I'm not sure what you are referring to here. Parrots have crops to digest their food and do not need any kind of grit as this can cause an impaction.Birds with gizzards are the soft bills like songbirds, doves, finches, canaries, etc., and they need grit as it helps them break down the food they eat. They do not shell seeds and eat them whole, so it is harder for them to digest, which is where the gizzard comes in. Parrots have a crop that partially digests food and empties it into the stomach.
If you are a novice at handfeeding, then this is where the damage could have occurred or at the inexperienced breeder's. Hand feeding with a syringe is a learned skill and it is not a snap to learn either. There are many problems that can arise when handfeeding with a syringe. One is putting the syringe too far into bird's mouth. Only the tip end needs to go into the mouth. The other problem that can sometimes arise is feeding either too hot or too cold formula. With too hot formula, the crop is burned causing a chronic irritation that will not allow the bird's crop to pre-digest food before going into the stomach.Too cold, and the crop cannot process food, and it rots. Soft bill birds like finches, songbirds, doves, crows, have gizzards where they store small rocks and grit to help in the grinding of their food which they normally swallow whole. Parrots do not eat like this so do not need a gizzard to store rocks in and never need any grit.
If the vet did not find any infections either bacterial or viral, then this was a problem that came during handfeeding. May I suggest you take in NO MORE baby birds until they have been finished off with handfeeding by the breeder. As I said, handfeeding is NOT the snap a lot of people think it is as there can be many problems arise that a seasoned breeder/feeder will not have and the novice will.
So, to answer your question, I don't think this was genetic, I think this was an injury to the crop when bird was being handfed either by you or the breeder he came from. You said they were also novices, so considering his age when acquired, I would say the breeder injured this bird and did not even know they did.
Novices CANNOT GO OUT ON THEIR OWN AND START HANDFEEDING BABY BIRDS. They have to kind of apprentice with an experienced feeder to learn all the joys and possible pitfalls of this.
We are sorry for your loss, and please talk with the breeder so they can be better prepared before the next clutch of babies is born. They need to learn how to handfeed so they can show people buying their birds the correct way to make the formula and feed the babies. Breeder is kind of handing down a death sentence for some of her birds because of not taking the time to learn with an experienced breeder/feeder.So very sorry!
