De-oiled cake, usually shortened to DOC, is the meal left after most of the oil has been taken out of an oilseed by solvent extraction. Because the oil is removed, the protein is concentrated, so feed mills use DOC as a protein source for poultry, cattle, fish and pigs.
In India the term covers soybean, groundnut, rapeseed and mustard, cottonseed, sunflower, rice bran and castor. All but castor are used in feed. Castor DOC is toxic to animals and goes to fertiliser instead.
How DOC is made
Most oilseeds are first pressed in an expeller. The press leaves a cake that still holds some oil. A solvent plant then washes that cake, or the flaked seed, with a food-grade solvent, usually hexane, to pull out most of the remaining oil.
The meal then passes through a desolventiser and toaster. Heat drives off the solvent and, for soybean, also destroys anti-nutritional factors such as trypsin inhibitors. The meal is cooled, ground or pelleted, and bagged or sent to bulk storage.
DOC versus expeller cake
Buyers sometimes mix up the two. They are different products with different uses.
- Expeller cake: pressed only. It keeps more residual oil, so it carries more energy but goes rancid sooner.
- DOC: solvent extracted. Residual oil is usually low, often around 1 percent or less, so protein is higher and storage life is better.
- Form: both may be sold as powder, flakes or pellets. Pellets handle and ship with less dust.
- Naming: Indian quotes often say DOC, while overseas buyers say meal, for example soybean meal or rapeseed meal.
How feed mills use it
A feed formulator buys DOC for protein and amino acids. The choice between meals depends on the animal, the protein needed, fibre, palatability and any anti-nutritional factors.
- Poultry: soybean meal is the standard protein source for broilers and layers. Other meals are used at lower inclusion.
- Dairy cattle and buffalo: cottonseed, groundnut, mustard and rice bran DOC are common in Indian cattle feed.
- Aquaculture: fish and shrimp feed uses soybean and other meals, with tight limits on contaminants.
- Pigs: soybean meal is preferred. Meals with higher fibre or anti-nutritional factors are limited.
What to check before you buy
Protein is only one number. A sound specification also covers moisture, residual oil, crude fibre, sand and silica, aflatoxin and salmonella, and for some meals a specific factor such as urease activity in soybean meal or free gossypol in cottonseed meal. The tests are set out in what tests should be on a feed ingredient certificate of analysis.
Typical figures differ by seed, plant and season, so treat any number you see as an illustration. Agree limits that suit your animal and market, and confirm them with a test on a sealed sample. The general method is in how to write a good specification for an agri product.
How we help
We find solvent plants that make the meal you need, visit them, and have samples tested at NABL-accredited labs before you commit. We then follow the order through to loading and check the documents. Start with a free sourcing review.