Dr. Jacquie Jacob Ph.D., University of Kentucky
NOTE: Before using any feed ingredient make sure that the ingredient is organic, listed in your Organic System Plan, and approved by your certifier.
Canola is a variety of rapeseed with lower levels of glucosinolates in the oil and erucic acid in the meal than in other rapeseeds. Canola was developed in the early 1970s using traditional plant breeding techniques. The name canola was coined to distinguish it from rapeseed. The can is for Canada, where it was developed, and ola is for oil low acid. In Europe, canola is often referred to as double-zero rapeseed. Canola meal is a byproduct of oil extraction from canola seeds.
Care must be taken when purchasing canola for organic poultry diets, as there are transgenic varieties that were developed for herbicide resistance, and no genetically-modified (GE) products can be used in organic poultry feed (United States Department of Agriculture [USDA], 2000).
§ 205.2 Terms defined.
Excluded methods. A variety of methods used to genetically modify organisms or influence their growth and development by means that are not possible under natural conditions or processes and are not considered compatible with organic production. Such methods include cell fusion, microencapsulation and macroencapsulation, and recombinant DNA technology (including gene deletion, gene doubling, introducing a foreign gene, and changing the positions of genes when achieved by recombinant DNA technology). Such methods do not include the use of traditional breeding, conjugation, fermentation, hybridization, in vitro fertilization, or tissue culture.
The nutrient content of canola meal varies with the method of oil extraction (Woyengo et al., 2010). Although solvent extraction is the most efficient method, resulting in a meal with less than 5% residual oil, it is important to note that solvent-extracted canola meal cannot be used in organic poultry diets (USDA, 2000).
§ 205.270 Organic handling requirements.
(c) The handler of an organic handling operation must not use in or on agricultural products intended to be sold, labeled, or represented as “100 percent organic,” “organic,” or “made with organic (specified ingredients or food group(s)),” or in or on any ingredients labeled as organic:
(1) Practices prohibited under paragraphs (e) and (f) of §205.105.
(2) A volatile synthetic solvent or other synthetic processing aid not allowed under §205.605: Except, that, nonorganic ingredients in products labeled “made with organic (specified ingredients or food group(s))” are not subject to this requirement.
Expeller extraction methods are less efficient than solvent extraction, resulting in a canola meal with high residual oil (8-15%). For expeller-extracted canola meal, the level of residual oil is influenced by the number of times the seeds are passed through the system. The seeds can be passed through once (singly extracted), or repeated (doubly extracted). During solvent extraction, the seeds are subject to relatively high moisture levels (15-18%) and moderate temperatures (95-115°C). Conversely, during expeller extraction, the seeds are subject to lower moisture levels (less than 12%) and higher temperatures (up to 160°C). The high processing temperatures reached during expeller extraction are known to adversely affect the nutritive value of the resulting meal. This is especially true regarding the availability of some amino acids (Woyengo et al., 2010).
Table 1. Nutrient content of solvent and mechanically extracted canola meal (Canola Council of Canada, 2009)
|Nutrient||Solvent extracted||Mechanically extracted|
|Dry matter, %||88||82.9|
|Metabolizable energy for broilers, AMEn kcal/kg||2000||n/a|
|Metabolizable energy for layers, AMEn kcal/kg||2390||n/a|
|Crude protein, %||36.0||36.3|
|Crude fat, %||3.5||11.1|
|Crude fiber, %||12.0||10.6|
n/a = Not available
There are both yellow-seeded and brown-seeded varieties of canola. Seeds from yellow-seeded varieties are reported to contain more protein and energy but less fiber than those from brown-seeded varieties (Slominski et al., 1999).
The use of canola meal has historically been limited by its low available protein and energy content relative to that of the more commonly used soybean meal (SBM). The main factor affecting nutrient availability of canola meal is its fibrous hull, which is poorly digested and dilutes the levels of available crude protein and energy. Canola meal contains non-starch polysaccharides (NSPs) and glucosinolates, which also reduce nutrient availability. The problem with glucosinolates is that they break down into toxic aglucons. There are a number of glucosinolates, each with its own breakdown products.
The crude protein of canola meal (36-39%) is lower than that of soybean meal (44-48%). Canola meal has a good amino acid profile. While canola meal is high in methionine and cystine, it is low in lysine and arginine (Izadina et al., 2010). The digestibility of the essential amino acids in canola meal is, however, lower than in soybean meal. If the reduced digestibility is taken into consideration and the diets formulated on digestible amino acids, it is possible to include higher levels of canola meal in poultry feeds. The nutrient profile of canola meal will vary from country to country because of varietal differences and oil extraction techniques.
