# Swine Ration Formulation Basics: Nutrients and Ingredients ## Key Takeaways - Swine ration formulation prioritizes meeting specific nutrient requirements over simply providing ingredients, with energy, protein/amino acids, minerals, vitamins, water, and fiber being the six essential classes. Lysine is the primary limiting amino acid in typical corn-soybean meal diets, necessitating precise balancing of essential amino acids for optimal growth and reduced nitrogen excretion. - Corn and soybean meal form the foundational components of North American swine diets, but alternative ingredients like Distillers Dried Grains with Solubles (DDGS) and bakery meal can be cost-effective substitutes, though their inclusion rates must account for variations in nutrient digestibility, amino acid profiles, and fat quality. - Calcium and phosphorus must be maintained in a specific ratio, typically 1.2:1 to 1.4:1 (Ca:P), for growing pigs, with supplemental inorganic phosphorus sources or phytase enzymes often required due to the low bioavailability of phosphorus in plant-based ingredients. - Phase feeding, which adjusts diet composition based on the pig's age, weight, and production stage (nursery, grower, finisher, sow), is critical for optimizing nutrient utilization, reducing feed costs, and minimizing nutrient excretion. - Accurate ration formulation relies on understanding ingredient nutrient variability through regular analysis, proper mixing techniques to ensure uniform nutrient distribution, and gradual diet transitions to prevent digestive upset and performance losses. - Monitoring feed intake, growth performance, body condition scoring (especially for sows), and carcass quality, alongside meticulous record-keeping, is essential for evaluating the efficacy of the feeding program and making necessary adjustments. --- Feed represents the largest single cost on most swine operations, often accounting for 60 to 75 percent of total production expenses. Getting the ration right matters for your bottom line, for pig health, and for growth performance. This guide explains the core nutrients pigs need, the common ingredients used to supply those nutrients, and the practical steps for building a balanced ration on your farm. It is written for independent producers, farm managers, and those new to swine diet formulation who want a working understanding of the process without needing an advanced degree in animal nutrition. ## At a Glance - Pigs require six major nutrient classes: energy, protein and amino acids, minerals, vitamins, water, and fiber. - Amino acids, not crude protein, are what pigs actually need. Lysine is the first limiting amino acid in most corn and soybean meal diets. - Corn and soybean meal form the backbone of most swine rations in North America, but alternative ingredients can reduce cost when prices shift. - Calcium and phosphorus must be balanced in a specific ratio, typically 1.2 to 1.4 parts calcium to 1 part phosphorus for growing pigs. - Feed budgets change with pig age and weight. Nursery pigs need highly digestible, nutrient dense diets, while finishing pigs need less protein and more energy. - Phase feeding matches the ration to the pig's changing nutrient requirements, which reduces feed cost and minimizes nutrient excretion. - Always consult a qualified nutritionist or extension specialist before making major changes to your feeding program. Small errors in formulation can cost thousands of dollars over a finishing cycle. ## Understanding Swine Nutrient Requirements Pigs need nutrients, not ingredients. This is the foundational idea behind ration formulation. You build a diet from available ingredients to meet the pig's requirements for energy, amino acids, minerals, vitamins, and water. The ingredients are simply vehicles for delivering those nutrients. Nutrient requirements for pigs vary by age, weight, sex, genetics, and production stage. A lactating sow has very different needs from a 30 pound nursery pig or a 250 pound finishing hog. The National Pork Board and land grant university extension services publish tables of nutrient requirements that serve as the standard reference for most US producers. The National Research Council also publishes detailed nutrient requirement tables, though the most current edition is now several years old and many nutritionists use updated university recommendations. ### Energy Energy is not a nutrient in the chemical sense, but it is the first thing you balance in most swine rations. Pigs need energy for maintenance, growth, reproduction, and lactation. Energy comes primarily from carbohydrates and fats in the diet. In swine nutrition, energy is expressed in several ways. Metabolizable energy (ME) and net energy (NE) are the two most common systems. Net energy accounts for the energy lost in digestion and the heat produced during nutrient metabolism, so it more accurately reflects the energy available for productive purposes. Most modern formulation programs use net energy values for corn and soybean meal based diets. Corn is the standard energy source in US swine diets. It provides starch, which pigs digest readily. When corn prices are high, you can substitute other grains or