Generations of DNA slash eggs question...?

[nao57]

So...

When you look at ducks for sale or what people say about breeds, or look at genetics different breeds will say averages X number of eggs per year.

Example, Khaki Campbell... ToNs of EgGs.
Peking.... Tons of eggs - Y
Caguya...Tons of eggs - Y - Z

Well enough with the math.

What I'm wondering about is how long you will retain those figures in child and parent generations passing?

Like, example.... you go buy 5 khaki campbells...and then you raise them. Let's say they really do give 300 eggs a year. Then you raise their ducklings to adults and those...would probably also give you the same numbers of eggs right?

But how many generations after the first set, would you still get those egg numbers (particularly the higher ones) without having to introduce new fresh genetics outside of your own drakes?

One would hope you'd get a few generations at least before needing new DNA.

 

[cheezenkwackers]

I would think it would depend what you or nature select for. I have Khaki Campbell's. My first pair came from a hatchery. I suspect the hatchery kept females who laid a lot of eggs and did not keep the poor producers. That female laid over 340 eggs her first year (counting from when she started laying). I then hatched some Khaki eggs from a family who had their ducks on a pond and did not lock them up at night. They were probably the third generation the family had. I ended up with two females. One was a pretty good layer (maybe 300) but the other was terrible. I still have her and am lucky to get an egg every other week from her. I can't help but wonder if in those circumstances, a female who produced a lot of eggs is at a disadvantage. Sitting on a nest, even just to lay eggs, makes you more prone to predators (and the family had lost several ducks to fox and raccoons). It also has a high energy cost and could shorten a duck's life on the pond. The ducks I got from that family are also much more high strung than my original two, which might be a good thing for survival on a pond.

One other thought. I think I remember reading that egg laying ability comes from the father. In which case, my argument has issues and you may be able to keep that trait going for a longer time without adding new blood.

 

[Knighstar679]

If you only hatched eggs from your highest producing hens you could go a few generations. It also depend on how many unrelated ducks and drakes you have in your flock. If say all of your ducks came from one parent source you would likely get 3 or 4 generations before you start seeing inbreeding problems. If you had say three or four sources that you were parent genetics for the original flock set that you were selecting from it would be much longer before inbreeding problems kicked in.
In Story’s guide to ducks I believe it is recommended to get new blood in the flock every three years to prevent inbreeding problems.

 

[TomCahalan]

I think I remember reading that egg laying ability comes from the father.

That's not true. DNA almost never works that way.

 

[nao57]

Wow.

This is a neat topic. Thanks for all the things people brought up.

Its pretty interesting to think about.

 

[cheezenkwackers]

That's not true. DNA almost never works that way.

I over simplified it but hens do get their laying ability from their fathers since they get their Z chromosome from him. I looked up where I read it, Storey's Guide to Raising Ducks by Dave Holderread. He says egg-laying ability seems to be a sex-linked trait. The actual quote from the book is on p.108-9 and says, "At a poultry research station in the Caribbean during the 1970s, my students studied many sex-linked crosses as we searched for combinations that might produce useful birds for subsistence farmers is developing countries. We found that any cross using Khaki Campbell drakes out of high-producing strains produced marvelous laying ducks, no matter what breed their mates were (excluding Muscovy)." He goes on to list how many eggs the hens of the different crosses laid. In the discussion of hybrids on p.106 he says, "If you decide to produce hybrid ducks, it is important to understand that cross (AB) can look and perform differently from cross (BA). For example, when Khaki Campbell drakes from a high producing strain are crossed with Black Cayuga ducks, their sons will be black, whereas the daughters will be chocolate and capable of laying approximately 300 eggs per year. In the reciprocal cross of Cayuga drakes x Khaki Campbell ducks, all the offspring are black and the daughters are capable of laying about 250 eggs per year."
So, assuming he is correct, laying ability is a recessive trait carried on the Z chromosome. Since drakes have two Z chromosomes and hens only have one (and a W which is sort of like the Y in mammals), drakes who have two of these genes can only have daughters who also have this gene. So, I will change my original response. If you start with good quality Khaki Cambell's who only carry the gene for high laying ability, the flock should maintain that trait for many generations (unless you have gene flow from an outside source which might make poor laying ability an advantage).

 

[TomCahalan]

Ok, but in that example he's talking about a cross between two different breeds. It could be the case that there is a gene on the Z chromosome that is quite important, and that campbells carry the better allele whereas most other breeds don't. In that situation, F1 offspring very well could take after their father in that one gene. However, if the gene were that powerful it would quickly move to fixation in subsequent generations.

However, there is no reason to believe that most laying productivity would be on the Z chromosome. Ducks have 79 other chromosomes, and genes on the autosomes benefit from recombination in every generation. Basically, Holderread may have found one specific situation in which laying ability is disproportionally affected by the drake's breed, but that does not lead to the general rule that laying productivity comes from the drake.

Even in his example, it still doesn't follow. Imagine that you have two excellent campbell drakes, meaning that they both have a superior Z chromosome. They are mated with two different ducks, one better than the other. Now look at all of the offspring. At least half of variation in the F1 generation is from the ducks, because all of the ducks in the F1 generation will have that excellent Z chromosome, so that isn't a source of variation.

I also have Holderread's book, and respect him as a breeder. However, there is at least one obvious flaw in his color genetics section (he believes in a dominant bibbing gene, when the phenomenon is simply an interaction between the black and mallard genes), and another possible flaw (sooty). So I would take everything he says about genetics with a grain of salt.