I have Aylesbury ducks and need ..

Brief：
Also do i need to make sand or grit avaiable now there having growers pellets?Answers: I am afraid there is very few sites that contain much info on w.. 

Also do i need to make sand or grit avaiable now there having growers pellets?

I am afraid there is very few sites that contain much info on what you need to maintain a healthy duck, below is the few sites I could find and info for you regarding this matter.

From this site

http://www.motherearthnews.com/livestock.

" FOOD AND FORAGE

Wild ducks eat a wide assortment of foods . . . including plants, seeds, insects, fish, crayfish, worms, and even an occasional mouse.

Domesticated ducks, too, will forage for most of their food whenever possible, but—if you want to keep your birds plump—some diet supplements should be provided. Such "storebought food" can be in the form of commercial waterfowl "chow" (pellets are best) or mixed whole grains such as corn, wheat, barley, and oats. Corn is by far the birds' favorite meal—and also a great winter warmth provider—but "maize" alone won't give them the balanced diet they need. Remember, too, that you must never give your ducks any commercial feed with chemical additives (or with more than 20% protein), since such a dinner might kill young birds and cripple older ones.

Greens are also extremely important and should make up about a third of the bulk of a duck's diet. (You won't have to worry about what to do with the excess vegetables and fruit from your garden and orchard if you have waterfowl around!) When no greenery is available, feed the birds rabbit pellets of pressed alfalfa. (Clover—before it blooms—and alfalfa will increase the fertility of your flock.)