Difference Between Extruded Feed And Pelleted Feed

Pelleted Feed Vs Extruded Feed : What Is The Difference

Manufacturing Processes

Extruded feed involves cooking ingredients under high pressure and temperature, then shaping them through a die, enhancing digestibility. Pelleted feed, on the other hand, is made by grinding and compressing ingredients into pellets without cooking, making it less costly but potentially less digestible. This difference affects their suitability for various animals, with extruded feed often preferred for high-performance needs.

Physical and Nutritional Properties

Extruded feed tends to have better buoyancy control and stability, crucial for fish that feed at different water levels, and studies show improved starch and protein digestibility [1]. Pelleted feed, while uniform and easy to handle, may lose nutrients faster in water, impacting its effectiveness, especially in aquatic environments.

Economic and Environmental Considerations

Pelleted feed is generally cheaper to produce, appealing for cost-conscious farmers, but extruded feed’s higher initial cost can be offset by better feed efficiency and reduced waste, particularly in aquaculture. Environmentally, extruded feed reduces water pollution by minimizing nutrient leaching, while pelleted feed’s rapid sinking can contribute to more environmental impact.

Comprehensive Analysis of Extruded Feed vs. Pelleted Feed

This detailed analysis explores the differences between extruded and pelleted animal feeds, covering manufacturing processes, physical and nutritional properties, economic considerations, environmental impacts, and practical applications.

The information is derived from extensive research and is intended for farmers, pet owners, and industry professionals seeking to optimize feeding strategies.

Types of Animal Feed Pellet

Animal feed is essential for ensuring optimal growth, health, and productivity across various species, including horses, fish, pigs, and poultry. Among the diverse forms available, pelleted and extruded feeds stand out due to their widespread use and distinct characteristics. Pelleted feed is produced by compressing ground ingredients into uniform pellets, offering convenience and reduced waste. Extruded feed, conversely, involves cooking the mixture under high pressure and temperature before shaping, enhancing digestibility and tailoring physical properties like buoyancy.

Manufacturing Processes Comparison

The manufacturing process significantly influences the feed’s properties and suitability for different animals.

Pelleted Feed Production:

• Grinding: Ingredients are ground to a fine consistency to ensure uniformity.
• Mixing: Thorough mixing ensures even distribution of nutrients.
• Pelletizing: The mixture is passed through a pellet mill, compressed through a die to form pellets, often using steam or water to activate natural binding properties.
• Cooling and Conditioning: Pellets are cooled to stabilize their structure and may be coated with additional ingredients if needed.

This process is relatively simple and cost-effective, making pelleted feed a staple in many feeding programs.

Extruded Feed Production:

• Grinding and Mixing: Similar to pelleted feed, ingredients are ground and mixed.
• Conditioning: The mixture is conditioned with steam or water to reach a specific moisture level, typically higher than for pelleting.
• Extrusion: The conditioned mixture is fed into an extruder, cooked under high temperature (100-150°C) and pressure (up to 50 bar). This step gelatinizes starches and denatures proteins, enhancing digestibility.
• Shaping: The cooked mixture is forced through a die to form specific shapes, such as pellets or floats.
• Drying and Cooling: The extruded product is dried to reduce moisture content and then cooled to ensure stability.

The extrusion process, akin to pressure cooking, involves higher energy inputs and sophisticated equipment, increasing production costs but offering enhanced nutritional benefits.

Physical Properties: Density, Buoyancy, and Stability

Physical properties play a critical role in feed selection, particularly in aquatic and free-range feeding scenarios.

Density and Buoyancy: 

• Pelleted Feed: Typically denser, pelleted feed sinks in water, which can be advantageous for bottom-feeding fish but may lead to feed loss if not consumed promptly.
• Extruded Feed: Can be formulated to float or sink, providing flexibility for surface-feeding or bottom-feeding species. This control is achieved during the extrusion process, making it ideal for aquaculture.

Hardness and Durability: 

• Extruded Feed: Generally harder and more durable due to the cooking process, which helps maintain shape during transportation and storage, reducing breakage.
• Pelleted Feed: May be less durable, potentially crumbling or breaking, which can increase dust and fines, affecting feed quality.

Stability in Water: 

• Extruded Feed: Exhibits better stability, maintaining structure and nutrients for 12 to 36 hours in water, minimizing waste and pollution.
• Pelleted Feed: Nutrients dissolve rapidly, with an estimated 10-15% feed loss due to sinking, impacting both cost and environmental impact.

