Many management alternatives are available to the commercial sheep producer. One major distinction among these alternative production systems is the season in which lambing occurs.
Fall lamb production. For fall lambing, an abundant supply of fall and winter forage, small-grain pasture, alfalfa stubble, or other crop residue is necessary.
For ewes to lamb in October and November, breed them in May and June. The ewe flock must be of those breeds that tend to breed out of season. The fine-wools, Dorset, and crossbred ewes that are at least 50 percent fine-wool are best suited for fall lamb production.
Even so, the lamb crop percentage from May and June breeding is likely to be low. Ewes may need hormone therapy to induce estrus and ovulation (see section on reproduction, page 11). Furthermore, farm labor often is busy elsewhere during fall lambing when the ewes need attention. Occasionally, fall-born lambs are weak and small because of heat stress during the summer gestation period.
Winter lambing. One advantage of winter lambing is that labor requirements of other agricultural enterprises are generally low at this time, so more attention can be diverted toward the ewes. This program is best for the producer who has an abundance of homegrown forages. Under this production system, slaughter lambs of market weight and condition are ready to be sold during May and June, when lamb prices are normally high.
For winter lambing, breed the ewes in late July, August, and early September. Since this is somewhat earlier than normal, it may be necessary to flush the ewes to increase ovulation rate. After the ewes are bred, graze them on good pasture that will satisfy their nutritional requirements until about four to six weeks before lambing. Prior to lambing, supplement the ewes with high-quality hay and possibly with grain to meet their nutritional needs. Lambs born in the winter should be creep-fed as soon as possible with grains and high-quality legume hay.
If feed and pasture are available, lambs can be weaned at about 60 days. It is generally more economical to feed lambs directly than to feed nursing ewes. Many producers keep the lambs in a drylot and put the ewes back on pasture. This helps to prevent internal parasite problems in the lambs.
Spring lamb production. Spring lambing coincides with the natural breeding and lambing seasons. When ewes are bred from late September through November and lamb in late February through April, a higher percent lamb crop can be expected. With ideal conditions, the lamb crop should be 150 to 160 percent. The ovulation rate in sheep is normally at its peak in late September through November. Temperatures at this time are typically not high enough to decrease ram fertility or to cause embryo loss. Normally, spring temperatures are mild and death loss associated with weather conditions is minimal. But newborn lambs must be offered some protection from spring winds. In this type of system, ewes are bred when ovulation rates should be high, so that flushing, teasing, or control of environmental conditions has less effect on conception rate or length of lambing season. Ewes must have adequate feed and should not be on a declining plan of nutrition when bred.
After breeding, the ewe's nutritional requirements are at the lowest level and they can be maintained on various crop residues and pastures, if available. Before they lamb and during early lactation, the ewe's nutritional requirements are the highest. Ewes may need a protein and energy supplement at that time. In some areas, spring pasture may partially satisfy their nutritional needs. But some irrigated pastures have a high water content and the forage is "washy." The ewes may need supplemental feeds in addition to the pasture if they are to lamb and produce milk most efficiently.
If pasture is available, it may be feasible to separate the lambs from the ewes daily and put the lambs in a drylot or on pastures separate from the ewes. Generally, best results are obtained when the lambs are not pastured with the ewes.
Accelerated lambing. Accelerated lambing is lambing more than once a year. This takes intensive management and is not recommended for the sheep producer who has not yet achieved maximum production from a conventional once-a-year lambing program. Accelerated lambing may increase the number of lambs raised over a given period, but it adds to the production cost and requires more feed, labor, and facilities.
In a carefully controlled environment, sheep can be bred every six months. However, breeding every eight months for three lamb crops in two years is more practical than a six-month lambing schedule.
Accelerated lambing also may be used to gain an additional lamb crop from ewes before they are culled. Ewes that are old or dry in the spring can be rebred for fall lambing in their last year. The advantages of accelerated lambing include increased lamb production, having lambs available for market at different seasons, year-round use of labor and facilities, and, theoretically, increased income per ewe.
Accelerated lambing necessitates the use of fine-wool or Dorset ewes and an understanding of exogenous hormones. Excellent management, disease control, and exact nutritional requirements are fundamental to the success of such a program.
Early weaning is essential in an accelerated lambing program because it is difficult to breed ewes that are lactating. Most commonly, lambs are weaned at 30 to 45 days. An excellent nutrition and health program must be incorporated into the plan to get these lambs as large as possible before weaning.
Confinement systems. Sheep can adapt to a complete confinement system of production. The confinement may vary from a drylot to small pens with slatted floors. The object is to produce market lambs in a small space using mostly feeds harvested from the farm. The advantages are that lamb production can be increased on a small area using automated feeding equipment.
This program requires intensive year-round management. Confinement rearing is best associated with an accelerated lambing program for maximum use of facilities and labor. One system of confinement that has possibilities is the confining of range sheep before lambing. Ewes are hand-lambed in lambing sheds and the lambs are weaned early, within 30 to 45 days. The ewes are then returned to the range and the lambs are finished in a drylot. This program is particularly successful where predation makes it almost impossible to raise lambs under range conditions.