# Sheep Energy Requirements: Understanding TDN and Net Energy ## Key Takeaways - Energy is the primary limiting factor for sheep production, powering all physiological functions from maintenance to reproduction and growth. - Total Digestible Nutrients (TDN) is a widely used, simpler system for estimating energy content, while Net Energy (NEm, NEg, NEI, NEp) offers greater precision by accounting for energy losses during metabolism. - Energy requirements escalate significantly during late pregnancy (50-75% increase) and lactation (50-100% increase), necessitating nutrient-dense feed supplementation, typically with grains, to prevent metabolic disorders like pregnancy toxemia. - Environmental stressors such as cold temperatures (below 20-30°F for sheep with full fleece), wind, and wet fleeces substantially increase energy demands, requiring adjustments in feed quantity and quality. - Body Condition Scoring (BCS) on a 1-5 scale is a critical, practical tool for assessing energy status, with a target of 3.0-3.5 recommended at breeding and throughout gestation to optimize reproductive performance and lambing outcomes. - Sudden dietary changes can lead to digestive upset (e.g., acidosis); all ration modifications must be implemented gradually over 7-10 days to allow for microbial adaptation in the rumen. --- Feeding sheep the right amount of energy is one of the most important decisions you will make as a flock owner. Get it wrong and you face thin ewes, poor lamb crops, cold weather losses, or overly fat breeding stock that struggles to lamb. This guide explains the two main systems for measuring sheep energy requirements, total digestible nutrients (TDN) and net energy, and shows you how to apply them to your own flock. It is written for commercial sheep producers, small flock owners, and anyone preparing for a veterinarian or extension consultation. You will learn how to calculate maintenance needs, adjust for pregnancy and lactation, evaluate feed labels, and build a practical feeding program that keeps your sheep in the right body condition through every season. ## At a Glance - Energy is the largest component of a sheep diet and the first limit on production. - TDN measures the total digestible energy in a feed and is the most common system used in the United States. - Net energy systems split energy into separate values for maintenance, growth, lactation, and pregnancy, which gives more precision but requires more detailed feed information. - A mature ewe at maintenance needs roughly 2.0 to 2.5 pounds of good quality hay per 100 pounds of body weight per day. - Late pregnancy increases energy needs by 50 percent or more compared to maintenance. - A ewe nursing twins needs about 50 percent more energy than a ewe nursing a single lamb. - [Body condition scoring](/knowledge/animal-farming/farm-management/body-condition-scoring-a-tool-for-feed-management) is the most practical tool for checking whether your sheep are getting enough energy. - Cold weather, wind, wet fleece, and poor forage quality all increase energy requirements. - Sudden feed changes cause digestive upset. Make all ration changes gradually over 7 to 10 days. - Call a veterinarian if a ewe is down and unable to rise, if multiple ewes are weak in late pregnancy, or if lambs are dying despite adequate feeding. ## Understanding Energy in Sheep Diets Energy is not a nutrient like protein or calcium. It is the capacity of a feed to do work in the body. When a sheep eats forage or grain, the carbohydrates, fats, and excess protein in that feed are broken down during digestion and metabolism. The energy released powers every bodily function from breathing and walking to growing wool, building a fetus, and producing milk. Sheep do not have a direct requirement for a specific feed ingredient. They have a requirement for energy, protein, vitamins, minerals, and water. Your job as a feeder is to combine ingredients that meet those requirements in the proper amounts. Energy is usually the most expensive part of the ration and the most common deficiency on sheep farms. Several factors influence how much energy a sheep needs on any given day. These include body weight, stage of production, ambient temperature, wind speed, hair coat or fleece condition, activity level, and health status. A thin ewe in a cold barn during