Sour crop in a whole flock.

[natvinyl]

Hi. I have a flock of 62 free range, various breed chickens who for the past 3 years have been trouble free. All of a sudden I have a large proportion who seem unwell, Looking forlorn and bobbing their heads like crazy. All seem to have very full crops. How could this happen to such a large amount in what appears to be 1 day? What foodstuffs could they have to cause this? Mine are fed layers pellets and corn and then Whatever they choose to pick up whilst out and about during the day. How do I treat an entire flock? Do I separate the few who seem well? I'm so confused

 

[Eggcessive]

Do you suddenly have long green grass growing? Have you fed any treats lately that might have clogged up the crops? Smell and look at your feed and corn to look for mold. I would stop the corn, and put water with ACV with the mother and a little plain yogurt in their feed, stir it in a big pan, and make it very thin. Then massage crops of those with doughy or hard crops. I have never had crop problems either, and just this past week lost one to impacted crop and gizzard, and helped another with sour crop. Feel of the crops first thing in the morning before they have eaten to see if they have gone down. Here is a good link to read:
https://www.backyardchickens.com/a/impacted-slow-and-sour-crops-prevention-and-treatments