Influence of carbohydrate solubility on non-protein nitrogen utilization in the ruminant.

Although soluble carbohydrates and carbohydrate solubility may sound synonymous, they, in fact, are not when one considers their influence upon the fermentat ion in the rumen. The former refers to a restricted class of carbohydrates of specified solubility whereas the latter portrays a characteristic of any carbohydrate or group of carbohydrates that often can be modified by pH and concentration as well as by chemical, physical, and microbial processing techniques. As such, the lat ter characteristic becomes more critical in a discussion of effects on non-protein nitrogen (NPN) utilization. This review is in no way an exhaustive review of the effects o f all forms of carbohydrate or NPN utilization. The subject of NPN utilization has been reviewed many times, most recently by Helmer and Bartley (1971). Far too many of the li terature citations which could be cited represent repetitive findings which contr ibute very litt le definitive or new information to our information bank on NPN utilization. References quoted herein are primarily for the purpose of setting the stage for the ideas and challenges to be presented. In effect then, the purpose of this paper is to stimulate the future investigators of this topic to (1) investigate newer, more novel areas of research, (2) accept the challenge of improving research techniques so that really new information can be obtained using them, and concurrently, (3) abandon those techniques which, although traditional, are not particularly definitive and are often a waste of t ime and effort.