byproducts. Wheat, barley, sorghum, and bakery meal can replace part or all of the corn in a ration, though each has different energy and nutrient values. Added fats and oils increase energy density and can improve feed efficiency, especially in nursery diets and lactation diets. ### Protein and Amino Acids Pigs require amino acids, not protein per se. Amino acids are the building blocks of muscle and other body tissues. When a pig eats protein, the digestive system breaks it down into individual amino acids, which are then absorbed and reassembled into body protein. There are 10 essential amino acids that pigs cannot synthesize in sufficient amounts and must get from the diet. Lysine is almost always the first limiting amino acid in corn and soybean meal diets, meaning it is the amino acid present in the lowest amount relative to the pig's requirement. Threonine, methionine, tryptophan, and valine are also commonly limiting. The concept of ideal protein is central to modern swine ration formulation. An ideal protein is one that provides all essential amino acids in exactly the proportions the pig needs. By formulating to meet the requirement for lysine first, then ensuring the other essential amino acids are present in adequate ratios to lysine, you can meet the pig's amino acid needs with less total protein. This reduces feed cost and lowers nitrogen excretion. Soybean meal is the standard protein source in US swine diets because it has an excellent amino acid profile and high digestibility. Other protein sources include canola meal, distillers dried grains with solubles (DDGS), field peas, and synthetic amino acids. Lysine, threonine, methionine, and tryptophan are available as feed grade supplements and are commonly used to balance diets when using alternative protein sources. ### Minerals Pigs need a range of macro and trace minerals. The macrominerals, those needed in larger amounts, include calcium, phosphorus, sodium, chloride, potassium, magnesium, and sulfur. The trace minerals, needed in smaller amounts, include zinc, copper, iron, manganese, iodine, and selenium. Calcium and phosphorus are the minerals you will pay the most attention to in formulation. Both are critical for bone development, and phosphorus also plays a role in energy metabolism and cell function. The ratio of calcium to phosphorus matters. For growing pigs, the recommended ratio is typically 1.2 to 1.4 parts calcium to 1 part available phosphorus. Too much calcium relative to phosphorus can reduce phosphorus absorption and cause bone problems. Most of the phosphorus in corn and soybean meal is bound in phytic acid, which pigs cannot digest efficiently. This means you must add inorganic phosphorus sources such as monocalcium phosphate or dicalcium phosphate to meet the pig's available phosphorus requirement. Phytase enzymes can be added to the diet to break down phytate and release more phosphorus, which reduces the need for supplemental inorganic phosphorus and lowers feed cost. Sodium and chloride are supplied by salt. Iodized salt is commonly used to ensure adequate iodine intake. Potassium is usually adequate in grain based diets, so it rarely needs supplementation. Trace minerals are typically added as a premix. Most commercial premises include zinc, copper, iron, manganese, iodine, and selenium at levels that meet or slightly exceed requirements. Zinc and copper are also fed at pharmacological levels in nursery diets to support growth and reduce post weaning diarrhea, though this practice is increasingly regulated in some regions due to environmental concerns. ### Vitamins Vitamins are organic compounds needed in small amounts for normal physiological function. They are divided into fat soluble vitamins (A, D, E, K) and water soluble vitamins (the B complex and vitamin C). Pigs can synthesize vitamin C and most B vitamins in their digestive tract, but modern production systems typically supplement all vitamins in the diet to ensure adequate intake. Vitamin E and selenium work together as antioxidants and are especially important for immune function and preventing nutritional muscular dystrophy. Vitamin D is critical for calcium and phosphorus metabolism and bone health. Vitamins are usually added as a vitamin premix. The premix is a concentrated blend of vitamins mixed with a carrier such as rice hulls or wheat middlings. Premixes are added at very low inclusion rates, typically 0.05 to 0.25 percent of the diet, so accurate mixing is essential. ### Water Water is the most essential nutrient. Pigs can survive for weeks without feed but only days without water. Water intake affects feed intake, growth, and overall health. Growing pigs need about 1.5 to 2 gallons of water per day, while lactating sows can need 5 to 7 gallons or more. Water quality matters. High levels of sulfates, nitrates, iron, or total dissolved solids can reduce water intake and pig performance. If you suspect water quality issues, have your water tested. Most extension services offer water testing for livestock operations. ### Fiber Pigs have a limited ability to digest fiber compared to ruminants. Fiber provides bulk and can help maintain gut health, but high fiber levels reduce energy density