The advantages of increasing the fat content of pig
diets range from increased weight gain in growing pigs to enhanced
milking ability in sows. The challenge for many on-farm feed
manufacturers is the incorporation of additional fat which requires
specialized equipment. Whole canola seed referred to as full
fat canola seed (FFCS) offers the opportunity to overcome this
hurdle. Each year canola containing small, off-color or frost-damaged
kernels enters the feed market because it is not suitable for
oil crushing. An economical method of adding fat to the diet,
full fat canola contains 400g kg-1 oil and has a crude
protein of 180-220g kg-1 (See composition section Table
N-6). It has been estimated that ground, frost-damaged canola
seed was worth from 121-151% the price of good quality barley
and that little difference exists between low, medium and high
frost damage in terms of nutrient content (Bell and Keith 1986
{1886}).
1.0 Nutrient Digestibility of Full Fat Canola
Ileal digestibilities of full fat canola seed (Table 5) in young piglets (8.9-11.8 kg) were higher, but very similar compared to extruded full fat soybeans and significantly lower than SBM. The lower values were attributed to tannins, pectins and crude fibre (Fan et al. 1995 {1619}; Shaw et al. 1990 {1824}). Agunbiade et al. (1991 {1797}) cautioned against estimating the energy value of full fat canola from its component parts as oil provided as whole seed was less available than that provided in liquid form.
Full fat canola can be fed whole. Busboom et
al. (1990 {1795}) found no significant differences in pig
performance whether they were fed 200g kg-1 ground
or intact canola seed. However, simple grinding of the seed has
been shown to markedly improve digestibility. Energy digestibility
almost doubled and protein digestibility nearly tripled in ground,
frost damaged canola seed, regardless of whether the damage was
low, moderate or high. Pelleting whole seed had a similar effect
to grinding, but very little effect if the seed was previously
ground. Ammoniation improved energy and protein digestibility
by ~ 6 percentage units, with the highest digestibility seen for
ground, pelleted ammoniated seed (Bell et al. 1985 {1890}).
The full nutritive value of full fat rapeseed is only obtained
when the product is mechanically disrupted and heat-treated to
allow glucosinolate destruction and to expose intra-cellular oil
to the lipolytic enzymes of the digestive tract (Smithard 1993
{1719}).
| Table 5 Apparent fecal and ileal digestibilities (%) of dry matter, protein and amino acids of full fat canola | ||||
| Fecal | Ileal | Ileal | Fecal | |
| T-C | T-C | |||
| Ground | Ground | Ground | Ground | |
| Pig Weight | 60 kg | 60 kg | 8.9 | 11.8 |
| Dry matter % | 71.69 | 59.75 | ||
| Protein % | 82.60 | 69.50 | 55.6 | 66.5 |
| Energy | 82.83 | 75.66 | ||
| Apparent DE MJ/kg | 19.71 | 17.61 | ||
| Indispensable amino acids | ||||
| Arginine | 70.8 | 77.6 | ||
| Histidine | 63.9 | 77.2 | ||
| Isoleucine | 63.3 | 66.1 | ||
| Leucine | 63.1 | 67.8 | ||
| Lysine | 75.90 | 72.10 | 64.1 | 69.2 |
| Methionine | 67.8 | 61.6 | ||
| Phenylalanine | 68.4 | 70.7 | ||
| Threonine | 57.8 | 70.1 | ||
| Tryptophan | ||||
| Valine | 63.6 | 66.7 | ||
| Dispensable amino acids | ||||
| Alanine | 65.0 | 71.2 | ||
| Asparic acid | 73.4 | 77.9 | ||
| Cysteine | 63.7 | 79.6 | ||
| Glutamic acid | 76.7 | 84.2 | ||
| Glycine | 62.4 | 73.6 | ||
| Proline | ||||
| Serine | 59.7 | 74.4 | ||
| Tyrosine | 55.2 | 60.0 | ||
| Reference {} | {1817} | {1817} | {1619} | {1619} |
| Table | 3 | 3 | 4 | 4 |
One concern with the use of full fat canola seed
is that during feeding or processing (grinding) glucosinolates
come into contact with myrosinase, enabling formation of toxic
products. Treatment with moisture and heat partially alleviates
the problem as Schone et al. (1994 {1669}) found glucosinolates
were reduced by 90 percent after grinding, soaking with water
and heating (60C). Similarly, RS moistened with water and heated
to 105C for 5 minutes decreased total intact GL from 15.5 to 8.5
mol/g (Kracht et al. 1996 {1614}). Heat treatment alone
was insufficient to entirely eliminate antithyroid activity because
GL remain intact even though myrosinase was inactivated. Certain
gut bacteria produce myrosinase with similar effect (Smithard
1993 {1719}). Autoclaving completely destroys myrosinase however,
it negatively affects lysine availability. Jet sploding®
(dry heat) did not offer any improvement (Shaw and Aherne 1987
{1868}) and the success of using extrusion to eliminate myrosinase
is temperature dependent. Ochetim et al. (1980 {1936})
found only a 100g kg-1 reduction by processing at 85C,
while complete elimination was achieved at 120 C.