Sheep Feeds and Management During Drought

Drought shortens the season sheep can graze and reduces forage quality, creating a need for supplemental feeding. Non-traditional or alternate feeds may then be useful. Sheep need energy, protein, vitamins and minerals, but these nutrients need not come from hay and grain. Availability, quality and relative cost per unit of feed value should determine feeds considered.

Table 1 lists feeds common on the High Plains and costs per pound of protein and energy at three different feed costs. All ration components must be converted to the same units and prices. For example, silage contains a lot of water. On a weight basis it has low protein and energy percentages, even though it is palatable and a good feed. Base comparisons on energy, protein and water content. Buying feeds on an "as fed" basis and comparing those to feeds defined as 100% dry matter is misleading. Table 1 allows feed price comparisons based on protein and energy values. These should be considered when planning a supplementation or feeding program. Note hays, especially late-cut hays, and straw are low in TDN. Feeds of less than 52% TDN will not meet even maintenance energy requirements and should not be used as the sole source of energy despite low cost. But feeding other energy or protein supplements makes them feasible supplementary ewe feeds.

A supplementation program is recommended when pasture is available but unable to supply the full nutritional needs or is of low quality. Supplementation means providing enough additional nutrients to meet the animals' needs when grazing alone does not. Protein usually is supplemented, which improves digestibility of grazed forages and also provides some digestible nutrients. Often this is the least expensive way to meet animal needs. As little as 0.1-0.2 pounds of protein supplement per day is enough to meet maintenance requirements.

Caution should be used when large amounts of fed forages are used on pasture. Fed forages become a substitute rather than a supplement to grazing. This is expensive and can create lazy ewes that wait for the feed truck rather than grazing. High-energy feeds such as corn or wheat also should be used sparingly. More than 0.25-0.5 pound per day will dramatically reduce forage digestibility. Sheep also may bloat on high-energy rations, especially when the have been on a forage diet. Feeding more than 0.25-0.5 pounds of concentrates per head per day should be considered only when pasture is not available, or fed forages are too expensive to fill most needs.

Note that when figuring a supplement or a total ration a ewe needs about 2 pounds of dry matter per day and cannot consume more than about 4 pounds of dry matter per day. This equals 3 to 6 pounds of dry feeds and as much as 20 pounds of silage as-fed. Animals normally cannot use silage as the total energy complement for the diet because they cannot handle that much water and still consume 4 pounds of dry-matter.

When grazing is limited, particular attention should be given to daily consumption. Production suffers when nutritional requirements to produce lamb and wool are not met. Likewise, an overfed ewe wastes limited feed resources. It may be prudent to limit nutrients at some points of the reproductive cycle. The nutrient requirements and feed nutrient contents must be known before a balanced program can be calculated (Tables 2 and 3). A ewe should lose 5 to 7% of her body weight during lactation, recover this during the dry period and then gain weight during gestation in proportion to the weight of the fetal tissues and fluids.

Body Condition Scoring

One of the best ways to determine how much a ewe should be fed is by monitoring condition changes. By condition scoring and using that information in the feeding program, available feed resources can be stretched and yet provide adequate nutrition. Condition scoring classifies ewes by differences in relative body fatness. It permits identification, recording and changing the feeding program of those sheep that are thin, average or fat. Thin and fat ewes can be sorted and fed accordingly. Major changes in the feeding program also can be determined.

Body-condition scoring is relatively easy and requires no equipment except a sorting chute and some chalk. Condition scoring should be "hands-on" rather than by eye. Hands-on scores give a better measure of condition, which during critical production periods (the last 4 to 6 weeks of pregnancy) is often hidden by wool growth. Scores are based on the amount of muscle and fat over and around vertebrae in the loin region. Sheep usually are scored from 1 to 5, 1 being extremely thin, 5 extremely fat, and 3 average. Typically, 70 to 80% of the flock will fall into two scores, and more than 90% of the flock into three scores (e.g., scores 2,3 and 4).

Although limited research exists, a great deal of practical evidence suggests extreme condition scores of 1 and maybe 2 should be avoided because of decreased performance and survival. Similarly, 4 and 5 scores should be avoided because of conception and lambing problems, and excessive feed costs. Ewes with scores of 1,2, 4 and 5 are good candidates for pregnancy toxemia. Ewes should have a condition score of between 2+ and 3+ and rams around 3+ at breeding. This condition should be maintained for the first 30 days post-breeding. During mid-gestation some loss of weight and condition is allowable at 3 and 4 scores. However, this weight loss should not exceed 5% of the mature ewe's weight at 3 or 3+. Ewes in late gestation should have sufficient body reserves to maintain lamb growth and initiate optimum milk production at birth. A 2+ to 3+ score is desirable 4 to 6 weeks before lambing. Ewes should score 3+ at lambing.

In an experiment conducted at Montana State University, more than 50% of lambs born to ewes with scores of 2 or less died or were bummed. Dying or bummed lambs born to ewes around 3 were significantly fewer. Regular scoring, and acting on results, will allow the most efficient and economical use of available feed resources. Thin ewes (scores 1 and 2) can be separated and given extra feed. Overfatness can be avoided by feeding only those that need it.

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