In the May issue, we covered the factors involved in nurturing sheep and keeping the livestock in excellent condition. Now it’s time to think about lambing. Dot Perkins of the University of New Hampshire Cooperative Extension, a Field Specialist in Livestock and lifelong resident and small farmer in the region, talks about the basics of breeding and birthing sheep.
See “Considering Raising Sheep? Here’s What You Need to Know,” in our May 2015 issue. Visit goo.gl/TqJ6zW.
When are ewes old enough to breed? “As a rule of thumb, ewes are old enough to breed when they are about 8 months of age and or have reached at least 70 percent of their expected adult weight,” Perkins said. Whether they were born in fall or spring, ewe lambs tend to reach puberty the following fall. Breed, body size and nutrition influence the age of puberty. The age of puberty may be reduced by high levels of feed both before and after weaning. Ewe lambs are not fully grown until they are 2 years of age, and physical maturity may lag behind sexual maturity. Ewe lambs may be too small to sustain a pregnancy while they are still growing. Before the breeding season, sheep should be examined, dewormed, vaccinated and have their hooves trimmed. Remember to include these health routines with your rams, too.
The season and number of hours of daylight profoundly affect the estrous cycle in sheep. As day length shortens, most sheep will begin to exhibit estrus. In the northern United States, the natural time for sheep to breed is October and November. Although some sheep are polyestrous, most are seasonally polyestrous, coming into heat every 13 to 19 days, but this period is difficult to detect. Ewes are receptive to the ram for 18 to 48 hours. Depending on the ewe’s breed, the gestation period ranges from 138 to 159 days (about 5 months).
Ewes can breed up to about age 10, but generally are not bred past age five. At age five, they are usually culled. To help yourself with this unpleasant task, think of your management goals. “If you are feeding sheep and maintaining them as pets, you can keep them for as long as you like, but if money and profit are your goals, culling is an important part of flock management,” Perkins said.
Half the Flock
The ram is half your flock. Rams become sexually mature between 5 and 7 months of age or when they have attained 50 to 60 percent of their expected mature weight. In order to have time to make sure the ram is in good body condition, purchase or select him well in advance of the breeding season. Rams need adequate reserves to carry them through the breeding season when they may lose as much as 15 percent of their body weight. During this period before breeding, treat your ram for parasites, put him on the flock vaccination schedule, and trim his hooves. A breeding soundness exam (BSE) may be given to evaluate a ram’s potential breeding ability, but a simpler way to evaluate a ram is to observe breeding performance as he is exposed to ewes. “If ewes are cycling and the ram is not settling them, you need to consider whether the ram is worth his salt,” Perkins said.
Six weeks before the breeding season, separate rams from ewes in space and time (no sight, sound or smell). When the ram is introduced to ewes after this period of separation, his pheromones will stimulate the onset of estrus and ewes will ovulate. If the ram is in constant contact with the ewes, this effect may not occur. Leaving the ram with the ewes constantly can result in ewes being bred when they are not in top body condition. Leaving the ram with ewes may also result in the ram’s breeding his dam or daughters and breeding undersized ewe lambs. Lambs may also be born in less-than-desirable times and places.
Up until about five weeks before lambing, maintain ewes on their regular feeding schedule. Then, during late gestation when the capacity of the ewe’s rumen is decreasing at the same time that approximately 70 percent of fetal growth is occurring, ewes should be fed a more nutrient-dense diet. Required nutrient level is dependent on the age and weight of the ewe and whether she is carrying singles, twins or triplets. Minerals should be available throughout pregnancy.
In preparation for delivery, shear or crutch ewes. Crutching involves removing wool from around the udder and vulva and, in cold weather, may be preferable to shearing. Also check manure for a rise in parasite eggs. If indicated, de-worm ewes four to five weeks before they are due to give birth.
Some 24 to 36 hours before a ewe is ready to give birth, her udder enlarges (a condition known as bagging up) and her vulva swells. These are your cues to put her into a lambing pen.
Separating a lambing ewe makes it easier for you if you need to be involved in the birthing process. Separation also fosters ewe and lamb bonding. A good temporary lambing pen can be constructed using 4- by 4-foot pallets.
Along with bagging up, the ewe’s muscles relax and her hips disappear. Within 12 to 24 hours, a clear whitish discharge will show. A water bag or bubble will appear and rupture, and within the hour the tip of the lamb’s nose and front feet will emerge. Once the lamb’s front feet and head are delivered, “birthing is as good as done,” Perkins said. When there are multiple lambs, the process of rupture and expulsion will be repeated for each lamb.
In situations where birthing does not appear to be progressing, you may need to help. Remove all jewelry, wash hands and wear elbow-length gloves. Look for the lamb’s feet – the lamb should be in the swimmer position. In other presentations, the ewe may need expert help. (This is a time when an established relationship with a veterinarian is important. A veterinarian who has not previously been to your farm may not respond, even in an emergency.) If you need to help the birthing process, wrap the lamb’s legs in an old terry towel and apply constant pressure. “Don’t try to rush things,” Perkins said. “Remember that birth is a process in which some comes out and a lot goes back in.”
Water can be offered throughout the delivery process, but never leave a bucket of water in the stall unless you are there because a lamb could be delivered into the water bucket and drown. Ewes tend to drink more warm water than cold. “Although there have been no confirming studies, experience indicates that dehydrated ewes will retain the placenta,” Perkins said.
The placenta should be expelled within about an hour of delivery of the last lamb. If this does not occur within 24 to 36 hours following birth, seek veterinary assistance. Never pull on the membranes that are dangling from the vulva after birth. Pulling may cause internal injury, excessive bleeding and death. If the membranes are very long and catching on things, they may be cut with scissors. The membranes have no nerves, and cutting them will not cause the ewe pain. “If you don’t see any membranes dangling and didn’t see an afterbirth, the ewe may have eaten it,” Perkins said. “If you are unsure, watch the ewe for a very bad odor indicative of an internal infection. Keeping in touch with your veterinarian will help ease your mind.”
Within 15 to 20 minutes following birth, remove the waxy plug from the ewe’s teat and check for milk. It is critical that lambs receive colostrum within 24 hours of birth. Lambs may receive colostrum (a ewe’s first milk following lambing) from the ewe or via tube or artificial nipple. Colostrum contains high levels of antibodies to several infectious diseases. While it is possible for lambs to survive without colostrum, the likelihood of disease or death is higher in lambs that do not receive it. If supplemental colostrum is needed, provide it in four 50-mL feedings. The ideal source is healthy ewes from the same flock.
Newborn lambs need to bond with their mothers very quickly. The two should be kept out of the way of the rest of the flock. Newborns need to be warm and dry. But be extremely careful using heat lamps, a common cause of barn fires. For the first three days of life, allow no visitors. Not only are visitors distracting to lambs and ewes, but they may also bring with them disease.
What Can Go Wrong?
Most times, all goes well with the birthing process. Some common problems include the following:
- Wrong presentation: Instead of the usual “swimmer” presentation (nose + two feet), you may see:
- Two lambs at once
- Head but no feet
- Bum but no feet
- Upside down feet
- The ewe may not be sufficiently dilated, a condition called ring womb.
- The ewe may have a prolapsed uterus.
- Other problems may include:
- Pregnancy toxemia
- Milk fever – Result of a lack of calcium
- No milk
- Sudden paralysis
- Hemorrhage – Blood is bright red
- Rejection – It is not uncommon for the ewe to reject the lamb.
“Birth is an event. Keep calm. Go slow. Ewes and lambs need to recover,” Perkins said.
Cover Photo by Kathleen Hatt.