and can limit feed intake, especially in young pigs. The fiber content of the diet is more of a constraint than a requirement. You need to keep fiber low enough that it does not limit energy intake, but some fiber is beneficial for gut health and reducing behavioral issues like tail biting. ## Common Swine Feed Ingredients The ingredient list for swine diets is long, but a handful of ingredients make up the vast majority of what pigs eat in North America. Understanding the nutritional value and limitations of each ingredient helps you make informed decisions when prices change or supplies tighten. ### Corn Corn is the primary energy source in US swine diets. It is high in starch, low in fiber, and highly palatable. Whole kernel corn should be ground before feeding to improve digestibility. A medium grind with a particle size of about 600 to 800 microns is generally recommended. Grinding too fine can cause stomach ulcers and dust issues, while grinding too coarse reduces nutrient digestibility. Corn is low in lysine and other essential amino acids, so it must be supplemented with protein sources. Yellow dent corn is the standard type used in livestock feed. High oil corn and other specialty varieties are available but are rarely economical for swine diets. ### Soybean Meal Soybean meal is the standard protein supplement in US swine diets. It is produced by extracting oil from soybeans, leaving a high protein meal. Solvent extracted soybean meal contains about 44 to 48 percent crude protein and has an excellent amino acid profile. It is highly digestible and palatable. Soybean meal is the reference protein source in swine nutrition. Most other protein sources are compared to soybean meal for amino acid content and digestibility. When soybean meal prices are high, nutritionists look for ways to reduce inclusion rates by using synthetic amino acids or alternative protein sources. ### Distillers Dried Grains with Solubles (DDGS) DDGS is a byproduct of ethanol production. It contains about 25 to 30 percent crude protein, 8 to 12 percent fat, and high levels of phosphorus. It is often cheaper per unit of energy and protein than corn and soybean meal, making it an attractive ingredient when prices are favorable. However, DDGS has limitations. The protein is less digestible than soybean meal protein, and the amino acid profile is less balanced. DDGS is high in fiber, which limits inclusion rates, especially in nursery diets. The fat in DDGS can vary in quality, and high levels of unsaturated fat can affect carcass fat quality, making the fat softer and less desirable for processing. Typical inclusion rates are 10 to 30 percent in grower and finisher diets, 5 to 10 percent in nursery diets, and 10 to 20 percent in sow diets. Higher inclusions are possible but require careful attention to amino acid balance and fat quality. ### Bakery Meal Bakery meal is a byproduct of the baking industry, consisting of unsold bread, cookies, crackers, and other baked goods. It is high in energy and can replace corn in swine diets. Bakery meal is often cheaper than corn on a per unit of energy basis. The main concern with bakery meal is variation in nutrient content. Different sources can vary widely in fat, salt, and moisture content. If you use bakery meal, have it analyzed regularly and adjust the formulation accordingly. Bakery meal can also contain packaging materials if not processed properly, so source quality matters. ### Wheat and Wheat Byproducts Wheat can replace corn in swine diets, though it has slightly lower energy content. Wheat is higher in protein than corn, so it can reduce the need for supplemental protein. Wheat middlings, a byproduct of flour milling, are lower in energy and higher in fiber but can be used at moderate inclusion rates in grower and finisher diets. When wheat is used in swine diets, it should be ground to a similar particle size as corn. Whole wheat can be fed to older pigs, but grinding improves digestibility. Wheat has a higher risk of causing digestive issues if the diet is changed suddenly, so introduce it gradually. ### Other Protein Sources Canola meal is a byproduct of canola oil production. It has about 35 to 38 percent crude protein and a good amino acid profile, though it is lower in energy than soybean meal due to higher fiber content. Canola meal can replace part of the soybean meal in swine diets, especially in grower and finisher phases. Field peas are a pulse crop that can be used in swine diets. They contain about 20 to 24 percent crude protein and are highly digestible. Field peas can replace both corn and soybean meal in some formulations, though they are lower in energy than corn and lower in protein than soybean meal. Meat and bone meal, fish meal, and poultry byproduct meal are animal protein sources that are highly digestible and have excellent amino acid profiles. They are more commonly used in nursery diets and in regions where plant protein sources are expensive. In the United States, the use of ruminant derived meat and bone meal is restricted in feed for ruminants due to BSE concerns, but it can be used in swine diets. ### Added Fats and Oils Added fats increase the energy density of the diet. Common