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

Zhou, X., Young, M. G., Zamora, V., Zijlstra, R. T. and Beltranena, E. 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. The energy value of canola meal is considered low because of its relatively higher fibre and depleted oil content. 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 compared with 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 (38 kg), housed in 40 pens by sex, were fed 0, 5, 10, 15, or 20% extruded B. juncea expeller-pressed cake (EPC) to slaughter weight (120 kg) to evaluate the effects on growth performance, dressing, carcass traits, and jowl fatty acids. Diets provided 9.6 MJ net energy (NE) and 1.0, 0.9, 0.8, 0.7, and 0.7 g standardized ileal digestible Lys:MJ NE over five growth phases (days 0-14, 15-35, 36-56, 57-74, day 75 to slaughter weight). Each 5% EPC inclusion linearly decreased (P<0.05) feed disappearance (ADFI) by 46 g and weight gain (ADG) by 8 g, but did not affect gain:feed. Each 5% EPC inclusion linearly decreased (P<0.01) carcass weight by 440 g, loin depth by 0.6 mm, and increased days on test by 0.43, but did not affect dressing, backfat thickness, lean yield, or carcass index. Each 5% EPC inclusion linearly increased (P<0.001) mono- and polyunsaturated fatty acid content and iodine value by 0.8, 1.0 and 1.4 g 100 g⁻¹ of jowl fat, respectively. In conclusion, increasing dietary EPC inclusions decreased ADFI, ADG, carcass weight, and loin depth, and increased jowl fat unsaturation. We attributed much of the decrease in feed intake to greater 3-butenyl (9.7 µmol g⁻¹) content in extruded B. juncea canola expeller-pressed cake, a glucosinolate more bitter than others in conventional canola.