EFFECTS OF CULTIVAR ON THE UTILIZATION OF GROUND RAPESEE IN DIETS FOR GROWING–FINISHING PIGS

Abstract

Low erucic acid cultivars of Brassica campestris L. (Span and Torch) and B. napus L. (Midas and Tower) were used to examine the effects of cultivar on the performance of 132 crossbred pigs fed, from 23 kg to 89 kg liveweight, diets containing ground rapeseed. The oil percentages and levels of total glucosinolates (mg/g oil-free meal) were, respectively, 39.1 and 8.2 (Span), 40.2 and 7.8 (Torch), 44.7 and 12.0 (Midas), 43.2 and 3.4 (Tower). Growth rates on 17% crude protein diets containing 10% rapeseed in experiment 1 ranged from 637 g/day (Midas) to 797 g/day (Tower), a significant (P < 0.05) difference, although feed:gain ratios and carcass measurements did not differ significantly between the four dietary groups. Results from experiment 2, in which B. campestris cultivars were used as 0 and 10% of pelleted diets fed for two 45-min periods daily, indicated that rapeseed depressed daily feed intake and gain significantly (P < 0.01) but did not adversely affect carcass measurements. Increasing the dietary level of B. napus cultivars, from 0 to 15% in experiment 3, depressed daily feed intake and gain of pigs fed Midas (P < 0.05) or Tower (NS) diets. Feed:gain ratios and carcass data were similar to those of the control pigs. Although Midas-fed pigs exhibited poorer (P < 0.01) live performance, their carcasses had less backfat (P < 0.01) with higher Carcass Value Indices (P < 0.01) and Record of Performance Scores (P < 0.05) than those fed tower diets. Results from the three experiments suggested that inclusion of rapeseed influenced the performance of growing–finishing pigs by an effect upon both the energy content and glucosinolate level of the diet consumed.