But Karen,
You can't gain back what is lost. Each generation loses genetic potential. So it's sufficient to say that these breedings can not me maintained without crossing to other lines.
While Mrs. Robertson has not added new stalk to her line, she does not need to yet. The key to having a great line of chickens is knowing when you need to cross, bring in new blood, or simply start over.
Mrs.Robertson did exactly what you said new people starting out do. But to the extreme I think she started with 5-6 different strains (even though they may have been from the same lines the strains were bred different)
Just some food for thought
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Hi call ducks,
I understand where you are coming from. We are dealing with 2 different trains of thought here. Mrs. Robertson could use 5 or 6 different strains because she is using
population genetics to breed for
utility in her Light Sussex. Absolutely no problems with selecting multiple strains to start such a program because of the selection criteria she was going to use later. ( Quite successfully, I might add).
However, if one is going to use any of the
classic animal breeding systems ( instead of population genetics), then one must take into account the number of strains, whether the gene pool is closed or not, and how to admit foreign blood into your breeding program.
Let's talk about breeding plans for a moment. Basically we have 3 fields of knowledge here. Some of the major ideas transfer from style to style, but the minor laws are different. Just like when Judge Card discusses breeding for color in the penciled and stippled breeds. Basically the major laws are the same, but the minor laws vary.
1. The Biodiversity movement. In this style of breeding, all selection is done for general phenotype and utility/health only. Breed hallmarks are ignored except as they serve to enhance utility and health. Sled dogs come to mind. Color is optional, all ornamentation unrelated to utility or health is optional. If this were poultry we would see color, spurs, feathering placement , eye color, beak and shank color, number of toes, , etc... all these things would be unimportant except as they related to health/utility. The biodiversity movement breeds "landraces".,
not animals bred to a Standard of Hallmarks which define their character and function ( classic animal breeding).
2. Population genetics. Here, math is king. Coupled with rigid selection and careful computations of Percentage of Line Inheritance plus production markers for utility aspects at certain ages, etc. The breeder combines strains with a view to winnowing out all but the best utility aspects of each strain as they skillfully meld the various strains together. Usually they raise many more young each year than the classic animal breeder. 1st, because they need the numbers of young to crunch the numbers for their calculations. 2nd, because they are melding strains and need to be able to select from the exponential number of genetic variations expected to crop up from such strain-crossing. When one crosses strains, the number of possible genetic variations increases exponentially ( not arithmetically) with each strain added into the project. This is why you see few average poultry people using population genetics. The number of young required each season usually is larger than their projects can handle. I know Mrs. Robertson raises hundreds of birds a year from which to select. A fine thing in population genetics.
3. Classic animal breeding systems. Line-breeding, in-breeding, out-crossing , female family inbreeding, 3 in and 1 out, Brackett's Formula, Close-breeding, spiral breeding, etc. All of these systems can work with smaller numbers of creatures which fit the average poultry breeders project size requirements. It's true, the larger number of birds one has, perhaps the
easier they are to accomplish. However, they can be started with a pair, trio or quad of birds from a single superior vintage line-bred gene pool. ( closed or not). Another advantage here is that these systems have been extensively discussed in easy-to-read, lit which are math "lightweights". Instead of math formulas, they also use much descriptive discussion carried over from the "art of breeding" to make their points.
All three of these fields of breeding have their positives and negatives. But one can't simply apply judgment from one field completely to the other 2. The major rules apply for computation, selection for health and utility. However, each of the fields has different basic parameters for being. The minor breeding rules vary enough prevent one being able to apply a complete comparison and mode of judgment across all three at once.
For instance,
Biodiversity praises health and utility but ignores the minor hallmarks.
The defining feature of this field is that the health and utility of the creatures they are breeding are their only "pedigree".
They are at the opposite end of the breeding system spectrum from classic animal breeding, regardless of how they promote their agenda.
Population genetics rests on using calculations of utility aspects at certain time periods to winnow superior animals from a certain gene pool. They do consider the minor hallmarks.
The "calculations of utility aspects at certain time periods" is the defining feature of this field .
Classic animal breeding uses careful selection plus time-proven methods of concentrating virtue in pedigreed creatures to enhance an existing gene pool or create a new one.
The defining features here are that a "method is used" and the animals are pedigreed.
So while we can hold our own counsel close to our chests, when we speak of the other 2 fields of animal breeding, we must couch our conversation in
terms which apply
within their framework of thought. It is a difficult thing. Almost like having to translate from one language to another . Yet needful if one expects the recipient to apply the shared knowledge to their own situation. As regards the Biodiversity folk? Forget it, they are close-minded and weeks of discussion will come to naught as soon as the conversation runs aground on one of their treasured principles.
Best Regards,
Karen
