Are animal shelters more in need of cat food or dog food?



I have gotten coupons in the mail from Purina. I can get a free 10lb bag and a free 25lb bag. I am not feeding this to my pets (yuck), but Im donating it to the shelter. So, should I get 25lbs of cat food and 10lb of dog food, or vice versa? What are they more in need of? Thanks!