Feeding your Cavy(Guinea Pig)?

My guinea pigs have Gerty Guinea Pig food a href="http://www.petcentreonline.co.uk/ecommerce/Scripts/prodView~idproduct~577.htm" rel="nofollow"http://www.petcentreonline.co.uk/ecommer…/a - I have had guinea pigs for 6 years and they have all had this. I know that pellet feeding would be best as it prevents selective feeding but they seem to enjoy the Gerty food best.It has a good variety in it and they only leave out the dark pellets and yellow pieces so they get the majority of the nutrition included. They also have fresh fruit and veg every morning and they also get hay and water so hopefully they have a healthy balanced diet.