Feather Shredding — Not the Color's Fault

A small note from the garden, on the lavender color and the "shredder" gene in the Orpington

"Why do our beautiful lavenders have tail feathers that look frayed and ragged, as if torn into strands?"

The first time I ran into this, I blamed myself before anything else. I wondered whether the feed was missing something, whether I was keeping them too cramped, whether something was getting at their feathers. I hunted for the cause for a long time, until I came to understand later that it wasn't my fault — and, more importantly, it wasn't the fault of the "lavender color" either.

How lavender works

Remember the two pigments — black (eumelanin) and gold-red (pheomelanin)?

The Lavender gene (symbol lav) is recessive, and it sits on an ordinary autosome (not a sex chromosome). Its job is to reduce the amount of pigment deposited onto the feather — both black and gold at the same time. The result is that deep black is diluted to a soft grey, and gold is diluted to a straw or cream, and together they come out as the soft grey-violet we call lavender.

This is where lavender differs from Blue, even though many people confuse the two for the same thing. Blue is an incomplete-dominant gene that dilutes black only, and it isn't stable — breed it and you get a mixed clutch of blue, black, and splash, with no way to get a whole clutch of pure blue. Lavender, by contrast, is recessive, dilutes both pigments, and is perfectly stable: lavender bred to lavender gives lavender every time. That stability and predictability is exactly why those of us building bloodlines are fond of it.

So where does the "shredding" come from?

This is the heart of today's note.

The shredding — what English speakers call shredder: tail and wing feathers that look thin and ragged, their fibers separating from one another — does not come from the lavender gene. It comes from another gene entirely, a completely separate one.

What makes the two seem like a single story is that this shredder gene sits "right next to" the lavender gene on the same chromosome, very close to it. When two genes lie close together on the same chromosome, they are passed down together almost every time. We call this phenomenon genetic linkage.

To put it plainly: we are not keeping "a color that ruins feathers." We are keeping two genes that happen to travel together. And the shredding shows up especially badly in soft, fluffy breeds like the Orpington, because their feather structure is already more delicate than that of tight-feathered breeds.

Can they be separated?

Yes — and this is the part I want lavender keepers to know.

Because they really are two different genes, there is a chance for them to come apart. In every generation, as reproductive cells form, the chromosomes swap segments with one another, and sometimes that swap point falls exactly in the gap between the two genes — letting the lavender gene break free without the shredder gene coming along. Our job is to watch for the one that has broken free, and keep it for breeding stock.

The method that works is to cross back toward a black carrier — what is called a black split: a black bird that holds one copy of the lavender gene without showing the color. Breed a split black male to a lavender hen and you get roughly half a clutch of lavenders with clearly better feather quality, because we are drawing the strong feather structure of the black line back in, while at the same time giving those two genes the chance to shuffle and separate.

It isn't a shortcut, and it doesn't finish in a single generation. But it is the most honest way. We are not fighting the genes — we understand how they work, and then we select, generation by generation, until what remains is lavender with whole, sound feathers.

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— A note from the garden, Tamahagane