The lambing season begins for you, the sheep producer, when the rams
are allowed access to ewes in estrus. At this time, you should make plans
for the lambing event, which will occur in 142 to 152 days, depending on
the breed. Dorsets, for example, have a shorter gestation period than Rambouillets.
Getting the lambing kit prepared early helps when those lambs arrive. It's nice to have everything on hand. Some supplies and drugs will need to be ordered each year. Check your kit to make sure you have everything on hand. A suggested list is at the bottom of this page.
Ewes can be dewormed when taken off pasture with anthelmintics, such as Panacur, that are safe during pregnancy. The ewes, as well as the newborn lambs, should remain free of worms until turned out on pasture in the spring. The ewe may be vaccinated 4 to 6 weeks prior to lambing with both Clostridium C & D toxoid, to prevent enterotoxemia or overeating disease, and Tetanus toxoid. This will increase the level of these antibodies in the colostrum (first milk) which protects against bacteria and viruses in the newborn. In areas where selenium is deficient, the ewe can be given vitamin E injections at 60 days and again 15 days before lambing.
During the last 4 to 6 weeks of gestation, ewes should be fed good quality hay, if pasture is not available, and about one pound of grain per day. Seventy percent of the fetal growth occurs at this time. The extra energy from the grain will help prevent pregnancy toxemia and offset shrinking of the rumen caused by the enlarging uterus. Exercise is important at this time. Keep ewes on pasture as long as possible in the winter.
Care of Buildings
The buildings should be cleaned and may be treated with lime. Check for obstructions that might cause injury to the ewe or lambs. Doors should be wide enough to prevent physical damage to the fetus. Have plenty of fresh water available.
Labor or parturition in ewes is divided into 3 stages. The first stage is uterine contractions and cervical dilation that usually lasts about 12 to 14 hours. The second stage is the actual labor and delivery. During this process, the membranes usually rupture and break the water bag, lubricating the birth canal. In this stage, the ewe physically strains itself in order to expel the lamb. If the lamb is not delivered in an hour, the ewe may need assistance. The third stage includes expulsion of fetal membranes and involution of the uterus.
Difficult birth is termed "dystocia" and may be caused by abnormal presentation of the lamb. Some causes are one or both forelimbs turned back, deviations of the head, breech presentation, posterior presentation or undilated cervix.
Whatever the problem, try to correct it as soon as possible. For example, you could manipulate the cervix with your fingers if necessary when it fails to dilate. Push the head back and correct the position of the head or forelimbs and bring them forward if necessary. A cord or lamb puller may be needed. Turn the ewe on her back when the adjustments have been made and pull up in a normal position as if the ewe was on her feet. If you can't correct the problem, call your local veterinarian. He or she may need to perform a caesarian section. The sooner surgery is performed, the greater the chances are of a live lamb being delivered. Breech and posterior presentations should be delivered as rapidly as possible.
Care of the Newborn
Breaking the umbilical cord will prevent oxygen from passing to the lamb; if this occurs, respiration must be established as soon as possible after expulsion. Gently pressing on the rib cage may start the lamb breathing. Other methods are tickling the nose with straw or gently swinging the lamb. Be careful to avoid all objects. Vigorous rubbing may also stimulate breathing.
Once the lamb is safely breathing, encourage the ewe to lick the lamb. If the temperature is below freezing and another lamb is on the way, put the newborn under a heat lamp to dry until the second and/or third lamb arrives. Turn off the heat lamp as soon as the lamb can maintain its body temperature. Heat lamps may cause pneumonia in the newborn lamb.
After delivery, dip or spray the navel area with a 7% tincture of iodine. A simple phrase to remember is, "clip-dip-strip." Clip the navel cord if it is unusually long, dip it in iodine and strip out the ewe's teats. Put the newborn lamb at the teat as soon as you notice a sucking reflex. If the lamb is weak and unable to nurse, milk out the colostrum and administer it with a catheter and syringe. Take special care not to get the tube in the lamb's lungs. Check for air by listening, or putting the tube in a cup of water and watching for bubbles. Afterwards, attach a 60 ml. syringe filled with colostrum and fill the stomach with 2 ounces, initially. Lambs usually respond quickly to colostrum. When the sucking reflex is evident, help the lamb to nurse on its own.
Colostrum provides passive immunity for the newborn. Vaccinations should begin when the lambs are 3-4 weeks of age. Clostridium C & D toxoid will protect against overeating disease and Tetanus toxoid will guard against tetanus. Two to four weeks later a second vaccination should be given.
