Establishing a Bloodline: Selection of brood stock and breeding styles
By Amy Greenwood Burford
Establishing a Bloodline
(part two) Selection of brood stock and breeding styles.
In the last issue of the Gazette, I covered some of the important issues that need to be considered when one makes the commitment to become a breeder of quality APBTs. This second article, I hope will give novice breeders more information on the next steps to take in moving the breeding program forward in establishing your 'bloodline'.
Once a breeder has developed a breeding plan, an evaluation of the brood stock that you are going to be using is the next step. First and foremost, the individual stud dog or brood bitch must possess the outstanding traits that the breeder is looking for in the offspring. The mating of animals with similar characteristics tends to produce offspring that resemble themselves. This is known as like-to-like, type-to-type or positive assortive mating. It is obvious that breeders should avoid mating animals with the same faults, as this type of mating will also tend to produce offspring with those faults set within the family of dogs.
An analysis of the dog's pedigree is the second but equally important step that must be considered in the selection of brood stock. For novices, a dog's pedigree is usually meaningless. For the experienced fancier, the pedigree is a profile of genetic potential, containing an unlimited amount of information. Knowledge about the individual dogs in the pedigree can be obtained firsthand from the dog's breeder. Pictures and information on the dogs can frequently be obtained from the numerous breed magazines and breeders websites. Conformation and weight pulling titles on the individual dogs can also be used in compiling your data base of information on the dog's pedigree. After a number of years into a persons breeding program, the breeder will have first hand knowledge of the dogs making up the pedigree of the breeding stock. Also a data base of information concerning the littermates as well as offspring from repeat breedings should be available to the breeder. This first hand information will always be the most reliable if the breeder remains objective in his evaluation of his pups.
Pedigree analysis will also reveal the style of breeding that produced the stud dog or brood bitch. Why would this be important? Certain styles of breeding, namely inbreeding and linebreeding tend to fix and preserve desirable traits by increasing homozygosity of the genes. This means that the gene pairs are the same. Since the gene pairs are the same, the genes for their quality will be passed to the dog's offspring 100% of the time. Outcross breeding increases heterozygosity of the genes. This is where the gene pairs are not the same. Dogs that are the product of an outcross breeding will pass the genes for their quality traits to their offspring only 50% of the time because most of the time their genetic makeup is heterozygous. The value of a stud dog or brood bitch lies in the dog's ability to consistently and predictably pass specific traits to their offspring. This is spoken of as being prepotent. This is what we are looking for in our brood stock. The ideal brood bitch or stud dog would be a dog that has the traits that the breeder was looking to produce and would be the product of an inbreeding or linebreeding.
STYLES OF BREEDING:
Inbreeding: Inbreeding is usually defined as the mating of closely related individuals. Some references include half brother to half sister mating as well as brother to sister, father to daughter, mother to son, grandsire to granddaughter and granddam to grandson breedings as examples of inbreeding. Other references define 'closely related' as brother to sister or closer. Another way I like to think of inbreeding is mating the individual dog to a dog that is IN the dog's pedigree. Regardless of how you define it, the goal of inbreeding is to fix and preserve the traits that the breeder is looking for by increasing homozygosity in the dog's genetic pool. You can calculate the inbreeding coefficient, or the probability of the genes being homozygous by looking at the number of times that a certain dog is present in the dog's pedigree. In every generation, each parent transmits only one half of his or her genes, and each subsequent generation again reduces the genes from an individual in half: in other words, 50 percent in the first generation, 25 percent in the second generation and 12.5 percent in the third. When the same ancestor appears in the pedigree of both the sire and dam, it increases the probability that the same genes will be present in the offspring and that they will be homozygous.
From breed to breed and bloodline to bloodline the popularity of inbreeding can vary. The more sound the bloodline (void of structural faults and health problems) the more successful inbreeding will be. This is because, inbreeding leads to random fixation of traits, increases homozygosity of the genes and for some genes, can cause inbreeding depression. Some genes causing detrimental health effects are only expressed in the homozygous state. They remain hidden (recessive) until as a consequence of inbreeding the genes are made homozygous. You then see the trait expressed in the offspring. One example of this is the gene causing juvenile cataracts in the Boston Terrier. When mating two dogs that are heterozygous or carriers for the gene together the probability is 25% of the bad genes becoming homozygous and causing blindness in the affected offspring. In the heterozygous or carrier state, the dogs are unaffected and will have good vision. A breeder could be totally unaware of a dog being a carrier for this gene unless a thorough pedigree analysis was done for this trait, or when the dog produces an affected pup.
Within a breed, it is not uncommon to see a breeder use half brother to half sister breedings with great success for about four generations, and then run into a brick wall where they find that a bad trait that was occasionally seen is now being expressed 100% of the time in the offspring. This is because of the fixing of the trait within the family because of the resulting homozygosity of the genes.
Knowledgeable dog breeders can use inbreeding as an effective tool to achieve specific goals and to enhance desired traits, if they are carefully alert for developing problems. Many novice breeders feel that inbreeding is the only way to develop their own strain or bloodline. In the wrong hands inbreeding can be dangerous. If the novice starts with a fair or poor quality dog then begins to inbreed to one of the close relatives they are likely to run into trouble. If one plans to use inbreeding in their breeding program, the breeder must have high quality, sound brood stock and a knowledge of what was behind them.