a January blizzard has very different energy needs than the same ewe in October on lush pasture. The two systems you will encounter for measuring and expressing energy are TDN and net energy. Both are used in feed tables, ration balancing software, and on feed tags. Understanding both will help you read a feed analysis, talk to a nutritionist, and make better decisions when you are standing in the feed store. ### What TDN Means Total digestible nutrients, or TDN, is an older system but still the most widely used for sheep in the United States. TDN is expressed as a percentage of the feed or as pounds per day. It represents the sum of the digestible components of a feed: digestible crude protein, digestible crude fiber, digestible nitrogen-free extract, and digestible ether extract multiplied by 2.25. The 2.25 multiplier for fat reflects the fact that fats contain about 2.25 times more energy than carbohydrates or protein. This is why adding fat to a sheep ration can boost energy density without increasing bulk. A feed with a TDN value of 55 percent means that 55 percent of the dry matter in that feed is digestible and available for energy. The other 45 percent passes through the digestive tract or is lost in fermentation gases and heat. Typical TDN values for common sheep feeds are: - Good alfalfa hay: 58 to 62 percent TDN - Mixed grass hay: 50 to 58 percent TDN - Corn silage: 65 to 70 percent TDN - Whole shelled corn: 80 to 85 percent TDN - Soybean meal: 80 to 85 percent TDN - Wheat middlings: 70 to 75 percent TDN - Mature pasture: 55 to 65 percent TDN The TDN system is simple and works well for practical on-farm feeding. Its main limitation is that it treats all energy as equal, when in reality different feeds convert to usable energy with different efficiencies. ### What Net Energy Means The net energy system is more precise than TDN because it accounts for the fact that not all digestible energy is equally useful to the animal. Energy is lost at several points. Some is lost in feces, some in urine, and some as heat produced during digestion and metabolism. What remains after these losses is the net energy, which is what the animal actually uses for maintenance, growth, pregnancy, lactation, and wool production. The net energy system divides energy into two or more categories. The most common split is between net energy for maintenance (NEm) and net energy for gain (NEg). Some systems add a separate net energy for lactation (NEI) and net energy for pregnancy (NEp). The reason for the split is that a feed may be very efficient for maintenance but less efficient for weight gain. High fiber forages have a higher NEm relative to their NEg because the heat generated during fiber digestion helps keep the animal warm. Concentrates like corn have high values for both maintenance and gain because they are digested more completely and produce less heat. Net energy values are expressed in megacalories per pound or per kilogram of feed. A megacalorie (Mcal) is one million calories. For example, good alfalfa hay might have a NEm of 0.58 Mcal per pound and an NEg of 0.28 Mcal per pound. Whole corn might have a NEm of 0.92 Mcal per pound and an NEg of 0.62 Mcal per pound. The net energy system is more accurate for predicting weight gain and for fine-tuning rations in feedlots. It is also the system used by the National Research Council (NRC) in its nutrient requirement tables for sheep. However, it requires more detailed feed analysis data and is more complex to calculate by hand. For most sheep producers, TDN is sufficient for day to day feeding decisions. Net energy becomes more useful when you are growing lambs for market, pushing for maximum gain, or working with a nutritionist to fine tune a high concentrate ration. ### Converting Between TDN and Net Energy You can estimate net energy values from TDN using standard equations if you only have a TDN value. These are useful for ration balancing: NEm (Mcal per pound) = (0.0268 x TDN percent) minus 0.0415 NEg (Mcal per pound) = (0.0268 x TDN percent) minus 0.127 For example, a hay with 58 percent TDN would have an estimated NEm of about 1.11 Mcal per pound and an NEg of about 0.43 Mcal per pound. These estimates are rough and work best for typical forages and grains. They become less accurate for feeds with unusual fat content