Care of the Postpartum Ewe
The ewe may be weak following the difficult labor and she may not claim her newborn immediately. Leave the lambs in the lambing jug with the ewe. If she attacks them, tie her with a halter. If the placenta is not expelled within 25 hours after birth, she needs to be treated by your veterinarian.
Provide plenty of fresh water for the ewe. Offer high quality hay, such as alfalfa on the day following delivery. Gradually add grain to the diet. The amount will depend on the size of the ewe and the number of lambs she is feeding. Check the NRC requirements.
The lamb's survival depends on a successful partnership between the lamb and ewe. About 90% of mortality cases occur within a week of birth. The major causes are starvation, mismothering and exposure, (the SME complex) with death occuring 1-2 days after birth. Starvation can be prevented with bottle feeding. This includes colostrum consumption within the first hour after birth. Colostrum can be frozen and kept on hand. Thaw slowly to prevent the breakdown of antibodies. Mismothering may require restraining the ewe. Eventually, she will claim the lamb. The most difficult situation to correct is the ewe claiming one twin but not the other. Exposure to cold or hypothermia, is caused when the lamb fails to maintain body temperature. The lamb prevents body temperature from falling to dangerous levels by increasing heat production through shivering. This burns the brown fat energy reserves. The lamb reduces heat loss by reducing blood supply to the skin and extremities. When ambient temperatures are above the lamb's body temperature, it may die of dehydration and heat stroke.
Some Causes of High Lamb Mortality
Minor causes of lamb losses are lethal congenital deformities, deficiency of specific minerals, such as iodine, cooper and selenium. Infections from Vibrio fetus (Campylobacter), and Chlamydia (EAE and other organisms) cause lamb losses in the last trimester, resulting in abortions. Vaccinations for these organisms and treatment with Chlortetracycline help prevent losses. Predation by coyotes, dogs and foxes are minor causes. Excess or deficient amounts of feed in the last third of pregnancy, also affect lamb survival. Two other factors are extremely high birth weights, which complicate birth, and very low birthweights, which cause sensitivity to cold exposure and hypothermia. Resistance to cold and high birthweight are positively correlated and highly heritable.
Studies in Australia by Haughey (1984) reported mean pelvic size among ewes repeatedly failing to rear lambs was significantly smaller than that of ewes which consistently reared them. Ewes having small pelvic area or oversized lambs, will have difficulty during birth, asphyxia and birth injury resulting in stillbirth or death within 1-2 days. The pelvic area of ewes matures between 21/z to 3 years of age.
Hemorrhage in and around the lamb's brain and spinal cord was the most common lesion found during autopsies of lambs dying 1-2 days following birth. Selection for rearing ability of ewes offers excellent prospects for improving lamb survival. Retention of ewes and their progeny from difficult births can perpetuate the genes for poor rearing ability.
Docking and Castrating Lambs
Dock lambs in 24 hours if using elastrator bands. Dock and castrate at one week with a knife and burdizzo clamp or other similar devices. Keep plenty of bedding in the building at this time. This is generally when lambs are vulnerable to tetanus organisms. Offer lambs creep feed at about 10 days of age. Corn and soybean meal at an 18% crude protein level provides a palatable creep ration.
Beginners should seek help from experienced producers during the lambing season. Experienced sheep producers and your local veterinarian are very cooperative and will provide expert assistance and advice.
7% Tincture of iodine -for disinfecting lamb navels.
Eartags -for lamb identification.
Lubricant (K-Y Jelly) -when assistance is needed by the ewe.
Burdizzo clamp -for docking and castrating.
Elastrator bands -for docking and castrating.
Balling gun -for boluses, capsules and pills.
Bottles and nipples -for orphan lambs.
Triple Sulfa -for infections.
Antibiotics -for infections.
Milk of Magnesia -for laxatives.
Mineral Oil -for constipation block.
Drenching syringe -for deworming.
3cc, 1 0cc and 25cc syringes and needles -for various treatments.
Nylon rope or equivalent -for pulling lambs.
Foot-trimmer -for foot trimming.
Shearmaster -for crutching and shearing.
Rectal thermometer -for sick animals.
Heat lamps, paper towels and rope halters.
Stomach tube -for lambs unable to nurse.
Gates -4 ft. in length for lambing jugs.
Buckets -for water in jugs.
Small feed boxes -for feed in jugs.
Feeders for ewes -grain and hay.