Methods for Determining the Nutritive Quality of Range Ruminant Diets: a Review

Abstract

Several methods are available for obtaining diet samples from range ruminants. Collection of samples from fistulated animals gives the most accurate representation of diets. Esophageal fistulated animals are generally superior to rumen fistulated animals because less labor is required and a diet sample more representative of forage actually consumed can be obtained. Salivary contamination of forage is a major problem when fistulated animals are used. This problem can be ameliorated by presenting data on an ash free basis. Fistula samples should not be used for P analysis because salivary contamination increases the P content. Salivary contamination may substantially lower forage sample digestibility although this needs further study. Methods for chemical analysis of the diet have been standardized with the exception of those for fiber. Presently, in vitro microdigestion is the preferred method for evaluating range ruminant diet digestibility. This procedure can produce results that are highly correlated to in vivo digestion and requires much less time. Rate of digestion provides an important measure of forage quality because intake of forages having rapid rates of digestion is greater than that for forages with slower rates of digestion but similar total digestibility. Near-infrared reflectance spectroscopy is a new technique showing great potential for evaluating diet digestibility and chemical characteristics. More information is needed on the relationship between nutritive characteristics of the feces and the forage consumed. Research shows that fecal analysis may have potential for evaluating the nutritive quality of range ruminant diets. Copyright © 1982. American Society of Animal Science. Copyright 1982 by American Society of Animal Science