In Poultry Science recently, F. Khajali (Shahrekord University, Iran) and B.A. Slominski (University of Manitoba, Winnipeg, Canada) reviewed the factors affecting the nutritive value of canola meal, including glucosinolates, sinapine, phytic acid, tannins, dietary fibre and electrolyte balance.

They also addressed the means of improving the nutritive value of canola meal throughout seed dehulling, development of low-fibre canola or application of feed enzymes.

Over the years, the glucosinolate content of canola has been declining steadily and is now only about one-twelfth of that of the older high-glucosinolate rapeseed (that is, 10 versus 120µmol per gramme). Therefore, the rations for broilers or laying hens could now contain 20 per cent of canola meal without producing any adverse effects.

Tannins are of lesser importance due to their presence in the hull fraction and thus low water solubility. Sinapine has been implicated with the production of a 'fishy' taint in brown-shelled eggs, which results from a genetic defect among the strain of Rhode Island Red laying hens. The White Leghorns have been reported not to be affected.

Although lower in protein, canola meal compares favourably with soybean meal with regard to amino acid content. Because canola meal contains more methionine and cysteine but less lysine, both meals tend to complement each other when used together in poultry diets.

Canola meal is low in arginine, which could be of importance when introducing canola meal to broiler diets at high inclusion rates. The arginine content of canola meal is approximately two-thirds of that of soybean meal. Chickens fail to synthesise arginine and are highly dependent on dietary sources for this amino acid. Supplementation of arginine to canola meal-based diets has been shown to partly restore the growth performance.

Dietary cation-anion difference in canola meal is also less than optimal due to the high sulphur and low potassium contents. Seed dehulling has not been very successful due to excessive fineness and thus difficulties with percolation of the miscella through the cake.

Finally, Khajali and Slominski report that the development of low-fibre, yellow-seeded canola and the use of enzymes have proven to increase the energy utilisation and the nutritive value of canola meal for poultry.

Reference

Khajali F. and B.A. Slominski. 2012. Factors that affect the nutritive value of canola meal for poultry. Poult. Sci., 91(10):2564-2575. doi: 10.3382/ps.2012-02332

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