Full-fat canola seed (FFCS) is a feedstuff that offers
moderate protein and high energy values (Table 11). Depending
on price considerations, this can make it attractive for broiler
and turkey rations. Canola seed provides a convenient package
for the high-quality oil and can be incorporated directly into
diets with reduced effects on pellet quality (Salmon & Stevens,
1988 {517}). For the producers who mix feed on-farm, this fat
source can be handled at any temperature, without additional equipment
requirements.
1. Nutritional Aspects of Full-Fat Canola
Western Canada has a large supply of top quality FFCS available to the feed industry. "Sample" grades of canola (containing > 20% green seeds or > 5% wild mustard) are financially attractive. However, wild mustard contains elevated total GL levels (164 mMol g-1, oil-free air-dry basis; Daun et al. 1983{549}) and this must be considered when determining dietary FFCS inclusion rates.
Large seed size has been related to improved digestibility of crushed FFCS. Dry matter, gross energy, protein (P<0.05) and apparent fat digestibility (P<0.001) were greater for the large seed fractions (>1.75 mm diameter) of two canola varieties (Lui et al. 1995 {334}). Brassica napus cultivars have a larger average seed size than those of B. rapa (Doug Declerq, CGC, personal communication), but this review did not encounter any nutritional comparisons of the two species.
Total GL levels averaged 13 mMol g-1 (8.5% moisture basis) in Canadian FFCS from 1992 to 1996 (Declerq and Daun 1996 {313}). Therefore, GL levels in diets containing FFCS are even less of a concern than with CM, which by definition contains less than 30 mMol g-1 aliphatic GL. Sinapines must be considered when recommending dietary inclusion levels for brown-shelled layers because if the level of sinapine exceeded 1g kg-1 diet, fish-taint was detectable in eggs (Goh et al. pg. 162 in Pokorny and Reblova, 1995 {331}). A survey of Canadian FFCS indicated B. rapa cultivars contained a range from 0.39 to 0.76% sinapine, and B. napus, 0.62 to 1.06% sinapine (Clausen et al. 1985 in Pokarny and Reblova, 1995 {331}). The suspected ANF, tannin, is located in the hulls and cotyledons of canola (Blair and Reichert, 1984 {541}. However, feeding trials with broilers indicated that the low levels present did not reduce the performance of poultry (Mitaru et al. 1983 {546}).
The potential for enzyme supplementation of FFCS diets has been examined, but results do not appear promising. Full-fat canola seed was incubated with Viscozyme 120L prior to inclusion in the diets of young broilers (4-14 d; 150 g kg-1 diet), but no significant improvement in performance resulted. Growth and FC were numerically enhanced with the Viscozyme 120L treatment, but this may have been due to viscosity-reduction effects upon the wheat component (340 g kg-1) of this diet (Ochodzki et al. 1995 {332}).
Full-fat canola seed is likely to be used in its raw form and will not benefit from heat-inactivation of ANF that occurs during the processing of CM, although this may not have a major impact on poultry performance. Heat treatment (85°C for 30 min) did not improve weight gains of broilers consuming diets containing ground FFCS (100 g kg -1). In a second experiment, FFCS at 100 or 200 g kg-1 dietary inclusion levels supported performance that was not significantly reduced from the corn-SBM control (P<0.05; Lee et al. 1991 {436}). Broilers (1-5 weeks) fed diets containing defatted canola seed (255 - 270 g kg-1) performed similarly to those fed diets containing equal levels of defatted, cooked (85°C) canola cake, or a conventionally toasted CM produced from the same cultivar. Glucosinolate levels were significantly lower in CM than in the canola cake or defatted seed (4.7, 17.6 and 17.7 mMol g-1 fat-free DM, respectively), but heating may also have reduced lysine (5.64, 5.77 and 6.10 g/16g N, resp.) and available lysine (4.42, 5.00 and 5.08 g/16 g N, respectively) levels in these products (Grala et al. 1994 {339}). Conversely, Shires et al. (1981{553}) indicated improved performance for broilers (0-4 weeks) consuming diets containing dehulled, autoclaved (121°C for 30 min) canola seed, despite a significant reduction in lysine content.
Researchers are including FFCS in poultry diets so that the unsaturated fatty acids may be deposited in the poultry carcasses and eggs, thus altering the fatty acid profile to a balance thought more favorable for human nutrition. Broilers fed diets containing FFCS (100 g kg-1) contained significantly (P<0.05) more linoleic and linolenic acid in dark and white meat as well as in abdominal and subcutaneous fat pads (Nwokolo and Sim, 1989 {480}); however, omega-3 fatty acid deposition in white and dark meat was lower than for birds fed full-fat flax seed (FFFS) diets (Ajuyah et al. 1991 {424}). Feeding FFCS as 120-200 g kg-1 of the diet enriched the level of omega-3 fatty acid present in the tissues of SCWL hens (Nwokolo and Sim, 1989 {480}). Consumption of FFFS diets stimulated greater deposition of LNA in eggs (P<0.05), but FFCS (100-160 g kg-1) diets supported omega-3 fatty acid deposition at a rate which was not significantly lower than with diets containing FFFS. Full-fat canola seed increased carcass levels of some omega-3 fatty acids in spent hens (Ajuyah et al. 1992{419}) and in 12-week-old turkeys (Ajuyah et al. 1993 {386}). Health and Welfare Canada (1990) recognizes omega-3 fatty acids as an essential part of the human diet; however, public demand for enriched products is required in order to make production economically feasible.
Full-fat canola seed is an alternative to FFFS as
a source of unsaturated fatty acids for poultry diets and may
support improved performance. The TMEn of FFCS was 530 kcal kg-1
higher than FFFS; however, the mean difference in TMEn (150 kcal
kg-1) was reduced when the oilseeds were tested in
combination with graded levels of barley (Barbour and Sim, 1991
{452}). Amino acids tended to be more available in FFCS than
in FFFS, in full-fat seeds than in corresponding meals, and in
oilseed ingredients fed in combination with a basal diet (Lee
et al. 1991 {436}).