I have been feeding my ducks Mazuri floating pond food. Its quite expensive 48 dollars for 50 lbs compared to the egg layer food we feed the chickens 18 dollars for 50 lbs. I recently lost one of my ducks to Rectal Prolapse, which was from a lack of calcium, egg bound problems. This morning my other female did not lay and egg and I am really concerned that my girls are not getting enough calcium. I gave them some powder calcium with their food this morning but would prefer for them to get their calcium in their feed. I know oyster shells are a form of calcium, but does anyone have any feed suggestions that have all the nutrients they need. I also feed them a head of romaine lettuce a day for some additional greens. If oyster shells are enough how do you feed them to your ducks? I mostly hand feed my ducks the floating pond food by a bucket of water. Any advice would be greatly appreciated as I am worried about my other female today and I need to do something different.