or processing methods. If you are using a commercial ration balancer or working with an extension nutritionist, you will not need to do these conversions by hand. The software handles the calculations. ## Energy Requirements by Production Stage Sheep energy needs change dramatically across the production cycle. A ewe in early pregnancy on good pasture may need only maintenance energy. The same ewe in the final six weeks of pregnancy with twins has requirements that are 50 to 75 percent higher. Understanding these changes lets you plan your feeding program and avoid the costly mistakes of underfeeding or overfeeding. ### Maintenance Requirements Maintenance is the energy needed to keep a sheep alive and healthy with no weight gain or loss, no pregnancy, and no milk production. It is the baseline from which all other requirements are calculated. The maintenance energy requirement of a mature ewe is approximately 0.75 to 1.0 Mcal of NEm per 100 pounds of body weight per day. In TDN terms, this works out to roughly 1.0 to 1.5 pounds of TDN per day for a 150 pound ewe. A practical way to think about maintenance is in terms of forage intake. A mature ewe at maintenance will eat about 2.0 to 2.5 percent of her body weight in dry matter per day. For a 150 pound ewe, that is 3.0 to 3.75 pounds of dry matter. If she is eating hay that is 90 percent dry matter and 55 percent TDN, she needs about 3.3 to 4.2 pounds of as fed hay per day to meet maintenance. Maintenance requirements increase with body size. A 200 pound ewe needs more total energy than a 120 pound ewe, but she needs less energy per pound of body weight. This is because maintenance is related to metabolic body weight, which is body weight raised to the 0.75 power, not simply body weight itself. ### Early to Mid Pregnancy For the first 15 weeks of pregnancy, a ewe's energy requirement is only slightly above maintenance. The fetus is small and grows slowly during this period. A ewe that is in good body condition can meet her needs on good quality forage alone. The main concern during this stage is not underfeeding but overfeeding. Ewes that gain excessive condition in early pregnancy are harder to manage later. They may have difficult lambing due to fat deposits in the birth canal, and they are more likely to develop pregnancy toxemia if they are then restricted in late pregnancy. Aim to maintain body condition during early pregnancy. Ewes should enter the breeding season at a body condition score of 3.0 to 3.5 on a 5 point scale. They should hold that score through the first 15 weeks of gestation. ### Late Pregnancy The last six weeks of pregnancy are the most critical feeding period for a ewe flock. Two thirds of fetal growth occurs during this time. A single lamb fetus gains about 0.5 pounds per day in the final weeks, and twin fetuses gain even more in total. Energy requirements increase by 50 percent for a ewe carrying a single lamb and by 75 percent or more for a ewe carrying twins. A 150 pound ewe carrying twins in late pregnancy needs roughly 2.5 to 3.0 pounds of TDN per day. This is the period when pregnancy toxemia, also called ketosis or twin lamb disease, is most likely to occur. Pregnancy toxemia develops when a ewe cannot consume enough energy to meet the demands of the growing fetus and her own maintenance. Her body mobilizes fat reserves, which overwhelms the liver and produces ketones. Affected ewes become dull, stop eating, grind their teeth, and may go down. The condition is often fatal without prompt treatment. The key to preventing pregnancy toxemia is to keep energy intake high during late pregnancy. This usually means adding grain to the ration. Start with 0.25 to 0.5 pounds of grain per ewe per day about six weeks before lambing, and increase gradually to 1.0 to 1.5 pounds per day by the time lambing begins. Ewes carrying twins may need more. Do not let ewes become fat in early pregnancy and then restrict them in late pregnancy. This is a common cause of pregnancy toxemia. Fat ewes have reduced appetite and cannot increase intake enough to meet late pregnancy demands. ### Lactation Lactation is the most energetically demanding period in a ewe's life. A ewe nursing a single lamb needs about 50 percent more energy than at maintenance. A ewe nursing twins needs about 75 to 100 percent more. Milk