Rouen or Meat Duck question

[BK79]

I wanted to ask what type of duck likes whole grain feeds more like wheat bran mash, layer pellets, cracked corn?
what is a good meat duck that puts on weight?
I noticed my indian runners are not really fond of grains, they started eating some wheat bran mash lately, but still not as fond of the grains as chickens. My indian runner's like greens and veggies more that are floating in water. And Indian runners don't even put on size, I've had them 7 months now and they are still thin looking. They don't have a full look.

 

[Kevin565]

Scovies and Rouens are great meat birds and can put on weight fairly rapidly. However most ducks are going to go for something green over grains.