Intelligence has nothing to do with it. Intelligence isn't even well defined or measurable. Things like IQ are designed for humans, so they would not be applicable to other beings. They're barely even useful for human applications.

It's an interesting question though. First, I'll ask myself why I eat beef in the first place.

• It's tasty
• It's relatively cheap
• Very nutrient dense, so it's easier to consume

Why do I not eat dogs or cats?

• They are not socially acceptable to consume
• They contribute positively to my life in other ways than being a food source

I'm pretty sure that a dog/cat could be dumb as a rock and I still wouldn't eat them because I'd still enjoy their company.

Now I do try to reduce the amount of beef I consume, but it's mainly for environmental reasons.