# Swine Feed Mixing and Batching Accuracy ## Key Takeaways - Feed mixing and batching accuracy directly impacts swine production costs and efficiency; a 5% error in microingredients can lead to performance deficiencies, while inaccurate batching results in wasted expensive components. - Mixer performance is dynamic and degrades over time due to wear on components like paddles and ribbons; regular testing (at least quarterly) using methods like salt or dye tests is crucial to determine optimal mix time and maintain a Coefficient of Variation (CV) of 10% or less for uniformity. - Ingredient sequencing is critical for protecting microingredients, preventing cross-contamination, and ensuring uniform distribution; a typical order involves adding bulk grains first, followed by protein sources, microingredients, and finally liquids, with a brief dry mix period before liquid addition. - Liquid ingredient management, particularly fats and molasses, requires careful control of temperature (90-110°F) and addition rate (30-60 seconds for batch mixers) to prevent clumping and ensure even distribution, with horizontal mixers generally handling up to 8-10% added fat. - Batch size significantly affects uniformity, with optimal working capacity typically at 60-70% of total mixer volume; running mixers too full or too empty reduces mixing action and increases the CV. - Comprehensive batch records, including ingredient weights, mix times, and operator initials, are essential for troubleshooting performance issues, ensuring feed safety audits, and meeting packer/certification program requirements. --- Feeding pigs is often the single largest variable cost in a swine operation, and the accuracy of your feed mixing and batching system directly determines whether that cost translates into efficient gain or wasted money. This guide covers the complete process of swine feed mixing and batching, from understanding the principles of feed uniformity to calibrating your mixer, managing ingredient sequencing, and keeping the records that prove your feed is what you think it is. It is written for farm owners, feed mill managers, herd managers, and anyone responsible for producing or overseeing on-farm pig feed. ## At a Glance - **Accuracy matters more than you think.** A 5 percent error in a vitamin or mineral premix can mean the difference between optimal growth and a deficiency that costs you weeks of performance. - **Mixer performance is not static.** Wear on paddles, augers, and ribbons changes mixing efficiency over time. Test your mixer at least quarterly and after any major repair. - **Ingredient order is a science, not a habit.** The sequence in which you add ingredients affects both mix uniformity and the risk of cross contamination or damage to microingredients. - **Liquids change everything.** Adding fat or molasses at the wrong time or temperature can create balls, clumps, or poor distribution that no amount of extra mixing time will fix. - **Batch size matters.** Running a mixer too full or too full of air reduces uniformity. Know your mixer's optimal working capacity, not just its total volume. - **Records are your defense.** Complete batch records protect you in a feed safety audit, help you troubleshoot performance problems, and are required for most packer and certification programs. - **When in doubt, test.** A simple salt test or dye test tells you more about your mixer than a year of guessing. ## Why Feed Mixing Accuracy Is Critical Pigs require a precisely balanced diet to express their genetic potential for growth, feed efficiency, and carcass quality. The margin for error in swine feed is much smaller than in many other livestock species. A pig's digestive system is sensitive to abrupt changes in nutrient density, and the cost of overfeeding expensive additives or underfeeding critical nutrients can be significant. The primary goal of feed mixing is to create a uniform mixture where every pig consumes the same balanced ration, regardless of where it eats from the feeder. This is called feed uniformity or mix uniformity. When feed is not uniform, some pigs get more of a particular nutrient and others get less. The pigs that get less grow slower. The pigs that get more may waste expensive ingredients or suffer metabolic issues. Over time, the average performance of the group drops, and the variation between individual pigs increases. Feed mixing accuracy has two distinct components. The first is batching accuracy, which refers to how closely the actual weight of each ingredient added to the mixer matches the target weight in the formulation. The second is mixing uniformity, which refers to how evenly those ingredients are distributed throughout the final batch. Both components matter. You can weigh every ingredient perfectly and still produce poor feed if your mixer does not blend it evenly. Conversely, a well functioning mixer cannot fix a batch where the ingredients were weighed incorrectly. Poor mixing accuracy has economic consequences beyond just reduced growth. Inconsistent feed can lead to feed refusal, reduced feed intake, and increased sorting at the feeder. It can also create safety issues. If a medication or a toxin binder is not uniformly distributed, some pigs may receive a subtherapeutic dose while others receive a dose that is too high. This is both an animal welfare concern and a potential regulatory issue. ## Understanding Feed Uniformity and Mixer Performance Feed uniformity is measured by the coefficient of variation, commonly referred to as CV. The CV expresses the variation in