Premix feed is a uniform mixture prepared by blending various additives of the same type or different types of additives in certain proportions. Although premix feed accounts for a small proportion of complete feed, it plays an extremely important role in the feeding effect of the complete feed. Scientific formulation of premix feed is the key to its production. To produce high-quality premix feed, not only a scientific formula is required, but also high-quality raw materials, sophisticated equipment processes, and a comprehensive set of management measures. Premix feed is not just a simple commodity; it is a high-tech product that integrates material quality testing, nutritional formula design, and livestock and poultry feeding management. To further promote and popularize the technology of premix feed, this article provides a brief overview of the production technology and its use.

1. Objectives, Characteristics, and Functions of Premix Feed Production

The purpose of producing premix feed is to evenly disperse the effective ingredients of trace component additives in the compounded feed after dilution and expansion. Premix feed can be produced by manufacturers specializing in this type of product or can be produced in specialized workshops attached to compound feed factories.

Premix feed has the following characteristics:

• Complex Composition: High-quality premix feed generally includes 6 to 7 trace elements, more than 15 types of vitamins, 2 amino acids, 1-2 drugs, and other additives (such as antioxidants and mold inhibitors), each with different properties and functions. The compatibility is complex.

• Small Quantity, Significant Effect: Generally, premix feed accounts for 0.5% to 5% of the compound feed. Although the quantity is small, it plays a significant role in improving animal production performance, feed conversion rate, and feed preservation.

• Not Suitable for Direct Feeding: The concentration of active ingredients in the additives of premix feed is very high, generally tens to hundreds of times the required amount for animals. Direct feeding can easily lead to animal poisoning.

The functions of premix feed mainly include:

• Even Distribution of Trace Components: It enables the even distribution of trace components of additives in the compounded feed.

• Compensation and Improvement: Through premixing processes, it compensates for and improves the undesirable characteristics of trace components, such as instability, water absorption, and static adsorption phenomena.

• Standardization of Additive Addition Levels: It standardizes the addition levels of additives.

• Simplification and Cost Reduction: It simplifies the production processes of general feed processing plants and reduces investment.

2. Key Points of Premix Feed Production Technology

2.1 Adopting Advanced Formulation

The formulation of premix feed is the core of the production technology. It is designed meticulously by animal nutrition experts from specialized premix manufacturers. They consider the nutritional requirements of animals at different growth and production stages, the basic nutritional content of domestic feed materials, and the principles of adding what is lacking, being economically reasonable, and efficient. Additionally, various external environmental factors and processing technologies are taken into account. On one hand, the appropriate and adequate amount of additive materials is selected based on nutritional needs, user farming level, and conditions. On the other hand, considering processing requirements, the key to formulation technology lies in mastering the appropriate amounts for most non-safety affecting components, such as nutritional additives. The dosage and usage of drug feed additives and certain sensitive ingredients (such as selenium, copper, etc.) must be based on sufficient scientific basis and necessary practical experience to avoid serious consequences. The ratio of raw materials is an important factor affecting the quality of premix feed products. The proportions of active ingredients to diluents in the premix, the ratios between various trace elements, and the ratios between related active ingredients should all be appropriately balanced. Formulation should not be fixed but should be adjusted based on market feedback, local conditions, seasonal changes, latest technology, and product information to ensure rigorousness while maintaining flexibility, always keeping the premix feed products close to the national conditions and actual production.

2.2 Selecting High-Quality Raw Materials

The quality of raw materials greatly affects the actual efficacy of premix feed. The basic requirements for high-quality raw materials are high purity, absence of toxic and harmful substances, and most importantly, high content of active ingredients, especially easily destroyed additives like Vitamin A and Vitamin C, which should be determined through actual testing before deciding on their quantities. Trace element compound raw materials must possess high biological efficacy, stable physical properties, and minimal toxic and harmful substances. Additionally, some additives may affect other additives due to their quality and dosage. For example, heptahydrate ferrous sulfate has strong hygroscopicity and can significantly degrade Vitamin A, while monohydrate ferrous sulfate has a smaller impact on Vitamin A, which can be further minimized with protectants.

Producers of premix feed should choose high-quality raw materials and conduct precise measurements of their quality and potency.

When selecting vitamins, attention should be paid to two points: 1) choosing those with high biological value; 2) selecting different vitamins according to climatic characteristics. For instance, mononitrate thiamine is more effective than thiamine hydrochloride in hot and humid summers. When selecting trace element materials, factors to consider include ingredient content, particle size, crystalline water, and toxic and harmful substance content. For drug feed additives, safety issues must be considered. Always refer to the instructions and testing materials provided by the manufacturer to fully understand usage periods, withdrawal periods, and precautions.

