Effect of untreated, HCl treated or copper and iodine supplemented high glucosinolate mustard (Brassica juncea) meal on nutrient utilization, liver enzymes, thyroid hormones and growth of calves

Twenty four growing calves were used to evaluate HCl treated (16 ml HCl per kg of meal with increasing the moisture content to almost 40%, diffused for 72 h followed by heating at 180°C for 2 h), CuSO4 and KI supplemented (500 mg kg−1 meal) and untreated mustard (Brassica juncea) meal on intake, digestibility of nutrients, calf growth performance, blood constituents, liver enzymes and thyroid hormone status. The HCl treatment of mustard meal reduced glucosinolates from 46.2 to 4.5 mg g−1 meal. Average daily gain of calves fed with HCl treated mustard meal, mustard meal+CuSO4 and KI, and SBM diets was similar but higher (P<0.05) than in calves fed untreated mustard meal. The HCl treated mustard meal fed calves gained more (P<0.05) weight than those fed untreated mustard meal. Differences in weight gain increased with a longer period of feeding. Treatment of mustard meal with HCl and supplementation with copper and iodine increased CP and ME intake, as well as digestibility of nutrients versus calves fed with untreated mustard meal. Untreated mustard meal probably reduced protein synthetic activities of the liver, as indicated by a decrease in serum albumen concentrations. Supplemental copper and iodine increased blood glucose concentrations. Higher values of serum GOT and GPT in untreated mustard meal fed calves indicate impaired liver function and cellular damage whereas, the lower level of serum ALP indicates poor bone formation. Reduced plasma thyroid hormone levels (T3 and T4) indicate a iodine deficiency in calves fed the diet with untreated mustard meal. Serum copper and iron levels were similar in the four groups, whereas, serum thiocyanate level was highest in the untreated mustard meal fed calves. Plasma T3 concentration was found to be positively correlated (r2=0.95, P<0.01) with growth rate of calves. Mustard meal, if treated with HCl or supplemented with Cu and I will result in better overall calf performance than if fed untreated and, similar to that of SBM based diets.