered more like a water soluble vitamin because it’s not stored as well as A and D, and may be needed on a fairly regular basis for health. Fortunately, forage usually meets the vitamin E needs of sheep. However, stored hay loses vitamins rather quickly and supplementation may be necessary during periods of prolonged hay feeding.
Vitamin D is made by the body in the skin and sunlight is needed for proper amounts. During long winter months or prolonged periods of confinement in buildings, sheep will need additional vitamin D.
Vitamin D is critical for sheep to be able to use related minerals, like calcium, magnesium and the trace mineral boron.
Vitamin A is generally adequate in forage but again, hay feeding means supplementation is necessary.
For short-term oral supplementation of vitamins A and D, cod liver oil is a good source.
Human-grade vitamin gel caps for vitamin E can be used and B complex or C capsules or liquid can be fed.
Herbs containing high amounts of these vitamins are also a good way to get quality, easily digested forms of the vitamins into sheep. Rose hips (Rosa species), dandelion leaves (Taraxacum officinale), parsley (Petroselinum crispum) and nettles (Urtica species) are all good sources of several key vitamins and minerals.
Ideally, sheep should be healthy enough to make their own B vitamins and a mineral supplement can provide the fat-soluble vitamins needed during winter.
The task of meeting nutritional needs of sheep may seem daunting when it comes to preventing and treating sheep illnesses, but much of their needs can be met by forage. Doing some simple soil, forage and liver testing can help a shepherd make informed decisions about what minerals need to be supplemented. Salt should always be offered and a loose mineral supplement containing the basic macro and trace minerals needed for health in forms that are easy to digest will improve the health of the sheep and life of the shepherd.
Alethea Kenney keeps Icelandic sheep in Northern Minnesota. She is also a traditional naturopath, herbalist and aromatherapist. For more information, contact: Reedbird Farm Icelandic Sheep, 25700 280th St., Shevlin, MN 56676; Phone: 218-657-2502.
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Originally published in the March/April 2015 issue of sheep! and regularly vetted for accuracy.