Richard Ehrhardt, Michigan State University Extension Specialist, Small Ruminants
(Previously published on MSU Extension, Sheep & Goat)
Shearing before 
lambing is a practice that benefits the welfare of the sheep as well as making management easier and increasing flock productivity. There are important considerations to keep in mind to perform this practice effectively. These relate primarily to timing relative to birth, stubble length, feeding, and protection post-shearing. If these conditions are considered carefully, the benefits are significant to both sheep and shepherd.
#1. Drier environment: Wool holds considerable moisture, with a full fleece capable of absorbing a lot of water under humid climates, even when sheep are housed indoors. This moisture holding capacity of wool creates a microclimate close to the lamb that is relatively damp, thus creating a prime environment for hosting pathogens and allowing them to proliferate. Both the
relative humidity of the barn and the microclimate near the lamb are drier when ewes are shorn, creating a healthier environment that is less conducive to pathogen growth.
#2. Cleaner environment: Wool also has the capacity to hold mud and manure as well as absorb fluids from the birth process, all of which can harbor and promote the growth of pathogens. A short fleece minimizes this situation, creating a much cleaner environment for the benefit of both the ewe and her lamb(s).
#3. Increased lamb birth weight: It has been well established that shearing during mid-pregnancy improves lamb birth weight. The increase observed is substantial, often in the 15-25% range. The improvement in birth weight is most evident in ewes with multiple births, although it has also been documented in ewes with singletons as well. The mechanism for this increase in birth weight is not entirely clear. Some studies indicate that an increase of voluntary feed intake by shorn ewes may be responsible, whereas other studies show no change in intake yet an increase in birth weight. The increase in feed intake is likely greater in cooler weather, as the ewes will eat more to maintain body temperature (often 15-25% more feed is needed in shorn compared to unshorn ewes). It is clear that in some studies, the increase in feed intake is not enough to explain the increase in birth weight, suggesting a metabolic adaption by the ewe to partition more nutrients to the lambs. Whatever the case, it is a biological phenomenon that we can use to our advantage as shepherds. Birth weight is a limiting factor for lamb survival, particularly in multiple births, so any management tool available to increase it should be utilized.
#4. Improved fleece quality: Pre-lambing shearing improves wool quality in two distinct ways. The metabolic stress that occurs in late pregnancy and especially in early lactation creates a weakness in the wool fiber often referred to as “wool break”. The wool may not actually break, but it will weaken due to the surges in cortisol that inhibit the wool growth process and also because of the lower flow of nutrients to the wool follicle bulb from decreased skin blood flow in the cold. With pre-lamb shearing, the wool break occurs at the very tips of the fiber; therefore it is not of consequence in terms of textile properties of the fiber. The other improvement in wool quality brought on by pre-lamb shearing is a reduction in vegetative matter in the fleece. This is especially observed in flocks that lamb indoors in winter, since in shorn ewes the vast majority of the winter feeding period occurs with the ewes in short fleece, which does not trap much vegetative matter from hay or silage. In some flocks, it is possible to move ewes off the winter grazing of annuals such as turnips and directly into the barn for shearing before lambing, thus avoiding any forage feeding contamination and allowing for harvest of full length staple that is nearly free of vegetative matter.
#5. Ewes have better access to feeders: Shorn ewes take up far less room at the feed bunk (15-20% less space), allowing better feed access for more of the flock. This allows for a more efficient feeding program and reduces the constraint for bunk access that is often observed in smaller ewes. It also contributes to better feed intake in late pregnancy when intake is often a limiting factor for lamb growth/development.
#6. Barn is warmer for winter lambing: For winter lambing, pre-lamb shearing allows for greater housing density and greater liberation of heat, thus increasing the temperature of the barn significantly. This can be especially helpful in improving survival in indoor lambing programs. Simply shearing ewes and insulating your barn can create a birth environment just above freezing, which greatly lowers the risk of losing newborns to the combination of hypothermia/starvation.
#7. Lambs access the teat easier: Lambs that can quickly seek and find the teat have a much greater chance of survival. A full fleece reduces access to the udder, making it hard for the wet newborn to find it. In addition, it not uncommon to see lambs literally sucking on tags of wool instead of the teat in full fleeced ewes. Shearing removes this obstacle, creating easier access.
