De-Oiled Rice Bran

De-oiled rice bran (DORB) is the by-product obtained after the extraction of rice bran oil from full-fat rice bran through solvent extraction or mechanical pressing. It is a highly valued ingredient in the animal feed industry due to its balanced composition of protein, fibre, and essential nutrients. DORB represents a sustainable use of rice-milling by-products and contributes significantly to the agricultural and livestock economy, especially in rice-producing countries such as India, Thailand, and Vietnam.

Background and Production Process

Rice bran, the outer layer of the rice grain removed during milling, contains about 15–22% oil. This oil-rich bran undergoes solvent extraction—commonly using hexane—to recover rice bran oil. The remaining solid material after oil extraction is known as de-oiled rice bran.
The production process involves several steps:

1. Collection and Stabilisation: Fresh rice bran is collected from rice mills and immediately stabilised by heating to prevent rancidity caused by lipase enzymes.
2. Oil Extraction: The stabilised bran is subjected to solvent extraction, where rice bran oil is removed using a solvent such as hexane.
3. Desolventising and Drying: The extracted material is desolventised, dried, and cooled to yield DORB, which is light brown in colour and free-flowing in texture.
4. Grinding and Packaging: The final product is ground uniformly and packed for use in feed or as a raw material for further processing.

Composition and Nutritional Value

DORB is rich in nutrients and is widely used as a cattle, poultry, and fish feed ingredient. Its composition varies slightly depending on the rice variety and extraction method, but on average it contains:

• Crude protein: 14–18%
• Crude fibre: 10–13%
• Ash content: 8–10%
• Moisture: 10–12%
• Crude fat: <1% (as the oil is extracted)
• Nitrogen-free extract: 45–50%

It also contains vitamins (B-complex, E), minerals (phosphorus, magnesium, potassium), and essential amino acids such as lysine and methionine. The removal of oil significantly increases the protein concentration compared with full-fat rice bran, while reducing the fat content and susceptibility to oxidation.

Applications in Animal Feed

DORB is one of the most widely used livestock feed ingredients in Asia. It serves as a cost-effective source of energy and protein in feed formulations. Its applications include:

• Cattle and buffalo feed: Improves milk yield and quality due to balanced fibre and protein levels.
• Poultry feed: Used as a partial substitute for maize and soybean meal, enhancing feed economy.
• Fish and shrimp feed: Serves as a carbohydrate and protein source in aquaculture diets.
• Pig feed: Enhances digestibility when blended with other protein-rich ingredients.

Its fibre content supports digestion in ruminants, while the phosphorus and vitamin B content improve metabolic efficiency in livestock.

Industrial and Agricultural Uses

Beyond feed applications, de-oiled rice bran has emerging industrial and agricultural uses. These include:

• Organic fertiliser: DORB contains nitrogen and organic matter that enrich soil fertility.
• Mushroom cultivation: Serves as a substrate component in mushroom farming.
• Biofuel and biogas: Acts as a biomass feedstock for producing biogas and pellets.
• Fermentation substrate: Used in the production of enzymes, ethanol, and other bio-based products.

Such uses contribute to circular bio-economy practices, ensuring that no part of the rice-milling by-product is wasted.

Economic and Environmental Significance

India is the largest producer of rice bran in the world and thus a major supplier of DORB, producing over 10 million tonnes annually. The de-oiled variant has a significant export market, especially in countries with large livestock and aquaculture sectors such as Bangladesh, Vietnam, and Myanmar.
Economically, DORB supports:

• Feed industry cost reduction, by providing a cheaper protein source compared to soybean meal.
• Farm income diversification, as it adds value to rice-milling by-products.
• Export earnings, particularly through trade in bulk feed materials.

Environmentally, DORB promotes sustainability by reducing agricultural waste and enhancing resource efficiency. The use of rice bran and its derivatives prevents wastage of nutrient-rich by-products that might otherwise decompose or be discarded.

Quality Parameters and Standards

The quality of DORB is influenced by factors such as extraction efficiency, bran freshness, and processing conditions. The Bureau of Indian Standards (BIS) has specified quality grades for DORB under IS: 1374, which define acceptable limits for protein, fibre, moisture, and sand/silica content.
Key quality parameters include:

• Moisture content: Not more than 11%
• Crude protein: Minimum 15%
• Crude fibre: Not exceeding 13%
• Sand/silica: Not more than 2.5%

Adherence to these standards ensures that DORB maintains feed safety and nutritional value. Improper storage, on the other hand, can lead to moisture absorption, fungal growth, or nutrient degradation.

Advantages and Limitations

Advantages:

• Provides a low-cost alternative to conventional feed ingredients.
• Enhances digestive health in ruminants due to fibre content.
• Rich in vitamins and minerals, improving livestock performance.
• Contributes to sustainable waste management in rice milling.

Limitations:

• Lower digestibility in non-ruminants due to high fibre.
• Possibility of aflatoxin contamination if stored under humid conditions.
• Variability in nutrient composition depending on source and process.

Hence, proper formulation, quality testing, and storage are crucial to maximise the feed value of DORB.