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United Suffolk Sheep Association |
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Improving Reproductive Performance of the Ewe
Clell V
Bagley, DVM, Extension Veterinarian The western range ewe is a tremendously productive animal as evidenced by the excellent reproductive rates that are achieved by some producers, some years. Yet many other factors such as weather, disease and forage availability can drastically reduce their productivity. It is a major management challenge to control or even minimize the effect of these interacting factors. Some of those of greatest priority are listed and briefly discussed. Nutrition and Flushing The nutritional status of the ewe has a great and direct impact on reproduction at breeding and at lambing. Body condition scoring should be used to monitor the flock status throughout the year but especially prior to these two critical periods. The majority of the ewes in the flock should be in good to moderate condition. If they are not, some additional feed sources must be found. If there are only a few in the thin category, then perhaps they can be removed to a more favorable area and the remainder of the flock can continue in their present environment. But be careful not to be too casual in this decision as it is one of the most important for the entire year and will have a direct bearing on the production for the year. Flushing is variable in its effect on fertility but may be of some help, especially if the ewes are just in good condition. The flushing of extra feed should begin 2 to 3 weeks prior to the beginning of breeding and continue for at least 3 weeks after. For range sheep, it usually has to be supplied as crop aftermath or pastures reserved for that purpose. Occasionally, it may be helpful to flush by daily feeding of whole corn on the open range. Don’t expect flushing to make up for prior nutritional neglect in a flock of thin ewes on poor feed. Breeding The major problem at breeding has been the use of a ram flock infected with Brucella ovis, ram epididymitis. This increases the number of dry ewes and decreases the numbers of twins as well as greatly extending the lambing period. Be sure this problem is eradicated or well under control and on the way to eradication. Other factors to look at would include the length of the ewes tails from docking and matting from fecal contamination around the vulva. Both of these could cause some interference with the breeding process. Crunching of the wool or shorter docking of replacement ewe lambs may be warranted. Lambing Season and System Is your flock lambing at the time which is most ideal for survival of baby lambs? Is the system used best for the conditions and time of year? Some producers could shift the lambing dates a couple of weeks later and improve the survival rate while not decreasing the weaning weight of the lambs in the fall. Shearing of the ewes before lambing will aid the newborn lambs to find the teat and get off to a good start. Changes such as these may also allow some producers to change from shed to “pasture” lambing and greatly decrease their feed and labor costs. If you consider such a change, you may want to try it with a small part of the flock for one year to learn what the problems and advantages really are, before you change the whole flock to a new system and end up with disaster. Abortion Control Vibriosis and Enzootic Abortion are common in western range flocks and have a serious effect on flock production some years. Be concerned if the abortion rate rises above 1 to 1 ½ % and proceed with diagnostic and treatment efforts. Realize that the diagnosis may not be of any help for the current year but will help you prepare for next year. Establish a reasonable vaccination program and then stick with it. Records and Marking of Ewes Some ewes are non-productive (barren) and yet they remain in the flock for several years because they are never identified and culled out. Keep records and mark the ewe herself (earmark, etc.) so the non-producers and poor producers can be culled out. The same applies to those with a bad udder, etc. Pregnancy Testing (Ultrasound) This procedure will help some producers to make better use of their feed resources, by separating those that are pregnant with twins as well as culling those that are open. Look at the economics for your situation and consider its use. Parasites These can certainly drain the condition from ewes on marginal feed. For most range flocks the priority of concern should be keds, lice, flukes and finally roundworms. Put your efforts and money toward control in that order unless there is some unusual condition with your flock.
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