#8. Ewes seek protection in bad weather: Shorn ewes are much more likely to find a more protected and less exposed birth site, as they naturally need to seek such protection to maximize their own comfort. This greatly reduces loss to hypothermia/starvation in early life.
#9. Ewes are easier to shear: Shearing ewes prior to lambing is much easier than during lactation. As the ewe reaches peak lactation, around a month after lambing, the lanolin in the fleece becomes much more “sticky”, with a higher melting point. In addition, ewes lose weight, becoming less smooth to run a comb over during shearing.
#10. Ewes are more active and easier to observe for health and nutritional status: When shorn, it is much easier to observe the ewes for body condition and also to tell when they are about to lamb. Shorn ewes are also more active than those in full fleece, and this exercise may improve maternal health in late pregnancy. Shorn ewes are also less likely to become cast or stuck on their backs during late pregnancy.
#11. Shorn ewes are better mothers: Beneficial maternal behavior including grooming of lambs are enhanced in shorn ewes at birth. This improves maternal bonding and decreases the risk of mis-mothering and starvation/exposure in early life.
Key considerations for pre-lamb shearing
Protection from cold exposure
Covered shelter is needed following shearing when shearing approximately during the period of October to April in the upper Midwest. The worst type of cold exposure is freezing rain between 33-45°F. Exposure of shorn ewes to these conditions absolutely must be avoided or catastrophic loss can occur. Freshly shorn ewes housed in the same 33-45°F range do fine if kept out the rain and wind, though. Shearing stubble length should be increased to approximately 0.2 inches (5 mm) whenever shearing in cold conditions. This extra stubble allows much greater protection from wind/rain/cold.
Conventional shearing practices with 13 tooth combs and standard cutter lead allow about half this amount of stubble (0.1 inch or 2 mm), so ask your shearer to adjust their gear to leave more stubble. This can be accomplished by any of the following practices or combinations: use combs with fewer teeth (9-10 teeth are common choices), allow more lead with the cutter on the comb, use specialized cover combs that lift the comb off the sheep with either a special spacer or with risers. Experienced shearers can create the desired 5 mm stubble with 9 tooth combs and adequate cutter lead. Wool grows about 7 mm (a bit more than ¼ inch) every 3 weeks. So, shearing with cover combs about 3 weeks before cold rain exposure will leave 12 mm (around ½ inch) of wool in total and greatly minimize cold stress. Furthermore, ewes housed outside without shelter in winter (out-wintering) must be shorn early enough prior to cold weather to allow for sufficient fleece length to protect from cold/wet/wind. In the upper Midwest, out-wintered ewes should be shorn prior to Sept. 1 to allow for enough regrowth prior to cold/wet/wind exposure. This allows the bare minimum fleece length entering winter, so shearing earlier is even better.
Time relative to lambing
Ideally, all ewes should be shorn 30-60 days prior to lambing to reduce stress on both the unborn lambs and their moms. The ideal shearing window is closer to 42-75 days prior to birth, but this can be hard to accommodate in many management systems in the upper Midwest because it may mean housing ewes under cover for extended periods, which may expensive or not even possible. Many prefer to shear closer to birth (never closer than 2 weeks pre-term), as it may eliminate or minimize the need for housing under cover. But this is pushing it for stress on the ewe and lambs, since shearing closer than 2 weeks to lambing will increase the incidence of stress-related problems including stillborn lambs, ketosis and milk fever. Experienced, skilled shearers will shear in less than 5 minutes per sheep, and this is a must for pre-lamb shearing.
Feeding before and after pre-lambing shearing
Feed removal for 24 hours is a common practice to improve the handling of non-pregnant sheep during shearing. For ewes sheared close to term (21-42 days pre-term), feed withdrawal should be lessened either by feeding a half ration the day before shearing or by withdrawing feed for only 12 h. More severe feed withdrawal during pre-lambing shearing will increase the incidence of both milk fever and ketosis, which are triggered by stress and feed withholding. Pre-lambing shearing will also increase the ewe’s caloric needs due to the increase in heat production, so ewes must be offered up to 25% more feed when wool is short (generally less than 3/4 inch) depending on climatic conditions.
Summary
Shearing before lambing allows for better lamb survival and flock productivity while improving fleece quality. During cold weather, shearing must be managed to allow sufficient stubble and/or recovery time post-shearing to protect from cold exposure. Following these simple guidelines will improve both the welfare of your flock and your bottom line.