sources include choice white grease, poultry fat, and vegetable oils. Fats are often added at 1 to 5 percent of the diet. Higher levels can cause handling problems in feeders and reduce pellet quality. Fat quality matters. Free fatty acid content, moisture, and impurities affect the energy value and palatability of the fat. Rancid fat has a reduced energy value and can reduce feed intake. Store fats properly and use them before they degrade. ### Synthetic Amino Acids Lysine, threonine, methionine, and tryptophan are available as feed grade supplements. These allow you to reduce crude protein levels while still meeting amino acid requirements. Reducing crude protein lowers feed cost and reduces nitrogen excretion. Lysine is the most commonly supplemented amino acid. In a typical corn and soybean meal diet, you can reduce soybean meal inclusion and add lysine to meet the pig's requirement. This is often cheaper than feeding extra soybean meal, especially when soybean meal prices are high. ### Mineral and Vitamin Premixes Most producers use commercial premixes to supply vitamins and trace minerals. These premixes are formulated to meet the requirements for a specific production stage when added at a specified inclusion rate. Premixes are available from feed companies and can be customized for your operation. Salt is often added separately at 0.3 to 0.5 percent of the diet. Some premixes include salt, so check the label before adding more. ### Feed Additives Beyond the basic nutrients, many diets include feed additives for specific purposes. Antibiotics and growth promoters were historically common, but their use is increasingly restricted due to antimicrobial resistance concerns. In the United States, the Veterinary Feed Directive requires veterinary oversight for medically important antibiotics used in feed. Other additives include probiotics, prebiotics, enzymes, organic acids, and phytogenics. These can improve gut health, nutrient digestibility, and growth performance, but their effects are often variable and depend on the specific product and farm conditions. Work with your nutritionist or veterinarian to determine if these additives are cost effective for your operation. ## Step by Step Swine Ration Formulation Ration formulation can be done by hand using the Pearson square method for simple two ingredient mixes, or with computer software for complex multi ingredient diets. Most commercial producers and feed companies use least cost formulation software, which calculates the lowest cost diet that meets all nutrient requirements. Even if you use software, understanding the process helps you evaluate the results and make informed decisions. ### Step 1: Define the Production Stage and Performance Target The first step is to know what class of pig you are feeding and what performance you expect. A nursery pig from 10 to 25 pounds has different requirements than a grower pig from 50 to 100 pounds or a finisher pig from 150 to 280 pounds. Sows have different requirements depending on whether they are gestating or lactating. Performance targets include average daily gain, [feed conversion ratio](/knowledge/animal-farming/poultry/feed-conversion-ratio-measuring-improving-poultry-efficiency), and carcass composition. Faster growing, leaner pigs have higher amino acid requirements per pound of feed. If your pigs are not performing at the expected level, the requirements may need adjustment. ### Step 2: Determine Nutrient Requirements Using a nutrient requirement table, look up the requirements for your production stage. The table will list requirements for metabolizable energy, crude protein, amino acids, minerals, and vitamins. Most modern tables express amino acid requirements as standardized ileal digestible (SID) values. SID accounts for the fact that not all amino acids in an ingredient are digested and absorbed by the pig. Using SID values gives a more accurate estimate of the amino acids available to the pig. ### Step 3: Select Ingredients and Determine Nutrient Content Choose the ingredients you will include in the diet. For most producers, this means selecting a base grain, a protein source, and a premix. The nutrient content of each ingredient should be based on laboratory analysis when possible, or on published tables when analysis is not available. Ingredient nutrient content varies by source, growing conditions, and processing. Corn from different regions can vary in protein and energy content. Soybean meal quality varies by processor. If you are buying ingredients by the truckload, have each load sampled and analyzed. ### Step 4: Calculate the Diet Start with the energy requirement. Set the inclusion rate of the energy source, typically corn, and the protein source, typically soybean meal, to meet the energy and protein requirements. Then check the amino acid levels and adjust as needed. For a simple corn and soybean meal diet, you can use the Pearson square method to calculate the ratio of corn to soybean meal needed to meet the crude protein requirement. Then check the lysine level and add synthetic lysine if needed. For example, suppose you are formulating a grower diet that needs 1.10 percent SID lysine. Corn has 0.25 percent