2.3 Growth and Feed Conversion of Pigs Fed Canola Meal
The economic advantage of including canola meal in the diet is often overshadowed by performance results lower than that of SBM diets (Baidoo et al. 1984 {1901}; Wetscherek et al. 1992 {1771}; Bell and Keith 1993 {1706}; Jacyno et al. 1996 {1610}). There appears to be no conclusive factors attributing to this phenomena. CM additions to ad libitum fed diets tend to give more variable results than restricted feeding (Homb and Matre 1989 {1841}). Adequate lysine supplementation is critical and recent ileal digestibility determinations confirm this. With supplementary lysine and/or SBM, growth rates equal to that of SBM diets (23-100kg pigs) were obtained (Bell et al. 1988 {1850}; Bell and Keith 1988 {1849}). Methionine addition also tended to improve ADG and FC. The response was significant for added lysine and added lysine plus methionine diets (Bell et al. 1988 {1857};Valaja et al. 1993 {1736}). Zollitsch-Stelzi et al. (1992 {1758}) concluded that canola meal diets supplemented with synthetic amino acids can be used to reduce dietary protein with no deleterious effects on performance.
The higher fibre in canola meal may be responsible
for the increased passage observed for CM (P<0.05) over SBM
(Imbeah and Sauer 1991 {1804}). Hull fractions of
canola seed comprise 140-160g kg-1 of canola weight
and therefore comprise 250-280g kg-1 of the meal dry
matter (Bell and Keith 1988 {1848}). Even so, triazine-tolerant
CM, with more protein and less fibre than regular CM, lead to
only marginally better growth rate and feed efficiency (Bell and
Keith 1987 {1875}). In comparing triple low RS (low GL, erucic
acid and tannins) to others, little benefit of reduced fibre and
tannin was conferred to the pig (Agunbiade et al. 1991
{1797}).
3.0 Meat Quality and Carcass Composition of Pigs Fed Canola Meal
Dietary supplementation with canola meal does not affect carcass traits (Bell and Keith 1993 {1706}). Neither intensity of pork flavour nor off-flavour were detected with CM replacement of SBM in a barley-based diet (Melton 1990 {1813}). Ractopamine administration with canola meal did not produce meaningful differences in either flavour or textural properties of pork in comparison with SBM (Jeremiah et al. (1994 {1664}).
When restrict fed either SBM or low glucosinolate
rapeseed meal (cultivar Tower) there was no difference in intramuscular
fat. RSM fed pigs did have increased pigmentation and produced
slightly darker meat. RSM was included at 330g kg -1
which is higher than generally accepted in pig diets therefore
it is concluded that low glucosinolate RSM at practical levels
would have no adverse affect on meat quality (Dransfield et
al. 1985 {1896}).
Pigs fed canola meal perform equally to SBM fed pigs
provided that the level of GL does not impair circulating T3
levels and FI are equivalent. This is more difficult to
achieve in younger pigs where fibre plays a more significant role
in limiting intake. The key is to pay scrupulous attention to
diet formulation to ensure that energy and digestible amino acid
intakes are adequate. The challenge to research scientists is
to establish by what method and which GL is responsible for diminished
T3 circulation. In order to produce the highest quality
ingredient possible, canola processors are urged to pay closer
attention to fibre levels, processing temperatures and duration.
As evidenced by the high meat quality of canola fed pigs and
the lower diet cost with canola meal inclusion, canola meal remains
an economical ingredient highly suited for swine diets.