* This is the Veterinary Version. *
Feeding Practices in Sheep
Sheep make excellent use of high-quality roughage stored either as hay or low-moisture, grass-legume silage or occasionally chopped green feed. Good-quality hay or stored forage is a highly productive feed; poor-quality forage, no matter how much is available, is suitable only for maintenance. Hay quality is determined primarily by the following: 1) its composition, eg, a mixture of grasses and legumes such as brome/alfalfa or bluegrass/clover; 2) the stage of maturity when cut, eg, the grass before heading and alfalfa before one-tenth bloom; 3) method and speed of harvesting because they affect loss of leaf, bleaching by sun, and leaching by rain; and 4) spoilage and loss during storage and feeding. In general, the same factors influence the quality of silage. Complete analysis of cut-stored forages enhances the utilization of these feedstuffs and allows for the most efficient use of supplemental grains and minerals.
The period from weaning to breeding of ewes is critical if a high twinning rate is desired. Ewes should not be allowed to become excessively fat but should make daily gains from weaning to breeding. The rate of gain depends on the desired weight but should be ~60%–70% of projected mature weight at breeding and 80%–90% of projected mature weight at lambing. If pasture production is inadequate, ewes may be confined and fed high-quality hay and a small amount of grain if necessary. Breeding while grazing legume pastures (eg, sage, white clovers) may tend to depress the size of the lamb crop, lowering the intake of certain feedstuffs. After mating, ewes can be maintained on pasture, thus allowing feed to be conserved for other times of the year. Good pasture for this period allows the ewes to enter the winter feeding period in good condition. When pasture is unavailable, an appropriate ration should be formulated (see Table: Rations for Pregnant Ewes up to 6 Wk Before Lambing).
During the last 6–8 wk of pregnancy, growth of the fetus is rapid. This is a critical period nutritionally, particularly for ewes carrying more than one fetus. Beginning 6–8 wk before lambing, the plane of nutrition should be increased gradually and continued without interruption until after lambing. The amount offered depends on the condition or fat covering of the ewes and quality of the forage. If ewes are in fair to good condition, 0.5–0.75 lb (225–350 g) daily is usually sufficient. The roughage content of the ration should provide all the protein required for all nonlactating ewes. If necessary, the ewes may be classified according to age, condition, and number of fetuses and divided into groups for different treatment.
Rations for Pregnant Ewes up to 6 Wk Before Lambing
Succulent pasture furnishes adequate energy, protein, vitamins, and minerals for ewes and lambs; no added grain is necessary. When pasture is not being used (confinement rearing), ewes should be fed one of the rations outlined for pregnant ewes in Rations for Pregnant Ewes up to 6 Wk Before Lambing, and 1–1.5 lb (450–675 g) of one of the grain mixtures in Grain Mixture for Pregnant Ewes. Ewes should have access to a mixture of trace mineralized salt and dicalcium phosphate. Ewes with twin or triplet lambs should be separated from those with single lambs and fed more concentrates (grain) and/or better-quality forages. Ewes nursing twin lambs produce 20%–40% more milk than those with singles. Under confinement rearing or accelerated lambing, lambs are commonly weaned at 2 mo of age. The ewe’s milk production declines rapidly after this period, and creep feed is more efficiently converted into weight gains when fed to lambs than to the ewe.
From ~2 wk of age, lambs should have free access to creep feed. Where pasture is limited, they should be creep-fed for 1–2 mo until adequate forages are available. If pasture will not be available until the lambs are 3–4 mo old, they can be finished in a dry lot. The grain used should be ground coarse or rolled, but as the feeding period progresses, whole grains may be used. Small amounts of fresh, clean grain should be slowly introduced to the lambs’ diet. The amount of grain is increased gradually until the lambs are on full feed.
