Body type from Hen or Roo?

[Minky]

So with a new roo added to my small flock I am excited to venture into the game of breeding my mixed flock for interesting egg colors or maybe body size for a dual purpose bird.

I'm wondering if there are basic genetics that can be assumed will happen with certain pairings.

ie- pea comb linked to blue egg layer

If I breed a (tall slender) CLB rooster with a plump round Buff Orpington hen who lays a nice large egg, will the body type of the BO be only passed down to pullets? or could I get big meaty cockerels out of this pairing? so I guess what Im asking is - can BO hens make babies that will be big stocky males, or will only the pullets have the BO weight and shape?

Thanks

 

[Ridgerunner]

Interesting question. There are some things passed down due to gender, males typically have larger bodies than females of the same breed, roosters have pointy saddle and hackle feathers while on females they are rounded, males tend to have a more upright posture and heavier legs, and so on. So yes, you can get some difference based on sex.

Chicken genetics is pretty complicated once you get beyond a few basic things. You are dealing with gene pairs, not individual genes. Don't complicate it with sex linked genes yet. Some genes are dominant, some are recessive, some are partially dominant, and some only act if other certain genes are present. There area lot of different gene pairs that can affect just one simple thing like comb type, size, and shape. When you start talking body confirmation the number of different gene pairs gets really huge. Not all those gene pairs have the same gene on both sides so either could get passed down randomly from both parents. That's called genetic diversity.

When you create a breed you eliminate genetic diversity to the genes that define that breed. Take the color of a Buff Orpington. During the breeding process you eliminate the genes that would cause the color to be anything other than buff. To further complicate it there are different genetic combinations that can make buff. Different Buff Orps from different flocks could easily have different genetic combinations that cause the color. It is quite difficult to eliminate all the recessive genes that could mess with the color. Given enough generations good breeders do a remarkably good job of removing genetic diversity in the things that define the breed and yet maintain a healthy level of genetic diversity in the other things.

The same thing is true for body conformation. Body conformation defines a breed but there are a tremendous number of gene pairs that affect conformation. Even the best of breeders do not hatch chicks where every chick hatches is perfect and a potential grand prize winner. I've seen some claim 1 in 5 or 1 in 10 do meet the SOP requirements, but that is a lot of chicks that don't.

When you cross certain breeds/colors/patterns you can predict with accuracy the first generation outcome as long as those genetics are pure, that both genes on each side of that critical gene pair are the same. That's why you can get sex links, the critical genes are pure. When you cross certain colors you can predict what the base color of the offspring will be but some of the not-critical genetic diversity may create different patterns of leakage in that basic color.

So what does all this rambling mean to you. Unless your chickens came from a grand prize winning line the genetic diversity in body size and conformation of your chickens is probably not all that pure. When you cross those chickens you will probably get the vast majority of their offspring, male and female, to be in between body size and conformation of their pretty different parents. Some males will be larger and stockier than others. Some females will be larger and stockier than others. The less genetic diversity the parents have in these critical genes the more consistent the offspring will be.

You will get some differences based on sex as I mentioned at the top of all this. You can get some males or females to be larger and stockier than others. But in general expect the males to be larger and stockier than the creme legbar rooster and smaller and skinnier than a Buff Orp rooster would be. Don't expect a tremendous difference if size and confirmation in the first generation, but if you cross your best chicks from this mating you can expect a pretty good variety in the next, not only size and conformation but in feather colors/patterns and egg color. That second generation is when it really gets fun.