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Discussion in 'General breed discussions & FAQ' started by hellbender, Dec 27, 2013.
To me a back cross to F-1 is part of the prelim before the grand finale and perfectly okay. It is really the next part of the puzzle that is crucial. I could be wrong to the contrary median.
It is not the method as much as it is the birds, and the one doing the selecting. Inheritance pays no respect to methods.
The fundamentals behind a purely utility cross or crosses, is that the parents come from flocks that perform well and uniformly well. Ideally every characteristic that is desired is on both sides, but certainly at least one side.
Without any degree of uniformity in the parent flocks, there is a large amount of variability in the offspring. That is not the result of a successful cross. A successful cross results in offspring that are consistent in type and performance. The more uniform the parent flocks are, the more consistent the offspring from the initial cross will be.
Occasionally a third strain is used with the offspring making it a three way cross. Even four way crosses are used commercially. Each strain representing the parent flocks is very uniform, and there are exacting reasons for making the cross or crosses.
Back crossing is done for a variety of reasons, but rarely for pure utility crosses. It would be more often for making something new, or for specific goals in mind. I am crossing strains this year, and I will be bringing the offspring back to one side in the next generation. I have a variety of reasons for doing this. Both for specific characteristics, and a matter of control in which direction I go.
Occasionally we hear of one say 3/4 this or 7/8 that. I use the expression myself, but it never represents inheritance. There is no way to predict the percentage, or even identify the actual percentage of inheritance.
Once we get past the initial cross, the variability in results gets high, whether we backcross or breed the offspring. Utility crosses rarely use this technique because of the variability that follows. Variability is not a friend of performance. We do not want variable results. We want consistent results and the birds performing uniformly well.
If there are specific goals, and specific reasons for doing so, then it boils down to the one doing the selecting, and there is waste.
X TWOOOOOOOOOOOOOOOOOOOO~~~ lololo
gjensen, Okay, lets get back to basics. If I cross rooster A to Hen B I should get both some hens and roos. Crossing the offspring hens back to their parent father does what? Yes, Iam trying to make something new. I have but 1 rooster to cross back to at this time. Is it recommended to cross the offspring hens back to another rooster of the same breed later?
Not George, but I'll give this a shot. This is, in plain language, a kind of cloning. By breeding offspring back to parents, one is reducing the number of expressions, in phenotype, the type we see.
The reason for doing this works best if the the starting pair is an outstanding pair. We'd like to "magically" have 40 more birds just like those two original birds. By tight line breeding, you reproduce a flock of birds that are level, or mostly all look like peas in a pod. If the original pair are wonderful, the goal is to produce a level bunch of birds "cloned" off that pair. Culling off anything not to the ideal desired. After four generations, you've got a group of birds that truly reproduce after their kind. Peas in a pod.
If the original pair is not great, but quite poor, this tight line breeding will likely only produce a "cloned" grouping of equally poor birds.
Hmmm, kind of like using Secretariat as the parent stud eh?
Beautiful day here today, so hubby and I spent most of it out of the house. We accomplished a good bit, but now we're both tired.
That is impossible to answer, because I do not know your goals, the birds, the families the birds are from etc. Not to mention any variability on either side means variable results. Sometimes we do not know what we want to do until we have grown that generation out.
A friend of mine likened it to setting up the table in a game of pool. Making a shot with future shots in mind. I am referring to your project. You have to know where you want to go, and have a "map" drawn out to get there. Any kind of breeding requires the map and a defined destination.
My more original post was speaking in general, and not directed at anyone in particular.