ANALYSIS OF FORAGE FIBER AND CELL-WALLS IN RUMINANT NUTRITION

Analysis of the fiber or cell wall present in forages is of major conc ern in ruminant nutrition because diets often contain large amounts of forage, and the fiber fraction affects both feed intake and animal pe rformance. Traditional extractive, gravimetric methods such as crude f iber and neutral detergent fiber recover variable amounts of the plant cell wall, but they remain popular because of their ease of use and t he large feed data bases available for these methods. More intensive c hemical methods utilizing chromatography and spectrometric analysis pr ovide greater detail on cell wall composition and structure, but they have been used little in ruminant nutrition. Lignin analysis has remai ned problematic because no definitive reference method exists. Recentl y attention has focused on the measurement of lignin composition and c ell wall phenolic acids; however, these methods have yet to be widely adopted in ruminant nutrition. The detergent fiber methods have been s emi-automated to increase sample handling capacity. Near-infrared spec troscopy is routinely used for prediction of fiber concentration in fo rages and has greatly increased the ease of obtaining fiber analysis o f forage samples. Widespread adoption in ruminant nutrition of the mor e sophisticated methods of cell wall analysis is unlikely to occur unt il these methods can be demonstrated to improve diet formulation and p rediction of animal performance.