Pressing oil leaves most of the seed behind as cake: 100 kg of seed at 40% oil gives 24 kg of oil and 76 kg of cake at 60% recovery, and that cake still holds about 21% oil and 30-40% protein, which makes it good animal feed. Sunflower cake suits chickens, pigs and cattle, rapeseed cake suits cattle and is limited for poultry, flax cake is fed to cattle and pigs in limited quantities, and castor cake is poison and is never fed.
Part of Oil Pressing at Scale
What is left after pressing: how much cake there is, what it contains, which animals can eat which cake and how to store it.
Most Of The Seed’s Weight Becomes Cake
The cake is seed minus the oil taken out. For 100 kg of sunflower seed at 40% oil:
- At 50% recovery: oil 20 kg, cake 80 kg holding 20 kg of oil, a residual of 20 / 80 = 25%
- At 60%: oil 24 kg, cake 76 kg holding 16 kg, residual 16 / 76 = 21%
- At 70%: oil 28 kg, cake 72 kg holding 12 kg, residual 12 / 72 = 17%
- After a second pressing that brings total recovery to 78% (see Processing Steps): oil 31.2 kg, cake 68.8 kg holding 8.8 kg, residual 13%
The carrier gives the cake as 10-15% residual oil and 30-40% protein. A hand press at 50-70% recovery leaves 17-25% residual on the arithmetic above, so the 10-15% figure applies to a cake pressed twice or by a stronger press. Residual oil is feed energy: it makes the cake richer, and it also makes it spoil sooner.
What A Village’s Cake Weighs
For the middle-case budget (seed 2,079-4,158 kg and oil 499-998 kg, Community Oil Budget) the cake is 2,079 - 499 = 1,580 kg up to 4,158 - 998 = 3,160 kg a year. At the carrier’s 30-40% protein that is 1,580 x 0.30 = 474 kg up to 3,160 x 0.40 = 1,264 kg of protein for livestock.
Which Animal Gets Which Cake
| Cake | Fed to | Limit |
|---|---|---|
| Sunflower | Chickens, pigs, cattle | None stated by the carrier |
| Rapeseed or canola | Cattle | Limit for poultry because of glucosinolates |
| Flax or linseed | Cattle, pigs | Limit quantities; contains cyanogenic glycosides |
| Castor | Nothing | Contains ricin; deadly (Oil Extraction) |
The carrier does not give amounts per animal, and none is invented here. Introduce any cake gradually, mix it into the ration rather than feeding it alone, and watch the animals. For the rest of the ration see Feeding Working Animals.
Hulls And Stalks
Sunflower hulls make mulch or fuel; the carrier says the stalks mulch the garden. Pressing hulls with the seed lowers the oil yield and quality, so dehull first and keep the hulls out of the cake.
What You Need
- A dry, airy store for cake, off the floor
- A mill or crusher to break cake into feed-size pieces
- A record of what each animal group has been fed
Method: Handling The Cake
Step 1: Break the cake into small pieces as it leaves the press.
Step 2: Dry it loose in a thin layer if it is damp.
Step 3: Store dry and loose, not in a tight pile.
Step 4: Feed by animal as in the table, mixing it into the ration.
Step 5: Keep castor cake, if any, away from animals.
Common Mistakes
- Feeding rapeseed cake freely to hens. The carrier limits poultry.
- Feeding flax cake in large amounts. The cyanogenic glycosides limit it.
- Stacking damp cake. It heats itself.
Poison, self-heating and dust
Castor cake contains ricin and must never be fed. Cake stored damp or in a deep pile can heat itself and ignite, as the corpus warns (Oilseed Crops); stack it loose and dry. Cake dust is combustible, so keep flame away and never test for dust with a flame.
What’s Next
- Learn next: Community Oil Budget - how much cake the plan makes
- Combine with: Pressing and Extraction - the second pressing that lowers the residual