concentration of a marker ingredient across multiple samples taken from a single batch. A lower CV means more uniform feed. The industry standard for swine feed is a CV of 10 percent or less, with many nutritionists and feed mills targeting a CV of 5 to 7 percent for critical microingredients. To test your mixer's uniformity, you need a marker that is easy to measure and present in the feed at a consistent level. Salt is the most common marker for on-farm testing because it is inexpensive and easy to analyze. You add a known amount of salt to a batch, collect samples from multiple locations in the mixer or at the discharge, and send those samples to a lab for sodium analysis. The lab results give you the salt concentration in each sample, and you calculate the CV from those numbers. The uniformity of a mixed feed depends on several factors. The first is mixer type. Horizontal ribbon mixers and paddle mixers are the most common in swine operations. Paddle mixers generally provide faster and more uniform mixing than ribbon mixers, especially for feeds with higher fat content. Vertical screw mixers are less common for swine feed because they are slower and tend to have higher CV values, but they can work for simple rations if managed carefully. The second factor is mix time. Every mixer has an optimal mix time that produces the lowest CV. Under mixing leaves ingredients poorly distributed. Over mixing can actually increase the CV for some ingredients, particularly those that are fragile or tend to separate. You need to determine the optimal mix time for your specific mixer by testing at different time intervals and comparing the CV results. The third factor is ingredient characteristics. Particle size, density, and flow characteristics all affect how well an ingredient mixes. Ingredients with very different particle sizes or densities tend to separate during mixing and handling. Adding liquid ingredients can help bind fine particles to larger ones, but it can also create clumps if not managed properly. Finally, the condition of the mixer itself affects uniformity. Worn paddles or ribbons reduce the mixing action. Bearing wear can change the clearance between moving parts and the mixer shell. A mixer that looks fine on the outside can be performing poorly on the inside. Regular inspection and maintenance are essential. ## Types of Mixers Used for Pig Feed Horizontal paddle mixers are the most common choice for swine feed in medium to large operations. They consist of a U-shaped trough with a central shaft fitted with paddles that move the feed in a figure-eight pattern. These mixers are fast, typically achieving good uniformity in 3 to 7 minutes, and they handle liquid additions well. They are also relatively easy to clean and inspect. Horizontal ribbon mixers use a double helical ribbon that moves feed in opposite directions to create a blending action. They are gentler than paddle mixers, which makes them good for feeds with fragile ingredients, but they take longer to achieve uniformity, usually 5 to 15 minutes. They are also less effective at incorporating liquid ingredients like fat or molasses. Vertical screw mixers are the simplest and least expensive option. They consist of a vertical cylinder with a screw that lifts feed from the bottom to the top, where it cascades down. These mixers are slow and produce less uniform feed than horizontal mixers. They are best suited to simple rations with few ingredients and no liquid additions. They are not recommended for feeds that require precise uniformity of microingredients. Twin shaft paddle mixers, sometimes called dual shaft paddle mixers, are the fastest and most uniform mixers available. They use two counter rotating shafts with paddles that create a fluidized bed of feed. They can achieve a CV of less than 5 percent in as little as 60 to 90 seconds. They are more expensive and require more maintenance than single shaft mixers, but they are the best choice for high volume operations or feeds with challenging ingredients. Continuous mixers are used in large commercial feed mills where ingredients are metered into the mixer at a constant rate. They are not common on farms because they require precise calibration of multiple ingredient feeders and are difficult to verify for uniformity. Batch mixing is almost always the better choice for on-farm feed production. ## Batching Systems and Weighing Accuracy The batching system is the part of the feed mill that measures and delivers ingredients to the mixer. It includes the ingredient storage bins, the scale hopper, the screw conveyors or bucket elevators that move ingredients, and the control system that sequences the additions. Weighing accuracy is the foundation of batching accuracy. Your scale system must be accurate and repeatable. Electronic load cell scales are the standard for modern feed mills. They are accurate to within 0.1 percent of the applied load when properly calibrated, which means a 1,000 pound batch can be weighed to within 1 pound. The scale system needs regular calibration. Load cells drift over time, and the mechanical linkages that connect the hopper to the load cells can bind or shift. Calibrate your scale at least quarterly using certified test weights. Test at multiple points across the scale range, not just at the top end. A scale that is accurate at 2,000 pounds may be inaccurate at 200 pounds. The scale hopper must be isolated from the surrounding structure so that nothing touches it except the load cells. A build up of feed on the hopper walls, a conveyor that rubs against the