Effects of feeding ensiled kale (Brassica oleracea) on the performance of finishing lambs

The use of forage brassicas, such as kale, in diets of ruminants is typical ly constrained by the presence of anti-metabolites that break down in the r umen to cause detrimental effects after absorption including haemolytic ana emia and tissue damage. Ensilage of kale before feeding may provide conditi ons that favour the degradation of potentially toxic anti-metabolites, ther eby improving the nutritive value of the feed. An experiment was conducted with eighty Scottish Blackface housed lambs, in which four levels of kale s ilage were used to replace grass silage and in which the forage component c omprised around 60% of the finishing diet. Productivity of lambs was not af fected other than to increase the killing-out percentage of the lambs. Gluc osinolate concentrations in kale were markedly reduced by the ensiling proc ess. Haematological parameters, such as packed cell volume, haemoglobin con centration and the presence of Heinz-Ehrlich bodies, were not significantly affected by replacing grass silage with kale silage. Similarly, there were no significant effects arising from the dietary treatments on the blood pl asma components, gamma-glutamyl transpeptidase, blood urea nitrogen, tri-io dothyroxine and thyroxine, which are conventional measures of glucosinolate toxicity. The results indicated that the ensilage of kale reduces its toxicity and he nce removes constraints on the maximum inclusion levels in the diet. Also, it was possible to reduce the potential contamination of carcasses with soi l by lambs not grazing the crop and thus keeping fleeces clean.