Is pet food safe for humans?

I have not tried any pet food yet but my father had tried a bit of dog food and he told me that it's quite tasty.

Actually, where I live, to eat pet food is even more expensive than to eat human food. Just as an example, a cheap, not well-known brand of dog food would sell for about 1.50 usd per kilo. Cheap rice can be bought for as little as 00.50 usd per kilo. Branded dog food can be even more expensive. For example, Royal Canine sells for about 5usd per kilo whereas the most expensive jasmine rice sells for only 1.20usd per kilo.