production peaks at about three to four weeks after lambing. A ewe nursing twins can produce 4 to 6 pounds of milk per day at peak. This milk is rich in fat and protein, which requires enormous energy output from the ewe. A 150 pound ewe nursing twins needs roughly 4.0 to 5.0 pounds of TDN per day at peak lactation. This is difficult to achieve with forage alone. Most producers feed 1.5 to 2.5 pounds of grain per ewe per day during the first six to eight weeks of lactation. Ewes that are underfed during lactation will milk less and wean lighter lambs. They will also lose body condition rapidly. A ewe that loses more than one body condition score during lactation is at risk of poor fertility at the next breeding season. ### Growth in Lambs Growing lambs have high energy requirements relative to their body size. A lamb gaining 0.5 pounds per day needs about 1.5 to 2.0 pounds of TDN per day, depending on its weight. Lambs gaining 0.75 pounds per day need even more. The energy system becomes more important for growing lambs because the efficiency of gain varies with diet composition. High concentrate rations produce more efficient gains than all forage rations. This is why feedlot lambs are fed increasing amounts of grain. For lambs on pasture, energy intake depends on milk supply and forage quality. Lambs from well fed ewes with abundant high quality pasture can gain 0.5 to 0.75 pounds per day without creep feed. Adding a creep ration of 15 to 18 percent protein grain can boost gains to 0.75 to 1.0 pounds per day. ### Wool Production Wool growth requires energy, but the amount is small compared to maintenance, pregnancy, and lactation. Wool production accounts for about 5 to 10 percent of a sheep's total energy requirement. A fine wool ewe producing 10 pounds of wool per year uses roughly the same energy as producing 10 pounds of milk. Do not make feeding decisions based on wool production alone. If your ewes are in good condition and producing adequate wool, their energy needs for wool are being met. ## Cold Weather and Environmental Stress Sheep are remarkably cold tolerant when they have a dry fleece and protection from wind. A ewe with a full fleece can withstand temperatures well below freezing without increasing her energy requirement. But cold stress becomes significant when the fleece is wet, when wind exceeds 10 miles per hour, or when temperatures drop below about 20 degrees Fahrenheit for sheep with short fleeces. The lower critical temperature for a well fed ewe with a full fleece is around 20 to 30 degrees Fahrenheit. Below this temperature, she must burn extra energy to stay warm. Her energy requirement increases by about 1 percent for each degree below the lower critical temperature. For example, a ewe with a full fleece in 10 degree weather has a lower critical temperature of 25 degrees. She needs about 15 percent more energy than at maintenance. A ewe with a wet fleece or a recently shorn fleece has a much higher lower critical temperature, possibly 50 to 60 degrees. She needs substantially more energy in cold weather. Wind increases heat loss dramatically. A 20 mile per hour wind can double the effective heat loss from a sheep. Windbreaks, barns, and shelter are often more important than extra feed for reducing cold stress. Practical adjustments for cold weather include: - Increase hay feeding by 10 to 25 percent during cold snaps. - Provide good quality hay so sheep can eat more without filling up on stems. - Add grain to the ration during extreme cold, especially for thin ewes and ewes in late pregnancy. - Ensure water is available and not frozen. Sheep will not eat enough if they cannot drink. - Provide shelter from wind. A three sided shed or a row of round bales can make a huge difference. - Keep fleeces dry. Wet fleeces lose insulating value almost completely. Do not assume that sheep can simply eat more to compensate for cold. Their gut capacity is limited. If the forage is poor quality and fills the rumen without providing enough energy, they cannot eat enough to meet their needs. This is why feeding higher quality forage and adding grain is important during cold weather. ## Body Condition Scoring as an Energy Check Body condition scoring is the single most useful tool for evaluating whether your sheep are getting enough energy. It is simple, requires