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Rendered Products
What tests should be conducted to assess the nutritional quality of rendered products?
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11 Replies
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Thanks for sharing valuable knowledge here
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To assess the nutritional quality of rendered products, several tests should be conducted, including proximate analysis, rancidity testing, and analysis of specific nutrients like protein, fat, and vitamins
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Proximate analysis
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To assess the nutritional quality of rendered products, several tests are crucial. These include nutrient profiling, which measures macronutrients (proteins, carbs, fats) and micronutrients (vitamins, minerals). Additionally, fatty acid testing helps determine the types and amounts of different fatty acids present, and amino acid profile analysis is important for evaluating protein quality. Finally, chemical contaminant testing and microbiology testing ensure product safety and identify any potential issues.
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I am in support of every reliable, proven and tested tests – proximate analysis, protein solubility in KOH, Grease activity, protein dispersibility index etc. However, the best I love most is a test on the animal on the farm. Here, the issue of contents, availability, digestion, absorption, utilisation is solved perfectly.
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To assess the nutritional quality of rendered products, a variety of tests should be conducted, including proximate analysis and micronutrient analysis.
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WHAT TESTS SHOULD BE CONDUCTED TO ASSESS THE NUTRITIONAL QUALITY OF RENDERED PRODUCTS?
The following should be considered as general information only, you should always seek professional advice, specific to your individual circumstances.
Below are my social media posts from a recent seminar;
Why Peroxide Value Falls Short As A QC Tool For Lipids
Peroxide value (PV) while widely used, tells you practically nothing and is of little use to QC of fats and oils, stated Dr Julian Wiseman during the Ecolex Animal Nutrition’s Innovative Nutrition Forum, in Bangkok.
This is because PV only measures primary oxidation products (hydroperoxides), which are unstable intermediates that decompose into secondary oxidation compounds like aldehydes and ketones. Low PV readings can occur in fresh oils where hydroperoxides have only just started forming, indicating minimal oxidation and good quality and highly oxidized fats where peroxides have already broken down into secondary oxidation compounds. These secondary compounds such as volatile aldehydes, ketones and polymers, that PV cannot detect result in misleadingly low readings in highly oxidized fats.
Instead, Dr. Wiseman recommended Non-Elutable Material (NEM) for lipid quality control in animal feeds, which we will discuss in next week’s Lipids And Livestock – From Feed To Function.
Non-Elutable Material – The Gold Standard For Lipid QC
The oxidation of lipids in animal feeds is a complex process that produces a vast number of molecules, making it impossible to measure all the by-products, noted Dr Julian Wiseman during the Innovative Nutrition Forum, hosted by Ecolex Animal Nutrition. As the industry seeks more reliable methods to ensure feed quality Non-Elutable Material (NEM), using quantitative gas chromatography is emerging as the preferred metric for lipid quality control, surpassing traditional methods like peroxide value (PV).
Key advantages of NEM include:
• NEM quantifies persistent toxic oxidation products (e.g., polymers, aldehydes, ketones) and processing residues (e.g., soapstock, heavy metals) that remain in lipids even after hydroperoxides (measured by PV) decompose. These compounds can harm animal performance and health and reduce feed palatability.
• NEM directly reflects the digestible energy of lipids by accounting for non-nutritive components like moisture, impurities, and unsaponifiables (MIU), which dilute energy content. This ensures more accurate predictions of the energy available to animals, improving feed formulation and performance outcomes. Dr Wiseman noted that you can observe differences in performance with only a reduction in energy value of only 0.2MJ/kg.
• NEM simplifies lipid analysis by focusing on stable markers of degradation, reducing the need for multiple tests to assess lipid quality. It enables feed producers to identify and avoid low-quality or oxidized fats more efficiently. Interestingly, NEM is measured using the same procedures as employed in determining fatty acid profile, the only difference being addition of an inert marker margaric acid.
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proximate analysis can be used.
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To assess the nutritional quality of rendered products, tests should include proximate analysis to determine moisture, protein, fat, and ash content. Additionally, amino acid profiling is essential for evaluating protein quality, while mineral analysis helps identify essential micronutrients. Lastly, digestibility studies can assess how well the nutrients are absorbed and utilized by animals.
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Assessing the nutritional quality of rendered products—such as meat and bone meal, blood meal, feather meal, and poultry by-product meal—requires a series of laboratory tests to determine their suitability for animal feed. Key tests include:
1. Proximate Analysis
This is the fundamental analysis for nutritional composition, including:
Moisture content – Determines the water content, which affects shelf life and quality.
Crude protein (Kjeldahl or Dumas method) – Essential for assessing protein value.
Crude fat (Ether Extract) – Indicates energy content.
Crude fiber – Measures indigestible plant material if present.
Ash content – Represents mineral content, including calcium and phosphorus.
2. Amino Acid Profile
Determines the levels of essential amino acids (e.g., lysine, methionine, tryptophan).
Useful for evaluating protein quality and digestibility.
3. Fat Quality Tests
Peroxide Value (PV) – Measures primary oxidation, indicating freshness.
Free Fatty Acids (FFA) – High FFA levels indicate rancidity.
Anisidine Value – Assesses secondary oxidation products.
Total Volatile Nitrogen (TVN) – Used to detect spoilage.
4. Mineral Analysis
Calcium and phosphorus – Important for bone meal and meat meal quality.
Trace minerals (Zn, Fe, Mn, Cu, Se, etc.) – Required for animal health.
5. Mycotoxin and Contaminant Testing
Aflatoxins, ochratoxins – Detect fungal contamination.
Heavy metals (Pb, Hg, Cd, As) – Ensures safety from toxic elements.
6. Microbiological Tests
Salmonella and E. coli – Checks for bacterial contamination.
Total Plate Count (TPC) – General microbial load assessment.
7. Protein Digestibility and Pepsin Digestibility Test
Measures how much protein is digestible and available for animals.
digestible and available for animals.
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CP, fat ash , moisture content, PV, FFA, fiber, MIU, IV, EAA, calcium and phosphorus.
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