SID lysine and soybean meal has 2.90 percent SID lysine. If you use a 50 percent corn and 50 percent soybean meal mix, the lysine level would be about 1.57 percent, which is too high and too expensive. A mix of 80 percent corn and 20 percent soybean meal provides about 0.78 percent lysine, which is too low. The actual calculation requires solving for the inclusion rates that meet all requirements simultaneously, which is why computer software is so valuable. ### Step 5: Check Mineral and Vitamin Levels Once the energy and amino acid requirements are met, check the mineral levels. Calculate the calcium and phosphorus from the grains and protein sources, then add inorganic phosphorus and limestone to meet the requirements. Add salt and the vitamin and trace mineral premix at the recommended inclusion rate. ### Step 6: Evaluate the Cost Calculate the cost per ton of the finished diet. Compare the cost to alternative formulations. Least cost formulation software will automatically find the lowest cost combination of ingredients, but you should still review the results for practicality. An ingredient might be cheap per ton but have a low nutrient density, making it expensive per unit of energy or protein. Compare ingredients on a cost per unit of nutrient basis, not just cost per ton. ### Step 7: Mix and Deliver The best formulated diet is worthless if it is not mixed correctly. Ensure your mixer is in good working order and that mixing times are adequate. Overmixing can cause ingredient separation, while undermixing leaves nutrient concentrations uneven. Add ingredients in the correct order. Start with the largest ingredient, usually corn, then add the protein source, then the smaller ingredients like minerals and premixes. Liquid ingredients such as fat should be added slowly to ensure even distribution. ## Phase Feeding Programs Phase feeding means feeding a series of diets that change as the pig grows. This allows you to match the nutrient supply to the pig's changing requirements, reducing feed cost and nutrient excretion. ### Nursery Phase The nursery phase covers pigs from weaning to about 50 pounds. This is the most critical and expensive phase of feeding. Weaned pigs have immature digestive systems and need highly digestible, nutrient dense diets. The stress of weaning often reduces feed intake, so diets must be formulated to maximize intake. Nursery diets are typically divided into three or more phases. Phase 1 diets, fed for the first week after weaning, are highly complex with milk products, plasma protein, fish meal, and other highly digestible ingredients. Phase 2 and 3 diets gradually become simpler and less expensive as the pig's digestive system matures. The goal is to get pigs eating quickly after weaning and to maintain steady growth through the nursery period. Feed intake in the first week after weaning is a strong predictor of lifetime performance. ### Grower Phase The grower phase covers pigs from about 50 to 100 pounds. During this phase, the pig's digestive system is fully functional and can handle a wider range of ingredients. Amino acid requirements per pound of feed are still high, but the pig can use less expensive protein sources. Grower diets typically contain 18 to 20 percent crude protein and 1.0 to 1.2 percent SID lysine. Reduced cost formulations using DDGS, canola meal, or synthetic amino acids are common in this phase. ### Finisher Phase The finisher phase covers pigs from about 100 pounds to market weight. During this phase, the pig's maintenance requirement increases relative to its growth requirement, so the amino acid concentration in the diet can be reduced. Energy becomes relatively more important. Finisher diets typically contain 13 to 16 percent crude protein and 0.75 to 0.95 percent SID lysine. The finisher phase is often split into early and late finisher diets to further match nutrient supply to requirements. Ractopamine, a feed additive that improves growth rate and carcass leanness, is sometimes used in the late finisher phase. Its use requires careful management and is not approved in all markets. ### Sow Diets Gestating sows need a diet that maintains body condition without excessive weight gain. Overfeeding gestating sows increases feed cost and can cause farrowing problems. Underfeeding can reduce litter size and increase sow culling. Gestation diets are typically limit fed at 4 to 6 pounds per day, depending on sow weight, body condition, and environmental temperature. The diet should provide adequate fiber to promote satiety and prevent behavioral issues. Lactating sows have the highest nutrient requirements of any class of swine. A sow nursing a large litter can produce 15 to 20 pounds of milk per day, which requires enormous amounts of energy and amino acids. Lactation diets are typically fed free choice and contain 18 to 20 percent crude protein and 1.1 to 1.3 percent SID lysine. Sows that lose excessive body condition during lactation may have delayed return to estrus and reduced subsequent litter size. Monitor sow condition and adjust feeding levels as needed. ## Common Mistakes in Swine Ration Formulation Even experienced producers make formulation errors. Knowing the common mistakes