Bella is a dominant and Eli's liver coloring is a recessive gene. Her dominant gene will always over power his recessive gene. If ever he replicates his own coloring it will be because he has been bred to someone else carrying the recessive gene, and even then, it will probably be from his offspring and not from himself.
Bella and Eli have been bred together twice and neither time, out of thirteen puppies, they have never produced a liver puppy, nor a puppy who appears to have a single resemblence to Eli.
Their offspring, however, carry a recessive gene of his. If their offspring were to be bred to another recessive gene, they would have about a 25% chance of reproducing another liver.
Inbreeding is an important part of the selection process when attempting to produce quality offspring.This method has merit, in that it concentrates both the good traits and the faulty traits in the progeny. It should be noted that inbreding does not produce degeneration - it only concentrates weaknesses already present so they can be identified in the offspring and eliminated. It also should be noted that inbreeding in animals and livestock is not genetically the same thing as in humans and should not suffer the same stigma as such.
For those interested in the inbreeding alternative, the closest partners possible are full brother to full sister, although less intensive inbreeding would be father to daughter, half-brother to half-sister, and son to mother. The close breeding of related animals is at the very root of many breeds, and the success of any breeder depends not only on his choice or combinations of breeding alternatives but also on his ability to;
1) select sires and dams which are as nearly faultless as possible;
2) to cull out those progeny of less than average appearance; and
3) to rigidly select from the remaining progeny.
Sterility- either the dam or the sire fails to produce live ova or sperm.
Impotence- disinterest or inability on the part of the male to copulate.
Permanant Sterility is neutering. Temporary sterility can be caused by changes in the dogs environment, food, or general care; in the case of the stud, his overuse can cause it. The most sensible approach or the first corrective step reccomended to deal with this condition is to provide the dog with a correct and complete diet which includes raw beef, milk and regular excersise. It has also been shown that dogs taken from the litter too early are not dog-oriented and sometimes will refuse to breed.
In 1866 Gregor Mendel of Brunn, Moravia (Czechoslovakia) published the laws that later revolutionized the science of genetics. His experiments (1853-1864) and the great mass of evidence now available point to the conclusion that all of the physical characteristics of an organism are transmissible from generation to generation. It is interesting to note that his experiments, although published in a scientific magazine, went unnoticed for thirty-five years until they were discovered in 1900 by Dr. Hugo DeVris of Holland. Mendel's research on garden peas and subsequently his laws of heredity were dependant upon single pairs of genes. Mendel died not knowing he had discovered a method for determining the phenotype of organisms. Based upon his work, we now know that dominant and recessive genes can be expressed in the appearance of the organism, or they can be present but not expressed in the appearance, or a combination of both.
Mendel was dealing with only two sets of genes; the breeder of the dogs has a more difficult problem. How easy it would be if there were only one set of genes determining whether the appearance of the head of a dog was good or bad, and another set for correct shoulders, another for coat, and so on. This is not the case, however; dog breeders are dealing with the thousands of sets of genes that determine the appearance and what can be transmitted to the progeny.
The biggest and single most important problem for most breeders in understanding the rules of good breeding has to do with the terminology, or the jargon, of the sciencce. Terms such as chromosomes, genes, zygotes, heterosis, genotype, meiosis, mitosos, etc., sound and are complicated. Genetics can become complicated but for our purposes this discussion will be straightforward and not so technical that it cannot be understood by most breeders of dogs.
In order to do this there are a few matters that must be cleared up; namely, the traits or characteristics of any breed are not transmitted through the blood, and the parents of a dog did not give up one half of their characteristics to their puppies.
In order to make our subject simple, lets begin with the basics. Each dog possesses 39 pairs of chromosomes - a total of 39 in each of its reproductive cells. Some other animals have fewer chromosomes, and some have more. Fruit flies have 8, while humans have 46.
One way to think of chromosomes is to visualize them as being filing cabinets in which genes are kept. The genes contain the material of whiich specific traits are built. The chromosomes then carry the factors which determine the offsprings' trait or characteristics. In order to understand the magnitude of the reproductive system, one must realize that the male dog has 78 chromosomes, and the female has 78, and in each chromosome, or filing cabinet, if you will, are the genes. Within each chromosome there are about 100,000 genes (or 78 x 100,000 = number of genes). In reality, the chromosomes of the parents separate, and one-half of the genes from the chromosomes of the sire unite with one-half of the genese from the chromosomes of the dam, and that mixture of genes makes the new individual.