hopper, or a person leaning on the hopper can all cause inaccurate readings. Inspect the scale hopper regularly for material build up and mechanical interference. The control system sequences the ingredient additions and records the actual weights. Modern systems use a programmable logic controller or PLC that compares the actual weight to the target weight and makes adjustments. The system should have a tolerance setting that alerts you when an ingredient is out of range. Set this tolerance tight enough to catch real errors but not so tight that it causes frequent false alarms. A common problem in batching systems is the free fall error. When a screw conveyor or gate shuts off, there is still material in motion that continues to fall into the scale hopper. The control system must compensate for this by shutting off the feeder early, based on a learned free fall amount. If the ingredient flow rate changes because of a plugged bin or a worn screw, the free fall amount changes and the batch accuracy suffers. Monitor the actual weights against targets and adjust the free fall compensation as needed. ## Ingredient Sequencing and Addition Order The order in which you add ingredients to the mixer is almost as important as the mixer itself. A good ingredient sequence protects microingredients, reduces dust, prevents cross contamination, and improves uniformity. The general principle is to add the largest volume ingredients first, then the smaller ingredients, and finally the liquids. This creates a base of feed that protects the smaller ingredients from being trapped in the mixer or blown out as dust, and it gives the microingredients a large volume of material to blend into. A typical sequence for a swine ration is as follows: Start with about half of the grain portion. This creates a bed in the mixer that prevents fine ingredients from settling to the bottom or sticking to the mixer surfaces. Add the protein sources such as soybean meal, then the remaining grain. This sandwiches the protein between layers of grain and helps distribute it evenly. Add the microingredients including the vitamin premix, mineral premix, amino acids, and any medications. These are the highest value and most critical ingredients in the batch. Adding them after the bulk ingredients are already in the mixer ensures they are not lost in the conveying system or stuck in the mixer corners. Add the salt and any other small volume ingredients. Salt is often used as a carrier for microingredients and helps with uniformity testing. Start the mixer and allow it to run for a short period before adding liquids. This dry mix time ensures the microingredients are distributed before the liquid is added. Add liquids such as fat, oil, or molasses slowly and evenly. Pouring liquid into a running mixer in one spot can create balls of feed and fat that never break up. Most mixers have a liquid addition port that disperses the liquid over the length of the mixer. If your mixer does not have a proper liquid addition system, you should install one before adding liquids to your feed. After all liquids are added, continue mixing for the remaining mix time. Do not stop the mixer to check the feed or scrape the sides. Let the mixer run for the full cycle. The total mix time depends on your mixer type and condition. Start with the manufacturer's recommendation and test from there. A typical horizontal paddle mixer needs 3 to 5 minutes for a dry feed and 4 to 6 minutes for a feed with added fat. A ribbon mixer needs 7 to 10 minutes for dry feed and 10 to 15 minutes for feed with fat. The order of ingredient addition is also important for cross contamination prevention. If you are mixing medicated feed, add the medication after the bulk ingredients and before the liquids. Run the mixer for the full cycle to ensure the medication is uniformly distributed. Then clean the mixer thoroughly before mixing a non medicated feed. Some operations dedicate a separate mixer or a separate production run for medicated feeds to eliminate the risk of carryover. ## Liquid Ingredient Management Liquid ingredients present the biggest challenge in swine feed mixing. Fat, oil, molasses, and liquid amino acids all need special handling to achieve uniform distribution. The temperature of the liquid matters. Fat and oil need to be warm enough to flow freely but not so hot that they degrade or create a fire hazard. Most operations heat fat to between 90 and 110 degrees Fahrenheit for handling. Molasses needs to be heated to around 100 to 110 degrees Fahrenheit to reduce its viscosity. The rate of liquid addition matters. Adding liquid too quickly overwhelms the mixer and creates clumps. Adding it too slowly extends the mix time and reduces throughput. The ideal rate depends on the mixer type and the liquid being added. As a general rule, add liquid over a period of 30 to 60 seconds for a typical batch mixer. The total liquid content of the feed matters. Most horizontal mixers can handle up to 8 to 10 percent added fat before the feed becomes too sticky to mix uniformly. If you need to add more fat than this, consider using a different fat source or adding fat at the feeder rather than in the mixer. Liquid addition systems need regular maintenance. The pump must be calibrated to deliver the correct flow rate. The nozzles or spray bars must be checked for clogs and wear. The flow meter or scale that measures the liquid addition must be calibrated. A liquid addition system that is out of calibration can deliver 20 percent more or less liquid than intended, which completely changes