For dairy cow rations, some urea can be fed in complete rations designed for medium and low producers. Urea does not appear to be effective in rations designed for high producers. The concept of feeding higher levels of protein which escape rumen degradation is relatively new and needs further refinement and simplification before becoming practical for ruminant ration formulation. The protein content of roughages is an indicator of digestible energy content. Energy Energy in feedstuffs is carried primarily in the carbohydrate and fat fractions.
Proteins also supply energy when fed in excess of protein needs.
Carbohydrates Carbohydrates supply most of the energy needed by cattle. Carbohydrates make up 65 to 75 percent of the dry weight of most grains, forages, and roughages. They include sugars, starch, cellulose, hemicellulose and lignin. As crude fiber increases, digestible energy usually decreases. In most concentrate feeds, crude fiber is the less digestible portion and NFE the most digestible portion of the carbohydrates.