helps you avoid them. ### Overformulating Adding extra nutrients above requirements is a common and costly mistake. Extra protein is not stored as muscle, it is excreted as nitrogen in the urine. Extra minerals and vitamins are wasted. The cheapest diet is the one that meets requirements without excess. More lysine does not always mean more growth. Once the lysine requirement is met, additional lysine is simply wasted. The growth response to lysine follows a diminishing returns curve, and the optimal level is where the value of the extra gain equals the cost of the extra lysine. ### Underformulating Underformulating is less common but can be equally costly. A diet that is deficient in an amino acid or mineral will limit growth and feed efficiency. The lost performance can cost more than the savings from the cheaper diet. Marginal deficiencies are hard to detect because the pigs do not show obvious signs of deficiency. They just grow a little slower and convert feed a little less efficiently. Over time, these small losses add up. ### Ignoring Ingredient Variation Ingredients are not constant. Corn protein can vary by 2 to 3 percentage points between loads. Soybean meal quality varies by processor. If you formulate based on book values and do not analyze your actual ingredients, you may be over or underfeeding nutrients without knowing it. Regular ingredient analysis is the solution. Most feed mills and extension labs offer near infrared spectroscopy analysis for a reasonable cost. Analyze each new load of ingredients. ### Poor Mixing A perfectly formulated diet is useless if it is not mixed properly. Inadequate mixing time, worn mixer parts, and improper ingredient order all contribute to poor mix uniformity. The result is some pigs get too much of certain nutrients and others get too little. Test mix uniformity by sampling the diet from different locations in the mixer or at different points in the delivery system. The coefficient of variation should be below 10 percent. If it is higher, check the mixer and mixing procedures. ### Sudden Diet Changes Pigs have sensitive digestive systems. Sudden changes in diet can cause feed refusal, diarrhea, and reduced performance. When changing from one diet to another, blend the two diets over several days. This is especially important when changing from a nursery diet to a grower diet or when introducing new ingredients. ### Ignoring Water Water is the most essential nutrient, yet it is often overlooked. Inadequate water supply, poor water quality, and malfunctioning drinkers can all reduce feed intake and growth. Check drinkers regularly and ensure the water supply meets the pigs' needs. ## Monitoring and Recordkeeping A feeding program is not a set and forget system. You need to monitor performance and adjust the program as conditions change. ### Feed Intake Records Track feed intake by pen or by barn. This tells you if pigs are eating as expected and if the diet is palatable. Sudden drops in feed intake can signal health problems, diet issues, or environmental problems. ### Growth Performance Weigh pigs regularly to track average daily gain and feed conversion. Compare your results to breed averages and to your historical performance. If growth is below expectations, review the diet formulation and ingredient quality. ### [Body Condition Scoring](/knowledge/animal-farming/farm-management/body-condition-scoring-a-tool-for-feed-management) Body condition scoring is especially important for sows. A simple 1 to 5 scoring system where 1 is emaciated and 5 is obese can help you adjust feeding levels. Sows should be in moderate condition, scoring about 3, at farrowing and should not lose excessive condition during lactation. ### Carcass Quality If you market pigs on a carcass merit system, track carcass weight, backfat, and lean percentage. These measurements reflect the effectiveness of your feeding program. Excessive backfat may indicate too much energy or not enough lysine in the finisher diet. ### Feed Cost Records Track feed cost per pig and per pound of gain. This is the ultimate measure of feeding program efficiency. Compare your costs to industry benchmarks and to your historical costs. ### Records to Keep Keep records of diet formulations, ingredient purchases, feed deliveries, and feed consumption. Record dates, weights, and any observations about pig health or behavior. These records help you identify problems and make informed decisions. ## When to Call a Veterinarian or Extension Agent Most feeding issues can be resolved with careful observation and adjustment. However, some situations require professional help. ### Signs of Nutritional Deficiency or Toxicity If pigs show signs of poor growth, rough hair coats, lameness, or other abnormalities that you cannot explain, consult your veterinarian. Nutritional deficiencies and toxicities can cause a range of clinical signs, and diagnosis requires professional expertise. ### Feed Refusal If pigs suddenly stop eating, there may be a feed palatability issue, a mycotoxin problem, or a health issue. Mycotoxins from moldy grain can cause feed refusal, reduced growth, and immune suppression. Your veterinarian or extension agent can help you test