Performance of crossbred calves on supplements containing soybean meal or rapeseed-mustard cake with varying glucosinolate levels

Growing crossbred calves (18) weighing 62.9±3.8 kg were given a basal diet of wheat straw, and randomly allocated to 3 dietary supplements OG, LG and HG containing soybean meal, rapeseed-mustard cake (RMC) from canola quality B. napus genotype [TERI-Uttam-Jawahar (TUJ) having glucosinolate 20 mmollg)] and RMC from a mix of genotypes of B. juncea (Pusa Bold, Rohini and RH-30) with high glucosinolate (100 mmollg), respectively, as major protein source. Though daily intake of dry matter, organic matter and wheat straw did not differ significantly among the dietary treatments, intake (g/kg wo.75) of concentrate moiety was significantly lower in animals given HG relative to calves given either OG or LG supplement. Nutrient digestibility and density (digestible crude protein and total digestible nutrient) and balances of nitrogen, Ca and P by calves did not differ significantly irrespective of dietary supplement. Average daily gain (g/day) was significantly lower in calves on HG supplement as compared to their counter parts given either DO or LG concentrate. Feed conversion ratio (kg feed DMlkg gain) was significantly more in calves fed supplement (HG) with high glucosinolate levels while comparable performance was observed in calves given supplement DO and LG All the blood biochemical parameters like haemoglobin, glucose, total protein, creatinine, aspartate transaminase, alanine transaminase and triiodothyronine (T3) remained within the normal range; however, thyroxine (T4) was significantly lower in HG group relative to calves of DO group. It may be concluded that incorporation of RMC from genotypes of B. juncea with high glucosinolate levels in supplements reduces their palatability and consequently growth rate in crossbred calves while costlier cakes like SBM can be replaced completely by canola quality rapeseed (B. napus, TUJ) without compromising the overall performance of the crossbred calves.