Q.
What minerals and vitamins do sheep/goats require in their diets?
A.
Sheep/goats have dietary requirements for many minerals and vitamins. They require sixteen minerals in all. The minerals required in larger amounts (grams, ounces, or diet percentage) are called macrominerals. These include calcium, magnesium, phosphorus, potassium, salt (sodium + chloride), and sulfur.
Animals have a natural craving for salt. Fed (housed) animals should have salt incorporated into their rations. Free ranging sheep/goats should be supplemented with salt. Loose is better than a block. Salt is frequentlly used as a carrier for other minerals or additives. It can be used to limit the intake of other nutrients. It can be used to increase water consumption.
Sheep/goat rations are usually balanced for calcium and phosphorus. An imbalance of calcium and phosphorus can cause urinary calculi in males, especially wethers. The ratio of calcium to phosphorus should be at least 2:1 in their diets. Pregnant and lactating ewes/does have higher requirements for calcium and phosphorus. Too little or too much calcium can result in milk fever in periparturient females. In all animals, deficiences in calcium and phosphorus can cause bone problems (e.g., rickets).
Calcium is usually adequate in forages. Legumes have higher levels of calcium than grasses. Grains and oil seeds have very low levels of calcium, but are high in phosphorus. Limestone (feed grade) is the most concentrated source of calcium. Magnesium is sometimes low in lush growing spring pasture. A magnesium deficiency can cause grass tetany. Grass tetany seems to be more common in cattle than small ruminants.
Trace minerals
Minerals required in lesser amounts (mg, PPM) are called micro or trace minerals. Even though they are needed is smaller amounts, they are no less important. Trace minerals include cobalt, fluoride, iodine, iron, cobalt, copper, manganese, molybdenum, selenium, and zinc.
Selenium is probably the mineral mostly likely to be deficient in sheep/goat diets. Many US soils are deficient in selenium; thus, forages are likely deficient in selenium. A selenium deficiency can cause white muscle disease and various other problems, including ill thrift, reduced wool growth, and infertility. It's best to supplement selenium in the diet: feed or mineral. Selenium suppplemention is regulated by the government. There is a maximum amount of selenium that livestock are allowed to consume. In some situations, animals may need selenium injections.
Copper is the most misunderstood mineral. While copper is required in the diet of sheep, there is a narrow margin between requirements and toxic levels. Sheep are the animal most likely to experience copper toxicity. Copper metabolism is also complicated. Several minerals bind out copper and can cause deficiencies or toxicities, depending upon whether their presense in the diet is high or low. These include molybdenum (especially), sulfur, and iron. Unless a copper deficiency has been identified, it is recommended that sheep not consume minerals or other supplements that have added copper.
Copper deficient soils can result in feedstuffs that are deficient in copper. Signs of copper deficiency include steely wool, loss of crimp, loss of pigment, and swayback. A copper deficicy can also cause anemia and reproductive loss. Goats have higher requirements for copper and can tolerate much higher levels in their diets. They should be fed mineral products that have been formulated specifically for goats (with added copper). If sheep and goats are comingled, sheep products need to be fed, and it may be necessary to provide goats with supplemental copper by other means (e.g., boluses).
In some places, soils are deficient in iodine. The most obvious sign of an iodine deficiency is goiter (enlarged thyroid gland). Iodine deficiencies can also cause various reproductive problems including abortion, stillbirths, premature babies, small and weak lambs/kids. There can also be a lack of hair in wooled lambs. Free choice iodized salt is the best option for supplementing iodine. Otherwise, additional iodone can be added to mineral mixes.
Cobalt is the precursor to vitamin B12. Some producers supplement it. Some mineral products contain cobalt. Sheep/goats may be cobalt deficient (thus, B12 itamin deficient) if they consume forages grown on cobalt deficient soils. Signs of a cobalt deficiency are rather generic: poor growth and body condition, open fleece, reduced appetite, lethargy.
Vitamins
There are two kinds of vitamins that are required by sheep/goats: fat soluble and water soluble. The fat soluble vitamins are A, D, E, and K. The water soluble vitamins are C and B. B vitamins and vitamin K are synthesized in the rumen. Supplements are usually unneccesary. B vitamins (complex) are often given to animals that are stressed or off-feed. B12 is sometimes supplemented in the feed. Vitamin B1 (thiamine) is the treatment for polio.
Vitamin C is synthesized in the tissues. Vitamin D is derived from sun-cured forage or exposure to ultraviolet light. While sheep/goat diets usually contain adequate amounts of vitamins A, D, and E, they are often added to supplements and diets, especially if low quality or minimal forage is being fed.
05/23/2021
Additional reading
Minerals and vitamins for sheep - Virginia Tech
Sheep mineral nutrition - Youtube video
Salt and trace minerals for livestock, poultry, and other animals
Selenium supplementation strategies for livestock in Oregon