Crambe meal subjected to chemical and physical treatments in sheep feeding

Two experiments were conducted to evaluate the effect of alkaline treatments (20, 40 or 60g CaO/kg) or water extraction on glucosinolate (GIs) concentration in crambe meal (CM), and to determine effects of replacing soybean meal with CM on intake, digestibility and nitrogen balance in sheep. Twenty-five samples of CM (300g each) were randomly assigned to one of the following treatments: Control (446mg GI/kg dry matter (DM)); alkaline treatment (20, 40 or 60g CaO/kg CM); and water extraction. Alkaline treatment and water extraction of CM did not differ (P > 0.05) in GI concentration. In addition, the level of CaO added (20, 40 or 60g/kg CM as feed) did not affect (P = 0.47) the GIs concentration. Eight Santa Inês male sheep (25.6 ± 2.6kg body weight) were distributed to two 4 × 4 Latin squares with four periods of 15 days each (10 days of adaptation and 5 days of sample collection) and received one of the following four different isonitrogenous diets (160g CP/kg dry matter), formulated by substituting soybean meal: Control (soybean meal); untreated CM; Alkaline-treated CM (40g CaO/kg); and water extracted CM. Replacing soybean meal with CM did not affect (P > 0.05) feed intake, apparent total-tract digestibility, nitrogen balance and urinary excretion of allantoin. Alkaline treatment or water extraction partially decreased GIs concentration in CM by 46 ± 12% (P < 0.05), but did not affect (P > 0.05) feed intake, apparent total-tract digestibility, nitrogen balance and urinary excretion of allantoin. The processing method (alkaline treatment vs. water extraction) had no effect (P > 0.05) on feed intake, apparent total-tract digestibility, nitrogen balance and urinary excretion of allantoin. Therefore, CM with GIs concentrations under 450mg/kg DM can be used as substitute for soybean meal as an exclusive protein source in ruminant diets.