Effect of high dietary levels of canola meal on growth performance, carcass quality and meat fatty acid profiles of feedlot cattle.

摘要

Effects of substituting canola meal (CM) for barley grain were investigated on growth performance, carcass quality and meat fatty acid (FA) profiles of feedlot cattle. Cross bred calves (n = 140; 285 +or- 27 kg) were individually fed diets comprised of a barley grain based concentrate (including 5% supplement) and barley silage at ratios of 45:55 and 92:8 (DM basis) during growing and finishing periods, respectively. Pressed CM from Brassica napus, containing 11.4% residual oil and solvent-extracted CM derived from B. napus or B. juncea canola seed were compared. Canola meal was substituted for 0 (control), 15 or 30% barley grain (DM basis) in both growing and finishing diets. Regardless of diet, cattle did not differ (P > 0.05) in average daily gain in either the growing or finishing period. For the overall feeding period, inclusion of 30% CM increased (P < 0.01) DMI of cattle compared with 15% CM groups, but reduced (P < 0.05) gain: feed (G:F) as compared with control and 15% B. juncea and 15% pressed CM. Gain:feed ratio of cattle fed CM was also reduced (P < 0.05) during the finishing period as compared with the control diet, with this reduction being more notable at the 30% level. Carcass quality and incidence of liver abscesses were not affected (P > 0.05) by inclusion of CM. Inclusion of 30% pressed CM resulted in higher (P < 0.05) %FAME of total PUFA, n-3, alpha-linolenic acid and CLA, as well as a decrease (P < 0.05) in n-6-3 ratio in the pars costalisdiaphragmatis muscle compared with the control diet. In conclusion, inclusion of CM did not alter growth performance or G:F of beef cattle during the growing period, but did lower G:F during the finishing period. The inclusion of 15 or 30% solvent-extracted CM did not alter carcass quality, whereas 30% pressed CM increased levels of desirable fatty acids (i.e. n-3 and CLA) in beef.