My 2 week mallard duckling has some really big jugs( large breast) and it seems un-proportioned with the rest of her body. It looks she swallowed a chicken egg and is harvesting it in her breast. For reference she is about 6-7 in. long. We feed her around 10 mini slugs (ranging in size but no bigger than a shelled sunflower seed) and maybe a worm or 2, whatever she eats from our grass which doesnt have fertilizers and a near endless supply of duck mash and water. She walks around fine and happy, but just wanted to make sure i wasn't over doing it. She also has grit should I be feeding her anything else? I wish I could post pictures so you could see what i was talking about....