A table summarizing these properties is provided below for clarity:

Property	Pelleted Feed	Extruded Feed
Buoyancy	Sinks (rapid sinking speed, 10-15% feed lost due to sinking)	Buoyancy can be controlled (buoyant, fast or slow sinking)
Stability in Water	Nutrients dissolve rapidly	Stable for 12 to 36 hours while maintaining nutrients
Manufacturing Cost	Lower compared to extrusion	Higher than pelleted feed
Density	Denser	Denser
Moisture Content	Lower	Requires higher moisture levels
Process	Compression of small particles into pellets, involves moisture, temperature, and pressure	Involves high temperatures and short times, “cooked” process, requires higher moisture, temperature, and pressure for expansion
Nutrient Loss	Higher (dissolves rapidly in water)	Minimized due to high temperature short time process
Digestibility	Lower (compared to extruded)	Improved digestibility of starches and proteins
Environmental Impact	Higher pollution due to sinking and nutrient dissolution	Lower pollution
Conversion Rate	Not specified	High conversion rate
Quality and Profitability	Lower quality, less profitable due to feed loss	Higher quality, increases profitability of fish farms

Sources: MG Alimentación, FAO, Aquafeed, Fishfeed Machinery

Nutritional Properties: Digestibility and Nutrient Retention

Nutritional properties are crucial for meeting animal dietary needs and optimizing performance.

Digestibility: 

• Extruded Feed: The extrusion process breaks down complex carbohydrates and proteins, increasing digestibility. Studies on pigs show higher apparent ileal digestibility (AID) of gross energy (e.g., 78.56% vs. 72.83% in meal form for low fiber diets) and amino acids compared to pelleted feed. For horses, research suggests improved starch digestion in the small intestine, reducing the likelihood of hindgut fermentation issues.
• Pelleted Feed: While digestible, it may not match extruded feed’s levels, especially for starches, due to less extensive processing. However, pelleting can still improve digestibility over meal form, with increased AID of starch in medium fiber diets (97.95% vs. 95.31% in meal).

Nutrient Retention: 

• Extruded Feed: Better stability in water minimizes nutrient leaching, ensuring more nutrients are available for consumption, particularly in aquatic environments.
• Pelleted Feed: Rapid dissolution can lead to significant nutrient loss, reducing effectiveness, especially for fish where feed is exposed to water for extended periods.

Economic Considerations: Cost vs. Efficiency

Economic factors are pivotal for feed selection, balancing initial costs with long-term benefits.

Manufacturing Cost: 

• Pelleted Feed: Lower due to simpler equipment and processes, making it attractive for cost-conscious producers.
• Extruded Feed: Higher due to the need for extruders and increased energy consumption, but potential savings arise from improved feed efficiency.

Feed Efficiency and Profitability: 

• Extruded Feed: Despite higher costs, improved digestibility and reduced waste can lead to better feed conversion ratios, offsetting expenses. In aquaculture, reduced feed loss due to buoyancy control can increase profitability.
• Pelleted Feed: Lower cost but may require higher feed quantities to achieve similar performance, potentially increasing overall costs in the long run.

Environmental Impact: Pollution and Sustainability

Environmental considerations are increasingly important in feed selection, particularly in aquatic systems.

Water Pollution: 

• Extruded Feed: Reduces water pollution by minimizing nutrient leaching and feed loss, with controlled buoyancy preventing accumulation at the bottom .
• Pelleted Feed: Rapid sinking and nutrient dissolution can contribute to water quality issues, increasing environmental impact, especially in fish farming.

Dust and Fines: 

• Both types can be designed to minimize dust, but pelleted feed is often noted for producing less dust compared to meal forms, though comparisons with extruded feed suggest similar outcomes depending on processing.

Applications: Tailoring Feed to Animal Needs

The choice between pelleted and extruded feed depends on the animal species, production system, and specific requirements.

Aquaculture: 

• Extruded Feed: Preferred for its buoyancy control and stability, reducing waste and pollution, ideal for both surface-feeding and bottom-feeding fish .
• Pelleted Feed: Used where cost is a priority, but may lead to higher feed loss and environmental impact.

Horses: 

• Extruded Feed: Gaining popularity for improved digestibility, especially for performance horses, with studies suggesting better starch and protein absorption. However, some research indicates no significant digestibility difference with pelleted feed under identical formulations .
• Pelleted Feed: Common and cost-effective, suitable for general maintenance, offering uniformity and ease of handling.

Poultry and Livestock: 

• Both types are used, with the decision based on cost, nutritional needs, and feeding behavior. For pigs, extruded feed shows higher digestibility, potentially improving growth rates.

Conclusion

In conclusion, extruded feed offers superior digestibility, physical properties, and environmental benefits, particularly in aquaculture and for high-performance animals, but at a higher cost. Pelleted feed remains a cost-effective option with broad applicability, though it may lead to more waste and lower nutrient retention in certain scenarios.

Farmers and producers should consider their specific needs, balancing cost, animal performance, and environmental impact. For example, in fish farming, extruded feed’s buoyancy control can significantly reduce waste, while for horses, extruded feed may be preferable for performance, though cost may favor pelleted feed for maintenance.