Estimation of the Botanical Composition of Oesophageal Extrusa Samples. 1. A Modified Microscope Point Technique

Extras samples were collected from ocsophageally fistulated sheep that had been fed mixtures of known proportions of a legume and a grass. The botanical composition of these samples was estimated by two microscope point techniques. When estimates were made by recording hits on each species the legume content of the ingesta was consistently underestimated by up to 23%. Much of this underestimate was attributed to the weight per unit area of the leaves of the legume being approximately twice that of the grass leaves. When the microscope hits were adjusted for the weight per unit area of each of the plant components (leaves, petioles, flowers and seed pods) the relationship between the estimated and actual legume consumed was improved, the greatest difference between actual and estimated legume being approximately 5%.