Abstract: A re-entrant cannula device for use in the proximal duodenum and/or the site to terminal ileum of, for example, sheep and pigs, which comprises a casing of resilient material and a cylindrical plug cock which is pressed into the casing and has two digesta passages extending through the cylindrical plug cock along separate, isolated, curved paths. The casing has two, splayed intestine connectors and the cylindrical plug cock is rotated, by a connector tube in one digesta passage, from a "maintenance" position wherein digesta flows through one connector, along one digesta passage in the cylindrical plug cock and back to the intestine through the other connector, to a "collection" position where digesta flows from one connector along one digesta passage for collection and is returned to the intestine along the other digesta passage and connector back to the intestine.