Before deciding to use inbreeding in your breeding plan there are some questions that a breeder might consider: How inbred is the brood bitch or stud dog itself? Are there any recessive hereditary disorders known in your stud dog or brood bitch's bloodline? What breed faults might you be concentrating or passing on to the resulting offspring? What are the positive effects that you are hoping to achieve by inbreeding?
Careful inbreeding is often of great value to a breeder. It is most successful when the highest quality dogs are used as brood stock, the breeder has a thorough knowledge of the dog's pedigree and intends to fix within the bloodline specific desirable traits.
Linebreeding: This term is often used to denote breeding among related individuals or dogs from the same family or bloodline. Examples would be mating between first or second cousins, uncle to niece, aunt to nephew, and in some references half brother to half sister is also listed as an example of linebreeding. Linebreeding is the breeding style that is a compromise between inbreeding and outcross breeding. Breeders use line breeding to preserve the traits of a family of dogs while at the same time retaining the variability in the gene pool. Variability is good as it counteracts the potential detrimental effects of doubling up on bad genes that is sometimes seen as a consequence of inbreeding. Line breeding is a slower and less direct way to fix desirable traits in a bloodline, but does offer more options and fewer risks than inbreeding. Diligent selection of quality brood stock from bloodlines known for their soundness and breed type is also very important when a breeder is choosing to do linebreeding.
Outcross breeding: The definition of outcross breeding is the mating of purebred dogs within the same breed that are relatively unrelated. The style of breeding increases heterozygosity and creates new genetic combinations by bringing together genes from totally unrelated individuals. There are two primary reasons that a knowledgeable breeder will choose to make an outcross breeding. The first is to introduce into their family of dogs a trait that is absent or lacking, and secondly to dilute undesirable traits that are caused by homozygous recessive genes. Outcross breeding is essential when a breeding program begins to show signs of inbreeding depression such as loss of vigor, disease resistance and infertility. Many times breeders will have two basic inbred or linebred families of dogs or bloodlines within their kennel and will do outcross breeding between these two lines. The result will be dogs that are 'better' than the two original lines. Breeders speak of this as a 'nick'. Geneticists speak of this as 'hybrid vigor'. No matter what you want to call it, this type of breeding will many times produce animals that are better than each of the original lines. Many times these dogs produced from outcross breeding have gone on to become athletic top performance animals. We have seen many famous 'nicks' within our breed, none more notable than the Tudor/ Colby breeding of Howard Heinzl and the Boudreaux/ Carver breeding of the Honeybunch line. Both of these bloodlines have produced many outstanding individuals as well as becoming the foundation of many other quality bloodlines today.
Many times using these talented performance dogs that are the product of outcross breeding as brood stock will result in a disappointment for the breeder, as the dogs will tend to produce the norm of their respective bloodlines. Many an old time breeder has been heard to say, "don't breed to the top performance dog of the day, breed to his parents". On the downside, many breeders frown on the use of outcross breeding as it does introduce unknown and sometimes undesirable traits into the bloodline. Also with an outcross mating of dogs that are already the product of outcross breeding, there is little predictability and uniformity in the traits that one will see in the offspring. Within a litter of pups, you can see good pups, poor quality pups and everything in between. Uniformity and predictability in the quality of the pups produced is the goal and the hallmark of a good breeder.
One of the most effective ways I have seen an outcross breeding used by breeders is to select to breed to an unrelated dog with a sound pedigree that possesses an outstanding quality that is absent or lacking in the breeders bloodline. From the resulting offspring an individual is selected for the trait that the breeder is looking to introduce into his line. That dog is then bred back into the original bloodline (linebred or inbred) fixing the new desirable trait into the original bloodline. One breeder explained the breeding strategy of bringing a quarter outcross into his line to be used as a 'catalyst' for the line. A 'catalyst' in the sense of bringing together all the goodness and quality of his bloodline with an added kick of hybrid vigor.
Grading Up: Breeding the females on hand to a male of better quality is known as grading up. The best females in each generation are then kept and again bred to a top sire from an outstanding bloodline. This is one of the tried and true ways to improve the quality of a cattle herd and other livestock. This is also true of many dog breeders. Many breeders have started with a very average bitch from a good bloodline and have invested their money wisely in breeding to an outstanding champion stud. As their experience increases they have refined their selection process, retaining the best in each generation. Careful selection of the top studs have in many cases produced a foundation of brood stock that have gone on to develop into a quality bloodline. There have also been many examples of breeders going astray and developing bloodlines that have consistently produced average or inferior dogs because of loss of focus into the selection of quality brood stock or chasing after the latest fad in breeding style or individual dogs.
Selection of breeding stock, the pedigree analysis and the styles of breeding are all tools that a breeder can use to develop his bloodline of dogs. High standards, diligent pedigree research and honest evaluation of the dogs the breeder is producing are also essential to guide the breeder to a successful program. What might work for one breeder may or may not work for another. This is why breeding dogs is considered as much as an 'art' as it is a 'science'. In the next issue of the Gazette, I will present a look into some breeding programs of some top breeders as examples to demonstrate the principals that have been outlined in my first two articles.
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