no equipment, and gives you immediate feedback on your feeding program. The standard system uses a 5 point scale: - Score 1: Very thin. Spine and ribs are sharp and easily felt. No fat cover. - Score 2: Thin. Spine and ribs are felt with slight pressure. Some muscle cover. - Score 3: Moderate. Spine and ribs are felt with firm pressure. Smooth fat cover over the loin. - Score 4: Fat. Spine and ribs are difficult to feel. Thick fat cover. - Score 5: Very fat. Spine and ribs cannot be felt. Heavy fat deposits. To score a ewe, stand behind her and place your thumb on her spine and your fingers on the ends of her ribs. Run your hand along her loin area. The amount of flesh you feel over the spine and ribs tells you her condition. Score ewes at key points in the production cycle: - At breeding: target 3.0 to 3.5 - Mid pregnancy: target 3.0 - Late pregnancy: target 3.0 to 3.5 - At lambing: target 3.0 - At weaning: target 2.5 to 3.0 If ewes are losing condition, increase energy intake. If they are gaining too much, reduce grain or move them to lower quality forage. Body condition scoring catches problems before they become emergencies. ## Calculating Rations by Hand You can balance a sheep ration by hand using TDN values and published requirement tables. This is useful for understanding the process and for checking the output of ration balancing software. The steps are: 1. Determine the body weight and production stage of your sheep. 2. Look up the TDN requirement for that weight and stage. 3. Determine the dry matter intake of your sheep. 4. Calculate the TDN provided by each feed in the ration. 5. Adjust the ration until TDN supplied equals TDN required. ### Step 1: Determine Requirements Use the following approximate TDN requirements for a 150 pound ewe: - Maintenance: 1.2 pounds TDN per day - Early pregnancy: 1.3 pounds TDN per day - Late pregnancy, single: 1.8 pounds TDN per day - Late pregnancy, twins: 2.2 pounds TDN per day - Early lactation, single: 2.5 pounds TDN per day - Early lactation, twins: 3.0 pounds TDN per day For heavier or lighter ewes, adjust proportionally. A 120 pound ewe needs about 85 percent of these amounts. A 180 pound ewe needs about 115 percent. ### Step 2: Determine Dry Matter Intake Sheep eat about 2.0 to 3.0 percent of their body weight in dry matter per day. Pregnant ewes in late gestation may eat less due to the space taken up by the uterus. Lactating ewes eat more. For a 150 pound ewe, dry matter intake is about 3.0 to 4.5 pounds per day. Use 3.5 pounds as a starting estimate. ### Step 3: Calculate TDN Supplied Multiply the pounds of each feed by its TDN percentage. For example, if you feed 4 pounds of hay that is 55 percent TDN, the hay supplies 2.2 pounds of TDN. If you feed 1 pound of corn that is 85 percent TDN, the corn supplies 0.85 pounds of TDN. ### Step 4: Adjust the Ration Compare TDN supplied to TDN required. If the ration falls short, add grain or switch to higher quality forage. If it exceeds requirements, reduce grain or feed lower quality forage. This hand calculation method is approximate. It does not account for individual variation, feed quality differences, or environmental stress. But it gives you a solid starting point and helps you understand what your sheep need. ## Using Feed Analysis and Feed Tags You cannot balance a ration accurately without knowing the nutrient content of your feed. Hay varies enormously in quality depending on maturity, species, growing conditions, and storage. A load of hay cut at early bloom may test 60 percent TDN, while the same field cut at full maturity may test only 45 percent. Send a hay sample to a forage testing lab before making major feeding decisions. Most state extension services can direct you to an accredited lab. A standard forage analysis costs between 20 and 50 dollars and includes dry matter, crude protein, TDN, and mineral content. Take hay samples with a hay probe, not by hand. Probe at least 10 to 15 bales from different parts of the lot. Combine the cores into one sample and submit it to the lab. When you buy commercial feed, read the tag. The tag lists crude protein, crude fat, crude fiber, and sometimes TDN or net energy. Feed tags are required by law to list guaranteed analysis, but the guarantees are minimums or maximums, not exact values. A typical sheep feed