Nutritional Characteristics of EU-Sourced Animal By-Product Meals and Rendering Methods

In the European pet food industry, animal by-product meals are being re-evaluated as high-quality protein sources. By-products such as poultry and fish materials, as well as blood and organs, can be converted through appropriate rendering into safe, nutrient-dense ingredients—supporting stable supply while reducing environmental burden.

Under EU regulations—Regulation (EC) No 1069/2009 and Regulation (EU) No 142/2011—only low-risk materials classified as Category 3 (Cat. 3) may be used as pet food raw materials. In recent years, technology has advanced (e.g., low-temperature continuous rendering), and more ingredients are now available with improved digestibility and palatability compared with conventional products.

This article explains, from a product developer’s perspective, the nutritional value, production methods, key precautions, and formulation applications of EU-sourced animal by-product meals.

Classification of Animal By-Products (ABP)

In the EU, more than 20 million tons of animal by-products (ABP) are generated annually from livestock and meat processing. When properly processed, these materials can be utilized as sustainable resources with high nutritional value.

ABPs are classified into three categories (Cat. 1–Cat. 3) based on risk level, and only Category 3 (Cat. 3)—the lowest-risk category—is permitted for use as feed ingredients (especially for pet food).

In particular, Cat. 3 by-product meals are regarded as high-quality protein sources because their safety is assured by meeting strict hygiene and processing standards defined in Regulation (EC) No 1069/2009 and Regulation (EU) No 142/2011.

In EU dry pet food, a wide range of animal by-product meals are used as protein sources, including chicken meal and poultry meal, fish meal, blood meal, and organ meals. These ingredients are rich in essential amino acids and fatty acids, vitamins, and minerals, and they tend to have high palatability—supporting overall health in dogs and cats.

FEDIAF (the European Pet Food Industry Federation) also points out that effective use of Cat. 3-derived animal fats and related materials can reduce waste and improve sustainability, while still delivering “high-quality, nutritionally balanced diets.”
　

Types of By-Product Meals and Their Characteristics

Meal type	Protein content	Key nutrients	Digestibility	Typical uses	Notes
Meat & bone meal	50–60%	Calcium, phosphorus	Moderate	Growth & maintenance diets for dogs/cats; mineral supplementation	High mineral (bone-derived) content
Poultry meal	Standard: 60–70% / High-grade: 75–90%	Lysine, fatty acids	High	Grain-free formulas; high-protein foods; premium diets	Strong aroma → often highly palatable
Hydrolyzed feather meal	80–85%	Cystine	Moderate	Protein fortification ingredient	Hydrolysis required (benchmark: pepsin digestibility ≥75%)
Fish meal	62–70%	Omega-3, methionine	Very high	Cat diets; senior dog diets; skin & coat support	Lipids oxidize easily → antioxidants required
Blood meal / organ meal	Blood meal: ~94% / Organs: 60–75%	Lysine, iron, B vitamins	High	Palatability booster; vitamin/mineral fortification; high-nutrition formulas	High mineral content → avoid excessive inclusion

Meat & Bone Meal

Meat and bone meal is produced by heating, drying, and grinding meat and bones (typically from cattle or pigs). Protein content is usually around 50–60%, while ash (bone-derived minerals) is often around 25–35%, making it an efficient source of calcium and phosphorus.

Digestibility may be somewhat lower than poultry-based meals in many cases, so it is advisable to consider protein source combinations (e.g., blending with poultry meal or fish meal), particle size, and thermal history. Higher bone content (higher ash) can also affect extrusion performance and palatability, so selecting the appropriate grade for the product objective is important.

Poultry Meal

Poultry meal is made by cooking, defatting, drying, and grinding edible by-products such as meat, organs, and bones from chicken or turkey. It typically contains about 60–70% protein, offers relatively strong essential amino acid content (including lysine), and tends to provide stable digestibility—making it a core protein source in many dry pet foods.

Because it often delivers strong aroma and palatability, it can serve as a main ingredient in grain-free and high-protein formulations. While Europe has detailed BSE-related regulations, Cat. 3 poultry-derived proteins are widely used in pet food applications.

Hydrolyzed Feather Meal

Hydrolyzed feather meal is produced by processing feathers (primarily keratin) via high-pressure cooking and/or alkaline hydrolysis to improve digestibility. Untreated feathers are very poorly digestible, so processing is designed to meet pepsin digestibility standards (e.g., ≥75%).

