breeding methods

Line breeding :
A breeders tool used to develop, isolate and set specific desirable traits into succeeding generations. Line breeding can be seen in registered dogs by having specific high caliber or quality ancestors two or more times in the recent pedigree as noted in the table above. Line breeding often has more than one high quality ancestor multiple times in the same pedigree. However, from a purely scientific point of view, linebreeding can also be defined as breeding two individuals containing at least one common ancestor. This common ancestor may contribute a negligible amount to the descendants, or a great amount. This makes the scientific meaning lacking in true art and practice. You can do a line-breeding that has absolutely nothing to do with refining or setting specific traits or you can practice the art and craft of breeding better animals and make rational choices in your program.

Ultimately, linebreeding is simple concept that is extremely complicated as a breeding tool. One must remember that linebreeding is a program that produces animals from a single line of descent from a common or a few common and outstanding ancestors. The goal is not to reproduce the quality of the ancestors but to try maintain as many of their good qualities as possible while improving their deficiencies by refining the genetics of the line. If you know a breeder that is producing the perfect animals then why the hell do you need to breed? Just buy all your dogs from this breeder. If a breeder is producing superior dogs and you breed off their lines will you produce better dogs than that breeder? If not then do the breed a favor and do not breed.

Inbreeding :
Willis (1989) defines INBREEDING as the mating of animals "more closely related to one another than the average relationship within the breed." From the introductory table we can see that these involve brother/sister or parent/child breeding.

With all the negative connotations associated with inbreeding why discuss it as a viable breeders tool?

It is true inbreeding can create horrific genetic mistakes or it can be the best and fastest way to improve and standardize a line (set traits). IN the first sense it is a useful genetic tool to reveal hidden recessive genetic problems in your line by doubling up on them and making them express themselves (as it were LOL). Note this is a tool used to reveal hidden defects and these defectives should be culled from the breeding pool. In the second sense when your line is heterotrophic for beneficial traits you can do inbreeding to make them homozygous (set the trait). Note it must be a tremendously important trait or preferably numerous traits you are trying to set within your line to consider inbreeding as the best method to set the trait. So here inbreedings are done to verify the superiority of a particular strain or to check for recessive problems. Any weaknesses, faults, deformities, etc. are likely to show up. If a truly superior line or strain has been developed, containing only desirable qualities, these desirable qualities will be seen in the resulting offspring.

Outcross:
Outcrossing brings together two APBTs that are less related than the average for the breed. By convention both the sire and dam during an outcross should have some linebreeding in their background because no matter how you slice it, breeding a scatterbred dog to a linebred dog produces a scatterbred dog (see our case study below). Many breeders feel this is outcrossing but in reality you now have only half your lines genes and no rational idea what the other half may be. Thus we usually consider outcrossing to involve two linebred or inbred animals from different bloodlines.

A reason to outbreed would be to bring in new traits that your breeding stock does not possess or to decrease the inbreeding coefficient or typically both. When you are looking for high quality traits, also termed aptitudes, that are not present in acceptable members of your germline, then the most obvious way to bring in missing aptitudes is to outcross to a line prepotent for these. Thus, if you are experiencing inbreeding depression you can seek dogs outside your lines with aptitudes that compliment your lines weaknesses. Example one would choose a mate that does not possess the same faults while phenotypically complements and hopefully maintains your dog's good traits. By convention both individuals should be linebred but share no common ancestors in 5 generation pedigree. This promotes more heterozygosity, and gene diversity within each dog by matching pairs of unrelated genes from different ancestors. Note that the key type genes that define our breed will always stay paired. Unfortunately, outbreeding can also mask the expression of recessive genes, and allow their propagation in the carrier state.

Overview of Breeding Methods

Ok ...Now we have a VERY brief overview of breeding methods and what each is lets talk about GENES. The very thing those methods revolve around.
Think of all the characteristics of your dog as individual paired packets of information. The black nose, the red nose, the temperament, strong working drive, dog aggression, good angulations, strong front, laziness, weak underjaw, tendency to be fat, tremendous muscle tone, big head, too long tail, straight topline, short back, powerful reach and drive and essentially all other characteristics that make up or are missing from a specific “breed type” or “line type”. All these traits are determined by paired packets of information. In a simplistic form the sire of a dog provides one packet and the dam provides the second packet to create this pair.
Now lets look at some terms so we can go forward and understand genentics in its basics.