This does not mean that the sire has given up or lost one half of himself to be united with one half of the dam, but it does mean that both of them have contributed one half of their genes to proudce each puppy in their litter. Further, since each parent contributed one half, either one of both of the parents could have some undesirable genes to the puppies. In more dramatic terms, lets remember that male dogs produce about 600 million sperm at one service of a female and only one sperm is needed for each puppy.
One must remember that the sire and the dam received their genes from their parents. Hence, it is possible that genes that a sire received from his father could be passed on to a puppy. When this happens, the puppy could be more closely related to his grandsire than to his sire. This is important to remember when studying pedigrees because of the obvious implications for line or inbreeding.
Another way to understand the subject of genetics is to think of genes simply as the material that carries the directions or instructions for developing an animal. All living things, both plant and animal, have one thing in common- a unique set of genetic directions. Each set of directions is simply some combination of instructions from each parent. The blueprints are the chromosomes, and each chromosome can be considered to be similar to a drawer in a master filing cabinet. Within each drawer of this very large filing cabinet are the single sheets of instructions, each of which controls a single process. These sheets of instructions are the genes. Since each chromosome represents a long strand of instructions, all the genetic information needed to make a dog is contained in 78 chromosomes. It is not the number of chromosomes that is important but rather the length of the chromosomes and the complexity of these instructions.
Each puppy is the product of the genetic information provided by the puppys father and mother. Unfortunately, the breeding of two animals is more than the blending of genetic instructions. In the final analysis each puppy results from a double set of genetic instructions, one set from the sire and the other from the dam. In other words, there are two large master filing cabinets, one for the sire, containing the legacy of information accumulated from his ancestors, and the other containing the legacy of information from the dam's ancestors. Since there are two sets of instructions, one from the sire and the other from the dam, to form each puppy the question is: which set of instructions will be followed when the egg and sperm unite? When one set of instructions supercedes the other, we call these genes dominant. If the instructions are blended together the result is known as incomplete dominance.
The genetic result of mating two animals, then, is a massive shuffling of instructions. Therefore, the breeder who hopes to produce in one puppy all the genetic instructions which produced a grandfather or a grandmother is working against great odds. Unfortunately, one gene does not completely control each trait, and the presence of a dominant gene on one of the matched chromosomes would cause the trait to appear. However, if the infomation were absent from chromosomes of both parents, the trait would fail to appear in the progeny. The genes which do not carry any instructions for a trait are considered subordinate to dominant genes.
As a matter of conveinence, the study of genetics uses a shorthand system for ease of understanding. This is done by using a letter to represent each characteristic. Capital letters refer to a dominant trait, while lower case letters represent a recessive trait. An example may help. If we let E represent the appearance of dew claws and let e represent the absence of dew claws, and animal can genetically be EE or Ee or ee. If EE occured, the animal would have dew claws. If Ee occured the animal would have dew claws in that case also, because the dominant gene E supercedes the recessive e. If ee occured, however, the dog would be born without dew claws. When breeders mate dogs who are not pure dominants for all traits, different things occur. Note that a mating of a dog whose gentetic makeup is Ee to a dog Ee (Ee X Ee) produces the following puppies:
Male Sperm E e
This simple diagram illustrates that a sire and a dam who both show a trait can produce offspring who neither show nor genetically posess the trait. Therefore, the appearance of a trait in either parent is no guarantee that it will be passed along to the progeny.
One of the many stages involved in the reproductive process begins when the bitch is bred. Although not a point for discussion here, suffice it to say that a bitch will encourage the sexual attention of the male during her menstrual heat. After the animals have been bred the males deposited sperm will live for a few days in the uterus and fallopian tubes of the bitch to await the ripened ova. When a sperm reaches and makes contact with the ovum, it attaches itself to the ovum and then appears to be sucked into the egg. Once the sperm has made its penetration, an immediate chemical reaction begins. This reaction prevents the sperm that entered from leaving, and it also prevents other sperm from penetrating the same egg. Within the head of the sperm is the nucleus of the new puppy. Within each of the females eggs is also a nucleus containing her hereditary contributions to the new puppy. The fusion of the two nuclei, each containing 39 chromosomes, which is half the number required (78) for a dog, is what prduces the new pup.
The cell mass immdeiately after fusion of sperm and egg, is no longer an amorphous looking object; instead, it has begun to grow and take the shape of a puppy.
