WELLS MAY BE PROVIDED WITH STRIPS OF WOOD (as an enclosure). . .IT IS PERMITTED TO BRING [THE STRIPS] CLOSE TO THE WELL, PROVIDED A COW CAN BE WITHIN [THE ENCLOSURE WITH] ITS HEAD AND THE GREATER PART OF ITS BODY WHEN DRINKING
Our page discusses this in some detail. (Some? A lot!)
[This refers,] does it not, to a case where [the keeper] holds both the cow and the vessel? — No, [it may refer to one] who holds the vessel but not the cow. . .
But is it at all permitted [to give drink to a cow on the Sabbath] where one holds the vessel and not the animal? Was it not in fact taught: A man must not6 fill [a vessel with] water and hold it before his beast on the Sabbath but he fills [his bucket] and pours it out
[into a trough] and the cow drinks of its own accord?
The concern being that the animal could pull the bucket out of the enclosure – or worse still – some cause the keeper to carry the bucket out, thus removing it from private to public domain. But what about a camel?
Come and hear: A camel whose head and the greater part of its body is within [a private domain] may be crammed within [that domain]. Now is not the act of cramming, the same as holding the bucket and the animal, and yet it is required that its head and the greater part of its body [shall be within the private domain]. R. Aha son of R. Huna replied in the name of R. Shesheth: A camel is different since its neck is long.
His head is enough!