To help with the understanding I like the following symbolisms to put together a mental image. Take “your” perfect image of “your” perfect APBT. Think of this perfect dog as the perfect BOOK (DOG = BOOK). This BOOK is a masterpiece of binding leather bound and hand stitched, the best edition of the book you have ever seen (Top 10 #1 dog of all time) and has all of your favorite fonts and pagination (type). The book is written in a particular language that is universal (genome), these books are divided into chapters (chromosomes), these chapters are made up of paragraphs (operons). The paragraphs are made up of sentences (genes), these sentences are formed by words (codons), and these words are created by single letters (Deoxyribonucleic acid or DNA). Thus, we see that DNA is the most fundamental unit of heredity.

NOW that we have language we can communicate in lets get some ground rules in how Genes work.
Genes occur in pairs in the dog. The dog has 39 chromosome pairs (total of 78 chromosomes). This is what is meant by diploid (diploid = double). There is another term of importance which is haploid (haploid = half) that describes the genome of the egg and sperm.

DNA is an amazing molecule (even to a geneticist) and its primary and most magical characteristic is that it has over billions of years developed the ability to replicate. In other words it is able to make exact copies of itself. This ability to make functional copies is the basis for heredity. It is not the parent’s genes which are passed on to the puppies but copies of the parental genes. Another thing I’d like to throw in here is that: It is not copies of all the parental genes it is only half of the parental genes that are passed to any given puppy .

The first stage of inheritance is the production of either the sperm or the egg. Do not view the sperm and the egg as perfect little genetic representations of each parent. Do not consider that when these two "sex" cells combine (one from rover and one from foxy) and that there is a blending to create "roxy". Combining a dog that lacks "x" with a dog with too much "x" will NOT likely produce a dog with perfect "x". Again this concept cannot be stressed too much or too often at the beginning of our learning: There is no melting together or blending of genetic traits. Most likely from such a cross you would get half the litter that has poor "x" and half the litter that has too much "x". This prediction is also simplistic but it serves to distinguish between blending and particulate inheritance. Particulate inheritance means that genetic information is transmitted from one generation to the next in discrete unchanging (not accounting for evolutionary and mutation events ;-) ) units ("genes"). .
The dogs themselves are diploid but both the egg and sperm are haploid meaning that they (unlike the actual dogs) only contain one of the two alleles encoded by the dog. This is what is known as segregation. Segregation is the next concept of importance. Segregation as a concept, is vital to understanding what goes on when you are doing outcrosses, family and line-breeding. We will delve more into segregation and random selection later. However, what we mean by segregation is that when the pregnant dog produces eggs, her chromosome pairs are segregated equally into haploid states in the eggs. Meaning The members of the gene pairs segregate (separate) equally into the gametes. The same is true for the male. His diploid genome is segregated equally into individual sperm which are haploid. A good example to use and one we will return to eventually is sex determinant. Thus the Gametic content states that each gamete (sperm or egg) carries only one member of each pair.

bloodline

A line is a family that is inter-connected by breeding close relatives who all have ancestors in common within the first three generations of each parent's pedigree. A line reproduces family traits such as soundness, health, size, body structure, temperament, eye color, coat type, color patterns, and pigment, or any lack thereof. Inbreeding, or line breeding magnifies what is already in the gene pool. It is natural for herd animals like deer, and horses to inbreed in the wild, as it is for pack animals such as dogs, wolves and coyotes. Feral dogs the world over tend to have the same physical characteristics. It is only when humans become involved in breeding dogs for specific purposes that their physical characteristics take on those of the various breeds. It is only by inbreeding that breeds are developed.

It is impossible to line breed scatter-bred dogs, but they can be inbred, i.e. breeding littermates is inbreeding, but, as there is no family line behind the sibling parents their offspring are not line-bred. An out-cross is breeding unrelated dogs of the same breed. Continuous out-crossing is called scatter-breeding. Scatter-breeding dogs may produce an outstanding individual, but it's next to impossible for it to reproduce those same fine qualities in its offspring.

Back-crossing is breeding back to a great-grandsire, or great uncle, or great grand-dam, or great aunt. The younger dog, or bitch carries this dog, or bitch, or it's sibling in his/her pedigree. It's a great way to bring older traits forward again, and refresh the gene pool without going outside the line.

The offspring draw 50% of their genes from their sire, and 50% from their dam. The reason that dogs within a litter look different is because no two have inherited the same genes, in the same combination, unless they are born from the same sac, and are monozygotic, or identical twins. The tighter the gene pool the narrower the differences among littermates. Breeders must take genotype, and phenotype into consideration when planning breedings.

