Peas are good for ducks because they are high in niacin. Ducks need higher levels of niacin than chickens so many duck owners give peas as a treat/supplement. My flock gets peas at least once a week. They come running when they see the container I use for their peas because they love them so much.

As for bread, It's like going to dinner at a restaurant and filling up on bread before the main course comes. You're missing out on the healthier stuff. Eating large amounts of bread when ducks are young can result in angel wing too because it keeps them from getting the nutrients they need. So even though small amounts of bread may not be too bad it's better to just avoid it. My ducks favorite treats are lettuce, peas, and halved grapes. Everyone likes those things. They also eat kale , cabbage and spinach. Worms and feeder fish are a special treat for my flock.