Sunflowers (Helianthus annuus) are grown mostly in cold climates for their seeds. These are used for oil production or as a confectionary item. There are distinct varieties for each use because confectionary seeds are not rich enough in lipids for efficient oil extraction.
Sunflower meal is the residual matter after oil extraction, usually by the use of solvents (as in the case of soybeans), but also by hydraulic pressure (older but still used method). The latter process produces sunflower meal rich in residual oil, and this should be taken into account during feed formulation.
Pigs will readily consume diets based on sunflower meal, assuming upper crude fiber limits are not exceeded. The appetizing effect of sunflower meal is due to the small concentration of sugars, which give a slightly sweet taste to feed. This is very important, especially for piglet feeds, where a sweet taste is often simulated by the use of artificial sweeteners.
No anti-nutritional factors
Sunflowers contain no known anti-nutritional factors, in contrast to other protein sources such as soybean meal that contains a plethora of such compounds. Nevertheless, the use of sunflower meal in poultry and pig diets is restricted by its concentration in crude fiber, something that is considered undesirable, with a few notable exceptions (as in diets for gestating sows). In any case, sunflower meal can be included freely in diets as long as dietary crude fiber concentration does not exceed 3-5 percent.
Sunflower meal is available commercially in three forms, depending on the level of hulls in the final product (see table), which determines the final crude fiber level.
Dehulled sunflower meal contains no hulls and is the most desirable, albeit the most expensive, product. It has about 38 percent crude protein and 14 percent crude fiber. This is the preferred type of sunflower meal for piglet and sow lactation diets.
Partially dehulled sunflower meal contains a (variable) part of the hulls. Usually, it has approximately 32-35 percent crude protein, and 20-25 percent crude fiber, with exact levels depending on the concentration of hulls. This product is suitable for growing pigs and sow gestating diets.
Standard sunflower meal contains all the seed hulls. Here, the crude protein concentration is usually less than 30 percent, with approximately 25-30 percent fiber. This product should be avoided in low-fiber diets, but it can be used in maintenance diets (boars, gestating sows), or when growth rate must be reduced (as in late finishing pigs).
Sunflower seeds (full fat) are often available after being discarded by the oil or confectionary industry for a number of reasons pertaining to their quality. Whole seeds contain about 16 percent crude protein, 45 percent oil, and 16 percent crude fiber. Research has demonstrated that the high fiber content in whole seeds places them in the same level with sunflower meal in terms of usage limits. But, in addition, it appears the high oil content in full-fat seeds creates further feed intake problems, related to palatability, even in cases where a high-fiber concentration is not a major concern, such as in gestating sows.