tag might guarantee: - Crude protein: minimum 16 percent - Crude fat: minimum 3 percent - Crude fiber: maximum 12 percent - Calcium: 0.8 to 1.2 percent - Phosphorus: minimum 0.5 percent The tag may also list TDN or net energy. If not, you can estimate TDN from the ingredients or ask the feed company for their analysis. ## Feeding Management Strategies How you deliver feed matters as much as what you feed. Sheep are creatures of habit and do best with a consistent routine. ### Feeding Forage Provide forage free choice or in measured amounts twice daily. Free choice feeding is simplest and allows each sheep to eat as much as she needs. The risk is that some sheep overeat and become fat, while timid sheep may not get enough. Group feeding by body condition and production stage is the best approach. Sort thin ewes, fat ewes, ewes with singles, and ewes with twins into separate groups. Feed each group according to its needs. This requires extra pens but pays for itself in reduced feed costs and healthier sheep. When feeding hay, use a feeder to reduce waste. Hay on the ground can be trampled and soiled, leading to 20 to 40 percent waste. A simple hay rack or bale feeder reduces waste to 5 to 15 percent. ### Adding Grain Introduce grain gradually over 7 to 10 days. Sudden grain introduction can cause acidosis, a serious digestive disturbance. Start with 0.25 pounds per ewe per day and increase by 0.25 pounds every few days until you reach the target amount. Feed grain in troughs with enough space for all sheep to eat at once. Provide 18 to 24 inches of trough space per ewe. If timid ewes cannot access the grain, they will not get their share. Consider feeding a complete pelleted ration if you want precise control over nutrient intake. Pellets prevent sorting and ensure each sheep eats a balanced diet. They are more expensive than whole grains and hay but reduce waste and simplify feeding. ### Water Clean, fresh water is essential for energy metabolism. Sheep drink 1 to 2 gallons per day depending on size, production stage, and weather. Lactating ewes drink more. Cold weather reduces drinking if water is cold or frozen. Check waterers daily in winter. Break ice or use heated waterers. A ewe that cannot drink will reduce feed intake and lose condition rapidly. ### Mineral Supplementation Energy metabolism requires phosphorus, and many sheep rations are low in phosphorus relative to calcium. Provide a loose mineral supplement formulated for sheep. Do not use cattle mineral, which often contains copper at levels toxic to sheep. Sheep mineral should contain 6 to 8 percent phosphorus and no added copper. Offer it free choice in a covered mineral feeder. Monitor intake and adjust if sheep are consuming too much or too little. ## Common Mistakes in Meeting Sheep Energy Requirements Many feeding problems on sheep farms come from a few recurring mistakes. Recognizing these can save you from costly losses. ### Mistake 1: Assuming All Hay Is Equal Hay quality varies more than any other factor in sheep feeding. A beautiful looking bale can be low in energy if it was cut late or rained on. Do not judge hay by color or smell alone. Test it and feed according to the analysis. ### Mistake 2: Underfeeding in Late Pregnancy The last six weeks of pregnancy is when energy needs climb fastest, but it is also when ewes have the least room in their abdomen for feed. The uterus takes up space, reducing rumen capacity. Ewes cannot simply eat more hay to meet their needs. They need energy dense feeds like grain. ### Mistake 3: Overfeeding in Early Pregnancy Fat ewes in early pregnancy are at risk for lambing difficulty and pregnancy toxemia later. Do not let ewes get fat during the first half of pregnancy thinking you are doing them a favor. Maintain condition at 3.0 to 3.5. ### Mistake 4: Ignoring Body Condition Scores Body condition scoring takes two minutes per ewe and tells you more about energy status than any feed tag. If you are not scoring your ewes, you are flying blind. Score at breeding, mid pregnancy, and lambing. ### Mistake 5: Sudden Ration Changes Sheep rumen microbes need time to adapt to new feeds. A sudden switch from hay to grain, or from one grain to another, can cause acidosis, founder, or off feed problems. Always transition over 7 to 10 days. ### Mistake 6: Forgetting About Water