Feeding value for lambs of rapeseed meal arising from biodiesel production

Abstract

AbstractMeals prepared from low glucosinolate rapeseed screenings (SCREEN) and from seed which had heated during storage (HEAT) were compared against commercial rapeseed meal (COM) for feeding value. Oil, crude protein (CP) and acid-detergent insoluble nitrogen contents in SCREEN, HEAT and COM, respectively, were (g/kg): 118, 246 and 13; 227, 315 and 436; and 17, 64 and 21.in situdry matter (DM) and protein disappearance rates, soluble protein fraction and effective rumen degradability of protein (EDCP) were lower (P< 0·05) in HEAT than in SCREEN or COM. Comparing oil-extracted meals in situ, EDCP of HEAT was lower (P< 0·05) than EDCP of SCREEN or COM but protein and DM disappearance rates of HEAT were only lower (P< 0·05) than those of SCREEN. Four isonitrogenous barley-based diets (150 g/kg CP, DM basis), containing SCREEN, HEAT, COM or COM supplemented with rapeseed oil (OIL), were given to lambs. For DM, organic matter and neutral-detergent fibre apparent digestibilities, the diets ranked SCREEN > HEAT = OIL > COM (P< 0·05). Digestion and retention of nitrogen were lower (P< 0·05) in lambs given HEAT than in lambs given other diets. Food efficiency of lambs given HEAT was improved (P< 0·05) as compared with lambs given SCREEN or COM. Dressing proportions were higher (P< 0·05) with HEAT, SCREEN and OIL diets than with COM. Other than minor changes in fatty acid composition of subcutaneous fat with HEAT and OIL, carcass traits were not altered by treatment. Feeding SCREEN or HEAT did not adversely affect animal performance or food utilization.