Sticky: vitamin K
BSAVA: "Vitamin K is synthesized by caecal bacteria, and, providing a rabbit is able to ingest its caecotrophs, deficiency is unlikely." [10] Harcourt-Brown: "Vitamin K is produced by caecal microorganisms and is a constituent of caecotrophs. ... Deficiencies are unlikely to occur in pet rabbits." [36]
BSAVA adds that lucerne/alfalfa is a source of vitamin K.
Posted to save quotes for future use in letters to companies who produce rabbit food pellets, asking them to stop the use of synthetic vitamin K3, also known as menadione dimethylprimidinol sulfate, as research suggests that it may not be safe and veterianary medical textbooks suggest that rabbits obtain sufficient vitamin K from cecotrophy.