I can definitely believe this about pigs, and I suppose it could be true about cows and goats, but I have a serious problem with believing that chickens have complex emotions (having raised chickens, they are some of the stupidest animals on the planet).
Flowers also turn to face the Sun.
I don't know about emotions, but they certainly have intraspecies relationships--"pecking order"!
I had a pet chicken when I was young. My mom was kind enough to leave her out of the stew pot even when she didn't lay many eggs, but some critter got her eventually. I do remember the lesson of my mother explaining gently that she was "just a chicken" when the hen pecked me once and I couldn't figure out why.
I can say scrub chickens are a lot smarter than the incubator-raised breeds.