Line-breeding Warning! Hatching runner eggs from siblings led to in-shell deaths, deformities, and crested ducklings.

[OneEggToRuleThemAll]

Disclaimer: I'm still a beginner when it comes to breeding ducks, and I have trouble wrapping my head around genetics.

Almost two years ago, I received 5 sibling runner ducklings from a local backyard duck keeper. Four were males--we kept one female and one male. These ducklings grew into happy, healthy ducks who taught my other ducks (a Blue Swedish, a Pekin, a Buff Orpington, and a Magpie) how to forage around the garden for greens, slugs, and bugs. They did wonderful in the intense Florida summer heat and knew how to run under cover when they spotted aerial predators. They did much better than the rest of my ducks, so after reading a little about line-breeding and learning that it usually causes few problems in poultry, I decided to hatch their eggs.

I set 10 of my runner's eggs in the incubator (I knew they were all from my runner because she is the only one of my ducks who lays green eggs). One of them never developed. Nine made it to hatch day. Three hatched out by themselves on hatch day. Two never pipped internally and later died in-shell--when I opened the shells, they each had a twisted beak and a large squishy lump on top of their heads. The remaining four were able to pip internally and externally, but did not progress further. I made their pip holes larger and after another 24 hours, I assisted them with hatching--the final one took forever to absorb its yolk and wasn't ready to come out of its egg for another 12 hours after its other siblings. Phew. I now have 7 vigorous ducklings in the bathtub.

However...FOUR of them are CRESTED. One of the crests is HUGE and the rest have much smaller crests. They are adorable and are way more interested in the water than my Muscovy ducklings are. We love them, but what the heck?!

I am still kind of shocked and annoyed with myself over this entire experience. I was completely unprepared for hatching difficulties with my runner ducklings, and now I'm worried about the crested babies because I've read that they can have health issues throughout their lives.

I have 8 more runner ducklings due to be delivered tomorrow from Metzer, and my original intention was to breed Metzer's runners with my own Florida-born-and-raised, landrace runner ducklings, so that I might have a genetically diverse flock that thrives in Florida's summer heat and can forage for a substantial amount of their dietary needs. Now I'm not sure that this is a good idea because I'm worried that my crested ducklings, even if bred with Metzer's non-crested ducklings, would breed out more crested ducklings, and I don't want that!

Does anyone here understand genetics more than I do and have any advice as to whether or not it would be wise/foolish to breed my Florida runners with Metzer's runners?

Also, I'm attaching photos of our new babies because CUTENESS. And photos of Scout and Dandy (siblings), who are mother and father of the ducklings.

 

[ruthhope]

@OneEggToRuleThemAll so sad that this has happened to you.

The first part of the genetics of creating crested ducklings is straight forward. There is 1 genetic error that causes the midline skull deformity and associated crest. A crested duck has that error on a chromosome (not a sex determining chromosome) from one of its parents.

Fertilized eggs get half their chromosomes from the drake and half from the female. So if one parent has one chromosome with the error, it will pass on the error to half of its eggs. But if both duck and drake have the error, they both pass on the error to half the fertilized eggs. In this situation, a quarter of the eggs will receive the error from both parents, half the eggs will receive the error from one parent but a normal chromosome from the other parent. One quarter of the eggs will receive normal chromosomes from both parents.

Eggs that receive the abnormal chromosome from both parents are not viable and die in the egg as you experienced. Those eggs that receive one abnormal chromosome and one normal, develop as crested ducklings. Those eggs with two normal chromosomes, develop into normal ducklings.

Unfortunately, as you have eggs that died in the shell with the deformities you described, you have both a hen and a drake that have the error on a chromosome.

The complicating factor, that your story also demonstrates, is that there is variable expression of the abnormality. That means a duck with a large crest can produce ducklings with small crests, and vice versa. So ducks and drakes with small crests can produce ducklings with big crests.

Crests are commonly seen as fluffy poofs of feathers, but under the poof is a midline defect where the skull has not closed properly. There can also be midline defects in the brain and it is defects in the brain that lead to lifelong neurological problems. The hole in the skull is generally covered by fatty-fibrous tissue and, if not large, often gives no trouble.

As you had non-viable eggs, both the hens and the drake have the genetic error and are crested, but obviously they dont have large crests. You might carefully examine the backs of your ducks' and drake's heads with your fingertips to see if you can feel a very tiny bump, or depression. There does seem to be one feather sticking out in the duck in photo P2010415. That might indicate it has a tiny crest deformity (or maybe an artifact of the photo!)

But whether or not you can find anything, the drake and the hens that produced the eggs both carry the genetic error with little to no expression of the crest.

Whether or not you breed with your ducklings depends on your view of the ethics.

I have had 2 crested ducklings -- one came in a straight run batch of pekin ducklings from Tractor Supply in 2021. She is now a loud and healthy 4.5 year old. She is smaller than her clutch mates and she is a little ditsy: periodically she seems to forget how to get out of the duck house. Instead of following the others out she goes the wrong way and stands by the screens shouting, until the drakes goes to get her. But she is a sweet little duck, she survived a horrific dog attack last year (a husky climbed the fence into my son's back yard) and has had no health problems. I also had a crested Pekin drake rescue so I dont know the back story but it was likely a Tractor Supply duckling. He and another were bought as Easter ducklings and then attacked by a raccoon that killed the clutch mate and left the crested boy severely injured. He was abandoned at the vet's office. That crested boy was loud and bossy. He lived with my rescued muscovy drakes and had a happy life as self identified boss duck, albeit with special needs as a result of his injury. He died nearly 2 years ago from an unrelated pelvic tumor.

So your ducklings may all live long and happy lives without neurological problems. We cannot predict which or how many will not have neurological issues.

Personally, I would never intentionally breed crested ducks together because of the 1 in 4 eggs that are non-viable. My son decided he would not breed from his crested hen duck in case half the eggs carried the error and the resulting ducklings had neurological issues. Some duck breeders are willing to breed to get crested ducklings as there is a market for them: you notice how cute your crested ducklings are.

The problem for you is that you cannot be certain that the ducklings without visible crests are normal.

I think that as long as you separate out the crested drakes along with your existing drake, and do not breed from them, you could breed your Florida hens with a Metzinger non-crested drake. Half the ducklings from your crested hens will be crested. And some of them, but not all, may have neurological issues. Half of the ducklings from the crested hens and all the ducklings from non-crested hens, should be normal.

Good luck raising these little cuties. With some luck non-will have neurological issues.

 

[OneEggToRuleThemAll]

@OneEggToRuleThemAll so sad that this has happened to you.

Ruth, thank you so much for your thorough and thoughtful reply! I'm going to re-read it a few times to understand this situation more completely. I really appreciate you taking the time to respond.