When Mendel conducted his experiments with flowers, he found that when he crossed red flowers with white flowers, the first generation of flowers produced were all read in color. Byt when he crossed these all red first generation flowers with each other, he produced both red and whtie flowers. In some dog breeds the same kind of results occur. For example, black is dominant and red is recessive in Cocker Spaniels, but in German Shepherds sable is dominant to black. Therefore, one should study the breed of their interest for known dominant and recessive characteristics. A specific example may be helpful. If we bred a red Cocker to a red Cocker all the offspring would be red. However, since black is dominant in Cockers, pure dominant blacks bred with pure dominant blacks would produce only all black Cockers. Sometimes, however one can cross a black Cocker with a black Cocker and get puppies which are black, red or parti colored. The explanation for this occurrence is that the blacks are not pure dominant for black. They showed the black trait because they posessed the gene for the dominant black color, but they also posessed - and therefore were able to pass along to their offspring - the trait for the recessive red. These are called hybrids (or heterozygotes).
It can readily be seen that knowing which traits are dominant or recessive helps the breeder to sorth them out in his breeding program. That way the dominant and recesive genes act and interact affects the color, shape, size, temperament, bone, muscle, top line, feet, etc; of dogs.
In order to build a soubnd breeding program one must begin with the inside of the dog through the sorting of his genes. The genes that a dog gets from his parents are known as the genotype and the outside or the traits we can see is known as the phenotype.
The breeder who is serious about producing good dogs knows that carefull selection and time are two ingredients for which there are no substitutes. Ultimate success or failure depends upon the ability to select the right dogs for parents and the ability to recognize which puppies should be kept for breeding. It is unlikely that any breeder will be 100% successful, but stacking the deck in your favor obviously increases your chances of winning. Through the knowlege and correct use of Mendels laws the deck can be stacked in favor of success and in this way breeders can produce more of the quality type dogs desired in a breed.
Inbreeding, line breeding and outcrossing are terms frequently used by those who talk about or, in fact, breed dogs. The most popular or general concern of those who breed dogs is the relationship of the parents to each other and the consequent fear of producing degenerate puppies from closely related animals. In order to clarify this matter, it is well to keep in mind that breeding is not so much the mating of two dogs as it is the combining of sets of genes.
Once can easily recognize in discussions about breedings that there is a conspicuous absense of clear definitions for the terms inbreeding, line breeding and outcrossing. The fact that there is a lack of universal definitions and that at best there are only loosely agreed upon terms hinders further understanding. For example, the exact degree of relationship between two dogs will vary when compared with two other dogs. Cousins when compared to full brothers or sisters may be (although they usually are not) more closely related genetically than would otherwise be suspected. This occurence is possible because of the genetic probability that family traits will occur within each generation and will be passed along to other family members. Since the frequency of this occurence varies, a full sister can be genetically more closely related to one brother than to another. Hence, the breeding of two cousins could be inbreeding, while the breeding of a brother to his full sister would be only a line breeding in terms of genetic relationship.
Outcrossing, as it is commonly understood, means the mating of unrelated dogs. In practice, outcrossing rarely occurs in the technical sense of the term. Proof of this statement can easily be found by simply examining a six generation pedigree for two dogs. The similarity of ancestry - particularly in the fourth, fifth, and sixth generations - generally will be of no suprise to most breeders. Generally, line breeding is the mating of dogs whos relationship as shown by their pedigrees is comparatively remote, while inbreeding is the mating of closely related dogs.
Because of the loose usage of these terms, one breeder will consider certain matings as inbreedings and others will consider the same matings as line breedings. The rule of thumb most often used is that inbreeding involves the mating of brother to sister, parent to offspring, uncle to niece and aunt to nephew. Line breeding, then would generally be considered the mating of animals that are related, but not with the same degree of closeness as in inbreeding; examples would include mating an animal to its cousin or grandparent.
It is perhaps of some value to note that the true relationship between two dogs is determined by the similarity of their chromosomes and genes, and not by the similarity of labels such as brother, cousin, or uncle.
The earlier breeders who mated closely related dogs observed that inbreeding worked. However, they also noticed that great progress was acheived along with the occurence of poor results. Because inbreeding tends to double up on things, that is to concentrate both faults and good points, breeders in the past have become frightened of using the technique.
