Replacement of groundnut cake with low-glucosinolate rapeseed meal on performance, nutrient utilization, immunocompetence and carcass characteristics in lambs

An experiment was conducted on 14 Nellore male lambs to study the feasibility of utilizing low glucosinolate rapeseed meal (RSM) (41.84% CP and 30 μmol total glucosinolates/g) replacing groundnut cake (GNC) in diets. Two isonitrogenous and isocaloric diets (10.5% CP) were formulated with GNC or RSM as sole protein supplements. The lambs were randomly allotted to these two diets (seven in each) and fed the respective diets for a period of 155 d. The lambs fed the RSM diet on average consumed 5.256 mmol of total glucosinolates/d. Lambs in both groups grew linearly with no significant difference in average daily gain and dry matter (DM) intake and utilized DM and nutrients with similar efficiency. The RSM fed lambs had higher DM, organic matter, ether extract and crude fibre digestibilities than GNC fed lambs. The antibody titres against heat-killed Brucella abortus (P<0.05) and chicken RBC (P<0.01) antigens was depressed, with no effect on cell-mediated immune response and carcass characteristics with RSM feeding compared to GNC. No appreciable lesions were observed in any vital organs except for very mild fatty changes in the liver, rupture of alveolar walls at few places in lungs, mild swollen and shrunken glomerular tuft in few nephrotic tubules of lambs on RSM diet. The study suggested no adverse effect on performance and carcass traits of lambs with the feeding of 12% RSM, as the sole protein source in complete diets, except for lower humoral immune response compared to those fed GNC diets.