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

Abstract

Extrusa samples were collected from oesophageally fistulated sheep that had been fed mixtures of known proportions of a legume and a grass. The botanical eomposition of these samples was estimated by two microscope point techniques. When estimates were made by recording hits on eaeh species the legume content of the ingesta was eonsistently 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 ditferenee between aetual and estimated legume being approximately 5%.

Effects of sward structure on the diet selected by guanacos (Lama guanicoe) and sheep (Ovis aries) grazing a perennial ryegrass‐dominated sward

“…The proportions of the four main plant parts (pseudostem, dead stem, dead leaf and sheath and green leaf) in the extrusa and sward samples were calculated as proportions of the total OM weight less the OM weight contributed by inflorescence and non-grass species; the proportion of green leaf in the extrusa was corrected taking into account the OM weight of the liquid fraction of the extrusa minus a fixed amount of 3·6 mg OM ml Ϫ1 contributed by saliva, according to the procedure of Hamilton and Hall (1975). This procedure homogenized the data and allowed the relationships between the proportions of plant parts in the diet and those in the grazed horizon of the sward to be studied as, although the amounts of inflorescence and non-grass species in the sward were undetectable, some extrusa samples contained a small proportion (< 0·05) of these plant parts.…”

The effects of stocking rate and nitrogen fertilizer on a perennial ryegrass‐white clover sward

“…Samples were collected each morning and evening, over a 30-min period; these were bulked and a subsample was taken to determine botanical composition using the microscopic point technique of Hamilton and Hall (1975).…”

“…The botanical composition of ingested herbage was determined using extrusa samples collected from the oesophageally fistulated sheep. Samples were collected each morning and evening, over a 30-min period; these were bulked and a subsample was taken to determine botanical composition using the microscopic point technique of Hamilton and Hall (1975).…”

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

“…The extrusa were squeezed in muslin to separate the solid and liquid fractions. The botanical composition of a 24 g sub-sample ofthe solid was estimated by the microscope point technique in which hits were adjusted by WAC based on fresh herbage (3). A second sub sample was separated manually after being divided into four replicates of 6 g. Each replicate was agitated in distilled water and was dispersed on 3 filter papers in the same manner as the samples that were observed under the microscope.…”

“…Hamilton and Hall (3) have shown that the accuracy of the microscope point technique can be improved by adjusting the microscope hits for the weight per unit area of the various plant components. In the present experiment, estimates of botanical composition were made by manual separation and by a microscope point technique with adjustments made by weight per area constants (WAC) (3). These estimates were compared with the known composition of ingesta and some of the possible sources of error in manual separation were examined.…”