
I think it depends on how the pig has been reared...whether intensively farmed or organically farmed.
I give mine pigs trotters...they seem to prefer ones that have been frozen first...fresh ones that I get occassionally from the butchers have to be rolled around in the grass....and sometimes buried first and then dug up again....they must have an odour on them that isn't immediately attractive to them..??
Certainly my own dogs will turn their noses up at pigs liver (and kidneys) from a supermarket...so it makes me wonder if they can smell antibiotics and stuff as the liver and kidneys are the waste disposal system of all animals. (I also tried them with pigs pancreas once....every single one of them just snifffed it and walked away)
(Mine have a liver meal every week so now I stick with lambs liver which they absolutely love...!)