Whole Canola Seed Canola (WCS), Presscake (PC), Screenings and Canola Hulls
Chemical Composition of Whole Canola Seed (WCS) and Presscake (PC)
An extensive review of full-fat canola was done by Bell (1988 {1091}) and a review of all oils seeds was reviewed by Kempen and Jansman (1994 {881}). Under most economic situations processing of WCS is justified, but in the case of price discounts for poor quality canola seed or transportation costs associated with delivery to distant processing plants, the use of WCS in livestock diets is justified. When canola seeds are added to a diet, they should be incorporated on a protein and energy basis rather than just a protein source (Parker 1992).
Whole canola contains 40% ether extract, primarily
triglycerides and 20% CP, making it an excellent high-energy supplement
for lactating cows (Khorasani et al. 1991 {988}). Compared with
CM, WCS contains more EE, more GE and less CP (table 13). The
values for presscake are intermediate compared to WCS and CM.
On a fat-free basis WCS and canola presscake have similar AA
compositions except lysine is higher in WCS compared to presscake
(Mustafa 1996). Total GL are higher in WCS compared to presscake,
but myrosinase activity is 65% less in presscake than WCS (Keith
and Bell 1991 {1784}).
| Table 13. Chemical composition of canola seed and presscake relative to CM (DM basis). | ||||
|---|---|---|---|---|
| Canola seed | Press Cake | Press Cake | CM | |
| CP | 28.7 | 35.24 | 23.9 | 20.4 |
| Ether Extract | 44.1 | 10.37 | 21.2 | 3.9 |
| Gross Energy (Mcal kg-1) | 6.8 | 5.7 | 4.9 | |
| Crude Fiber % | 8.96 | |||
| Ash % | 7.60 | |||
| Total GL (mol g-1) | 38.4 | 35.8 | 21.1 | |
| Reference | 1784 | 885 | 1784 | 1784 |
Several studies have been carried out on WCS, whole,
ground or crushed, and treated with various processes to increase
the energy density of beef and dairy diets. Several processes
including extrusion, alkaline FA treatment, heat, Jet Sploding
(JS) (high temperature for a short period, uses moisture in the
seed), Protec® (product=FA WCS + CM), have been used to increase
the bypass value in order to obtain the most benefit from the
canola oil and protein for milk production
(Bell 1988 {1091})
and milk FA composition and animal composition (Hussein et al.
1996 {801}).
Protected fat supplements are advantageous due to
the detrimental effects of fat supplementation on carbohydrate
fermentation by ruminal microbes (Khorasani et al. 1991
{988}).
These microbes also hydrogenate dietary unsaturated fatty acids,
resulting in a more saturated milk and carcass composition in
comparison to the highly unsaturated diet. C18:2 and
C18:1 have been identified to have a hypocholesterolemic
effect and has the ability to decrease the risk for incidence
of coronary heart disease in normal persons (Mattson and Grundy
1985 as cited by Hussein et al. 1996
{801}).
This has prompted
some milk marketing boards to calculate the ideal milk fat for
the human diet; <10% polyunsaturated FA, 8% saturated FA, and
8%, 82% monounsaturated FA. Of all oil seeds, canola seed has
a unique FA profile of which C18:1 contributes about
58% of the total FA (Bell 1988 {1091}).
Effect on Feed Intake and Diet Digestibility
There have been inconsistent results on the relationship between dietary fat addition as oilseeds and DM intake. Khorasani et al. (1991) reported that DM intake and net energy for lactation of early lactating dairy cows was not influenced by supplementation of Jet-Sploded canola seed at inclusion levels of 4.5-17.4% (% of dietary DM) (Khorasani et al. 1991 {988}). Beaulieu et al. (1990 {1045}) reported that inclusions levels of 4.5% for WCS and 22% for presscake did not effect DMI in lactating dairy cows.
If WCS makes up more than 12-14% of the ration it
may lead to depressed rumen function reduced feed intake and digestibility
of nutrients (Bell 1988 {1091}). Conversely, Ferlay et. al (1992
{934}) fed dairy cows WCS, raw or extruded, at 14% of the diet
without effecting CF digestibility. Murphy et al. (1987 {1133})
reported reduced rumen digestibilities of DM, NDF and cellulose,
however hindgut fermentation compensated for the reduction at
1 kg WCS/d supplementation, but not at 2kg/d. In another study
by Murphy et al. (1990 {1013}), supplementation of 150 g/kg of
WCS, ground or unground, had a large and negative effect on DM,
OM, energy and fiber digestibility. The ground canola seed reduced
silage DMI, but WCS did not. It was concluded ground canola seed
had a higher rumen available oil effecting rumen digestion more
severely leading to a decrease in silage intake (Murphy et al.
1990 {1013}). At 5% of dietary DM WCS, whole or crushed, treated
with alkaline FA had no negative effects on ruminal fermentation
of OM, carbohydrates, or energy when steers were given low and
high forage intake (Hussein et al. 1995 {817}).
