Essential Nutrient Requirements of Sheep

Of primary importance in sheep nutrition are water, energy, protein, minerals (with salt, calcium, and phosphorus the most critical components), and vitamins (with vitamin A of primary concern).

Energy. Insufficient energy limits performance of sheep probably more than any other nutritional deficiency. An energy deficiency may result from inadequate amounts of feed or from feeds (generally forages) that do not contain enough protein to sufficiently “unlock” the energy in the feedstuff. The major sources of energy for sheep are hay, pasture, silage, and grains. Milo, barley, corn, oats, and wheat also can be used to raise the energy level of the diet when necessary. Energy deficiencies can cause reduced growth rate, loss of weight, reduced fertility, lowered milk production, and reduced wool quantity and quality.

Protein. In sheep rations, the amount of protein is much more important than quality of protein. However, since the sheep is a ruminant, mature sheep use effectively the naturally occurring protein and nonprotein nitrogen (urea) in their diets. Common sources of natural protein supplements include cottonseed, soybean, sunflower, linseed, and peanut meals. These oilseed meals contain from 40 to 50 percent protein and are excellent sources of supplemental protein. High-quality legume hays can contain from 12 to 20 percent protein and provide adequate protein for most classes of sheep when fed as a complete ration. Grains, however, are low in protein. They generally contain only 8 to 11 percent protein. Additional protein is necessary in high-grain, lamb-finishing rations for maximum performance.

Nonprotein nitrogen sources should not be fed to young lambs. Young lambs are not functioning ruminants until they are approximately 2 months old, depending upon how soon they have access to grain and forage. However, mature sheep can be fed low levels of nonprotein nitrogen. In general, supplemental nonprotein nitrogen is beneficial only when adequate energy is available. Urea should never make up more than one-third of the ruminally degradable protein in the diet. Additionally, nonprotein nitrogen sources should not be used when lambs are limit-fed. Urea can be toxic if consumed in large amounts over a short time, especially when the diet lacks ruminally available energy. Furthermore, urea is very unpalatable.

When supplementing range sheep in New Mexico, it is important to consider the quantity of available forage in the pasture. If adequate forage is present, but the standing forage is dry and brown (containing < 5 to 6 percent crude protein), it may be necessary to supplement with a high-protein feed (> 35 percent protein). However, if the amount of available forage is insufficient or if the forage is still somewhat green (> 6 percent protein), a lower-protein supplement should be fed to provide additional energy, if needed. Lactating ewes have the highest protein requirement and may require supplemental protein if the range forage contains less than 10 to 12 percent crude protein.

Water. Water is essential for all livestock. Producers must plan for an adequate supply of clean water when designing any type of sheep enterprise. The quality of the water is also important. Sheep will not consume enough water if it is stagnant or of poor quality.

Ordinarily, sheep consume two to three times as much water as dry matter. Abundant, clean, ice-free water is a must in lamb feedlots. Without water, lambs may eat less. Water running through a low trough or water dripping into the trough can help to start the lambs drinking and eating.

Minerals. Approximately 13 different minerals are essential in sheep nutrition. Most of these requirements are met under normal grazing and feeding habits in New Mexico. Those that are most deficient are salt (sodium chloride) and phosphorus.

Salt is essential for many body functions. When sheep are deprived of salt, they generally consume less feed and water, produce less milk, and grow slowly. Animals that are deprived of adequate salt may try to satisfy their needs by chewing wood, licking dirt, or eating toxic amounts of poisonous plants. Inadequate salt intake may cause decreased feed consumption and decreased efficiency of nutrient use. When adding salt to mixed feed, add 0.3 percent to the complete diet or 1 percent to the concentrate portion. In general, supplemental salt should be provided to range ewes at a level of 8 to 11 g of salt per head per day. Provide loose salt rather than salt blocks. Sheep tend to bite instead of lick salt blocks; as a consequence, their teeth may break or wear down prematurely.


Almost all pastures and hays contain an abundance of calcium, but grains are lower in calcium. When lambs are fed on a high-concentrate diet, calcium supplementation may be necessary.

In New Mexico, pastures and hay are generally low in phosphorus. In grains, however, the amount of phosphorous is moderate to high. Since any efficient sheep operation uses a high percentage of roughage or pasture, it is good insurance to assume that the sheep need phosphorus supplementation. Phosphorus deficiency causes slow growth, reduced appetite, unthrifty appearance, listlessness, abnormal bone development, and poor reproductive performance. It may be beneficial to provide phosphorus supplements year-round for the breeding flock.

When purchasing commercial mineral blocks or loose forms of mineral supplements, look at the calcium-to-phosphorus ratio. The narrower this ratio, the better. However, it is important to make sure that the ratio is not inverted (more phosphorous than calcium). If producers prefer to mix a mineral supplement, mix 50 percent salt with 5 percent cottonseed meal and approximately 45 percent bone meal or dicalcium phosphate. Provide this supplement free choice and year-round in a feed box protected from rain and moisture.

Mature sheep require all the fat-soluble vitamins: A, D, E, and K. They do not require supplemental B vitamins, which are synthesized in the rumen. Normally, the forage and feed supply contain all essential vitamins in adequate amounts, except vitamin A, which is sometimes deficient in dormant forage. However, sheep can store vitamin A for a considerable time. If ewes have been pastured on green forage or have had access to high-quality legume hay, vitamin A is not usually deficient.

In some areas, lambs may develop white muscle disease. This is thought to be caused from a deficiency of vitamin E, selenium, or both. Treatment is most effective with early diagnosis and injection of a vitamin E-selenium material.