Genotype is the genetic composition of the animal, in other words the combination of alleles it possesses. There are two alleles, one from each parent, which occupy the same position on homologous chromosomes. Homologous chromosomes have the same pattern of genes along the chromosome, but the nature of the genes may differ. In diploid nuclei, pairs of homologous chromosomes can be identified at meiosis (cell division). In animals all the cells except the reproductive cells are diploid. Two sets of chromosomes are present, one set from the female parent, and one set from the male parent. Reproductive cells formed as a result of meiosis are haploid. Fusion of two such cells restores the normal diploid number (XX or XY). One allele is often dominant to the other allele which is called the recessive. The dominant allele determines which aspect of a particular characteristic that the dog will display. The aspect of the recessive allele only appears when two such alleles are present, as in the double recessive condition. As an example, in AST's blue coat color was the result of a recessive allele. Breeding blue, to blue caused a double recessive that has become as a dominant allele in aspect. In many programs blue has become the dominant color. This same principle holds true for red nose, or liver, a variant dilute.

Phenotype is the observable characteristics of the dog, or what you see. It is determined by the genes, and by the dominance relationship of the alleles. Phenotype can also be determined by the dog's environment, and nurture. For instance if a dog's ears are cropped, or its dew-claws removed, nurture is the reason for the difference in it's appearance. If a dog is starved, it won't have the same appearance as a dog that has been nurtured. Phenotype is a combination of genotype, environment, and nurture, all playing a role in the dog's appearance.

Breeding sound, healthy dogs that are closely related increases the odds for reproducing very similar genotype, and phenotype. The key words here being sound, and healthy. It also unmasks masked genetic traits. Dogs, like humans, have two kinds of sex chromosomes, the X chromosome, which is similar in size to the other chromosomes, and the Y chromosome which is smaller. Two X chromosomes makes a female, and one X, and one Y make a male. Sex chromosomes not only carry genes that govern the development of sex organs, and sexual characteristics, they also carry other genes which are unrelated to sex. They are called sex linked genes. They govern coat color, eye color, and pigment, or lack of pigment.

The reason that stud dogs get blamed more often that the bitch for defective puppies is that females have two X chromosomes. If one carries an abnormal allele it is likely that its effects will be masked by a normal allele on the other X chromosome. Males, only having one X chromosome, their abnormal alleles will not be masked. A female with an allele for a defective condition that is masked by a normal dominant allele may not suffer from the condition, but as a carrier pass on the defective allele to the offspring.

Scatter-breeding masks defects, but they will eventually surface with devastating effects upon the breed. Line breeding tests the strength of a breeding program. A gene pool is only as strong as its weakest gene.

Breeding the dog or the pedigree:

All dogs carry defective genes. These defective genes are usually "recessive"-that is, their expression can be covered up by the presence of a normal gene for that function. It is estimated that the average dog carries 4 to 7 defective genes in it's DNA. (The human estimate is 10 to 12). Since genes are always carried in pairs, most of these abnormal genes are carried in a only single dose, so that their presence is completely concealed by the other, normal gene. What is a gene? A useful analogy is that a gene is like a set of instructions given to a particular workman doing a small job on a very big construction site. Each workman gets two sets of plans. If one set is damaged, he still has one good set, and the job can proceed. But if both sets are damaged, the job will not be finished, or it will be done wrong. A gene is a large molecule, a long double strand of DNA, composed of a backbone of two long sugar molecules linked by pairs of smaller molecules called "bases" or "nucleotides". It is the sequence of these nucleotides that encodes the information contained in the gene.

How does a gene become defective? During normal cell division, an exact copy is made of each and every gene in the cell, and then it divides into two daughter cells which are each an exact copy of the original cell. Defective genes are caused by a "mutation". If something happens to disrupt the exact replication of the DNA during cell division, a defective gene results. Only a few changes in the base sequence can render the information in that gene useless. The process of aging is undoubtedly the effect of accumulated random defects of this sort, as are most types of cancer.

In the formation of egg and sperm, a special type of division takes place. Instead replicating the genetic material, so that both the daughter cells have a full complement of genes (two genes of each type), the genetic material is divided, so that each reproductive cell has only one gene of each type. When sperm and egg finally meet, the full complement of genes is restored, and a new individual, carrying half of its mother's genes and half of its father's genes is created.

Selective breeding. Nearly all breeding of domestic animals is selective as opposed to random. Years ago, before the era of scientific genetics, breeding was done more by phenotype than by pedigree. Race horses tended to be bred by the stopwatch. That was where the money was. Dairy cattle were bred by the volume and quality of their milk, meat animals, by the speed of maturation and ratio of feed to meat, and so on. Later, it was recognized that breeding together closely related animals tended to speed up the process of "fixing" the desired traits within a few generations.