Feather meal is rich in cystine (cysteine/cystine), but it tends to be deficient in lysine, methionine, and tryptophan. For this reason, it is generally used as a supplemental protein ingredient rather than a primary protein source—typically combined with other meals or supplemented amino acids. It is usually low in fat and can be formulated with relatively low ash, though effects on palatability and stool quality depend on inclusion rate.

Fish Meal

Fish meal is produced by cooking, pressing, and drying by-products from small pelagic fish such as sardines and mackerel-type species. It typically contains around 62–70% protein, has a favorable essential amino acid profile (notably lysine), and may provide n-3 polyunsaturated fatty acids such as EPA and DHA.

Fish meal generally offers high digestibility and can be particularly useful for cat foods and senior dog formulas. However, fish oil-derived lipids oxidize easily, so oxidation control during production and storage is essential (antioxidants, low-temperature storage, nitrogen flushing, low-OTR packaging materials).

While the EU has historically enforced strict controls on animal proteins in ruminant feed, fish meal use in pet food is widely permitted.

Blood Meal and Organ Meals

Blood meal (including plasma fractions) is produced by drying blood from livestock or poultry. It is extremely high in protein (around 90%) and is particularly rich in lysine. Because excessive inclusion can negatively affect palatability, coloration, mineral balance, and stool quality, it is typically used at low inclusion levels for targeted functionality.

Organ meals (including liver and other edible organ by-products) can supply micronutrients such as vitamin A, B vitamins, heme iron, and (depending on species) taurine. Because oxidation and flavor variation must be managed, organ meals are often used as secondary ingredients at low-to-moderate inclusion levels.
　

Benefits of Using Animal By-Product Meals

By-product meals upcycle parts that might otherwise be discarded and function as nutrient-dense sources of “high protein, high energy, and high minerals.” Essential amino acids and essential fatty acids in meat & bone meal or poultry meal are generally well absorbed and can support muscle maintenance as well as skin and coat health in dogs and cats.

They also contain natural savory components that enhance palatability and can improve feed intake. FEDIAF notes that Cat. 3-derived animal fats can support skin and brain function, improve palatability, and contribute to better resource utilization.

Additionally, as animal proteins that can complement grain resources, they are valuable for grain-free, high-protein, and natural-style dry pet food designs.

Key Cautions When Using By-Product Meals

Variability in Raw Material Characteristics

Because the composition of by-products can fluctuate, lot-to-lot variation in protein, fat, and mineral content is more likely. It is important to analyze each production lot and adjust inclusion rates and nutrient balancing (e.g., supplemental amino acids or mineral design) based on results.

Lipid Oxidation Risk

Fish meal and poultry fats are rich in unsaturated fatty acids and are prone to oxidation. Use antioxidants appropriately (e.g., mixed tocopherols, rosemary extract), adopt low-temperature storage, apply nitrogen flushing, and use low-OTR packaging to reduce rancidity, flavor deterioration, and nutrient loss.

Considerations for Allergy-Sensitive Diets

Some animals may have allergies to specific animal proteins. For hypoallergenic diets, consider alternative protein sources (e.g., kangaroo meal or salmon meal) or a single-animal-protein approach to improve control and clarity.

Rendering Under EU Regulations

Rendering is the process of converting animal by-products (ABP) into safe, stable ingredients through heat, pressure, and separation. For Category 3 raw materials used in pet food, the key objective is to reliably inactivate pathogens and standardize the material while minimizing deterioration of protein and fat quality. In the EU, standard processing methods (Methods 1–5) are defined, and conditions are selected and validated based on equipment design and raw material characteristics.

EU Standard Processing Methods (Methods 1–5)

Method 1: High Pressure / High Temperature

The strictest method. Raw materials are reduced to ≤50 mm particle size and processed at 133°C for 20 minutes at 3 bar absolute pressure (without interruption in continuous systems). This method is highly effective for inactivating a wide range of pathogens, but the thermal load is high and can more strongly affect nutrition and palatability.

Method 2: Medium-Temperature Heating

A batch method assuming particle size ≤150 mm, using one of the following options:

• 120°C for 50 minutes, or
• 110°C for 120 minutes, or
• 100°C for 125 minutes
  Compared with Method 1, conditions are milder, but uniform heating and strict holding-time control are essential.

