Duck egg with a sac attached?

Our Pekin duck has been laying eggs for the last two weeks. A couple days ago she laid an egg with what looks like a membrane tube at the one end. The egg was fully formed. I was a little concerned about her but she was running around fine. Looked happy. Then the next day a fully formed egg. Thought everything was good. Yesterday, while I was with her and her male companion in the yard, she laid an egg right in the dirt. Like it fell out. It also had a membrane tube coming from it and the end where the membrane tube was attached didn't have shell covering the insides. I could look right in and see the insides. Anybody know what is happening? I tried to do a search, but I have no idea what I'm searching for.

This sometimes happens when ducks aren't getting enough calcium or are having other issues with their reproductive systems. Are you able to post a pic of one of these odd eggs? What are you feeding this duck and is she getting extra calcium to help her egg production? That might be the problem.

I got rid of the eggs. Sorry, wasn't thinking at the time. I'm giving the two ducks about a tablespoon of brewer's yeast on top of their pellet food per day. the food is Nutrena Nature Wise all flock 18% pellet. it says complete natural diet no need to supplement. For mixed flocks - layers, broilers, turkeys, ducks, geese and pheasants older than 7 weeks. They do get to free range part of the day. Of course, as I was hunting for amount of calcium in pkg., I found on the bottom a tag of analysis and it says "laying birds should have ad libitum access to coarse oyster shell". Well then why say it's "complete" urgh! My guess is I need oyster shells then.

I was reading someplace, don't remember where as I have been all over the Internet, that the males shouldn't have more than 14% protein. How do I do that as there is only the two of them I can't feed them separately. They are a pair and don't go anywhere in the yard without the other. It didn't say why. Is this something I should be concerned with?

I believe it's just extra calcium that is not so good for the drakes, I haven't heard that extra protein isn't good. But that is why alot of people (myself included) feed a "maintenance" diet year-round and just offer oyster shell on the side for the females during laying season. The girls will eat what they need of that. So yeah, just offer some oyster shell on the side and her laying issues should subside. If they don't though, it might be time for a trip to the vet to be safe as there could be another issue going on.

Ok thanks, heading to the farm store today.