Feeding something non poisonous two to three times a week won't harm a duck! My ducks even get stale bread during the week - now y'all bash me for feeding bread to my ducks…Hi folks, I feed Cat biscuit to my Cayuga Ducks 2 or 3 times a week and they like it. Do you think its harmful in the long run or its okay? Thanks
I am feeding cat-kibbles twice a day to my ducks as a treat and none of my ducks has shown any signs of overweight, diabetes, fat-liver or growing horns from their foreheads so far. And they still quack and don't meow!
The point is: You can feed anything your ducks like as a treat as long as it is not replacing their main food or is given in excess.
This summer my ducks even treated the potato plants as treats

Ducks line their digestive tracts with Teflon, i guess.