Estimation of the Botanical Composition of Oesophageal Extrusa Samples. 2. A Comparison of Manual Separation and a Microscope Point Technique

Abstract

The botanieal composition of extrusa collected from oesophageally fistulated sheep fed diets of known proportions of a legume and a grass was estimated by manual separation and a microscope point technique. The microscope hits were adjusted for the weight per unit area of each plant component in order to estimate composition by weight. The microscope point technique was more accurate than manual separation. The deviations between the actual lucerne percentages and percentages estimated by manual separation were explained by higher losses of organic matter prior to separation from the legume than the grass and by the presence of unidentifiable particles that resulted in only a portion of the samples being separated. After adjustments for these sources of error the estimates determined by manual separation were similar to the actual botanical composition of the ingesta.