It's not a problem and you're not 'nit picking' to want a more accurate analysis. To be academic, pigs are a strict 60%. We lack the means of production here for pigs as a rule. Cows, a lot is domestic (this can all be found on Gov.UK if you don't want to trawl through academic papers) and we also export a lot of cows' meat bred here, to other countries. Some bovine meat is from Ireland too, a smaller percentage from farther (I believe Aus is the biggest contender of late but a google will tell you more about this).
Hens are mainly domestic too however the british diet is not as diverse as some countries hence we export a lot of their flesh and import more of it(put simply we are fussy about which parts of hens we eat).
We send our lamb's meat and sheep's meat to other countries more than we eat it ourselves too.
So, if you are more about the import of pigs and cows, cows you have less to worry about than pigs. A lot more research has gone into the intelligence of pigs, to that of cows, same with the exposure of said research. I do not lack the intelligence to assume that humans can even comprehend the intelligence of animals with differences to our own species (I compare this to our lack of understanding, quite recently in the great scheme of things, to be able to comprehend that being Caucasian does not equal intellectual superiority). I also do not buy that intelligence=more deserving of empathy and care, if we do believe this, should we not still be treating those with learning disabilities with contempt?
'Intelligence' is also contested in terms of what it actually means. We lack the vocabulary for exploration of other animals' experience of life.
It is worth thinking about, whether our brains, that are geared for being more empathic toward those who are similar to us, care more about cows and pigs (as you reference in your post) than hens because cows and pigs are not SO dissimilar, when compared to a hen. Humans, cows and pigs are all mammalian. They have similar skin, they live on the ground, they don't have wings, even their faces have similar eyes and nostrils etc etc.
Hens have feathers, are capable of flight (to an extent) have beaks. They're different to use more so. Is this why we value them less albeit not very much less? Rather than size.