PRACTICAL GENETICS

 

Here we will explore the realms of genetics . I will provide practical examples using my litter from my own bitch and the upcoming litter from her sister. This will be an ideal example to show the different genetic makeup starting with two bitches who for our purposes to be considered to be genetically the same. and see the very different results that can be achieved through an outcross as opposed to a linebred dog as described in Part 5 of owing an Amstaff explained. The purpose in using these two bitches is also very relevant as Cruise is a Grand Champion and the winner of the Specialty and the sire of Bonnie who won the last Specialty and also of Starlette and Mojo is the winner of the first Specialty Not only do we have two similar sisters but two sires who have won at the same level of competition both of whom are the results of outcrosses. I cannot think of a better example to use.

First we need a basic understanding of genetics.
Everything that happens in our dogs can be attributed to genes. Genes are situated on chromosomes and chromosomes are within cells. Genes are either dominant, recessive or sex-linked and are usually in pairs. Sometimes there are sets of genes which occur in exactly the same place on a chromosome and these are called multiple alleles

Dominant Genes can be broken down into two groups. Semi Dominant or Dominant. Dominant means that only one copy of the gene needs to be in the animal for it to express. This is called the heterozygous state and means that there is no difference in phenotype when there are two copies of the gene or the homozygous state. Semi Dominant on the other hand means that when one copy of the gene is present one phenotype will occur and when two copies are present a different phenotype will occur.

Recessive genes are just that. They need two copies of the gene to be expressed.

Sex-linked genes are located on the sex-determining chromosomes. "In mammals males have an X and a Y chromosome and females have two XX chromosomes.
It is on these X chromosomes that sex-linked traits are carried. I am not aware of any sex linked genes in dogs.

Now that we have a basic understanding of genetics, we will deal with the example above. I will use tables in an effort to emphasize the difference between line breeding, outcrossing and why line breeding is always preferred but outcrossing is always necessary and how to obtain the benefits of both.

 

Linebreeding

 

First lets consider our two bitches Starlette and Bonnie and their parents, Cruise and Ninja. For these purposes Cruise and Ninja are unrelated. They are an outcross related only distantly through an ancestor called Ka Hanahous Seamist. This was one of the earlier imported dogs and his bloodline is irrelevant to today's matings.

Cruise

Ninja

Starlette, Bonnie and Siblings 50% Cruise 50% Ninja

Now here we see the mating of Cruise to Ninja has produced a litter. In genetic terms, these are called F1. The first generation. Each of these F1's are 50% Cruise and 50% Ninja. Now as the genes required to create a dog far outnumber those in seeds used by Gregor Mendel, we cannot apply simple Mendelian theory to our dog breeding program as we will have a host of dominant and recessive genes to cope with. We can, however, over time purge the genes we don't want and strengthen those we do. First let us consider that Starlette, Bonnie and her other siblings do not look identical. This is genetic diversity. While each is 50% of their respective parents, they each receive a slightly different mix of genes from each parent. The only guide we have as to the genes they acquire is to use our eyes and examine the breeding results.

In the following table we will examine Starlette starling first with details of Blaze, the stud dog used. Firstly, the choice of Blaze was not random. He was chosen specifically as the stud as he is everything that Starlette isn't. In my opinion, I couldn't have got a better dog to use.

(Editors Note: There are three pups in the show ring from this mating and all of them have won In Group awards)

Cruise

Cleo

Blaze and siblings 50% Cruise and 50% Cleo

Here we see that Blaze is also 50% Cruise and that the mating was also an outcross.

The advantage of our current mating is that Cleo is far superior to Ninja so as well as line breeding we are introducing better quality into our line.

