Nutritional evaluation of very low glucosinolate canola meal

Abstract

Two very low glucosinolate (VLG) canola meals from crop years 1987 and 1988 (CM; 1.66 and 0.53 μmol g−1) and two Tobin CM (B. campestris) (10.71 and 15.62 μmol g−1) were evaluated in experiments with pigs. In exp. 1, 1987 Tobin CM, VLG-CM and soybean meal (SBM) were compared in individually fed meal and pelleted diets. Daily gains from 23 to 57 kg were similar for the CMs (VLG-CM 662 g, Tobin CM 645 g) but lower than those obtained with SBM (730 g; P < 0.01). Daily feed intakes of pigs fed CM were lower than for those fed SBM (P < 0.05). Plasma thyroxine (T4) levels were similar for SBM and VLG-CM and were above those from pigs fed Tobin (P < 0.05) CM. Triiodothyronine (T3) levels were lower for VLG-CM than for SBM (P < 0.05) and the T3 value for Tobin CM was intermediate. Pelleting enhanced T3 (0.70 vs 0.94 ng mL−1) and T4 (50 vs. 60 ng mL−1) levels with all protein supplements (P < 0.01). In exp. 2, similar diets were fed ad libitum. Daily gains for SBM were greater than for Tobin CM (803 vs. 744, P < 0.05) and gains for pigs fed VLG-CM was 774 g. Daily feed intakes were similar (2.01, 1.99 and 1.92 kg). In exp. 3 energy digestibility of 1987 VLG-CM was greater (P < 0.01) than for Tobin CM (75.0 vs 67.4% for 30-kg pigs). Apparent digestibility coefficients of crude protein (CP) were 71.9, 71.2 and 71.6 in 16% CP diets. In exp. 4 Tobin and VLG-CMs from 1987 and 1988 crops were compared with SBM and commercial CM using 96 pigs (48M, 48F). Daily gains and feed intakes were similar for the CMs but T3 and T4 values were below those of SBM (P < 0.05). Key words: Canola meal, very low glucosinolate, digestibility, feeding value, pigs