the nutrient density of the feed. One strategy to improve liquid distribution is to add liquids after the dry ingredients have been mixed for a short time. This allows the dry ingredients to be uniformly distributed first, then the liquid coats the particles evenly. Another strategy is to use a carrier for very small amounts of liquid. If you are adding only 1 to 2 percent liquid, you can mix it with a portion of the grain first, then add that mixture to the main batch. ## Determining Optimal Mix Time Every mixer has an optimal mix time, and you need to determine it for your specific equipment. The manufacturer's recommendation is a starting point, but wear, ingredient characteristics, and batch size all affect the actual optimal time. The process for determining optimal mix time is straightforward. Prepare a batch of your typical feed formulation and add a marker at a known concentration. Salt at 1 percent of the batch is the standard marker for this test. Mix for a short time, take samples, continue mixing, take more samples, and continue until you have samples at several time points. For a typical paddle mixer, sample at 1, 2, 3, 4, 5, and 6 minutes. For a ribbon mixer, sample at 5, 8, 10, 12, and 15 minutes. Take at least 10 samples at each time point. Collect samples from different locations in the mixer if possible, or collect a series of samples from the discharge as you empty the mixer. Send the samples to a laboratory for sodium analysis. Calculate the average salt concentration and the standard deviation for each time point. The CV is the standard deviation divided by the mean, multiplied by 100. Plot the CV against mix time. The optimal mix time is the point where the CV reaches its lowest value and starts to level off or increase. If the CV never reaches 10 percent or less, your mixer may be worn or damaged. Inspect the paddles or ribbons for wear, check the clearance between the moving parts and the mixer shell, and look for material build up in the corners. Repair or replace worn parts and retest. The optimal mix time will change as the mixer wears and as your ingredient sources change. Retest your mixer at least quarterly and after any major repair or adjustment. Keep a record of the test results so you can track changes over time. ## Batch Size and Mixer Capacity The amount of feed you put in the mixer affects uniformity. Every mixer has an optimal working capacity that is less than its total volume. Running the mixer too full leaves no room for the feed to move and blend. Running it too full of air, meaning too little feed, reduces the interaction between particles and can actually increase the CV. For horizontal paddle and ribbon mixers, the optimal working capacity is typically 60 to 70 percent of the total mixer volume. The manufacturer should provide a recommended working capacity, usually expressed as a percentage of total volume or as a maximum batch weight based on the density of the feed. The density of the feed affects the batch weight. A mixer with a 1,000 cubic foot capacity can hold more pounds of a dense feed like corn and soybean meal than a light feed with added fat and low density ingredients. Use the manufacturer's working capacity in cubic feet and multiply by the expected feed density to determine the maximum batch weight. Running the mixer at less than 50 percent of its working capacity is also a problem. The feed does not have enough volume to create the proper mixing action, and ingredients can separate. If you need to mix small batches, consider a smaller mixer or reduce the batch size only to the minimum recommended by the manufacturer. When you change the batch size, you may also need to adjust the mix time. A larger batch may need slightly more time to reach uniformity. A smaller batch may reach uniformity faster but may also be more prone to over mixing. Test your mixer at your standard batch size and at any other batch sizes you use regularly. ## Ingredient Quality and Particle Size The quality of the ingredients you put into the mixer affects the quality of the feed that comes out. Ingredient particle size is particularly important for mixing uniformity. Pigs digest feed more efficiently when the particle size is consistent. Corn ground too coarse passes through the digestive tract undigested. Corn ground too fine creates dust, increases the risk of stomach ulcers, and makes the feed flow poorly in bins and feeders. The recommended particle size for corn in swine feed is 650 to 750 microns. Particle size also affects mixing. Ingredients with very different particle sizes tend to separate during mixing and handling. Fine particles sift to the bottom of the mixer and the bottom of bins. Coarse particles stay on top. This separation is called segregation, and it is one of the main reasons feed can be non uniform even when the mixer is working perfectly. To minimize segregation, grind all grains to a consistent particle size. Use a hammer mill or roller mill that is properly maintained with sharp hammers or rolls set to the correct gap. Test the particle size regularly using a sieve shaker or a commercial particle size analysis service. Adding fat or molasses to the feed helps reduce segregation by binding fine particles to larger ones. The liquid coats the particles and makes them stick together slightly. This is one reason feeds with added fat tend to have better uniformity than completely dry feeds. Ingredient quality also matters. Soybean meal that has been overheated during processing has reduced amino acid availability. Moldy grain can contain