Starlette (50% Cruise 50% Ninja)

Blaze (50% Cruise 50% Cleo)

What becomes obvious here is that in our offspring they should get a minimum of 50% Cruise (25% from each parent) Now, genes pass to their offspring at random so it is possible for the 50% of Cruise Genes carried by Starlette to pass onto one of her offspring and the same to happen with Blaze so we could end up with 100% Cruise. It is also possible again at random to get 50% Ninja and 50% Cleo and no Cruise and any number of other combinations.. Both of these 0% and 100% are unlikely. With the most likely scenario being that on average all pups will get 50% Cruise so we most likely will have our litter of pups fall in the 25 -75% range with with our linebreeding.
Below we have Cruise and Cruzette, his granddaughter from the mating above. Here we achieved about 98% Cruise. There are minor differences in markings but look at the underjaw. This little girl is showing more underjaw already. This is the result of the Sierra influence. Cruzette's new owner Ben Hatchard from South Australia is looking at a show career for her but more importantly, being deaf, he wants to teach her to react to sign commands. Go Cruzette!!!!

In the next table we examine the outcross mating

Bonnie (50% Cruise 50% Ninja)

Mojo (50% Dam 50% Sire)

Mojo's Sire and Dam are overseas and it is not possible to breed back into his lines. He himself is an outcross and I would suggest that breeding back to his line would be the most correct choice. Who his parents are becomes irrelevant here as we only consider the Mojo blood in the pups.

From the above mating, again, using extremes the possible percentage of Cruise in the pups is 0% but only to a maximum of 50% as that is all Bonnie has to give. On average pups will inherit 25% with a range of 12.5%-37.5%. Every pup will be 50% Mojo without fail as this is the F1 cross to his line and the balance of the 50% will be Cruise 12.5%-37.5% and Ninja 12.5%-37.5%. We now have Mojo as the dominant gene donor and the amount of Cruise blood reduced dramatically. If you want to linebreed on Mojo then this is the first move, however, if you want to linebreed on Cruise it is a step in the wrong direction. There is a remedy but that would be giving my competitors a heads up in their breeding program if I put it to print and not relevant to anyone else.

In my opinion, generally, the use of Mojo in this instance is incorrect and linebreeding on him not recommended unless you are a very experienced breeder. The mating of Bonnie to Mojo is also, in my opinion. not the right mating as he has too many of the wrong kind of faults and there are too many cross faults between the two dogs. The best use of Mojo, in my opinion would be to a linebred bitch who excels in the areas that Mojo is deficient while taking advantage of his good points.

(Editors Note: There are at least three pups from this litter being shown. There are no group winners to date)

Next we will examine a Grandfather/Granddaughter Linebreeding.
A perfect example of this would be a bitch from my litter from Starlette and Blaze. Lets call her
Miss M.

Cruise

Miss M

Now as I said before. We have to use our eyes first when we determine what we have. Now Miss M is a big bully bitch. She has a lot of substance and bone. What does this tell me? We know genetically she is 25-75% Cruise. She is a bully type whereas Cruise is Moderate so we can conclude that there is quite a bit of Cleo in there as well as she IS bully. How much? It isn't possible to tell, we simply have to estimate based on what the bitch looks like. Let's assume that Miss M ends up at right on average of the percentages and We will assume that from Starlette and Blaze, Miss M gets 50% Cruise 25% Cleo and 25% Ninja.

Cruise (100%)

Miss M (50%Cruise)

Offspring 50-150% Cruise

Now we have our Grandfather/Granddaughter mating. The first thing that is obvious here is that we have 150% Cruise to deal with. Our average percentages will be 75% Cruise (50+25) The Cruise percentage here can only vary on Miss M's side as Cruise must always give 50% so the minimum percentage here is 50% and the maximum 150%. What's that you say 150% Cruise? The genes from both dogs add to 150% and yes it is possible to get more than 100% This is because genes are complete units of heredity and, as such can be transmitted from animal to animal as complete units we can double up, even triple up on certain features. It is important that you "Get This" now!! As we shall show in the next part, This is an extremely important feature when using an outcross properly. What we need to remember here is the at we took 50% of Cruise' genes in the original matings to Ninja and Cleo. Now we are putting them back into the complete dog. They do not cancel each other out but can double up as say, increasing bone substance or doubling a good topline so that all offspring inherit it (Dominant) instead of half (Semi-Dominant)

I would hope that by now you would have seen that Linebreeding is the only way to go as it is a means of not only maintaining quality but using the right combination, improving on the original.