Effect on Milk Yield and Composition
Supplementation of 4.5 or 5% Jet-Sploded whole canola seed in early lactating cows may result in a positive productive response, but the inclusion of higher levels may be associated with reduced energy availability in the rumen and decreased fat digestibility postruminally (Khorasani et al. 1991 {988}; 1992 {988}). Supplementation of Jet-Sploded whole canola seed to early lactating dairy cows at increasing rates (4.5-17.4% of DM) displayed quadratic trends for milk fat, protein and lactose yield (P < 0.10) with a maximum at 4.5% Jet-Sploded whole canola (Khorasani et al. 1991 {988}). Milk fat and lactose percentages were not effected by treatment, but milk protein percentage declined linearly (P = 0.08) as inclusion levels of Jet-Sploded canola seed were increased (Khorasani et al. 1991 {988}; Strzetelski et al. 1992 {964}). True and casein protein both tended to decline with increasing JS whole canola. An optimal inclusion level of JS whole canola in early lactation ratios appears to be 4.5% and the benefits seem related to maintenance of body condition and a trend for greater persistency of lactation (Kwiatkowski and Luczak 1993 {912}) rather than a substantial increase in milk yield (Khorasani et al. 1991 {988}). No benefits were reported for adding JS WCS for dairy cows in mid and late lactation.
Feeding high oil products generally alters the normal make-up of milk fatty acid profile by increasing the proportion of long chain fatty acids and decreasing the short chain fatty acids. Long chain FA of dietary origin can be directly incorporated into the milk fat (Kennelly 1996 {808}). With supplementation of 4.5-17.4% (% DM) Jet-Sploded WCS concentrations of milk fatty acids C6:0, C8:0, C14:0, C15:0, C16:0 and C17:0 declined linearly with increasing levels of canola, but C18:1 showed a linear increase. Concentrations increased from 18.7% (control) to 30.3% (% of total fatty acids) at 17.4% (% DM) canola. No significant treatment effects were observed for C18:2 and C18:3 fatty acid (Khorasani et al. 1991 {988}), unlike supplementation of full fat soyabeans (Murphy et al. 1995 {820}) that reportedly increased levels of C18:2 (P < 0.001) and C18:3 (P < 0.01) . Emanuelson et al. (1991 {985}) indicated that the proportion of C18:0 increased and those of C16:0 and C16:1 decreased in the milk fat of dairy cows fed heat-treated and untreated WCS and resulted in a softer milk fat (Murphy et al. 1995 {820}; {821}; 1992 {930}). In agreement are other studies with similar findings (Khorasani et al. 1991 {988}; 1992 {988}; Jahreis and Richter 1994 {879}; Ashes et al. 1992 {954}; Strzetelski et al. 1992 {964}). The changes in the milk fatty acid would be beneficial in terms of human nutrition and prevention of coronary heart diseases (Murphy et al. 1995 {821}; Kennelly 1996 {808}).
An additional benefit of incorporating WCS into diets
is an increase in vitamin-E concentrations in milk (Jahreis et
al. 1993 {915}) and other body samples. However, WCS that has
been through an expeller reduced the vitamin E concentration in
animal products (Flachowsky et al. 1997 {788}).
At 5%/h flow rate, effective CP degradability of
WCS, CM and SBM were 86.7, 66.1, and 68.2%. Extrusion did not
effect WCS rumen CP degradability. Protec® and JS EDCP were
60.8% and 42.9% significantly (P < 0.05) lower than untreated
WCS. Gralak et al. (1997 {792}) reported WCS effective CP degradability
to be 74.98%. Without some form of protection WCS CP is obviously
highly degradable (Deacon et al. 1988 {1097}; 1986 {1145}). Crude
protein disappearance for unextracted WCS (93.5%) was higher than
for canola presscake (91.1%) or canola meal (75.1%) following
a 12 h rumen incubation (Beaulieu et al. 1990 {1045}).
Hussein et al. (1996 {801; 802}; 1995 {817; 810})
studied the effect of alkaline FA treatment on WCS on FA, OM,
energy and carbohydrate digestibility, ruminal composition, and
duodenal flows of AA in steers. The alkaline FA treatment is
suppose to weaken the seed coat while simultaneously protecting
long-chain unsaturated fatty acids from ruminal biohydrogenation
without reducing lower gut digestibility. Treated WCS was added
to the diet at 10% DM as whole or crushed and contributed 5% added
fat to the total diet. The canola was added to a diet with a
70 or 30% corn silage content. Treated WCS was superior to crushed
seed (received more ruminal biohydrogenation) in protecting unsaturated
C18 FA from microbial biohydrogenation and in supplying these
FA to the small intestine where they can be digested and absorbed.
The effect was more significant on the low forage diet than the
high forage diet. This will increase the ability of the producer
to increase the unsaturated C18 FA in meat and milk products,
which is more desirable from a human nutrition standpoint (Hussein
et al. 1996 {801}). Bulls and steers were fed CM, extruded WCS,
ground canola, SBM and extruded soybeans at 6.8 to 21.6% of DM
to determine the effects on FA composition of adipose and organ
tissue. Dietary WCS decreased 16:0 and 16:1 and increased 18:0,
18:1 and 18:2 in subcutaneous and perirenal adipose tissue and
increased 20:1 in all tissues. Bulls were less effected than
steers and extruded WCS was more efficient than ground (Rule et
al. 1994 {849}). Similar findings have been reported by Ashes
et al. (1993 {882}). Protected canola seed at 10% of the diet
increased the proportion of C18 FA in the subcutaneous, perirenal
and omental fats with a 3 fold increase in 18:2 and five fold
increase in 18:3.