Due to the increasing demand for protein for livestock feeding, the interest in using canola meal in diets fed to swine is increasing. Canola meal is a product of the rapeseed plant, an abundant oilseed crop grown in Canada, the Northern United States, and parts of Europe. Recently, new varieties of canola that contain more protein and less fiber than conventional canola have been selected. The de-oiled meals of these varieties have a concentration of crude protein that is close to that of de-hulled soybean meal.

It has been speculated that changes in the traditional pre-press solvent extraction oil removal procedure may improve the quality of canola meal. The traditional procedure involves use of heat to desolventise the de-oiled meal, but a new procedure allows for production of canola meal using a low-temperature procedure.

There is no information about the digestibility of energy in high protein canola meal. There also is no data comparing the digestibility of energy in canola meal processed at low temperatures versus high temperatures. Therefore, an experiment was conducted to compare the concentrations of digestible energy (DE) and metabolizable energy (ME) in high protein, high-temperature-processed, low-temperature-processed, and commercial canola meals, and to compare these values with the DE and ME in corn and soybean meal.

Forty eight growing barrows with an average initial body weight of 20 kg were allotted to a randomized complete block design. Six diets were formulated (Table 1). One was based on corn, one diet contained  corn and soybean meal, and four diets were based on corn and each of four different sources of canola meal. One source of canola meal was produced from a new high-protein variety of canola (CM-HP) and contained 44.7% crude protein. Two additional sources of canola meal were produced from a conventional source of canola, but one source was produced using a traditional prepress-solvent extraction procedure using heating to desolventise the meal (CM-HT) whereas the other source was produced using a low-temperature crushing procedure (CM-LT). The last source of canola meal was a conventional source of canola meal (CM-CV). The soybean meal that was used was also a conventional source of de-hulled soybean meal, and the corn was a conventional source of yellow dent corn.

The apparent total tract digestibility (ATTD) of energy and the concentration of DE and ME in corn were determined directly from the corn-diet. The contribution of corn to the DE and ME of the diets containing corn and SBM or canola meal was then calculated, and the ATTD of energy and the DE and ME in SBM and each source of canola meal were calculated by difference. 

The apparent total tract digestibility of gross energy in diets containing the four sources of canola meal was less (P > 0.05) than in diets containing corn or soybean meal (Table 2). Apparent total tract digestibility of gross energy did not differ among the four diets containing canola meal.

Concentrations of  digestible and metabolizable energy were less (P < 0.05) in all four sources of canola meal than in corn or soybean meal (Table 3). No differences were observed among the four sources of canola meal.

• All sources of canola meal contained less DE and ME  than corn and soybean meal.
• Selection for high protein content did not affect energy digestibility or concentration of DE and ME in canola meal.
• Processing temperature did not affect energy digestibility or concentration of DE or ME in canola meal.

Table 1. Composition of experimental diets containing corn, soybean meal, and 4 sources of canola meal

Table 2. Gross energy (GE) and apparent total tract digestibility (ATTD) of energy in diets containing corn, soybean meal, and 4 sources of canola meal fed to pigs

^a-b Within a row, means without a common superscript differ (P < 0.05).

Table 3. Energy values of corn, soybean meal, and 4 sources of canola meal fed to pigs

^a-c Within a row, means without a common superscript differ (P < 0.05).

This report is based on unpublished research by T. Maison and H. H. Stein.