 

Outcrossing

 

This brings us the the outcross. If linebreeding is so successful, why outcross at all? If you do outcross is there a right way and a wrong way to go about it?

Outcrossing is also called assortative mating. Most definitely there is a right and wrong way to outcross. Many backyard breeders do just this. They obtain a dog from here and a bitch from there and mate them together regardless of the consequences. In the worst, these people are just puppy farmers. At best, although they may be breeding from dogs that are from purebred stock, they often have little resemblance to the original registered stock and, as the generations pass, they look less and less purebred. Well enough said on the backyard breeders and let's get back to outcrossing in a serious situation. For the most part an outcross is a dog. It is unusual for a bitch to be used as an outcross, however, often a breeder may forego a stud fee in exchange for pick bitch from a litter in order to introduce new blood. Generally speaking, though we will be talking "dog" and as such you must remember that you must never use a dog who is not "all that" He must me a quality specimen if you are to reap the benefits. From a purely phenotypical standpoint, our main reasons to outcross fall into the following categories.

To maintain fertility and hybrid vigour.

Inbreeding cannot be done for ever. As the generations pass, our dogs will become more homozygous and, without outcrossing may become less fertile or less vigorous. Isn't this what we want - more homozygous? Yes, but we always need to keep in mind that whilst we want to double up on all the good points, we want to avoid any negative aspects. This will depend upon the health of the specimens you start with, the degree of linebreeding and the susceptibility of the particular breed to disease. When selecting an outcross, one cannot just select a dog at random, no matter what he may have won or what reputation he may have. Outcrossing, as I have said is an assortative mating. This means that unlike a linebreeding where the goal is to purge genes for unwanted phenotype and double up on the desired phenotype, the genes from the outcross will assort at random. Let's make sure we understand this point as it is crucial you understand the difference. With linebreeding, we reduce the numbers of genes in the gene pool, by selection, and fix breed type through the genes that are left. We therefore have significant control over the phenotype of our offspring. With an outcross, we automatically introduce 50% of the outcrosses genes to the gene pool and those genes will assort at random with 50% of our linebred dog. We have no control over this at all in the total outcross. The resulting young may be all different sizes and shapes, they may look all like the father, all like the mother. My preferred outcross in this category would be a distantly related dog. He should closely resemble my own stock but be sufficiently unrelated that we can consider him an outcross.

To improve breed type

Here is the classic case. To improve breed type!! This falls into two categories.

1.Where breed type is lacking altogether.

The first consideration here is should we bother at all if breed type is so bad. First you need to examine the pedigree of your own animal. If it was a good pedigree but you have a poor specimen, I would try linebreeding rather than an outcross using perhaps a half brother/sister who excels where yours does not. If the pedigree is not so good or it contains numerous outcrosses then your dog contains a mishmash of genetic material. Again, consider first whether you should breed at all. If you decide to breed, I would look at outcrossing to a heavily linebred line for best results as the linebreeding is more likely to be dominant over your assortative animal and will most likely bring about the most improvement in the shortest possible time.

2. Where we have good type but need better or we may be losing say, a little in bone or want to improve in that area but are satisfied with the dog overall.

This scenario is where we have good animals but want to improve. This is where many quality breeders import a dog or frozen semen to improve the lines. This dog must be or excellent overall quality and excel in the areas you feel your animals need improving. If he is a total outcross I would look at putting him to a few bitches and then linebreeding on him. If he is a distantly related outcross, put him to the bitch that suits him most and examine the results. If he is a line breeding with your own stock then you can please yourself.

I hope you have enjoyed and gained some insight from this article. Genetics involves much more than what I have written but it is impossible to cover everything. Remember that everything here is a guide as to what to do. There may be any number of reasons why what you try won't work. For example you may use a stud dog on a bitch and expect great results and breed a litter of rubbish. You have not failed, that litter just didn't work. The same stud dog to a sister of that bitch may produce the results. Using the examples I have given you and developing your own skills should see you make improvements each year. Good luck with your breeding and showing.

 

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