Ewes are first mated...
Ewes are first mated in their first or second years. Ewes naturally come into heat in autumn or winter and gestation period is about five months meaning lambs are born in spring or summer when the weather is warmer and grass is growing. However this can be altered by controlled breeding with ewes being brought into heat by administering hormones. This means lambs can be born throughout the year providing a constant supply to market.
Rams are usually from special breeding farms. A single ram will usually serve 30 to 60 ewes. Artificial insemination is uncommon in sheep though new techniques are being developed to make it more efficient.
Ewes generally lamb once per year though selective breeding has meant some can lamb twice per year. Breeding has also encouraged ewes to have twins or triplets rather than a single lamb. If a ewe has only a single lamb the unborn lamb may grow too large to pass through the narrow birth canal, sheep having been bred to be smaller. Many farmers may choose to cut the front legs off the live lamb whilst still in the womb. This is called embryotomy and is carried out to avoid having to pay a vet to perform a caesarean. The practice is widespread and more than 50,000 lambs are believed to be killed in this manner during the lambing season.
Around 4 million lambs die each year. Exposure, hypothermia, starvation and disease account for most of these. Sometimes there may be too many lambs in the flock (due to multiple births or the death of ewes.) These orphan lambs may be auctioned at markets at only a few days old. These lambs are especially prone to disease and mortality is high. 35,000 orphan lambs are sent to market during the lambing season.
A trend towards intensification means lambs are weaned earlier, fed on milk substitute and feed concentrates and housed indoors. Indoor housing has lead to increasing disease problems including coccidiosis, watery mouth and sheep lice.
Male lambs are castrated before three months old. The commonest method is by the application of a tight rubber ring cutting off the blood supply. Castration can occur without anaesthetic in lambs up to three months provided the ring is applied within the first week of life. The Farm Animal Welfare Council (FAWC) stated in 1992 that castration by means of a rubber ring causes considerably greater pain than the alternative clamping method which is sometimes used. Acute pain lasts for several hours following application of the ring. Sometimes castration may be performed surgically using a knife. Again, this can be carried out without anaesthetic or a vet being present. Tail docking of lambs may also occur without anaesthetic.
Between 15-25% of ewes are culled each year because of lameness, poor health or failing to lamb. These are replaced in the flock. Flock stocking densities are steadily increasing. This is causing environmental problems in upland areas as overgrazing by sheep leads to loss of vegetation and soil erosion.
In common with other farm animals, sheep suffer from a wide range of diseases. The commonest is foot-rot which often results in lameness. Foot-rot is encouraged by a high stocking density in housing and pens. Lameness can also be caused by other infectious diseases and is a major welfare problem in sheep.
Sheep scab and myiasis (blowfly strike) are distressing and potentially fatal contagious diseases in sheep. These are prevented by sheep dipping. Sheep dipping was made compulsory twice a year in 1985 but made non-compulsory again in 1992. Sheep dips contain toxic organophosphates which are believed to be responsible for a high incidence of severe illness in farmers. The possible toxic effects of sheep dips on the sheep themselves has not been studied.
Other diseases affecting sheep include mastitis, toxoplasmosis, liver fluke and scrapie (related to BSE in cattle). Many sheep suffer from pneumonia and hypothermia during the winter when exposed to harsh weather conditions. This is a particular problem for sheep in upland areas. Around 40% of sheep in the UK live in hard upland conditions where winter hand feeding is restricted and shelter minimal.
Some sheep are housed indoors during the winter in enclosed sheds or barns. These may be poorly lit with concrete or slatted floors.
Integrating sheep into a farming operation can contribute to the economic and environmental sustainability of the whole farm. Sheep will enhance the farm's biological diversity, and may fit economic and biological niches that would otherwise go unfilled. The relatively small investment required, and the gradually increasing size of the flock, make sheep production a good choice for the beginning small-scale or part-time farmer. For the established farmer seeking to diversify, sheep offer a number of benefits.
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.