Meals 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 situ dry 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.

In each of three experiments, 60 Limousin × Holstein Friesian bulls, initially of 191, (s..e. 5·0), 177 (s.e. 5·5) and 210 (s.e. 7·2) kg mean live weight for experiments 1, 2 and 3 respectively, were offered maize silage ad libitum plus one of three barley-based, isonitrogenous compound diets containing 200 g rapeseed meal, 575 g maize-gluten feed or 100 g fish meal per kg fresh weight. Compound diets were given at the rate of 3·0 kg (fresh weight) per head per day up to 320 kg live weight and at 3·3 kg per head per day from 320 kg to 420 kg live weight. In experiment 3, when bulls were taken through to slaughter, the compound diet was further increased to 3·5 kg per head per day from 420 kg live weight to slaughter. Experiments 1 and 2 were conducted over 128 and 194 days, with mean live weights at the end of the experiments of 347 (s.e. 17·2) and 414 (s.e. 24·2) kg respectively. In experiment 3, bulls were slaughtered at 16 months of age at a mean live weight of 544 (s.e. 25·0) kg.

In experiment 1, the fish-meal diet gave the highest rate of daily live-weight gain at 1·34 compared with 1·17 and 1·16 (s.e.d. 0·041) kg for rapeseed-meal and maize-gluten diets, respectively. In experiments 2 and 3, daily gains were similar on all treatments at 1·21, 1·19 and 1·26 (s.e.d. 0·036) kg and 1·06, 1·09 and 1·11 (s.e.d. 0·035) kg for the rapeseed-meal, maize-gluten and fish-meal diets respectively. Total daily dry-matter intakes did not show consistent trends: in experiment 1, intakes were 5·8, 5·6 and 5·8 kg/day, in experiment 2, 6·2, 6·2 and 6·3 kg/day; and in experiment 3, 7·1, 7·3 and 7·1 kg/day for rapeseed-meal, maize-gluten and fish meal, respectively. The higher intakes of dry matter in experiment 3 were due to the greater intakes of maize silage by bulls taken to heavier weights in this experiment.

The effects on animal performance of barley-urea (BU), maize gluten (MG) and rapeseed meal (RSM) offered with ad libitum winter wheat straw, were examined with 138 pregnant Hereford (♂ × Friesian ♀ cows over two winters (1987/88 and 1988/89). In each year, seven young cows and 16 old cows per treatment were offered respectively 3·0 or 1·5 kg fresh weight per head per day, of BU, MG or RSM for 167 days. There were no treatment effects on live weight, condition score or calf birth weight. In terms of animal performance BU, MG and RSM were equally effective.