"But I will say this in order of stupidest mammals that we eat I will put the cow as first then the horse then the pig."
Cows have been bred for gentleness and taste, not for intelligence. In case you have not noticed a smart cow will not be around for very long. It will be first in line at the slaughter house.
You can say the same of most meat animals.
Domestic turkeys are some of the most stupid animals on earth but the wild turkeys are very wiley.
But domestic pigs as I said are still pretty smart they can be trained quite well. They can be trained at least as well as a dog.