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Excerpts from Part of a 1996 VIB LESSON

on Genetics

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Written by Dana Russe

 

This is an article on breeding theory and genetics ---now don’t freak out -- genetics are easy to understand when explained in regular language. I have "borrowed" a short chapter on breeding and genetics and present it here for all to read and use in conjunction with the fabulous Shiloh pedigrees which list both dominant and recessive genetic characteristics — an incredibly invaluable feature that I have never seen in any breed registry before. Once you understand the concepts, you can use those excellent pedigrees to evaluate your dog and figure breeding results.

Dog breeding is kinda like life, if you don’t have a map, how can you get to your destination without getting lost along the way? And without a map, you may not end up in Beautifulcity like you wanted, but in Disasterville! Without a map (or plan), success in breeding is just dumb luck. You don’t know how you got there, or how to get there again.

Introduction

A dog is considered a purebred if it is a member of a recognized breed or has five generations of like-to-like breeding behind it. The breed standard will specify all areas of coat, color and conformation and a purebred will approach this standard in all areas. Breeding should be about predictable results. Take two bitches that look exactly alike, one a purebred and one a mutt, and breed them to a purebred male —you’ll see the value of predictable results. But do not accord an equal status to every dog called "purebred", for genetic purity, like a multi-generation pedigree, means little in and of itself. It is important only in terms of the individual breeding animal or program to which it applies. Just as a mutt can have a pedigree, an ugly, nasty tempered and sickly dog can be a purebred, though I hope nobody would want to perpetuate such an animal.

Terminology — genetics

An animal has both a phenotype, or outward appearance, and a genotype, or genetic make-up. Part of the genotype can be determined from the outward appearance. For example, if a dominant gene is present, such as the gene for plush coat or strong ears, it will be visible. Part of the genotype can be hidden. A smooth coat, strong eared Shiloh can carry genes for plush coat and soft ears, both recessives. A smooth coat Shiloh with soft ears — both recessives — must be homozygous for these two traits: one gene for coat and one for ears was received from each parent, and in this case, both genes are the same. A plush coat, strong eared Shiloh can also be homozygous for plush and strong ears if it received identical genes from both parents for these features. However, it may also be heterozygous if it carries smooth coat and soft ears as a hidden recessive, and these can be passed to its offspring. An animal is homozygous or heterozygous only in respect to a gene pair; the whole animal is homozygous for some features and heterozygous for others. An animal that is homozygous for a large percentage of genes will be prepotent since the variation in genes it passes to the next generation will be smaller than in the largely heterozygous animal. When dogs are bred together they can be inbred or outcrossed. Inbreeding is the mating of near relatives; outcrossing is the mating of unrelated individuals.

Prepotency

A breed is created when its characteristics are fixed by breeding to other animals with the same characteristics. In most breeds this has been done by breeding together closely-related animals. The continual breeding together of inter-related animals results in the fixing of the breed characteristics by raising the level of homozygosity in the breed population. Every purebred animal is prepotent to a certain degree: and herein lies the value of breeds. A high degree of homozygosity can result in a breed that is extremely prepotent, that is, likely to pass on its characteristics to its progeny, even when bred to an unrelated animal. Individuals, breeds and strains within breeds can be more or less prepotent than others. As a breeder, you should attempt to determine the prepotency of your breeding animals through litter evaluations and in your study of other strains and animals in your breed. Most breeds have a few individuals that stand out as especially prepotent (Kari!). Keep in mind that an animal can be prepotent for poor characteristics as well as good. Prepotency is valuable only in terms of the individual. A purebred dog of impeccable ancestry is no more valuable to a breeding program than the mutt next door. unless it is able to pass on its high merit to succeeding generations.

Inbreeding and Outcrossing

Most human societies have been prejudiced against inbreeding, and this prejudice is often carried into animal breeding. The term linebreeding was coined to bypass this bias, though the distinction between the two is nebulous. Inbreeding will increase prepotency, result in puppies that have a similar look, i.e., a true strain, and can be used to fix the characteristics of an outstanding individual for future generations. With each generation of inbreeding the strain is further purified as the recessives are weeded out. If an inbred animal is outcrossed, it's unwanted recessive will remain hidden behind the dominant genes of the unrelated animal: the recessive must be passed on by both parents before it can be made visible. This can happen when an outcross puppy is then inbred.