2.3 Using Optimal Carriers and Diluents

The carrier is the particle that carries or adsorbs trace active ingredients and is the inert substance in the premix. Carrier selection should follow principles of strong chemical stability without damaging adsorbates, moderate particle size for good mixing with complete feed, and affordability. The particle size of the carrier should be between 0.1770.59mm; its density should be close to the density of the carried trace components. Adding 1.5% vegetable oil when mixing carriers and additives can improve adhesion. The water content of the carrier should be controlled between 8%10% without affecting the activity of carried active ingredients. The pH of the carrier should be close to neutral. Common carriers include shell powder, wheat bran, corn, bran, defatted rice bran, stone powder, zeolite powder, and table salt. Diluents reduce the concentration of active substances in the premix and separate trace particles. Like carriers, diluents are also inert substances that reduce reactions between active ingredients and stabilize them. Requirements for diluents include: water content below 10%, non-hygroscopic, non-caking, particle size between 0.050.6mm, smooth surface with good flowability, pH between 5.57.5 without static charge, and being edible, harmless, and stable.

2.4 Pre-treatment of Raw Materials

Vitamins are sensitive to factors such as oxygen, moisture, heat, light, and metal ions, which can reduce their activity. To meet production requirements, all vitamin additives must undergo special pretreatment to maintain stability and activity. Emulsification technology can be used to form microparticles evenly dispersed in the substrate, followed by encapsulation technology to form gelatin-coated microparticles, producing microcapsules. These treated microparticles are resistant to mechanical operations, have good antioxidant properties, and mix well. Trace element additives mainly refer to mineral salts and oxides of copper, iron, manganese, zinc, etc. Some of these compounds are poorly soluble in water, some are hygroscopic and prone to moisture absorption, and appropriate pretreatment is required before application to alter certain physical properties to meet processing requirements and ensure product quality. Pre-treatment technologies include drying, adding anticaking agents, coating, grinding, and premilling.

2.5 Using High-Precision Production Equipment

Accurate measurement and proportioning are essential to achieve scientific formulation. To ensure accurate proportioning according to formulation requirements, advanced metering equipment and reasonable processes are necessary. The premix production has high requirements for the accuracy and stability of various metering equipment, so relevant equipment needs to be managed and calibrated regularly. For additives with small dosage but significant safety impacts, such as selenium and high-copper additives, special care must be taken in measuring and diluting. The mixer is the most important equipment for premix production. Different types of premix require different mixers, such as gravity-free mixers, conical mixers, double-spiral belt mixers, double-shaft paddle mixers, and fast residue-free mixers. Generally, mixer requirements include: 1) high mixing efficiency with short optimal mixing time; 2) high mixing uniformity; 3) reasonable structure with low internal residue and easy cleaning; 4) convenient loading and unloading; 5) good sealing with minimal leakage; 6) antistatic.

2.6 Ensuring Uniform Mixing

Although feed mixing is a physical process, due to differences in raw material density and other characteristics, it requires scientific selection of equipment, mixing time, and appropriate carriers or diluents. The process should be as simple as possible, striving for uniform mixing. In high-quality premixes, all components should be evenly distributed. Any sample should match the formulation in terms of component ratios. However, due to various factors, differences may exist between different samples or batches. Poor uniformity of premixes means that the actual intake by animals does not match the prescribed supply, directly affecting the additive and feed efficiency. Especially for some trace components where the difference between a safe and toxic dose is small, poor uniformity can lead to unsafe usage. Therefore, uniformity is an important quality indicator for premixes. Uniformity is measured by the coefficient of variation, with national standards stipulating that it should be less than 7%.

2.7 Implementing the HACCP Management System

Given the increasing focus on meat food safety, introducing the HACCP management system in premix production is essential. The first step is to analyze potential hazards during feed production and processing, determine key control points, establish control standards, and then implement practical and effective control measures. Establish testing methods and procedures to promptly detect deviations from control measures and set standards. Effective corrective measures should be taken timely, adjusting production and control methods accordingly, followed by comprehensive validation of the HACCP system. Implementing HACCP can enhance the quality control awareness and level of premix production companies, promoting overall improvement in premix production levels.

3. Issues to Consider During Production

3.1 Base on Feeding Standards

Feeding standards represent the nutritional requirements of animals under different feeding purposes and can serve as a basis for formulating premix feed. In specific applications, a broad knowledge of animal nutrition is also required.

• Nutritional requirements on feeding standards should represent the total amount of the same nutrient provided by various components, not the amount to be added.
• It's best to use pre-mix raw materials after direct determination of ingredients, while considering the synergistic and antagonistic effects between various nutrients.
• The nutritional requirements on feeding standards are just the minimum needed to meet the animals' requirements. When formulating the mix, additional amounts should be added based on actual conditions to ensure the true needs of animals for certain nutrients under different conditions.