Method 3: Medium Temperature / Long Time

Raw materials are reduced to ≤30 mm particle size and processed using one of the following options:

• 120°C for 13 minutes, or
• 110°C for 55 minutes, or
• 100°C for 95 minutes
  Total thermal load is moderate, offering a practical balance between hygiene and quality retention.

Method 4: Medium-Temperature Continuous Step Process

A step-wise approach suitable for continuous systems. With particle size ≤30 mm, all steps below are applied (offsets may be allowed):

• 130°C for 3 minutes
• 120°C for 8 minutes
• 110°C for 13 minutes
• 100°C for 16 minutes
  Quality stability and throughput can both be achieved, but the equipment’s temperature profile and residence time control directly determine consistency.

Method 5: Dry-Heat Processing

After adjusting particle size to ≤20 mm, the material is preheated to coagulate, pressed to remove fat and water, and then heated using one of:

• 100°C for 60 minutes, or
• 80°C for 120 minutes
  Because this is a dry process, oxidation and browning management is critical—minimize oxygen exposure time and integrate oxidation control through drying, cooling, and packaging.

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In general, Method 1 provides the largest safety margin but can cause more quality impact. Methods 3–4 are often selected in practice to balance safety and quality. Method 5 requires particularly strong oxidation management due to its dry-heat nature.

Stable meal quality and finished product reproducibility depend on validating the right combination of method conditions (temperature, time, particle size), considering bone content, moisture level, connective tissue content, and equipment heat-transfer characteristics.
　

Wet vs. Dry Rendering

Wet Rendering

Wet rendering applies low-temperature heating (around 90°C) in a steam- or moisture-rich environment. Heat transfer is generally stable with fewer temperature gradients inside equipment. However, efficient downstream dewatering and defatting design is required.

Dry Rendering

Dry rendering typically uses higher temperatures (around 140°C) under low-moisture conditions. While energy-efficient, it requires careful control of local overheating and oxidation risks (agitation, ventilation, dehumidification, minimizing oxygen exposure time).

Batch vs. Continuous Systems

Batch Systems

Batch processing handles a set amount at a time, offering flexibility for recipe or raw material switching and easier residence-time control. To minimize lot variation, loading amount, particle size, and moisture must be tightly managed.

Continuous Systems

Continuous systems include long conveyor-type cookers and low-temperature continuous units designed for gentler, slower heating. In low-temperature, long-time approaches, protein heat damage is reduced, helping maintain digestibility and amino acid quality. Newer low-temperature continuous systems are therefore considered suitable for premium pet food ingredients due to improved protein quality retention.

Typical Rendering Process Flow

1. Raw material receiving (classification, inspection, weighing)
   Confirm Cat. 3 status; rapidly assess temperature, odor, foreign matter, and moisture; assign traceability identifiers.
2. Pre-treatment (grinding / particle size adjustment)
   Reduce to target particle size to prevent uneven heating. Particle size uniformity directly improves sterilization reliability.
3. Heat processing (select Method 1–5)
   Define time/temperature/pressure/residence profiles clearly and monitor continuously with real sensors.
4. Separation (solids / oil / water)
   Use centrifugation and related systems to separate and recover meal, fats, and water. Add filtration/deodorization as needed.
5. Finishing (drying, cooling, grinding, screening, packaging)
   Adjust to target moisture and residual fat levels; implement oxidation control (nitrogen flushing, low-temperature storage, antioxidants).

Formulation Examples in Pet Food

Animal by-product meals can be used across a wide range of product designs. They are well-suited for:

• Working dogs / sporting dogs requiring high protein and energy
• Puppy and kitten diets for growth
• Large-breed and highly active dog formulas

They are also valuable in gluten-free and natural-style dry foods as animal protein sources that can replace or reduce grain usage. Blood meal and organ meals are typically used at low inclusion as nutrient boosters, supporting vitamin and mineral fortification. In recipe design, the key is to leverage the nutrient strengths of each meal while balancing the complete diet appropriately.

Summary

EU-sourced animal by-product meals are safe, nutrient-dense ingredients when produced and controlled under the proper processing methods and regulatory framework. By referencing European practices and standards, manufacturers can select and formulate the most appropriate meals to match product purpose and concept—achieving both cost-efficiency and high nutritional performance in premium dry pet food development.