Sheep specialist answers common questions
If you’re reading this and you own sheep, you know the joy and frustration during lambing season is as manic as the spring weather in Wyoming. It’s the busiest time of year for everyone in the sheep business, and time is a precious commodity.
Every spring I receive a wide array of questions related to managing the ewe pre- and post-lambing, newborn lamb management and everything in-between. As diverse as these sheep production questions are across a variety of management systems, there are some common themes, which are good to revisit.
In the spirit of brevity, fitting of this busy time of the year, here are a few anecdotes to have crossed my desk recently in conversations across the state.
Too often we’re forced to get out the crystal ball and predict whether a ewe can raise twins based on a visual evaluation of the udder in the first 24 to 48 hours after lambing. Considering peak lactation ranges from 21 to 28 days, predicting milk potential at 24 hours isn’t always straightforward.
Although counter intuitive, ewes which have carried more than one lamb have been programmed to produce more milk than their single bearing counterparts.
Placental lactogen is a hormone produced during pregnancy at 50 to 140 days post-conception, which stimulates udder growth and helps ensure milk production matches the number of lambs born.
Research at the U.S. Sheep Experiment Station in the 1990s found twin-bearing Rambouillet, Columbia and Polypay ewes produced 13 to 17 percent more milk than their single-bearing counter parts. Twin-bearing Suffolk ewes produced a whopping 61 percent more milk than single bearing ewes over the course of a 100-day lactation.
Similarly, twin-bearing ewes produced 14 percent and 20 percent more milk fat in colostrum and four day milk, respectively, than single-bearing ewes. In instances where the twinning ewe is in poor condition, it’s safe to assume she won’t produce enough milk and will only continue to lose condition, but if she’s in good condition maybe think twice about pulling one of the lambs too quickly.
First time lambing ewes need extra oversight to make sure they’re not kicking off lambs due to sore udders or inadequate milk production in the critical 10 to 30 days post-partum.
Recent research at the University of Wyoming indicates somatic cell counts, indicators of udder infection, peak during the 10 to 15-day post-lambing period, especially in western shed lambing systems. Many producers have a set limit on how many ewe/lamb pairs are in a group pen which helps them intervene in a timely fashion, but protocols to identify at-risk pairs can’t be revisited enough throughout the lambing season.
Ever-changing environmental factors, age and disposition of ewes, delegation of labor and inevitable fatigue from the grind of lambing all make contingency planning a moving target.
Nutrition and minerals
Pregnancy toxemia, milk fever, mastitis or any other ailment due to a nutrient deficiency are much harder to fix than prevent. We’ve all heard and seen the figures showing the greatest amount of growth in the unborn lamb is in the last 40 days of pregnancy. Yet, what is not stated enough is the net sink of glucose the late-pregnant ewe experiences because of the rapid growth of the lamb.
Approximately 60 to 70 percent of all the glucose produced by the ewe is shuttled to the growing lamb in late pregnancy. And when the glucose-account overdrafts, pregnancy toxemia results.
Whether you’re hanging onto ewes longer, recently purchased aged-ewes or are seeing an increase in your twin or triplet percentage, then supplementing an additional pound to a pound and a half of grain will go a long way in preventing clinical problems.
Similarly, mineral requirements increase from breeding to gestation and need to be provided well in advance of lambing so storage pools can be mobilized as the stages of pregnancy advance. Still, I’ve found ewes to be relatively illiterate when it comes to reading the fine print “target consumption” on the mineral tag.
Significant proportions of the flock, more than 25 percent will under consume, over consume or not consume the free-choice mineral at all. Monitoring consumption and calculating estimated mineral intake across the flock takes some math, but it can tell us if a group of ewes are over-consuming or under-consuming.
One way to calculate this is to first divide the total amount of mineral fed, by the number of days it took for the amount to be consumed, and then divide by the number of ewes consuming the mineral.
For example, if a group of 80 ewes consumed a 50 pound bag of mineral, or 800 ounces, in 60 days, then estimated average consumption was 0.16 ounces per head per day. If the mineral tag stated a one ounce per head per day target consumption rate, then your ewes may not be consuming enough mineral, in contrast if the same amount was consumed in 10 days, then ewes on average were over consuming at one ounce per head per day.
If intake is far above or below manufacturer recommended levels, consider palatability issues due to weathering or location of mineral feeder (e.g., near or far from water). We can’t manage what we don’t measure, but we can enjoy the peace of mind coming from good nutritional management.
Identify and cull problem ewes before next lambing season
Paint brands and chalk marks fade; so does one’s memory of a problem ewe in the lambing shed months after the fact. Identifying ewes which fail to raise a lamb, have an intramammary infection, a chronic “hard bag” or perennially poor dispositions towards their lambs don’t deserve many second chances. Good records when culling decisions are made can help ensure these problem ewes don’t reappear in the lambing jugg next year.
Whether it’s an ear notch, color-coded button tag or other unique form of identification, make sure the ewe is clearly identified to see her this fall at the cut gate. Electronic ID tags continue to improve in reliability and can save significant time and energy but require a degree of patience and commitment to implementation for their return on investment.
Taking time to archive multi-year records on lambing, docking and weaning percentages, in addition to more detailed health records, can help identify production trends and better inform troubleshooting when problems arise. Without knowing production trends over a span of years it’s guess work at best to implement strategic improvement.
Ultimately whether it’s culling or keeping, estimating milk production or revisiting your nutrition plan, all lambing time management require a game plan so everyone remembers and adapts as needed. Cheers to healthy ewes, lambs and shepherds in the busy months ahead.
Whit Stewart is a professor and the University of Wyoming Extension sheep specialist. He can be reached at firstname.lastname@example.org.