Feeding lambs from birth to market in a dry lot, together with early weaning at 2–3 mo of age, has become more popular throughout the USA. A complete diet of hay, grain, and vitamin-mineral supplement is ground, mixed, and either fed as is or pressed into pellets 3/16- or 3/8-in. (5–10 mm) long. Such lambs usually reach market weight in 3½–4 mo. See table: Creep Rations for Suckling and Early-weaned Lambs for examples of creep rations used in dry lot feeding.
Creep Rations for Suckling and Early-weaned Lambs
Orphaned lambs, extras, triplets, or those from poor-milking ewes can be raised on milk replacers to improve productivity. Such lambs should receive 10%–20% of their body wt in colostrum divided into multiple feedings within 18–24 hr of birth. If ewe colostrum is unavailable, a frozen, pooled supply from several cows can be used. Milk replacers designed specifically for lambs are available and contain ~30% fat, 25% protein, and a high level of antibiotic. Under certain conditions, it may be advisable to inject orphaned lambs with vitamins A, D, and E and selenium. In handrearing systems, ewe milk replacers are preferable; however, good quality replacers designed for calves may be fed to lambs. When mixing milk replacers, care should be taken to ensure that the powder and water are properly mixed into a suspension. Feeding small quantities throughout numerous feedings helps reduce the incidence of bloat and/or diarrhea. Milk replacers should be fed at 10%–20% of the lamb’s body wt, divided into 4–6 feedings/day during the first week of life. The number of feedings can be reduced over time to twice a day by 3–4 wk of age.
Multiple-nipple pails or containers can be used. Cold milk replacer can be used by older lambs who nurse more often. By 9–10 days of age, lambs should be given water in addition to the milk if a creep ration is offered. They can be weaned abruptly at 4–5 wk of age if consumption of creep feed and water intake is at a reasonable level.
Lambs should be preconditioned before they leave the producer’s property. This includes starting on feed, vaccinating, worming, and under some conditions, shearing. If this is not done, the lambs should be rested for several days and fed dry, average-quality hay after arrival at the feedlot. See table: Recommended Formulas for Finishing Lambs a for some recommended formulas for finishing lambs.
Recommended Formulas for Finishing Lambs a
There is no best method or diet for finishing lambs. They may be finished on good to excellent quality forage (alfalfa, wheat) with no supplemental grain. They may be started on pasture or crop residue and moved to grain feeding systems as the forage is used up. When fed in a dry lot, they are usually allowed free access to feedstuffs. These diets may be completely pelleted, ground and mixed, a mixture of ground forage (alfalfa) pellets and grain, and/or high-concentrate type. Self-feeding usually results in maximal feed intake and gain, and labor costs may be reduced. Hand-feeding can be mechanized with an auger system or self-unloading wagon. It involves feeding at regular intervals so that the lambs consume all the feed before more feed is offered. Feed consumption and gain can be controlled. When used, corn silage should be hand-fed to minimize spoilage.
Producers who feed lambs year-round, or feed heavy lambs, usually prefer to place the lambs on full feed as soon as possible (10–14 days). Lambs can be started safely on self-fed, ground, or pelleted diets containing 60%–70% hay. Within 2 wk, the hay can be reduced to 30%–40% when the ration is not pelleted. Other roughages such as cottonseed hulls or silage can be used in a similar manner.
Corn, sorghum, or alfalfa silage can replace about half the hay with hand-feeding, but finish and yield will be decreased to some extent. See table: Pattern for Range Supplements for Sheep for rations that can be used in self-feeding. Corn, barley, milo, wheat, or a mixture of these are used; 0.5% salt and 0.5% bone meal or equivalent should be added to the grain. Pelleting of rations for finishing lambs is beneficial when low-grade roughages or high-roughage rations are used. Caution should be used when feeding large amounts of wheat; lambs not adapted to it are more apt to develop acute indigestion than if fed grains such as corn, sorghum, or barley.
Mineral supplements, including salt, should be offered separately whether or not they are included in the grain mixture. Approved growth stimulants usually increase growth rate 10%–15% and feed efficiency 8%–10% but may decrease carcass quality.