In order to realize the benefits of inbreeding while avoiding its sometimes bad effects, the early breeders of animals devoloped the concept of line breeding. This technique produces results more slowly than does inbreeding, and time is a factor worth considering in a breeding program. Inbreeding, on the other hand, quickly brings to the surface physiological faults that are expressedin the phenotypes of the puppies. The undesirable traits, once surfaced, can be eliminated from the breeding stock.
The third alternative is outcrossing, which generally has beenknownto produce animals with great vogor and stamina. The explanation for this occurence is found in what is known as heteroisis or theburying of the recessive traits for one generation. These recessive factors, it must be remembered, are only arrested, not eliminated and are likely to recur in later generations. An excellent example of heterosis is provided by the mating of two unrelated dogs from unrelated breeds. The progeny are called mongrels, and they will demonstrated great strength and vigor in the first generation. The average size of these mongrels generallly will be greater than that of their parents. The breeding of these first generation mongrels to each other or to purbred animals will produce animals of many sizes who will demonstrate varying amounts of stamina. In other owrds, the gains acheived through heterosis generally are lost after one generation, and what was buried reappears. In short, the gtains reahed in the first breeding are lost in the second breeding adn therefore have limited value.
By now it should be clear that inbreeding obviously involves some risk and requires an understanding of pedigrees and the traits of various lines. Its use quickly allows the breeder to identify and sort the desirable and undesirable factors and to produce progeny of consistent quality. When the puppies from a litter become a puzzle to explain or when the quality in a litter varies from high to low, one should take time to seriously question the breeding plan and the information used in selecting the dam and the sire. A quick review is always warranted whether inbreeding, line breeding, or outcrossing is involved.
It now appears a certainty that the manifestation of characteristics in the phenotype is caused by the influence of more than one set of genes. In addition there are modifiers which are separate genes that superimpose themselves on other genes. These modifiers may intensify theeffect of a given trait (light vs. dark color), or they may alter it altogether.
The term dominant as applied here to a parental animal is used to mean that the dog or bitch produces a trait at the exclusion of others. Further, it means the trait does not skip a generation, will appear and be carried by a large number of progenym and will amke the breeding of some characteristics more certain. Concersely, the term recessive means that the dog or bitch carries the gene for one or more traits which can remain buried. The trait tends to skop one or more generations and may be carried by one or bothe parents but it is expressed in the offspring only when both mates carry it.
The intelligent breeding of dogs requires a recognition of the complexity of the behavior of the genes. Sometimes breeders obtain good results through persistent efforts of trial and error. The knowlege of Mendel's laws is the single best guide for the breeder of dogs. These laws govern heredity, and the breeder who either ignores them or violates them does so at the risk of breeding inferior animals.
In the years past breeders thought of heredity in terms such as "Like father like son" or "Like begets Like". Thinking that if they bred two similar dogs with traits they preferred, that they would then produce a litter of puppies with those very traits. And when that didn't happen they were befuddled. They did not know about hybrids or dominants.
A combination of unlike genes can also occur. Recessive traits can remain hidden since only the dominant gene in the hybrid parent is expressed. For example, a pair of recessive genes is required if the recessive characteristic is to be expressed in the offspring. (If you want to produce a liver puppy, then both parents must carry the liver gene.)
When the parents are hybrid, they show the dominant trait, but each parent could contribute one recessive gene to their offspring. If this occured the recessive trait would be expressed in the phenotype of the puppies. This explains why recessive traits can remain dormant for many generations before their reappearance. The longer a recessive trait is buried, the less likelihood of its appearance. For example, we know that a recessive trait cannot appear in the phenotype of an organism of which even one parent is a pure dominant for the set of genes, the likelihood that the dominant trait will appear is three to one, while there is a 25-75 chance that the recessive trait will appear.
Inbreeding, linebreeding and outcrossing are the best ways to identify and eliminate the genes which are recessive.
And so, it is the process of selecting the parents and later their offspring that provides the means that the breeder can gradually select out of his stock the undesirables until he has dogs that are pure dominants (prepotents) for the deisred traits. In this manner, recessive genes can be completely eliminated.
The greatest value of Mendel's work is that it enables us to evaluate animals not for what they appear to be (their phenotype), but for what they will produce (their genotype). It is this knowledge that explains why of two litter brothers, both of equal appearance, one can be a prepotent force for breeding better stock, and the other cannot produce stock cannot produce stock of even average quality. As an aid to the breeder a technique has been devoloped which will assist in the identification of important information on which decisions can be made. The rationale for this approach focuses on the notion that the desirable animals are usuallly the ones that produce the desiarable progeny. This is generally true because the genotype expresses itself for the most part in the phenotype. The serious breeder can predict what he expects of the progeny by analysis and close examination of the pedigrees of the dam and the sire.
