The energy value of canola meal is considered low because of its relatively higher fibre and depleted oil content, according to a paper in the current issue of Canadian Journal of Animal Science.

Lead author, Eduardo Beltranena of the University of Alberta and colleagues explain that Brassica juncea is a novel canola species with thinner seed coat and reduced fibre but twice the glucosinolate content of B. napus. Remaining oil in canola cake provides greater dietary energy than solvent-extracted meal. Extrusion prior to expeller pressing may increase fat and protein digestibility and decrease the antinutritive effects of glucosinolates.

A total of 880 pigs (38kg), housed in 40 pens by sex, were fed 0, 5, 10, 15 or 20 per cent extruded B. juncea expeller-pressed cake (EPC) to slaughter weight (120kg) to evaluate the effects on growth performance, dressing, carcass traits and jowl fatty acids.

Diets provided 9.6MJ net energy (NE) and 1.0, 0.9, 0.8, 0.7 and 0.7g standardised ileal digestible Lys:MJ NE over five growth phases (days 0–14, 15–35, 36–56, 57–74 and day 75 to slaughter weight).

Each five per cent of EPC inclusion linearly decreased (P<0.05) average daily feed intake by 46g and average daily weight gain by 8g but did not affect gain:feed ratio.

Each five per cent EPC inclusion linearly decreased (P<0.01) carcass weight by 440g, loin depth by 0.6mm, and increased days on test by 0.43 but did not affect dressing, backfat thickness, lean yield or carcass index.

Each five per cent EPC inclusion linearly increased (P<0.001) mono- and polyunsaturated fatty acid content and iodine value by 0.8, 1.0 and 1.4g per 100g of jowl fat, respectively.

The researchers concluded that increasing dietary EPC inclusions decreased average daily feed intake, average daily weight gain, carcass weight and loin depth, and increased jowl fat unsaturation.

They attributed much of the decrease in feed intake to greater 3-butenyl (9.7µmol per gramme) content in extruded B. juncea canola expeller-pressed cake, a glucosinolate more bitter than others in conventional canola.

Reference

Zhou, X., M.G. Young, V. Zamora, R.T. Zijlstra and E. Beltranena. 2014. Feeding increasing dietary inclusions of extruded Brassica juncea canola expeller-pressed cake on growth performance, carcass characteristics, and jowl fatty acids of growing-finishing pigs. Can. J. Anim. Sci. 94: 331–342.

July 2014