Hello all! I have 7 layers and 3 pullets close to POL. 1 is older (6-7 years is our best approximation) 1 is 2 years old the other 5 are a little over a year old. The older gal has had some thin-shelled eggs as she has aged. The others have been fine... until now... as of about a month ago, I started having multiple thin and broken shells in the nesting boxes. At the time I thought it was due to a lack of calcium as when I integrated the chicks everyone was fed grower feed, with access to oyster shells at all times (which they ate on a regular basis). I thought that once I returned to layer feed (which was about a month ago) things would return to normal. But it has gotten worse. In fact, of the 3 eggs layed today so far, 2 were broken and the third was thin-shelled and broke in my hand. As I have been processing and problem-solving, I read over the article on egg laying: https://www.backyardchickens.com/articles/common-egg-quality-problems.65923/ And read this: Causes are similar to shell less eggs: - Immature shell gland; - Nutritional deficiencies, usually lack of calcium, vitamins E, B12 and D as well as phosphorous and selenium; *** My best guess is the feed. For the longest time I fed a layer feed that was pelleted and 20% protein/3.2-4.2% calcium. When I gave the grower feed I switched over to a different company/feed (Fehringer Farms) - one that is not processed into pellets and is basically seeds and grains. I stayed with this company and feed type when I switched back to layer feed; it is somewhere between 15-16.5% protein but I don't know the calcium content. *** Vitamin D - sunshine... their run is such that there is sun and shade available at all times of the day, so vitamin D *shouldn't* be a problem. - Disease such as infectious bronchitis, avian influenza, egg drop syndrome; an internal or external parasite infestation; *** As far as I can tell, they are fine in every other respect - Exposure to very high temperatures and/or very high or low humidity levels; *** It's hot and dry, but - it was way worse during the summer than it is right now - Egg laid prematurely due to stress or a disturbance during the calcification process; - Egg laying while molting ***There is a light molt happening in the flock right now, but nothing to write home about I am about to go out and switch back to the old feed, but I'm wondering if there are any other options... or if anyone has any thoughts about what might be the cause... . Thanks in advance for any help you can give!