The 1996 NRC for Beef Cattle contains a feed library that has a estimate of crude protein and then the portion of the crude protein that is degraded intake protein (DIP) and the portion that is undegraded intake protein (UIP) or by-pass protein. As a general rule, forages would be 70% or above DIP and therefore 30% or less UIP. These values change based on maturity and type of forage. Corn is about 45% DIP and 55% UIP, meaning if corn is 10% crude protein, that 45% of the 10% is DIP and 55% of the 10% is UIP. Urea is 100% DIP. Blood meal and feather meal are high in UIP, between 70% and 75% UIP. Not many feed companies carry feather meal and blood meal any more. Distillers grains can be 35% DIP and 65% UIP.

The amount of DIP and UIP needed in a diet depends on the class of livestock and the performance you are trying to achieve. Remember that is important to supply the rumen microbes with DIP as that is what is used for the microbes to make their own protein, and it is important for this to happen. Growing cattle likely need more UIP in their diets, whereas mature cattle need less UIP. Again, the 1996 NRC would contain the requirements.

If you want a copy of the 1996 NRC Nutrient Requirements for Beef Cattle, go to the www.nationalacademies.org Web site, and look on the right-hand corner for "beef NRC," and then follow the instructions for ordering. Also included is a diagnostic model to check diets you develop.

Acid detergent fiber (ADF) primarily consists of cellulose, lignin, silica, insoluble crude protein, and ash, which are the least digestible parts of the plant. Because ADF percentage in forages negatively relates to digestibility, it is used to calculate energy values. ADF is one of the most common analyses made, particularly on forages. Low ADF usually is preferred because it means higher net energy. As the plant matures, ADF increases.