Mendel found that dominants crossed to recessives produces all dominants; i.e.;
Tall x dwarf = all Tall offspring.
It has been demonstrated many times over that some great show dogs have produced only average offspring while their little known little brother or sister produced many better than average progeny. The explanation is explained by the fact that the individual dog is only the custodian of his own genes. It is the genes that produce the traits we see; the genotypes determine the exterior appearance or phenotype. It is the genes carried by each litter brother and sister that account for the difference in ability to produce quality offspring.
Selection of Sires and Dams
Most Experts agree on three important considerations in the selection of a brood bitch or stud dog. For the brood bitch they are:
1) The individual - how nearly does she approach the breed standard?
2) The pedigree - what is genetically available in the ancestry?
3) The progeny- after a few litters a check can be made. Are they consistent?
Consistency, as Mendel would explain it, means that when an animal produces indifferent stock, expected traits do not occur, and that animal should not be used for breeding. Remember, it is much easier to find a stud for a brood bitch than the reverse, the reason being that the stud dog can be evaluated more easily because of his large number of offspring.
The selection criteria for the stud dog are exactly the same as for the brood bitch:
1)The individual; 2) the pedigree; 3) the progeny. If the three factors mentioned are used, chances are that the sire and dam selected will be in some way related to one another. This then forces one to face the question of line breeding or inbreeding, which simply means that you are doubling up on what you had to start with. Experiments by Helen King of the Wistar Institute showed that brother to sister matings of rats for 70 generations produced no ill effects. Similar matings for 200 generations were made by Dr. L. Butler of the Ramsay Wright Zoological Laboratories in Toronto.
The purpose, of course, in selecting a related sire and dam is to combine and increase the number of similar genes. This can be done by using half-brothers, uncles, aunts, grandsires, first cousins, etc. The breeders task is to sort and re-sport the genes through the culling of progeny. Howegver, it should be stressed that while many puppies prove to be faulty and unsuitable for breeding as per the breed standard, these dogs, if healthy, must be eliminated from the breeding program but can be neutuered and still enjoyed as pets. The breeder must be carefull to evaluate each litter critically and select only the finest representative dogs that carry the desireable genetic makeup for inclusion in the breeding program. Only superior dogs should be allowed to reproduce themselves because only through such matings will puppies that enhance the breeds quality be produced.
Criteria for a Brood Bitch
When selecting the brood bitch, one should especially avoid those who have straight fronts, poorly angulated rear quarters, long or soft backs, coarse or common heads or bad feet. These faults of the skeletal structure are very difficult to eliminate and therefore should be avoided in the bitch.
In addition to considering her phenotype, one must take into account the quality of progeny she has already produced. If the bitch is young and has no progeny to evalutate it becomes of even greater importance that she be free of skeletal faults. On the other hand, if she has one or more litters it is important to consider the over all quality or mediocrity of the progeny. If her offspring are inferior, the studs quality should be considered. If the sire is known for his ability to stamp his merits onto his progeny the bitch should be rejected as a candidate for brood bitch.
The third factor to consider is the pedigree of the bitch. As indicated earlier, FULL SISTERS AND FULL BROTHERS MAY BE GENETICALLY UNRELATED. Although this occurrence is rare, the differences between the show wins and breeidng potential of litter brothers and sisters are well known. Therefore one shouldnot always assume similar show and breeding qualities of closely related relatives. Close examination of any pedigree will undboutedly reveal the names of dogs whos traits would not want to reproduce in the offspring. The wise breeder can reduce this risk by making a comparison of the pedigrees with the individual dog.
When examining pedigrees, the more important names to be considered are those of the dams. This is because there are many dogs sired by great studs, but only a few born of an outstanding dam. If the bitch is a recognized producer it dosnt matter whether she is a good show specimen - not to say the sire of the dam is unimportant - it is just that its generally expected that sires will be of superior breeding quality. The names of animals of the dams pedigree and the frequency with which they occur provide clues relative to the line and inbreeding that produced her. names of many dogs represent certain genetic traits which provide the breeder with information about the kinds of studs with which she can be mated.
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