Lambs are remarkably functional at birth — within seconds or minutes they stand up and demand attention from their mother, and a short while later, they’re hunting for a nipple to get at her milk.  But they’re born without their superpower.

Sheep, like all ruminants, have a multi-chambered stomach that allows them to digest the cellulose in fibrous plants like grasses.  The star of the show is the giant first chamber, the rumen, that’s filled with bacteria and protozoa that break down the cellulose on the sheep’s behalf.  So a sheep eats big mouthfuls of grass until its rumen is full, then goes to rest somewhere comfortable and starts to systematically regurgitate the grass for further chewing and mixing with saliva.  The mechanical breakdown that occurs when a ruminant chews its cud helps the critters in the rumen complete their digestive work.   This (in a wildly oversimplified telling) is how sheep are able to convert sunshine, via the earth’s vast grasslands, into more sheep, at least as impressive a superpower as turning green and musclebound when annoyed.

The catch is that lambs are born without a functional rumen — it’s small and it’s missing the microbiota that do the digestive magic — so they can digest milk but little else.  The rumen develops as they start to nibble on hay or grass at their mother’s side.  Like so many things in the realm of sheep, I knew this in theory, but I was delighted when I saw #702, born on 11 February, relaxing in the barn and chewing her cud.

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