While full fat canola is a potential feed ingredient for poultry, its use in poultry diets has been limited for economic reasons–with the price of canola oil favoring oil extraction. Leeson et al. (1987) recommend that no more than 10% be used in broiler diets. Higher levels result in reduced feed consumption and poor broiler performance. There are a few reports indicating that enzyme supplementation improves energy availability with diets containing full-fat canola seeds (Meng et al., 2006). Enzyme supplementation of diets containing canola meal, however, has not been shown to be beneficial (Mushtaq et al., 2007)
Canola meal is most commonly used in layer diets. In the past, the inclusion of canola meal in layer diets was limited to less than 10% because of a low level of liver hemorrhage mortality that occurred with higher levels of inclusion. This appeared to be due to residual glucosinolates in the initial varieties of canola. However, plant breeding has steadily reduced the level of glucosinolates.
Care must be taken when including canola meal in the diet of brown-egg layers because of an increase in fishy flavor in the eggs (Hobson-Frohock et al., 1973). This appears to be due to reduced levels of the enzyme needed to break down trimethylamine (Ward et al., 2009)—a heritable trait. Trimethlyamine is produced during the bacterial fermentation of choline in the digestive tract. Choline is rapidly absorbed from the gut, and is therefore less available for trimethylamine production. In canola meal, however, the predominant form of choline is an ester of choline and sinapic acid—sinapine. The bond between choline and sinapic acid must be broken before the choline is available for absorption from the gut, which happens further down the digestive tract. The delayed release of choline makes it available for fermentation to the odor-causing trimethylamine. Some brown-egg laying chickens are unable to convert the bad-smelling trimethylamine into the odorless trimethylamine nitrogen-oxide. As a result, trimethylamine accumulates in the blood and is deposited in the developing follicles in the ovary of the hens (Ward et al., 2009). This also explains why feeding choline chloride to brown-egg layers does not result in fishy-smelling eggs. Breeding programs are making progress in selecting for brown-egg layers that do not have this trait.
Canola meal is one feed ingredient that can be used to increase the omega-3 fatty acid levels in eggs and meat. Others include flaxseed, fish oil, fish meal and marine algae (González-Esquerra and Leeson, 2001). However, an increase in omega-3 fatty acid content presents problems in production and in the sensory quality of eggs and meat. The production problems are related to anti-nutritional and physiological effects, while the product sensory problems appear to be due to interaction with volatile substances. Strategies to overcome the undesirable effects include restricting the level of omega-3 fatty acid sources, adjusting time of feeding, mixing different omega-3 sources in feed, and including high levels of vitamin E (which acts as an antioxidant) (González-Esquerra and Leeson, 2001).
Up to 30% canola meal can be included in broiler diets without negatively influencing growth rate and feed efficiency, as long as they are formulated on a digestible amino acid basis. The lower energy content of canola meal compared to soybean meal often limited its use in high-energy broiler feeds for economic reasons. In wheat- and corn-based diets, canola meal is normally limited to 10% because of its low energy content. Supplementation with feed enzymes does not appear to improve broiler performance (Kocher et al., 2000).
Feeding corn/canola meal-based diets to broiler chickens raised at high altitude has been reported to reduce performance as well as increased incidence of ascites. Arginine supplementation partly improved performance (Khajali et al., 2011).
Another issue related to feeding canola meal to broilers has to do with processing of the chickens at market weight (Canola Council of Canada). Canola seed hulls tend to stick to the inside of the digestive tract. If the digestive tract is torn during processing, the black canola hulls can stick to the carcass, causing it to downgrade. A solution to this problem is to remove canola meal from the diet five days before processing. Canola meal can also be included in turkey diets as long as extra animal fat is added to increase the energy level of the diet, and the diet is formulated on available amino acid levels. (Note: The use of slaughter byproducts is prohibited in organic production.) Canola meal can also be fed to ducks and geese with the same concerns as with broilers and turkeys.
The Canola Council of Canada recommends the following maximum inclusion levels of canola meal in nutritionally-balanced poultry diets:
The restriction to 10% for chick starter diets is based on inclusion in wheat or barley based diets, which are more common in Canada than in the United States. The level of inclusion in corn-based diets can be higher and is more dependent on economic factors.
In North America the level in the diet of brown-egg layers should be restricted to less than 3%.
For more information, refer to the Canola Meal Feed Industry Guide published by the Canola Council of Canada.
This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.