The in vitro digestibility technique has been used to determine the organic matter digestibility (OMD) of dried samples of malt distiller's grains (MDG). The method gave highly reproducible results for OMD of fresh and ensiled samples when different batches of rumen liquor from hay‐fed sheep were used. The results were consistently lower than values determined by in vivo digestibility trials. The OMD values were increased by raising the calcium ion Concentration of the digesta and by extraction of lipids from the MDG samples. The addition of calcium had no effect on fat‐extracted samples of MDG.

Digestibility and intake data have been obtained from sheep fed on rations consisting of fresh and ensiled malt distiller's grains (MDG) fed alone and with hay and silage. The effects of calcium supplements have been measured with all rations, and calcium lactate has been compared with calcium carbonate. The results of digestibility trials with cattle have been included; in these the effect of additional calcium has been estimated with rations of barley straw + MDG.When MDG was fed alone the intakes of fresh and ensiled forms were similar and there was a significant decrease in intake with duration of feeding. Fresh MDG had a significantly higher digestibility, and additional calcium increased the digestibilities of fresh and ensiled samples.The intakes of rations containing hay i-MDG and silage + MDG were positively correlated with digestibilities of the whole ration. Additional calcium resulted in higher intakes of hay and MDG but silage intakes were unaffected. The effect of added calcium was greater with hay + fresh MDG than with other combinations of constituents. Calcium carbonate and calcium lactate were equally effective in increasing intake.The addition of NaCl during the ensilage of MDG reduced the retention of magnesium by sheep given grains with hay and silage.Addition of calcium to cattle rations of barley straw and MDG produced an increase in the intake but digestibility of the diet was not affected. The rations with calcium provided 0-75 x maintenance requirements of the cattle for metabolisable energy and about twice the maintenance requirements for digestible crude protein. Introduction Malt distiller's grains (MDG) have been evaluated by chemical analyses and by the in vitro digestibility technique.1.2The results showed that MDG fresh from the distillery contains relatively high levels of structural carbohydrates, lignin, lipids and protein with correspondingly low levels of soluble carbohydrate, potassium and sodium. Before being fed to farm animals the wet material may undergo varying degrees of fermentation depending on the duration of ensilage on the farm and whether salt is added.The relatively high lipid content is an important factor in determining the digestibility of MDG. Extraction of the lipids results in a marked rise in the in vitro organic matter

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