Water is the most essential nutrient and the one most often overlooked. Frozen waterers, empty tanks, and low pressure lines cause sheep to reduce intake. Check water daily, especially in winter. ### Mistake 7: Not Adjusting for Cold Weather A ewe in a full fleece can handle cold, but wet fleece, wind, and short fleece all increase energy needs dramatically. Do not assume your sheep are fine just because they have a winter coat. Provide shelter and increase feed during cold snaps. ## Monitoring and Recordkeeping Good feeding decisions depend on good records. Keep track of what you feed, how much it costs, and how your sheep respond. At minimum, record: - Hay analysis results for each lot of hay - Grain type and amount fed per day - Number of sheep in each feeding group - Body condition scores at breeding, mid pregnancy, and lambing - Lamb birth weights and weaning weights - Ewe losses and causes of death - Feed costs per ewe per day Use this information to evaluate your feeding program each year. If lamb birth weights are low, you may be underfeeding in late pregnancy. If ewes are too fat at lambing, you are overfeeding. If weaning weights are poor, lactation nutrition needs improvement. Body condition scores are the most valuable record you can keep. They give you a direct measure of energy status that is not affected by gut fill or wool length. Score every ewe at each handling and write the scores down. ## Decision Thresholds for Intervention Knowing when to act is as important as knowing what to do. Use these thresholds to guide your decisions. ### Thin Ewes If any ewe scores 2 or less on the 5 point body condition scale, she needs immediate attention. Separate her from the flock and feed her a higher energy ration. Provide good quality hay free choice and 0.5 to 1.0 pounds of grain per day. If a thin ewe is in late pregnancy, she is at high risk for pregnancy toxemia. Increase her energy intake immediately and monitor her closely. If she stops eating or becomes dull, call a veterinarian. ### Fat Ewes If a ewe scores 4 or more at breeding or early pregnancy, reduce her energy intake. Move her to lower quality forage or restrict grazing. Do not let her gain more condition. A fat ewe at lambing is at risk for dystocia and pregnancy toxemia. If she goes off feed in late pregnancy, she needs immediate veterinary attention. ### Down Ewes A ewe that is down and unable to rise is an emergency. This can be pregnancy toxemia, milk fever, injury, or another serious condition. Call a veterinarian immediately. While waiting, provide shelter, water, and good footing. Do not force feed a down ewe unless directed by a veterinarian. ### Multiple Cases of Weakness If several ewes show weakness, lethargy, or poor appetite at the same time, evaluate your feeding program. Check hay quality, grain amounts, and water availability. Test the hay if you have not done so. Call your extension agent for help with ration balancing. ### Poor Lamb Vigor If lambs are born weak, slow to nurse, or have low birth weights, the problem is often energy underfeeding in late pregnancy. Review your late gestation ration and adjust for next year. Consider pregnancy scanning to identify ewes carrying twins so you can feed them extra. ## When to Call a Veterinarian or Extension Agent You should call a veterinarian immediately for any of these situations: - A ewe is down and unable to rise - A ewe in late pregnancy stops eating and appears dull or depressed - A ewe shows signs of pregnancy toxemia, including teeth grinding, blindness, or staggering - Multiple ewes are off feed or showing signs of illness - A ewe has difficulty lambing and you cannot resolve it - Lambs are dying despite adequate feeding Call your extension agent for help with: - Hay testing and interpretation of results - Ration balancing and feed budgeting - Body condition scoring training - Evaluating your feeding facilities - Planning a feeding program for your specific flock size and production system Extension agents have access to the latest research and can often help you solve problems before they become emergencies. Do not hesitate to contact them. ## Frequently Asked Questions ### How much hay does a sheep need per day? A mature ewe at maintenance eats about 2.0 to 2.5 percent of her body weight in dry matter per day. For a 150 