Shell-less eggs

My ducks are free range during the day, topped up with bio-dynamic feed as required. They have free access to sea shell grit, which hardly goes down now, although it used to.  One duck consistently laid her eggs without a shell. And usually in the late afternoon.

I added Calc phos tissue salt (also called cell salt, mineral salt or Schuessler salt) to a bucket of water and over a few weeks, she has not only started to lay eggs with shells (started with delicate shells, now good ones), she lays them in the morning. And is the only one laying in the hot summer.

Hello Madeleine,

What kind of ducks do you have? I'm thinking of maybe getting a tiny flock of runner ducks ( 1 drake, 2 females ) to keep the slug invasion in check. What is your experience, do they gobble up slugs?

Shell-less eggs are caused by a calcium deficiency. I find my chicken use the oystershell grit to help their digestion, but they still crave their calcium on the side.
I also had a chicken laying 'leather eggs' until I started to feed some of the eggshells back to the chicken. They would also dumpster dive in the compost heap for eggshells.
I'm not sure salt is good for the birds... You might do a little test as to what they want? Offer the mineral salt free choice and crushed egg shells free choice, let the ducks decide :)

As for the pause in laying, as you've remarked, they lay less or not at all when it's very hot or, like here now, very cold.

Enjoy the peak of summer!