Not at all, it's completely useless and some brands even contain extra multivitamins that can cause problems in large quantities. If they're getting fresh veggies every day (at least 1 cup) they're having their vitamin C needs met.
We are as gods to the beasts of the fields. We order the time o' their birth and the time o' their death. Between times, we ha' a duty. - Terry Pratchett.
"Men have forgotten this truth", said the fox, "But you must not forget it. You become responsible, forever, for what you have tamed. - Antoine de Saint-Exupéry