The nutritive value of canola, heat-treated canola and fish meals as protein supplements for lambs fed grass silage

Abstract Twenty-eight lambs (23.4 ± 4.7 kg BW, 59 days old) were used to compare fish meal to canola and heat-treated canola meals as protein supplements to grass silage and their effects on the performance and apparent digestibility of diets. Silage was fed ad libitum, assuring 20% orts. In addition to silage, lambs received daily a fixed quantity of one of four supplements: C, a control supplement supplying 6.78 g kg −1 BW of a commercial diet (73.5% barley, 14.7% dry molasses and 11.8% minerals, vitamins and Bovatec); CM, control supplement + 8.05 g kg −1 BW of canola meal; HCM, control supplement + 7.52 g kg −1 BW of heated-canola meal (105 min at 150°C) and FM, control supplement + 4.0 g kg −1 BW of fish meal. Heating decreased the effective degradability of canola meal protein from 78.5% to 19.8%. Silage dry matter (DM) intake was not affected by protein supplementation. Supplementation with CM and FM improved the average daily gains (ADG) by 60.2% and 49.7%, respectively, when compared to lambs that were fed with C diet ( P P > 0.10). Feed efficiency was 32.4% higher in lambs fed with CM and FM than in those receiving the C and HCM treatments ( P P P