A comparison of methods of recovering oesophageal extrusa from grazing sheep

Extrusa samples were collected from two groups of oesophageally fistulated sheep grazing together. One group had foam plastic oesophageal plugs fitted below the fistula to assist in the complete collection of extrusa; the second group grazed without plugs. The extrusa were collected in four periods chosen to cover as wide a range of herbage conditions as possible varying from herbage with a high proportion of green leaves to predominantly dry material with a high proportion of dead leaves and stems. The plant components of the extrusa were determined and there was no evidence that stems or any other plant component preferentially by-pass the fistula in grazing sheep. It was concluded that it is not necessary to insert foam plastic plugs in the oesophagus of grazing sheep to obtain representative samples of ingested herbage.