Ewe feeding importance increases during breeding, pregnancy

As sheep producers across the country are preparing for the breeding season, Montana State University Extension Sheep Specialist Rodney Kott, Montana State University research scientist Lisa Surber and North Dakota State University Sheep Extension Specialist Reid Redden looked at feeding ewes during breeding and pregnancy for optimal production.
    Proper feeding of ewes has a direct affect on production, and nutrition respresents one of the largest costs for a producer.
    “The goal of any nutrition program is to maximize the use of our forages,” said Kott in the Aug. 29 webinar, sponsored by the American Sheep Industry and the National Sheep Industry Improvement Center. “The first thing in any nutrition program is that we have to follow the nutrient requirements of the animal.”
Optimum feeding
 strategies
    Redden began by identifying important considerations for feeding ewes and marked energy and protein as the main requirements.
    “One of the first things we realize is that sheep do not require any one specific feed,” Redden commented. “It is the nutrients within the feed that are most important.”
    He further encouraged producers to consider feeding on a 12 month scale.
    “For a ewe in maintenance, her dry matter intake is less than three pounds, and right before breeding we need to increase dry matter by 45 percent,” Redden explained. “Right after the breeding period, nutrient requirements drop to just about 10 percent above maintenance.”
    Requirements remain steady through early and mid-gestation, increase to 45 percent above maintenance again at late gestation for a single lamb and 50 percent above maintenance for twins.
    “We see a drastic increase for requirements at lactation,” he added. “Ewes require 95 percent more feed – almost twice what she needs to maintain – for a single, and if she has a twin, they require about 125 percent above maintenance.”
    Total digestible nutrients (TDN) and crude protein requirements follow similar trends, with increases just prior to breeding, at late gestation and during lactation.
Percentage versus amounts
    “Another key point on nutrient requirements is how much crude protein you need,” added Redden. “Animals require amounts, not percentages, of nutrients, and feed is often expressed as a percentage.”
    For example, Redden says if a lamb needs 0.5 pounds of crude protein, that nutrient could be gained from eating two pounds of a feed source with 25 percent crude protein, three pounds of a 17 percent source or four pounds of a food source that is 12 percent crude protein.
    “The only percentage we need to focus on is the requirements of the rumen microbes,” he noted. “They need a certain percentage – between six and eight percent crude protein – to maintain normal function.”
    He also mentioned, however, that optimum feeding strategies may not always involved meeting the exact nutrient requirements of each ewe at each stage.
    “In lactation, for example, we can rarely get the ewe to eat enough,” Redden explained. “We can use the ewe’s body resources at that time of negative energy balance.”
    “The question is, how much can we afford to lose?” he asked.
Body condition scoring
    In order to determine ewe body composition or assess nutrient status, Surber marked body condition scoring as an excellent tool.
    “We’d like our ewes to be at a body condition score of three,” she said. “It is pretty likely, and maybe even economical, that during certain times of the year she will fall below that body condition score.”
    Body condition score is an estimation of the muscle and fat development on an animal, according to Surber, and the scores range between a one, for extremely thin or emaciated sheep, to five, or obese.
    “We want to focus on the scores two and three, because that is where you want to see the majority of your sheep,” she noted. “As a trained producer, you should be able to identify body condition score.”
    Surber noted however, that while producers are learning to assess body condition score, it is important to actually feel the sheep.
     “In the wool, it makes it more difficult to assess body condition until you get your hands on them,” she said. “The differences in wooled sheep are more subtle.”
    Assessment of body condition should be done four to six weeks before breeding, according to Surber, who says that at that point, it is still possible to improve or change their nutrient status.
Flushing
    Kott noted that if ewes are in a body condition score of between two and 3.5, a flushing effect can be seen and can improve breeding results.
    “The true flushing response is something we don’t really understand, but it is real,” Kott said. “It is an ovulation rate increase and a response to an increase in nutrition.”
    While the response is dependent on a number of things, Kott noted that a short-term increase in nutrition can increase ovulation. Mature ewes respond better, but he still recommends that producers flush all ewes in the body condition score range.
    “There has been a lot of research. You can flush with protein or energy, and in some cases one-third or one-quarter pound of grains will get the job done,” Kott said.
Early pregnancy
    After ewes are bred, Redden noted that nutrition in the early stages of gestation is very important, largely because placental growth occurs during that stge.
    “The first fifty days of pregnancy are very important,” said Redden. “We have a lot of things going on that nutrition can have a large impact on.”
    Of primary concern, he said that increasing conception rate is very important, and feeding the ewes optimally can help with increasing implantation and decreasing abortion rates.
    “Overfeeding and underfeeding can have detrimental effects, and we might lose more lambs than we’d like,” Redden added.
    Though in the first trimester producers need to feed their ewes a bit more, he cautioned against overfeeding.
    “One thing that was clear in research is that overfeeding and underfeeding both alter blood flow to the reproductive track, which reduces progesterone,” Redden explained. “Reduced progesterone will increase embryonic loss.”
    In the first 50 days of pregnancy, he further explained that the majority of placental development occurs, and feeding influences placental development. Both over and underfeeding causes the placenta to be smaller. The smaller placentas do not allow the lamb to grow as large, resulting in neonatal losses from light lambs.
    “We need to feed the ewes what they need when they need it,” Redden added. “Feed the ewes what they need, and that’s it.”
    This webinar will be available online at sheepusa.org. The webinar was offered by the American Sheep Industry Association in conjunction with its Rebuild the Sheep Industry initiative.
    Saige Albert is managing editor of the Wyoming Livestock Roundup and can be reached at saige@wylr.net.

BCS determines ewe condition
    Montana State University research scientist Lisa Surber said,  “Body condition scoring is an excellent way to determine body composition or assess nutrient status.”
    Body condition scores range from one to five and describe sheep from very thin to obese.
    “A one is a very thin ewe with no fat cover. The loin muscle is severely underdeveloped, her spine feels sharp, and you should be able to fit your hand underneath the transverse process,” said Surber.
    On the opposite end of the spectrum, ewes with a body condition score of five are soft to the touch.
    Surber noted, “On a five, you won’t feel anything but fat.”