Yeah, I figured the second part out. Well, that's another vote for "I should read the original as well" ;)
That's why you are not strong Duo! Owls are supposed to be predators, you don't get all the needed proteins from just veggies.
Am I right in concluding that in this sentence, zamiast is used not as a conjunction, but as a preposition (+ genitive) ? In which case, "mięsa" would be genitive singular rather than accusative plural. Addition: i see that an answer to my question is already provided in the strain "śniadanie zamiast obiadu"