Mature breeding rams should be grazed on pasture when available, or fed rations 1, 2, or 3 according to Rations for Pregnant Ewes up to 6 Wk Before Lambing. If rams are in a thrifty condition at breeding time and the ewes are on a good flushing pasture, it should not be necessary to grain-feed the rams while with the ewes. Rams should be maintained at a good body condition (3–3.5 on a 1–5 scale) before the breeding season.
The condition of the sheep, the amount and kind of forage on the range, and the climatic conditions determine the kind and amount of supplement to feed. Supplements usually consist of high-protein pellets or cottonseed meal and salt, medium-protein pellets, low-protein pellets or corn, alfalfa hay, and minerals. When the diets of sheep on the western winter range are supplemented properly, the lamb crop can be increased 10%–15% and wool production increased by ~1 lb (400–500 g) per ewe.
One recommended practice is to feed ~0.25 lb (115 g) of high-protein (36%) supplement or 0.33–0.5 lb (150–225 g) of medium-protein (24%) pellets ~3 wk before and during the breeding season, during extremely cold weather, and for ~1 mo before green feed starts in the spring. In addition, small lambs, small yearling ewes, old ewes with poor teeth, and thin ewes should be separated from the main flock and fed one of the above supplements from approximately December 1 (northern hemisphere) until shearing time. In many instances, the old ewes, lambs, and yearlings from more than one band can be maintained in a flock for special dietary supplementation.
When sheep are unable to obtain a full ration of forage because of deep snow or other weather conditions, 1–3 lb (450–1,350 g) of alfalfa hay and 0.2–0.3 lb (90–150 g) of a low-protein pellet mixture or corn should be fed (see Table: Pattern for Range Supplements for Sheep). If alfalfa hay is not available, 0.5–1 lb (225–450 g) per head of a low-protein pellet mixture should be fed daily for emergency feeding periods.
Pattern for Range Supplements for Sheep
Deficiencies most apt to be seen among range forages are protein, energy, salt, and phosphorus. These are most prevalent as the forages approach maturity or are dormant, and they may appear singly or in combination. Range sheep often travel long distances and are exposed to cold weather, resulting in higher energy requirements. Protein supplements (soybean or cottonseed meal, alfalfa pellets, etc) increase digestibility and use of poor-quality forages. When possible, the inclusion of a phosphorus supplement (eg, dicalcium phosphate, monocalcium phosphate, defluorinated rock phosphate) to a salt or trace mineral salt mixture may greatly improve productivity.
Most ranges used for winter grazing are considered adequate in carotene, because many species of browse furnish as much carotene as sun-cured alfalfa hay. However, when sheep are required to graze dry grass ranges for >6 mo without intermittent periods of green feed, vitamin A supplements are recommended. The addition of 45–50 IU of vitamin A/kg/day improves productivity in cases of extended consumption (>2 mo) of dry or weathered forages.
On the range, portable mineral boxes are convenient for sheep. One of these mineral mixtures should be fed free choice. A salt and dicalcium phosphate or phosphorus supplement (defluorinated rock phosphate) can be used if there are no iodine or trace-mineral deficiencies. Iodized salt is substituted for regular salt when an iodine deficiency exists, and trace mineralized salt is substituted if deficiencies of trace minerals are present.
Under winter range conditions, the amount of phosphorus supplement that should be added to range pellets varies with the type of range forage available, the rate of feeding, and the ingredients used in the pellets. It is suggested that 36%, 24%, and 12% protein pellets contain 1.5%, 1%, and 0.5% phosphorus, respectively. When feeding supplemental protein, 36% protein pellets should be fed at the rate of 0.25 lb (115 g) per head daily, the 24% protein pellets at 0.33–0.5 lb (150–225 g), and the 12% protein pellets at 0.2–0.5 lb (90–225 g), together with alfalfa or clover hay. Care should be taken when adding supplemental phosphorus and magnesium to the diet of rams or whethers, because this is associated with urolithiasis.
* This is the Veterinary Version. *