Each generation of inbreeding will fix the characteristics of the foundation animals, until eventually a high degree of uniformity will be produced in all puppies. Puppies that are the result of an outcross breeding will vary much more: within each litter there may be one superb puppy, a few mediocre puppies and a couple of "dreadfuls"

Inbred individuals are not always superior show animals, but they’re generally preferred for breeding because they will produce offspring that fall within a narrow range of fixed characteristics, and because some of those characteristics are known in advance and can therefore be compensated for. Since perfect individuals are seldom produced it makes sense to choose breeding stock for its faults rather than its virtues. If therefore, the line is known for huge size but tends to have bitchy narrow heads, the preferred choice is the puppy with average size but an excellent head to the puppy with huge size and a narrow head, since this one breaks away from the general trend and is therefore more valuable. The first dog has a better chance of producing offspring with both huge size and good heads than does the second. Such selection will have to be balanced by the priority given to each feature.

Many breeders believe that outcrossing gives a better chance of producing an outstanding individual than does inbreeding. This has been borne out many times in practice. Outcrossing produces a much greater range of quality in the individuals produced. The characteristics of the parents, or of the parent’s bloodlines, do not match. Outcrossing within a breed will produce the occasional individual that is far superior to either parent or to any of its ancestors due to a fortunate combination of genes and many mediocre animals. But the superior individual is not necessarily a superior-breeding animal. The outcrossed dog’s genotype is largely unknown, and he may be entirely lacking in the ability to transmit his excellent features to his offspring. Outcrossing is experimentation, similar to the beginning of breed development. You keep the best puppy from an outcross breeding and then inbreed that puppy to fix desired characteristics. This is done over and over again for generations until you achieve inbred. prepotent puppies with desired characteristics.

Group Perfection

"I’d have the perfect dog if only I could take the coat from one, the head from another, the tail from another and the body from yet another and combine them all into one dog." Although dogs don't lend themselves to this sort of piecing together, you can make use of the same idea in aiming for group perfection. Group perfection means that, although no one dog may be ideal in all aspects, the group of dogs as a whole compromise perfection in every point, according to the breed standard. If you start with and maintain your breeding program according to this rule, your dogs may one day produce for you the puppy that has it all. Conversely, if you allow your breeding program to become deficient in one or more features, it is likely that all of the puppies produced will be deficient.

Shilohs

Now you can put together the pieces and understand what Tina has done to develop the breed. Very simply, she started with Kari, and then outcrossed to Ursa, keeping only the best and culling the rest. When the desired characteristics were fixed, she outcrossed to Sabrina and then to Ria and MAW —outcross breedings followed by inbreeding, keeping and culling over and over again. This is a lengthy and dedicated process that requires experience, careful record-keeping, love of the animals, personal integrity and hard hearted honesty. What has been created is a legacy and every Shiloh breeder has the responsibility of continuing her work — in pursuit of perfection

Tina has advised me that the "optimum" puppy is approximately 50% Kari. 25% Ursa and 25% Sabrina with some of the best of Ria and MAW lines thrown in for good measure. So this is your destination -Beautifulcity. From her experience of years and hundreds of breedings, Tina says that you can never get too much Kari, but don't overdo Ursa, never cross Sabrina and Ria or get too high of a percentage of either of them in one dog. And the MAW lines are great, once.

Understanding Your Dog

Now get out your 5 generation pedigrees and start mapping your route. First, evaluate your dog. Is your dog the result of an inbreeding (do you see the same names on both dad’s and mom’s side of the pedigree?) or an outcrossing (there are no names on dad’s pedigree that match mom’s pedigree). If your dog is a product of an outcrossing. your best bet is to breed closely back into one of the best lines he or she carries -- breeding to fix desired traits.

Count the number of times Sabrina or Ria names show up on a 5-generation pedigree. If you see Sabrina’s name 3 times in 5 generations that’s OK— the same goes for Ria. If you see Sabrina’s name 5 times in 4 generations that’s too much-- the same goes for Ria. MAW lines should only appear 1 time in 5 generations. Too much Sabrina or Ria may result in the pairing of undesirable genetic recessive genes. Too much MAW may result in, well, too much MAW. What do you do if Sabrina’s name is on your pedigree 5 times in 4 generations? Don’t panic, your dog is probably beautiful just don't breed it to another dog with Sabrina or Ria.

