Bunny,
(Sorry 'bout the fluffy bunny reference 
)
I think there are a number of possible avenues in responding to this, assuming you want to. You could go down the figures route, but be aware that in this industry figures are often quite woolly (sorry: another pun) and thus open to various interpretations; the arguments over the meaning of those GM field trial results is a case in point. Thus playing the numbers game might be a bit counterproductive.
Another route is to look at the welfare side, which that site seems to emphasise, presumably on the principle that most veggies (and kids) are sentimental about animals in distress. Well if we are going to exploit animals, there will be welfare issues, but here in the UK we have amongst the highest standards in the world. By targetting our home industry, they open us up further to imports from far less benign sources of supply - Brazil being the favourite bugbear of the moment. However on misinformation, they make a big deal, for example, about sheep diesases and health problems. Do they imagine sheep in the wild (no such thing, but I'll leave that 'till later) are free of disease? A Sheep may live a decade or more in captivity with the best of care, but in the wild they would be lucky to survive half that time: those diseases aren't man-made creations then there's predation, accident, etc etc. Perhaps they imagine some animal utopia where no beast is harmed just because man is absent!
Anyway, for most farmed animals, there is no such thing as 'in the wild'. We took the wild precursors, such as the European Aurochs, tamed and selectively bred them over centuries - millenia - these are now beasts whose original form (and habitat) has vanished. They depend upon us for successfull existence in terms of health, nutrition, shelter and so forth. No doubt some hardy survivors (such as my hill sheep and other 'primitive' breeds) could carry on without our support, but for the most part these breeds would vanish without our exploitation.
Next: if veggies want to stand on a high ground, then they should look to their own exploitation of the planet. So much 'organic' food is produced with more expensive inputs a lower yields leading to more long-term exploitation of the natural resource, and depends upon animal manure, see for example:
http://www.self-willed-land.org.uk/articles/doing_sums.htm
Much of the soya these people like to use to substitute for meat and milk is produced at the expense of the rainforests.
It goes on; try this site for more information regarding these subjects as the debates have flowed back and forth quite a few times!
Combat Claire: I suggest the local paper would be as good a battleground to fight this as the site itself since they carried the fightthere in the first place. It's the general public who need the education here.