By Janet McNally, Hinckley, Minnesota — How you manage your ewes between September 1 and November 1 will make or break next year’s lamb crop. Once winter weather sets in, outwintered ewes seem to be challenged to gain any further weight, especially if they are starting off thin. For us the magic date seems to be November 1. Whatever we can achieve by then is what our flock has to live with for the rest of the winter. Body condition determines ovulation rate, ability to withstand the cold, and future milk production. Sure, you can purchase body condition by supplementing heavily with the grain pail, but the same can be achieved on pasture through management without spending a dime.
There are three components to fall sheep management that will determine what kind of body condition your ewes will be sporting when the rams go in. The first is weaning date, the second is pasture allowance after weaning, and the third is intestinal parasite status. Mismanage any one of these three, and you have to pay, either through reduced lamb production the following year, or through purchased supplements.
High-performing ewes with genetics for good milk production are going to have a tough time gaining weight so long as lambs are suckling. At best, productive ewes will hold their own unless they are grazing high-energy crops such as turnips, grazing corn, legumes, or ryegrass. The decision on a weaning date should be based primarily upon available forage quantity and quality. Weaning can be postponed when quality forages are abundant, as ewes will start regaining weight when they are at least 60 days postpartum. But when quality pasture is limited, it may be time to wean. By weaning you can allocate the remaining quality grazing to the lambs, while removing the burden of lactation and subsequent weight loss from the ewes. Weaning can reduce the total energy and protein required for the flock by as much as one third.
July/August is a good time to assess your pasture resources and decide whether or not you should consider early weaning. (Early weaning of a pasture-reared lamb is anything under 90 days of age). Typically late summer has a spell of dry weather that will dictate fall forage supplies. Evaluate body condition scores on your ewes and decide how much weight you need to gain back. Each point of body condition score (see sidebar) is equivalent to 10 pounds of weight gain.
With a grazing intake of 4 lbs. dry matter, ewes will gain only .22 lbs per day. So if your flock has had a tough summer, and needs to regain two points of condition, the ewes need to gain 20 lbs. of body condition. This can possibly take 90 days of grazing from weaning to November 1. On the other hand, when feed conditions have been good and ewes are arriving in August with a body condition score of 2.5, they will only need 45 days between weaning and November 1 to reach the desired 3.5 in body condition score. In this case, weaning can be put off until September.
The post-weaning period is a time of opportunity. Dry, non-pregnant ewes in reasonable body condition can be asked to do a number of favors around the farm and still gain weight while cleaning up some neglected places. Ewes can clean up overgrown paddocks, remove weeds and brush from any number of areas, or be sent off to other parts of the neighborhood to graze crop aftermath. Pastures at home can be stockpiled while the ewes are grazing elsewhere. How hard you graze these areas will determine body weight gain.
On a quality pasture, gains will be reduced when grazing removes the residual to below 1,068 pounds per acre (according to Controlled Grazing Management for Sheep, published by the Department of Primary Industry and Fisheries in Tasmania). It is much more difficult to arrive at a recommended residual when sheep are grazing woody plants, weeds, or crop residual. Possibly the only accurate way to determine whether or not the flock is getting adequate dry matter intake is to become a good judge of fill by frequently observing your sheep. Watch that area behind the ribs and before the hips and learn to recognize when your sheep are not full. Only full sheep are gaining weight!
Another guide is to observe how many hours the sheep are up grazing. Sheep need adequate rest and time to ruminate, so if grazing requires more than eight hours of rustling feed per day, they may not be getting enough for weight gain. Observe how early in the morning they lie down. When grazing continues long past 10 a.m., it may be time to move. If in doubt, use a scale, mark a few average ewes and weigh them to monitor weight gain. The earlier you address your flock’s needs, and respond by providing adequate dry matter intake, the less likely you will be hauling pails of feed at breeding time.
Parasite management need not be elaborate. If in doubt, run a fecal and determine if your ewes need to be dewormed. Often ewes that have been adequately managed and dewormed through the summer lamb-rearing period need no further deworming in the fall. Producers in the Great Lakes region may need to address liver flukes in September and November. If ignored, parasites can completely undo your best efforts at managing grazing for body weight gain. By planning to do your post-weaning grazing in areas not inhabited by sheep all summer long, such as grazing a weedy new seeding for a neighbor, or grazing a hayfield that was too short or wet to harvest as hay, you will avoid reinfecting your flock with parasites. This also allows your own pastures to stockpile for winter grazing.
Fall is a time for rebuilding the ewe flock, for restoring what she has put into her lambs. Your ewe flock can be used as a forage management tool, and regain lost weight at the same time, but it is important to observe and adjust your management to be sure they are indeed gaining weight through this period. Your efforts will be rewarded with a few extra dollars in your pocket, and a good lamb crop next year.
Since wool can make a thin sheep look fat, it is essential to get your hands on your sheep to properly evaluate body condition score. Handle the loin as shown in the photo at immediate right, and estimate numerical scores as indicated by the drawings below.
How to evaluate body condition
Body condition is evaluated by placing your hand on the loin of the sheep. Put your thumb on the top of the spine, and your fingers over the horizontal transverse processes. Move forward and back along the spine, and evaluate how much padding (fat) is between these bony projections and your hand.
If you can feel the entire spine through the muscle tissue, you are handling a sheep with a condition score of less than 1.5. If the muscle is full enough to prevent finding the entire spine, but the ends of the spinous processes and transverse processes are still prominent and readily found, body condition score is 2.5-3. When all bony projections from the spine feel padded and are difficult to find, and the muscle is round and full, body condition score of 3.5-4. When the spine becomes nothing more than a dimple down the back, and no bony projections can be found, you have found an obese sheep, with a score of 5.
Ideal body condition is 3.5. However, it is normal and appropriate that body condition will change throughout the year depending upon production status. Productive ewes need to achieve a score of 3.5 for breeding and lambing.
Janet McNally grazes sheep near Hinckley, Minnesota.