Extruded full-fat soybean is an important energy and protein source in modern animal nutrition. Through a specific extrusion process involving either dry or wet heat, whole soybeans are treated to effectively inactivate anti-nutritional factors such as trypsin inhibitors and urease, while preserving the natural fats, proteins, and bioactive compounds to the greatest extent possible. The final product possesses a distinctive roasted aroma and good flowability, which significantly enhances feed palatability and nutrient utilization. It is widely used in diets for swine, poultry, aquaculture, and ruminants.
The industrial production of extruded soybeans requires rigorous pre-treatment procedures. Raw soybeans are first passed through a cleaning screen and a magnetic separator to remove impurities and metal contaminants. The cleaned beans are then crushed into 4–8 pieces by a crusher and subsequently ground in a hammer mill until the powder passes completely through a 2.8 mm sieve. The resulting soybean flour is fed into a Conditioner for hydrothermal treatment before entering the extruder. Under high pressure and temperature, the cellular structure of the material is physically disrupted, forming a porous internal matrix with increased bulk density. The extruded pellets are then cooled and dried to reduce moisture to safe storage levels before packaging.
Depending on whether steam is introduced during the conditioning stage, the process is classified into dry extrusion and wet extrusion. In dry extrusion, the initial moisture content of the material is approximately 8%, whereas wet extrusion involves injecting steam into the Conditioner, raising the moisture content to about 12%. Compared with dry extrusion, the wet process not only achieves higher throughput but also delivers more thorough heat treatment for eliminating anti-nutritional factors and improving product digestibility. Consequently, wet extrusion is more widely adopted in commercial production.
2. Key Equipment and Critical Parameters
The Conditioner is a critical front-end device that ensures effective extrusion. Its function is to uniformly mix steam with the soybean flour, softening the material and enhancing its plasticity, thereby reducing mechanical wear on the extruder screws and barrel while lowering energy consumption. Common Conditioner types include single-shaft paddle Conditioners, steam-jacketed Conditioners, and twin-shaft differential-speed paddle Conditioners. In China, single-shaft paddle Conditioners are often supplied as auxiliary components integrated with the extruder rather than as standalone products. The paddle angles are typically adjustable to ensure sufficient residence time for thorough steam–solid mixing, with the shaft speed generally maintained above 100 r/min. Notably, the twin-shaft differential-speed Conditioner (whose early patents have now expired) offers greater flexibility, allowing the conditioning time to be adjusted from several seconds up to 240 seconds by modifying the paddle angles.
The extrusion press is the core of the system, consisting of the barrel, screws, choke rings, and shearing segments. In a single-screw extruder, the material moves forward in a continuous helical ribbon around the screw and is finally forced out through the annular gap between the screw tip (or pressure ring) and the die plate. The barrel inner diameter is the primary specification defining the machine model, as seen in designations such as EXT200S, PHDS320, and similar, where the numbers indicate this value. The annular gap size directly affects both the degree of cooking and the throughput: a larger gap reduces shear force and temperature rise, thereby increasing output. Therefore, under the premise of achieving adequate gelatinization, appropriately reducing the screw or pressure ring diameter can effectively enhance productivity. Additionally, die orifice size is positively correlated with throughput; larger orifices reduce extrusion resistance and power consumption. Thus, provided product quality requirements are met, using dies with larger apertures is an effective strategy to improve production efficiency.
3. Application Guidelines in Different Livestock and Aquaculture Diets
Swine Diets
In pig production, extruded full-fat soybean provides readily digestible energy, high-quality protein, and essential unsaturated fatty acids. Its appealing aroma significantly stimulates feed intake, promotes weight gain, and improves feed conversion efficiency. For breeding sows, supplementation during late gestation and lactation enhances piglet birth weight and weaning survival rates; during lactation, it increases both milk yield and fat content, thereby boosting litter weight gain. In piglet creep and starter feeds, appropriate inclusion helps alleviate post-weaning diarrhea. Recommended inclusion rates: 5–20% for piglets, 2–10% for growing–finishing pigs, and 6–20% for sows.
Aquafeed
Extruded soybean serves as a plant-based source of fat and protein in extruded aquafeeds. It improves survival rates of fish and shrimp larvae, promotes growth, and can partially replace soybean meal or fish meal within certain limits, thereby reducing feed conversion ratios. The typical recommended inclusion level for conventional freshwater fish and shrimp diets ranges from 2% to 15%.
Poultry Diets
For poultry, the rich essential amino acid profile and high metabolizable energy of extruded soybean help alleviate heat stress (as fat oxidation produces less metabolic heat than carbohydrate oxidation) and sustain feed intake during hot seasons. Moreover, its nutritional characteristics enhance intramuscular fat deposition, improving meat flavor and quality, while also increasing fertility rates and hatchability of healthy chicks in breeding flocks. In laying hens, supplementation significantly boosts laying rates, average egg weight, and prolongs the peak production period. Typical inclusion rates: 5–25% for broiler starter/grower phases, 3–30% for broiler grower/finisher phases, and 6–20% for laying hens during the laying period.
Ruminant Diets
In diets for young calves, lambs, and high-yielding dairy cows, extruded soybean is a cost-effective rumen-bypass nutrient source. It not only improves the palatability of concentrated feed but also regulates rumen fermentation through its unique fat structure, increasing the supply of absorbable amino acids in the small intestine. This supports young animal development and enhances milk production performance in dairy cows. The conventional inclusion level in dairy cow diets ranges from 2% to 15%, and up to 25% in the concentrate portion without adversely affecting rumen function.
Media ContactCompany Name: Guangzhou Scikoon Industry Co., Ltd.Email: Send EmailCountry: ChinaWebsite: https://www.scikoonmachinery.com/
