Oh FFS!
"Suck cow" is a common enough abbreviation used by country folk where I come from.
A suck cow is a calf that is still suckling from it's mother but is old enough to graze and needs to be weaned.
It is not uncommon for a cow to suckle another cow. Usually the cow being suckled solves the problem by kicking out at the "suckler", just as it would wean it's own calf.
Of course cattle farmers who farm milkers know this and normally move the calves off from their mothers to prevent them from taking the mother's milk which they want to sell.
There are a number of weaning devices available to farmers who want to stop cattle from suckling one another.
http://www.cattlestore.com/p-1495-kant-suk-weaner.aspxNote: It is nothing to do with stuck
PS Also very common term used in the US cattle industry.
