The use of malt distillers grains (draff) in ruminant diets is limited both by its moderate digestibility and variable intake. This is due to the low digestibility of its fibre and to the inhibitory effects of its unsaturated oil on rumen cellulolysis. Treatment of draff with Ca(OH)2 may ameliorate these limitations in two ways. Firstly, alkali treatment increases fibre digestibility due to hydrolysis of lignocellulosic linkages. Secondly, under alkaline conditions and in the presence of calcium ions, the unsaturated fatty acids of the draff oil form insoluble calcium soaps, thus reducing their inhibitory effects on rumen function.

Thirty Blackface-cross lambs were allocated by sex and weight to three groups of ten. The animals were penned in pairs and were offered hay ad libitum and supplemented with 350g DM/d of either mineralised draff (MD), limed draff (LD - draff treated with 80g Ca(OH)2 /kg DM, held at 60°C for 18 hours and then dried at 60°C), or a proprietary lamb finishing concentrate (C - Premium Sheep Fattening Pellets, Carrs Farm Foods, Solway Mills, Silloth). The supplements were gradually increased to 1200g DM/d over 60 days. Dry matter intakes of hay and supplements were measured daily and animals were weighed weekly. The lambs were condition scored ‘blind’ on day 60 and were assessed for slaughter.