The feeding value of NPN products varies greatly with the digestible energy content of the diet, the vegetable protein content, the amount of NPN added, the frequency of feeding and the protein requirement of the animal. Thus in evaluating feeds, distinguishing between crude protein from natural sources and crude protein equivalent being supplied from NPN is important. One can determine the amount of vegetable or native protein which is contained in a feed by subtracting the percentage of crude protein equivalent from the total crude protein guarantee. Fat has an energy value approximately 2.25 times the value of carbohydrate feedstuffs. Including over 5 percent fat in the total diet of ruminant animals may cause digestive problems and reduce the efficiency of digestion.
Crude fiber is a measure of the indigestible or non useful portion of a feed.
Crude fiber is not as accurate a measure of feed nutritional value as desired, but it does provide a useful indication. Feeds having low fiber values tend to be higher in digestible energy than those feeds having high fiber values. The relationship between crude fiber and digestible energy or TDN is outlined in Table 1. The relationships described in Table 1 will not hold true for feeds containing non-fibrous energy diluents such as water or mineral matter. Back To Top Table 1.