Neither the cow nor the cow's food retains much water; the water is merely delayed a little in its journey to the local watershed, and in vast parts of the US, local rainfall is adequate for this purpose (power irrigation isn't required for the crops, and cattle may drink from a pond.) Even if a cow drinks pumped well water, the majority of its nourishment will have been itself sustained by local natural rainfall.

A datacenter's use of water over any timescale can hardly be compared with a cow's.