Breeding by pedigree is the type of selective breeding most often practiced today. It nearly always involves some degree of inbreeding. The logic is simple. We know that an animal's traits are genetically controlled. We can even calculate the percentage of a particular animal's genes residing in the cells of one of its descendants. When we mate closely related animals whose family shows (has the phenotype of) the desired trait, we are reasonably sure it will appear in the offspring. Some breeders have carried this practice to remarkable extremes, failing to realize there is a "catch" to the pedigree method. What about those defective genes? The ones you can't see because they are covered up" by intact ones. When we breed closely related animals, (let us say because they have super rears), we can see the desired trait. This trait is genetically controlled, like all traits. These two closely related animals share the genes for their super rears as a result of their close genetic relationship. What we can't see is the PRA gene or the kidney disease gene that these two animals also share as a result of their close genetic relationship. When we double up on the good rears we are also doubling up on the particular hidden defects they share. We can see the results of this type of concentration of mutations in some human populations which have been relatively inbred by reason of isolation due to status, geography, or religion. Some examples that come to mind are Tay-Sachs disease in eastern European Jews, and hemophilia in some royal families. Phenotype breeding has been largely neglected in recent years. It has fallen into undeserved disrepute as the more popular inbreeding has produced faster and more dramatic changes. I say undeservedly, because it has much to recommend it, and voids some of the serious pitfalls of inbreeding.

Again, we look at the phenotype of two relatively unrelated animals. They both have good rears, which we want. Why do they share this trait? For the same reason that he two related ones did: they both have the set of genes which produce good rears. But what about hidden, bad genes? Since these animals could not have been selected for unseen characteristics, (after all, if you can't see it you can't consciously select for it), they probably do not share many of these defective genes. To be sure, they still carry their load of defects in their own private collections, but they most likely each carry a different set. This being the case, it is very unlikely that any one offspring will inherit two copies of the same defective gene. It is very likely, however, that they will all have good rears.

Phenotype breeding is still selective breeding. We are selecting those animals which show the desired traits, while minimizing the probability of doubling up on hidden, undesired ones. Inbreeding and linebreeding, on the other hand, select for both the phenotypic and genotypic traits, and dramatically increases the probability of producing animals homozygous for defects.

The lesson in all of this is that we should pay less attention to pedigrees, particularly in terms of looking for similarities on paper when we breed, and more attention to the dogs themselves. All too many breeders make their breeding decisions on paper, and not in the flesh. We need to consider the pedigrees as they relate to the qualities of the parent animal - did his mom and dad have good rears - rather than to insist he be related to our prospective brood b#tch. We can get the results we want by breeding unrelated "like to like", without the tragic by products of inbreeding.

dam good piece of information

yeah

I bet you got in trouble for plagerism alot in school huh.

dunlapfan wrote:

I bet you got in trouble for plagerism alot in school huh.

You are awful new to this board to be coming on here and being a smart a$$. Again you need to make an Introduction

Its not being an ass Im just sayin that if we copy and paste things its only proper to let people know who wrote it. Im sure Midwest didnt expect people to believe that he wrote it himself, he seems like a cool guy.

I am going to interject here......After reading several post I didn't say anything but I see a pattern. Mike (Midwest Showdogs) is one of the good guys and he knows his stuff. This is not an English class, and although a source might be nice for someone in the future who is writing a paper, I do not feel it is neccassary. Maybe I am wrong...maybe I have been on here too long to notice, but I do not think Mike was in any way trying to say any of the post were his own writings. Although he is been into the dogs long enough he probably could have wrote it
Opinions and debates are always welcome. If anyone disagrees with another member please state it. Some members are here to learn and are more than curious to know others opinions on different subjects. As well as try to educate new members on different subjects...such as how to pick a new puppy...different bloodlines and vaccinations schedules. If one does not agree with a post...please state your opinion and why or why not you don't agree. There are people less knowledgable who would like to know.
And for those that are new or maybe ones that have forgot...we do have a private message system set up. If you have a personal dispute with someone you can keep that private. We also have moderators so if you have a problem with someone or something on this forum you can bring it to our attention. And last but not least, we have a report a post feature. At the very bottem of every screen there is a place where you can report a post that you may find offensive or completely misinformed.

Sorry to hijack the thread....back to the normal broadcast now

well i guess teaching someone somthing is a bad thing !! and yeah i didnt write it and no i didnt think it was a problem that i didnt give the names to the site i took it from now i posted this to help with ppl that comes here to learn something not to glorify myself. and yeah i probley could of wrote this its very simply stuff and if you dont know this then i guess you probley need to actually learn something. now if anyboby has a problem with me not putting were i got this information (which is pretty elementary) common sense. i got it from a site called steal hearts kennels and yes if im guilty of cheating i guess i am but i almost bet everyone thats on a forum has copy and paste something off another site.

Mike I totally agree. I didn't see what was the big deal either.