Malt distillers grains (MDG) and brewers grains (BG) are the fibrous residues remaining after the extraction of sugars from malted barley during the process of malt whisky and beer production, respectively. MDG and BG are popular supplements in beef finishing diets with up to 15kg/head/day being fed on Scottish farms (Lilwall, Smith and Wood, 1983). However, in some areas, close to distilleries and breweries, and particularly during the summer months, MDG and BG can be bought cheaply and ensiled, and could be fed to appetite as the sole or major part of the diet. This investigation explores this possibility.

Some unusual limitations of MDG and BG as a complete diet are that they are virtually devoid of soluble minerals such as Na and K and are low in some trace elements and vitamins. They also contain high levels of unsaturated fats which depress fibre digestion and voluntary dry matter intake (Miller et al., 1970). This effect can be partly overcome by supplementation with calcium carbonate (El Hag et al., 1972) probably by the formation of insoluble calcium soaps of fatty acids in the rumen. Based on these considerations a mineral/vitamin mix was designed specifically to supplement these materials.