2.0 Pig Performance on Full Fat Canola Seed
2.1 Grower- Finisher Performance on Full Fat Canola
Early studies concluded that the inclusion of full fat canola seed (FFCS) (150g kg-1) in a pelleted ration had no effects on pig performance except to improve FC (Castell and Falk 1980 {1934}). Since then feeding full fat canola to swine has given variable results. Several studies reported that inclusion of 150g kg-1 raw ground FFCS did not affect FI, ADG or FC; however, a marked reduction in FI and ADG was seen at 300g kg-1 inclusion (Shaw et al. 1990 {1824}; Gill et al. (1995 {1628}; Bell et al. 1987 {1871}). Warnants et al. (1995 {1639}) reported depressed feed intake and ADG (P<0.05) when levels of extruded rapeseed exceeded only 70g kg-1. Conversely, pigs (30-95 kg) on a restricted feeding regime, did not reduce feed intake, even when the diet contained 380g kg-1 rapeseed products (180g kg-1 RSM and 200g kg-1 FFCS). However, ADG was decreased by 88g when 200g kg-1 seeds were used (Raj et al.1995 {1647}). This variability is summarized by Kracht et al. (1996 {1614}) where in two experiments it was determined that for every 1mmol GL, ADG decreased 62g and that a 10g kg-1 increase in RS decreased ADG by 9g with no depression occurring below a threshold of 0.8 mMol GL/kg feed. Yet in a third experiment, where RS was included at graded levels up to 200g kg-1 of the diet, there was no impairment of growth or feed intake.
Possible explanations for this inconsistency may be factors affecting appetite. As noted in earlier sections, pigs restrictively fed canola respond better than those ad libitum fed. Pigs did show a preference for diets containing 150g kg-1 ground full fat rapeseed (eastern Germany, 21.4 mmol GL/kg DM) when soaked in water then gently heated, as opposed to untreated whole seed. Both FI (10%; P<0.01) and ADG (11%; P<0.05) improved for the treated diet, although feed conversion remained the same. Pigs consumed similar quantities when diets contained 40g kg-1 treated or untreated rapeseed. Some preference for the treated seed diet was detected at 80g kg-1 inclusion; at 160g kg-1 inclusion pigs consumed two-thirds treated feed and only one-third untreated feed (P<0.05) (Schone et al. 1994 {(1669}). In this study, the moisture and heat treatment may have been sufficient to degrade unpalatable GL or GL byproducts. A second factor, rancidity may be the cause of poorer feed intake of ground full fat canola. Busboom et al. (1990 {1795}) found feed intake was lower for ground as opposed to intact canola seed as did (Bell et al. 1985 {1890}). Once ground, the high oil content of full fat canola becomes highly susceptible to oxidative processes resulting in undesirable odours and flavours. Despite high levels of -tocopherol, treatment of the feed with an antioxidant is essential for long term storage of ground full fat rapeseed.
Digestibility depression has been noted in several studies. Jaskiewicz and Matyka (1995 {1618}) found digestibility of SBM was higher than FFCS. Digestibility of dietary fat, crude protein and energy declined significantly as whole canola seed increased from 15-300g kg-1 of the diet. ME of the diets decreased as RS increased changing the ratio of ME:DE from 0.958 to 0.941 (Bell et al. (1985) (1890); Raj et al. 1993 {1744}). Raj et al.(1995 {1647}) also reported lower crude protein digestibilities but found that digestibility did not depend on seed content, but rather on pig age. Although dietary ME increased as RS replaced barley, energy utilization declined with increasing RS concentration. Lower energy retention was explained as a result of lower protein deposition, in this trial full fat rapeseed was fed along with 200g kg-1 RSM. Since the seeds were not heat-treated they provided both intact glucosinolates and myrosinase. The resulting poorer performance of the animals fed this combination stems from possible GL effects as discussed in earlier sections. The authors calculated that a 1% increase in RS decreased protein deposition by 0.8g and a final recommendation was given not to feed RSM and RS together.
Various processes have been used to enhance the quality
of full fat rapeseed. Autoclaving completely destroyed endogenous
myrosinase, permitting normal performance of piglets (6 kg) consuming
200g kg-1 FFCS diets. Goitrogenic effects were noted
but they did not impair ADG and FC of the pigs. Digestibility
co-efficients were significantly lower though (Ochetim et al.
1980 {1936}. Grinding improved ADG, but lowered daily feed intake.
Pelleting, too, improved gains, with no effect on feed intake.
With frost-damaged canola seed, ADG increased with the extent
of damage, possibly due to improved palatability, since FI increased
while FC remained the same. Glucosinolates were lower in the
highly damaged seed which may reflect less maturity or frost-ruptured
cells, which allowed GL exposure to myrosinase (Bell et al.
1985 {1890}). Ammoniation of frost damaged (450g kg-1)
canola seed fed at 300g kg-1 of the diet gave ADG and
FI values similar to barley-wheat SBM formulated to the same protein
level. Neither freezing nor ammoniation of dietary canola seed
had any effect on carcass index of pigs (23-100kg) (Bell et
al. 1986 {1886}).
2.2. Feeding Full Fat Canola to Sows and Piglets
In sows, feed refusal occurred with 200 and 250g kg-1 ground whole canola seed diets between day 109 of gestation and day 21 of lactation. At 150g kg-1 FFCS (barley/SBM diet) feed intake by sows after farrowing was less than half (P<0.01) of the other diets, but milk solid and fat content were highest. Lower levels of FFCS had no effect. At 100g kg-1 inclusion there was no feed refusal. Piglets weighing <1.25 kg at birth were heavier at weaning with sows fed 150g kg-1 FFCS despite a reduction in milk yield due to decreased feed intake, but because of a higher fat content. However piglets weighing >1.25 kg were significantly smaller after seven days indicating that quality did not compensate entirely for quantity. Overall piglet growth was reduced prompting the researchers to recommend that at levels necessary to increase milk fat (200g kg-1 CS), intake was too limiting to advocate the use of ground, raw FFCS in sow diets (Spratt and Leeson 1985 {1897}).
When restricted to 150g kg-1 of the diet,
full fat canola seed is an excellent source of nutrients and oil.
Above this level, feed intakes and average daily gains appear
to be hindered by a combination of depressed digestibilities and
poorer palatability. Grinding markedly improves digestibility
but renders the product highly susceptible to oxidation, simple
treatment with an antioxidant would prolong the ingredient shelf
life.