You can use this same formula to determine your dog’s strengths and weaknesses using the dominant and recessive genetic characteristics listed on the 5 generation pedigree and compare this to your intended mate to make sure that you are not doubling up on faults, either dominant or recessive.

How much of each line-- Kari, Ursa, Sabrina, Ria -- does your dog have? There are two easy ways to figure this out:

1. Count the number of times Kari, Ursa, Sabrina, Ria or MAW names show up in your 5 generation pedigree. Now add up the total let’s say Kari’s name is on there 4 times, Ursa’s name twice, Sabrina’s twice and Ria once. This will give you a very approximate idea of your dog's makeup.

2. Figure percentages of bloodlines for each dog in the pedigree, starting with the 4th generation. When two dogs are bred together add their percentages and divide by 2 to achieve the percentage for the offspring. Do this until you reach your dog’s name.

Example:

 

 

 

Boeg

Shane (100% Kari)

Kari

Sasquach (50% Kari-25% Ursa-25% Sabrina)

Smoke (100% Ursa)

Mona (50% Ursa-50% Sabrina)

Sabrina

Shep (50% Kari-375% Ursa-12.5% Sabrina)

Smoke (100% Ursa)

 

Saber (50% Kari- 50%Ursa)

 

Kari

My Puppy (50%Kari -34.375% Ursa-12.5% Sabrina-3.125% Ria)

Boeg

Shane (100% Kari)

Kari

Sasquach (50% Kari-25% Ursa-25% Sabrina)

Smoke (100% Ursa)

Mona (50%Ursa- 50% Sabrina)

Sabrina

Trlnka (50% Kari-31.25%Ursa- 12.5%Sabnna-6.25% Ria)

Boeg

Shane (100% Kari)

Kari

Poca (50% Kari-37.5%Ursa- 12.5% Ria)

Smoke (100% Ursa)

Hope (75%Ursa-25% Ria)

Image of Ursa (50% Ursa-50% Ria)

 

Now let's say I want to breed My Puppy to His Puppy. I do a calculation on His Puppy as follows:

 

Boeg

Shane (100% Kari)

 

Kari

Cisco (50% Kari-25% Ursa —25% Sabrina)

Smoke (100% Ursa)

Mona (50% Ursa-50% Sabrina

 

Sabrina

His Puppy (37.5% Kari-25% Ursa-25% Sabrina-25% MAW)

Samson (100% MAW)

Goliath (50% Sabrina-50% MAW)

 

Sabrina

Asher (25%Kari-25%Ursa-25% Sabrina-25% MAW)

Smoke (100% Ursa)

Saber (50% Kari-50% Ursa)

 

Kari

I can then combine the percentage for My Puppy to His Puppy and divide by 2:
 
My Puppy + His Puppy Our Puppies
50% Kari 37.5% Kari = 87. 5% divide by 2 = 43.75% Kan
34.375% Ursa 25% Ursa = 59.375% divide by 2 = 29.6875% Ursa
12.5% Sabrina 25% Sabrina = 37.5% divide by 2 = 18.75% Sabrina
3.125% Ria 0% Ria = 3.125% divide by 2 = 1.5625% Ria
0% MAW 12.5% MAW = 12.5% MAW divide by 2 = 6.25% MAW

Our puppies will be fantastic!

DO NOT BE INTIMIDATED! All you need is paper, pencil, a calculator and a sense of adventure. Planning is part of the fun, plus you will educate yourself immensely about all Shilohs just by going through the process. The dogs you see will "make sense" to you in a way they never have before.

Tina's Footnotes (8/98)

As with any type of breeding, careful examination of both the individual dogs, their littermates, and pedigree must be utilized properly in order to attain the best possible results!

Linebreeding on inferior stock can lead to severe disasters, since you are "drawing" in all of the recessives that may have been hidden for up to 7 generations! Without carefully investigating the dogs (and their littermates, etc) that you have chosen to inbreed/linebreed on, you may be entering the "dark side" of inbreeding.

 

This article was published in the Shiloh Shepherd Learning Center in August 1998.
 

Genetics |Practical Genetics | Inbreeding--When is it too Much? | Coefficient of Inbreeding | Another Breeding Tool | Site Map |

 

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