I don't think that its a genetic predisposition.For now I just want to know what to look out for & if some of mine (having the same father) would be at risk. This month, I have all kinds of construction debris around. I would think that my flock would be at a higher risk right now because they're all over the place & not contained. (Technically, they're locked up right now because of a visiting hawk eyeing my coop, but they're usually out.)
If it was a sour crop, some are more prone to yeast infection which can be brought on by using antibiotics very much like in humans. And, of course, if a bird has a weakened immune system for any reason (including antibiotic use) they aren't as able to fight off what they may be able to handle under better circumstances. Sometimes molds/yeasts in feed items can contribute as well.
Anyhow...all of that is to say that I wouldn't worry about genetic predisposition as much as looking at possible things that they can be getting that might cause an impact. If sour crop is suspected, or if you have given any antibiotics lately, probiotics can be used for the rest of the flock to hopefully restore gut flora.
For probiotics I recommend Avi-Culture II - the only avian probiotic on the market that is cultured on non-gmo substrate. ( Website is bad but the product is good... a little goes a long way and has a good shelf life if kept in fridge http://www.avi-culture-2.com/shop.html )
They can have some plain yogurt. (I know that folks are concerned about lactose in milk products but that is not an issue with yogurt as the LABs digest the lactose.)
Another thing that works GREAT for treating sour crop is to let them eat organic coconut oil in it's solid state. They LOVE the stuff and it is anti-fungal. I've known several folks that used the coconut oil and nothing else with sour crop and each bird recovered nicely. They withheld grain-based feed for a few days, gave coconut oil, and some animal-based protein. ACV should NEVER be used when you have sour crop and should be withheld until the bird is well if you're inclined to use ACV at all.
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