for mycotoxins and adjust the diet. ### Water Quality Concerns If you suspect water quality issues, have your water tested. High sulfates, nitrates, or other contaminants can reduce water intake and pig performance. Your extension office can recommend a testing lab and help you interpret the results. ### Major Diet Changes Before making major changes to your feeding program, such as switching to a new ingredient or changing the formulation approach, consult a nutritionist or extension agent. They can help you evaluate the changes and avoid costly mistakes. ### Regulatory Compliance Feed regulations are complex and change over time. If you are unsure about the legality of a feed additive or the requirements of the Veterinary Feed Directive, contact your veterinarian or extension agent. Noncompliance can result in fines and market access issues. ## Frequently Asked Questions ### How do I know if my pigs are getting enough lysine? The most reliable way is to calculate the lysine level in your diet and compare it to published requirements for your pig's weight and genetics. If your pigs are growing at the expected rate with good feed conversion, lysine is likely adequate. If growth is below expectations, have your feed analyzed and review the formulation. Clinical signs of lysine deficiency are not specific, so performance data is the best indicator. ### Can I feed whole corn to my pigs? Pigs can eat whole corn, but grinding improves digestibility and reduces waste. Whole corn passes through the digestive tract partially undigested, so you get less energy from the same amount of feed. Grinding to a medium particle size of about 600 to 800 microns is recommended for growing and finishing pigs. Finer grinding is not recommended because it increases the risk of stomach ulcers. ### What is the difference between crude protein and digestible amino acids? Crude protein is a measure of the total nitrogen in the feed, expressed as protein. It does not tell you which amino acids are present or how well the pig can digest them. Digestible amino acid values, such as standardized ileal digestible (SID) lysine, measure the actual amino acids available to the pig. Formulating on a digestible amino acid basis is more accurate and allows you to reduce crude protein levels without reducing performance. ### How much DDGS can I feed to finishing pigs? Typical inclusion rates for DDGS in finishing diets are 10 to 30 percent. The upper limit depends on the quality of the DDGS, the price relative to corn and soybean meal, and your market for the finished pigs. High DDGS inclusion can cause soft fat in the carcass, which may be discounted by some packers. Start with a moderate inclusion rate and monitor carcass quality. ### Do I need to add synthetic amino acids to my diet? Not always. In a simple corn and soybean meal diet, the lysine requirement can often be met with soybean meal alone. Synthetic lysine becomes economical when soybean meal prices are high or when you are using ingredients that are low in lysine, such as DDGS or bakery meal. Your nutritionist can calculate whether synthetic amino acids are cost effective for your specific diet. ### How often should I have my feed ingredients analyzed? Analyze each new load of ingredients, especially if you are buying from a new source or if the ingredient is known to vary. Corn protein can vary between fields and between storage conditions. Soybean meal quality varies by processor. At a minimum, analyze ingredients when you change sources or when you notice changes in pig performance. ### What causes pigs to refuse feed? Feed refusal can have many causes. Poor palatability from rancid fat, moldy grain, or high mineral levels can reduce intake. Mycotoxins are a common cause of feed refusal. Health issues, heat stress, and water problems can also reduce feed intake. If pigs refuse feed, check the feed for mold and odor, check water supply, and observe the pigs for signs of illness. ### How do I know if my feed is mixed properly? The best way is to test mix uniformity. Collect samples from 5 to 10 locations in the mixer or from the feed delivery system and have them analyzed for a marker ingredient such as salt or a trace mineral. The coefficient of variation should be below 10 percent. If it is higher, increase mixing time or check the mixer for worn parts. ## Related Farming Guides This section will be populated programmatically with links to related farming guides on swine production, nutrition, and herd management. ## Related Clinical & Scientific Guides * [Pig Enrichment Programs and Behavior Monitoring](/knowledge/animal-farming/swine/pig-enrichment-programs-and-behavior-monitoring) * [Swine Handling Facility Design for Safe Pig Movement](/knowledge/animal-farming/swine/swine-handling-facility-design-safe-pig-movement) * [Swine Feeding Management for Grow-Finish Pigs](/knowledge/animal-farming/swine/swine-feeding-management-for-grow-finish-pigs) ## References - National Pork Board: https://www.pork.org/ - USDA APHIS Swine Health: https://www.aphis.usda.gov/livestock-poultry-disease/swine - FAO Pig Production: https://www.fao.org/pig-production-and-products/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.