Is it necessary to add supplements to raw cat and dog food?

I'm reading up on BARF diet recipes, and i'm wondering whether these supplements are really needed. Isn't raw meat and organs alone enough for wild cats and dogs?Is it necessary to add supplements to raw cat and dog food?
actually i heard many times a cat gets everything it needs from a mouseIs it necessary to add supplements to raw cat and dog food?
I've read both good and bad things about feeding a dog a raw diet. Back before there was commercial dog food available dogs ate scraps from the family table and or would eat what they could catch from hunting. I don't see why they would need supplements, since supplements don't grow on trees, right?

I'm not sure about cats.Is it necessary to add supplements to raw cat and dog food?
I was recently looking into homemade animal food myself and found that cats do need supplements. I'm not sure about dogs, I didn't find any info on supplements for dogs.