Feed quality (kilograms of dry matter) is the most common way of measuring feed. We often talk about the cost of purchased feeds on a kilograms of dry matter basis. An equally, if not more important measure, is feed "quality".
Feed "quality" is the energy value of feed. It is measured by the amount of usable or metabolisable energy (ME) in a given weight of feed. In New Zealand, the energy value of feed is referred to as the megajoules of metabolisable energy per kilogram of dry matter (MJME/kg DM) or M/D for short.
The higher the M/D value, the better the feed. A cow's milk production or gain in condition depends largely on the amount of energy eaten rather than the amount of dry matter eaten.