pound ewe, that is 3.0 to 3.75 pounds of dry matter, which is roughly 3.3 to 4.2 pounds of hay as fed. Pregnant ewes in late gestation and lactating ewes need more energy, so they may need additional grain or higher quality forage. ### What is the difference between TDN and net energy? TDN is a single value that represents the total digestible nutrients in a feed. It is simple and easy to use. Net energy splits energy into separate values for maintenance and gain, which is more precise but more complex. TDN is sufficient for most on farm feeding decisions. Net energy is more useful for fine tuning rations for growing lambs or working with a nutritionist. ### How do I know if my ewe is getting enough energy? The best way is to body condition score your ewes. A ewe at a body condition score of 3.0 is getting adequate energy. If ewes are dropping condition, they need more energy. If they are gaining too much, reduce energy intake. Also monitor lamb birth weights and weaning weights. Low birth weights suggest underfeeding in late pregnancy. ### Can sheep get too much energy? Yes. Overfeeding energy leads to obesity, which causes lambing difficulty, pregnancy toxemia, and reduced fertility. Fat ewes have more problems at lambing and produce less milk. Feed to maintain a body condition score of 3.0 to 3.5, not to maximize weight gain. ### What is pregnancy toxemia and how do I prevent it? Pregnancy toxemia, also called ketosis or twin lamb disease, occurs when a ewe in late pregnancy cannot consume enough energy to meet the demands of her growing fetuses. She mobilizes fat reserves, which produces ketones and can be fatal. Prevention focuses on keeping energy intake high in late pregnancy, especially for ewes carrying twins. Feed grain during the last six weeks of pregnancy and avoid letting ewes become too fat. ### How much grain should I feed a pregnant ewe? Start with 0.25 to 0.5 pounds per ewe per day about six weeks before lambing. Increase gradually to 1.0 to 1.5 pounds per day by lambing time. Ewes carrying twins may need more. Introduce grain gradually over 7 to 10 days to prevent digestive upset. ### Do sheep need more energy in winter? Yes, especially when temperatures drop below about 20 to 30 degrees Fahrenheit, when wind is strong, or when fleeces are wet. A ewe with a full dry fleece can handle cold well, but wet or shorn sheep need extra energy. Increase hay feeding by 10 to 25 percent during cold snaps and consider adding grain. ### What should I do if a ewe stops eating in late pregnancy? This is an emergency. A ewe that stops eating in late pregnancy is at high risk for pregnancy toxemia. Call a veterinarian immediately. While waiting, provide fresh water and offer palatable feeds like good quality hay, grain, or molasses. Do not force feed unless directed by a veterinarian. ## Related Farming Guides This section will be populated with links to related sheep management guides, including articles on ewe nutrition, lamb feeding, forage management, and flock health protocols. Check back for updates or browse the sheep category for more practical farming information. ## Related Clinical & Scientific Guides * [Sheep Grazing Lease: Terms, Rates, and Legal Considerations](/knowledge/animal-farming/sheep/sheep-grazing-lease-terms-rates-and-legal-considerations) * [Sheep Breed Selection for Meat, Wool, Dairy, and Low-Input Systems](/knowledge/animal-farming/sheep/sheep-breed-selection-for-meat-wool-dairy-and-low-input-systems) * [Sheep Barn Flooring for Hoof Health: Best Materials and Practices](/knowledge/animal-farming/sheep/sheep-barn-flooring-hoof-health-materials-practices) ## References - American Consortium for [Small Ruminant Parasite Control](/knowledge/veterinary-medicine/food-animal-medicine/small-ruminant-parasite-control-diagnostic-strategies-anthelmintic-stewardship) (ACSRPC): https://www.wormx.info/ - USDA APHIS Sheep Health: https://www.aphis.usda.gov/livestock-poultry-disease/sheep-goats - FAO Sheep and Goat Production: https://www.fao.org/animal-production/en/ - FAO Animal Production and Health: https://www.fao.org/animal-production/en/ - WOAH (World Organisation for Animal Health): https://www.woah.org/en/home/ > This article is educational and is not a substitute for veterinary diagnosis, treatment, public-health guidance, or regulatory reporting.