In young ruminants , nursing and afferents from the pharynx appear to stimulate reflex closure
Of the groove , which causes milk to bypass the rumen and reticulum and pass though the
omasum directly to the abomasum . The paunchiness of bucket – fed calves usually is attributed
to milk entering the rumen , where it is not properly digested . The use of buckets with nipples
tends to prevent appreciable amounts of milk from entering the rumen . After weaning , fluid
drunk from open containers largely passes into the rumen and reticulum . The groove has no
known function in adult animals , but reflex closure in adults has been produced with sodium salts
in cattle and copper sulfate in sheep .