mycotoxins that reduce feed intake and growth. Rancid fat has reduced energy value and can cause feed refusal. Test incoming ingredients regularly and reject loads that do not meet your quality standards. ## Common Mistakes in Swine Feed Mixing Several common mistakes reduce feed mixing accuracy and uniformity. Recognizing these mistakes is the first step to correcting them. The first mistake is not calibrating the scale system regularly. A scale that is off by even 1 percent can cause a 10 pound error in a 1,000 pound batch. Over a year of production, that error adds up to significant cost and performance loss. The second mistake is overloading the mixer. Operators often try to squeeze extra capacity out of a mixer by adding more feed than the recommended working capacity. This reduces mixing action and increases the CV. The feed may look mixed on the surface but be poorly blended underneath. The third mistake is inconsistent mix time. Some operators mix for a fixed time regardless of batch size or ingredient changes. Others mix for as long as it takes to complete another task, which can be too long or too short. Set a timer and follow it consistently. The fourth mistake is adding microingredients directly to the mixer without a carrier. Vitamin premixes, mineral premixes, and medications are concentrated products that need to be diluted before they can be uniformly distributed. Add them to the mixer with a portion of the grain and let them blend before adding the rest of the grain. The fifth mistake is poor liquid addition. Adding liquid too quickly, at the wrong temperature, or from a single point creates clumps and poor distribution. Install a proper liquid addition system with a pump, flow meter, and spray bar. The sixth mistake is not cleaning the mixer between batches. Feed residue in the mixer can contaminate the next batch, especially if you are switching between medicated and non medicated feed. Clean the mixer thoroughly between batches and flush it with a small amount of grain if needed. The seventh mistake is ignoring the condition of the mixer. Worn paddles, bent ribbons, and material build up on the mixer walls all reduce mixing efficiency. Inspect the mixer regularly and keep it in good repair. The eighth mistake is not testing the mixer. Many operations never test their mixer's uniformity and assume it is working correctly. A simple salt test every quarter tells you more about your mixer than a year of guessing. ## Monitoring and Recordkeeping Accurate recordkeeping is essential for feed mixing management. The records serve several purposes. They document what you produced, they help you troubleshoot problems, and they provide the documentation needed for feed safety audits and certification programs. The [batch record](/knowledge/molecular-biology/batch-record) is the core document for feed mixing. It should include the date, the batch number, the feed formulation or ration name, the target weight for each ingredient, the actual weight for each ingredient, the mix time, and the initials of the operator. If the actual weight differs from the target by more than your tolerance, record the reason and the corrective action taken. The [batch record](/knowledge/molecular-biology/batch-record) should also include information about the ingredients themselves. Record the supplier, lot number, and delivery date for each ingredient. This allows you to trace a specific batch of feed back to the specific loads of ingredients that went into it. In addition to batch records, keep records of your scale calibrations, mixer uniformity tests, and equipment maintenance. These records show that you are actively managing your feed mixing system and that your feed is produced under controlled conditions. Review your records regularly to identify trends. Are certain ingredients consistently weighing high or low? Is the mix time drifting from the standard? Are certain batches showing more variation than others? These trends can point to equipment problems or ingredient issues before they cause significant losses. Many packer and certification programs require feed records as part of their audit process. The National Pork Board's Pork Quality Assurance Plus program and the Common Swine Industry Audit both include feed mixing and recordkeeping requirements. Having complete and accurate records makes these audits straightforward and protects your market access. ## Troubleshooting Feed Mixing Problems When pigs are not performing as expected, feed mixing accuracy is one of the first things to investigate. Poor growth, variable growth within a group, feed refusal, and signs of nutrient deficiency or toxicity can all be caused by mixing problems. The first step in troubleshooting is to review your batch records. Were the actual ingredient weights close to the targets? Was the mix time correct? Were there any unusual events such as a scale malfunction or a change in ingredient source? The second step is to test the mixer uniformity. Run a salt test and calculate the CV. If the CV is above 10 percent, your mixer is not blending the feed properly. Inspect the mixer for wear, damage, or material build up. The third step is to sample the feed. Take samples from multiple feeders and multiple locations within each feeder. Send the samples to a laboratory for nutrient analysis. Compare the results to the formulation. Large variations between samples indicate a mixing problem. Consistent differences from the formulation indicate a batching or ingredient problem. The fourth step is to check the ingredient quality. If a