3.2 Consider Process and Processing Losses

During the premix feed processing, accurate ingredient feeding according to the formulation is essential. Different adding methods should be used based on the characteristics of various components. Lastly, uniform mixing (CV less than 7%) must be ensured. Nutritional components like vitamins can be damaged during feed processing (such as grinding, pelletizing), so these factors should be considered when developing formulations.

3.3 Pay Attention to Anti-nutritional Factors in Basic Feed

Many energy feeds and protein feed raw materials contain anti-nutritional factors that can damage nutrients in feeds. For example, flaxseed meal contains anti-B6 factors, and fat oxidation products in soybeans can destroy Vitamin A. These nutritional factors should be considered when formulating feeds.

3.4 Emphasize Stability Factors

Most vitamins have poor stability, especially when exposed to metal ions. For instance, with Cu, Fe, Mn in the feed, after storage for 3 months, Vitamin A can lose 80% and Vitamin B6 20%. Storage time should not be too long, and precautions like sealing and avoiding light should be taken.

3.5 Particle Size and Compatibility of Trace Components

The particle size requirement for trace components depends on their nature and the proportion they occupy in the complete feed. Poorly dispersed materials with small addition ratios require finer grinding to ensure mixing uniformity. Active trace components can greatly affect animal growth but can also chemically react with each other. Compatibility can be addressed by packaging vitamins, minerals, and other ingredients separately until full feed production, and by improving the stability of active components.

3.6 Safety and Efficiency

Most trace elements are chemicals. When adding, not only their effective dose but also their toxic dose should be considered. For example, copper is an effective trace element, but its dose for special effects is close to its toxic dose. Selenium, with its extremely low content in feed, also has a dose close to its toxic dose. Many vitamins and trace elements interact, such as Vitamin E and selenium having a synergistic effect in the body, and the ratio of calcium and phosphorus affecting efficiency.

3.7 Choline Issues

Choline chloride is a low-molecular-weight organic compound essential for the growth and development of young animals. It needs to be added in feed based mainly on corn to ensure healthy growth of livestock and poultry. 50% choline chloride powder is generally used as a feed additive. It has strong hygroscopicity and can damage other active ingredients like Vitamins A, D3, and K3. Therefore, it should be adsorbed and dried with bran, defatted rice bran, or rice husk to control carrier moisture.

3.8 Consider Weather Factors

Animals have different nutritional needs under different climatic conditions. The proportion of nutrients should be adjusted appropriately according to the climate to make the formulation more reasonable.

4. Use of Premix Feed

4.1 Understand the Efficacy of Premix Feed

Under intensive large-scale feeding conditions, animals must be provided with complete feed. A complete feed requires premix feed, which should first consider the nutritional indicators like crude protein, essential amino acids, energy, calcium, phosphorus, sodium, chlorine in the daily ration. Only with a scientifically and reasonably formulated premix feed can its role be fully utilized to improve animal production levels, reduce feed consumption, and promote health.

4.2 Reasonably Choose Premix Feed

The quality of premix feed on the market varies. When purchasing, choose based on actual conditions and the feed raw materials available. Different types of premixes should be selected based on the types of feed materials owned.

4.3 Strictly Identify Quality

When purchasing premix feed, prefer products from reputable large manufacturers and carefully check their packaging and label contents.

4.4 Clearly Identify the User

When using premix feed, select special premixes for different types of livestock and poultry and different growth stages based on the labels.

4.5 Accurate Dosage

Mix premix feed with other feeds according to the instructions. Generally, the dosage of premix feed should be 0.5%~6% of the total feed. Accurate weighing is necessary.

4.6 Mix Thoroughly with Basic Feed

Premix feed must be thoroughly mixed with other feeds before feeding, and ideally, should be used up once mixed.

4.7 Proper Storage

Keep track of the storage time and conditions of premix feed to maintain its freshness. Unopened premix feed should be stored in a ventilated, cool, and dry place. After opening, it should be used up as soon as possible to avoid effective ingredient content reduction.

5. Conclusion

Premix feed is a high-tech product formulated based on animal growth and nutritional needs, considering multiple influencing factors and using advanced equipment and technology. It contains most of the nutritional needs and, when mixed with protein and energy feeds, can balance and efficiently provide nutrients to meet animal growth and production needs. However, there are still some issues in the production and use of premix feed in China, such as the widespread use of the same trace element premix, problems with the mixing and packaging of complex premixes, and issues with high copper, zinc, and arsenic preparations. With technological development and social progress, these issues will be gradually resolved. Livestock producers can fully utilize the efficient nutritional functions of premix feed only by choosing and using it correctly.