specific load of soybean meal or grain is below standard, it can cause performance problems even when the mixing is perfect. Test incoming ingredients and keep records of the results. The fifth step is to check the feeders. Even perfectly mixed feed can become segregated in the feeder if pigs are sorting or if the feeder is adjusted incorrectly. Check the feeder adjustment and observe the pigs at the feeder to see if they are sorting the feed. ## When to Call a Veterinarian or Extension Agent Feed mixing problems can cause clinical signs that require veterinary attention. If pigs show signs of a nutrient deficiency or toxicity, contact your veterinarian immediately. Signs of salt toxicity include tremors, seizures, and death. Signs of vitamin or mineral deficiency include poor growth, poor feed conversion, lameness, and skin or hair coat abnormalities. If you suspect a medication error, contact your veterinarian immediately. Pigs that receive too much medication can develop toxicity. Pigs that receive too little medication may not be protected from disease. Your veterinarian can help you assess the risk and determine the appropriate response. If you are seeing feed refusal or poor growth that you cannot explain through your records and testing, contact your extension agent. They can help you troubleshoot the problem and connect you with laboratory services for feed analysis. They can also help you evaluate your mixing system and recommend improvements. If you suspect mycotoxin contamination in your grain, contact your extension agent or a feed testing laboratory. Mycotoxins can cause a range of problems including reduced feed intake, poor growth, immune suppression, and reproductive problems. Testing is the only way to confirm mycotoxin contamination and determine the appropriate response. If you are mixing medicated feed and have questions about withdrawal times or drug interactions, contact your veterinarian. They can help you ensure that your medicated feed program is safe and effective. ## Frequently Asked Questions **How often should I calibrate my feed scale?** Calibrate your scale at least quarterly using certified test weights. If you use your scale heavily or if you notice discrepancies between the target and actual weights in your batch records, calibrate more often. Also calibrate after any repair or adjustment to the scale system. Test at multiple points across the scale range, not just at the top end. **What is the ideal mix time for a horizontal paddle mixer?** The ideal mix time depends on your specific mixer, its condition, and the ingredients in your feed. A typical horizontal paddle mixer needs 3 to 5 minutes for a dry feed and 4 to 6 minutes for a feed with added fat. Determine the optimal time for your mixer by running a salt test at multiple time points and calculating the CV. Retest quarterly and after repairs. **How do I test my mixer for uniformity?** Add salt at 1 percent of the batch weight to a typical feed batch. Mix for a set time, then take at least 10 samples from different locations in the mixer or from the discharge as you empty it. Send the samples to a laboratory for sodium analysis. Calculate the average, standard deviation, and CV. A CV of 10 percent or less indicates acceptable uniformity. A CV of 5 to 7 percent is a good target. **Can I mix feed with added fat in a vertical screw mixer?** Vertical screw mixers are not recommended for feeds with added fat. They are slow, produce less uniform feed, and do not handle liquids well. If you must add fat to feed mixed in a vertical mixer, keep the fat level below 2 percent and expect higher CV values. For best results, use a horizontal paddle or ribbon mixer for any feed with added fat. **What is the proper order for adding ingredients to the mixer?** Add the largest volume ingredients first, starting with about half the grain. Add the protein sources next, then the remaining grain. Add the microingredients including premixes, amino acids, and medications. Start the mixer and let it run briefly. Add liquids slowly and evenly. Continue mixing for the full cycle. **How full should I fill my mixer?** Fill your mixer to 60 to 70 percent of its total volume. This is the optimal working capacity for most horizontal mixers. Running the mixer too full reduces mixing action. Running it too empty reduces particle interaction and can increase the CV. Check the manufacturer's recommendation for your specific mixer. **What should I do if my mixer CV is above 10 percent?** First, inspect the mixer for worn paddles or ribbons, material build up, and mechanical damage. Repair or replace worn parts. Clean the mixer thoroughly. Check the batch size and mix time. If the CV is still above 10 percent, contact your extension agent or a feed mill consultant for help. Your mixer may need major repairs or replacement. **How do I prevent cross contamination between medicated and non medicated feed?** Dedicate a separate mixer or a separate production run for medicated feed if possible. If you must use the same mixer, clean it thoroughly between batches. Flush the mixer with a small amount of grain and discard the flush. Keep detailed records of which batches are medicated and which are not. Follow all label directions for the medication, including withdrawal times. ## Related Farming Guides Additional farming guides related to swine production, feed management, and herd health will be listed here. Check back for updates or explore the farming section for more practical how-to content. ## 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.