Saturday, September 7, 2013

Breeding Bulldogs


(Disclaimer: I am not a professional dog breeder of "aces"  and caused havoc in the dog world since the days of Jimmy Boots and Benny Bob, but I have bred and raised what I consider to be superior specimens that can be called true "bulldogs" by anyone  like any.)

Much has been written about breeding strategies and techniques that have been used successfully to produce ace dogs. Inbreeding, linebreeding, outcrossing, and crossbreeding are breeding strategies that all have their place in the overall breeding program. These methods, when used appropriately, offer the breeder the best chance to maintain bloodlines and to produce consistently competitive gamedogs. The breeder should keep in mind that the foundation of any breeding method is to breed physically and mentally sound studs and bitches that come from winning families.

Before I discuss breeding methods, a quick discussion of basic genetics is needed. Genetics is a very complex subject. The inheritance and expression of DNA is subject to several known and unknown mechanisms of action, of which college textbooks cover in great detail. Complex genetic interactions, the inheritance of sex-linked traits, and traits influenced by multiple genes are certainly relevant to  breeding bulldogs  but are beyond the scope of this article.

Genes are made up of pieces of DNA, which carries the information about a particular trait. The genotype is the sum of all genes present on the chromosomes. The phenotype is the appearance of the traits, a visual expression of the genotype. Genes almost always occur in pairs. This means that each stud or female has two copies of any given gene for a specific trait, one derived from the father and one from the mother. A dog that has two different genes for a specific trait is said to be heterozygous for that trait. A dog that has the same two genes for a given trait is homozygous for that trait.

Some genes and their corresponding traits are dominant or incompletely dominant and others are recessive. A dog that is heterozygous for a particular trait (has one dominant gene and one recessive gene) will generally look the same as, or similar to (incomplete dominance), to one that is homozygous dominant (has two of the same dominant genes) for that trait. Recessive genes are hidden when paired with a dominant gene. When recessive genes are in a homozygous state (both are identical), they are expressed in the phenotype. An example of this is the nose color. The gene for Black nose is dominant to the gene for black nose, meaning a black nosed dog  could have one gene for black nose (B)and one gene for red nose (r), or two genes for black nose (Bb). If two heterozygous black nosed dogs were bred together (Br x Br), the offspring would be approximately 75% black nosed [Bb or Br] and 25 % red nosed [rr] because there is a same probability that the parents will pass the black or red nose gene to the offspring. In this case, the ratio of genes in the offspring would be 1 BB: 2 Br : 1 rr. Another way to say this is that 75% of the pups would carry the dominant gene for black nose and 25% would receive a recessive red nose gene from each parent. In this case where the recessive red nose gene is in a homozygous state, it is expressed in the phenotype as red nose.

Inbreeding is the breeding of two individuals who are related to each other. Typically all dogs from the same family are related to some degree, thus inbreeding is practiced whenever we maintain a “pure” line. Linebreeding is a form of inbreeding where particularly superior individuals are used in several generations, which tends to emphasize the genetic influence of the individual in the family. Inbreeding increases the probability that the two copies of any given gene for a particular trait will be identical, or homozygous for that gene. If the stud and bitch are related, there is a chance that the two genes in the offspring are both identical copies contributed by the common ancestor. Close inbreeding uncovers hidden, often undesirable homozygous recessive genes that are carried by both parent fowl. Inbreeding depression is a term used to describe the reduction in performance caused by the expression of these recessive genes in inbred individuals. Some breeders will use this as a tool to test a new bloodline by fighting young dogs from a brother/sister mating, since this intensive form of inbreeding will quickly bring undesirable qualities to the surface such as lack of gameness.

Since mating related and phenotypically-identical individuals also tends to increase the number of homozygous dominant genes in the progeny, bulldogs become more uniform in those traits emphasized in the breeding program. Although true with any breeding system, additional care must be taken with intensive inbreeding (breeding closely related, inbred individuals). Only the very best physical specimens should be retained for maintaining the bloodline and crossing with other bloodlines. Producing these exceptional individuals require whelping and raising a lot of dogs and proper selection to increase the probability of the right genetic combination occurring in the offspring.

Increasing homozygous genes in a family through inbreeding increases the probability of producing “prepotent” individuals. Prepotency is the ability of an individual to pass their desirable dominant genes to their offspring. For this reason, prepotent individuals are extremely valuable in linebreeding systems to improve and maintain bloodlines. Although inbreeding will increase the probability of producing prepotency, in my own experience an ace crossbred bitch was prepotent. Nearly all of his pups were virtually identical to the dam, including fighting style, body shape and station, nose color, and fur color. They even sounded the same as they all had his distinctive bark.

Outcrossing is the mating of individuals within the same bloodline but having no close ancestral relationships. For example, a same-sire pair of brothers were bred into a same-sire dam, and out of them came out several pups. When the pups matured, they were fought and the best multiple time winners were selected for breeding purposes. The original dams were bred to their best sons, and the original studs were used once in the third generation in each family. For the next 8 generations, the two lines were kept separate, and the original dam and her exceptional son were bred several times in the following generations to increase their genetic contribution to each family. After 16 or so generations, the lines were bred together, resulting in an outcross. The offspring from this mating were tested and the best individuals were bred back to the separate lines. This method of breeding, along with careful selection and progeny testing, can be used to maintain pure families without introducing outside blood. Using line-bred, prepotent individuals is highly desirable when outcrossing. Think of it as crossing  Eli Jr. strains to remotely related Bullyson strains. (Example: McCool dogs to later Boudreaux dogs)

Crossbreeding occurs when two unrelated dogs are mated. Crossbred individuals have many more heterozygous dominant genes present in their genotype. In a heterozygous genotype, dominant genes mask the influence of undesirable or desirable recessive genes. Many of the most successful battlecrosses are produced from crossing two or more unrelated, inbred families of dogs. In fact, the primary reason for maintaining inbred families of dogs is to produce individuals that can be used in crossbreeding systems. This is because crossing two unrelated, inbred bloodlines often results in hybrid vigor in the offspring. Hybrid vigor, or ‘heterosis,’ is the term used when a crossbred individual outperforms the parent. Crossbreeding is widely used in commercialanimal production and has proven successful. Hybrid animals and plants tend to grow faster, be more productive and more resistant to stress and disease. Once again, it must be emphasized that the greatest degree of heterosis is seen when inbred, prepotent individuals are used as the parents.

So how does one select the bloodlines to cross? Some breeders advocate crossing dogs that complement each other, such as breeding a heavy mouth stud over game bitches, in hopes of producing the ultimate combination of desirable qualities. Others advocate breeding dogs that are similar in type and action, contending that the resulting offspring are more likely to be consistent and predictable.

In my opinion, both schools of thought are likely correct because both have proven to be successful. For example, the popular cross of various Jeep and Red Boy families clearly indicate the theory of complementary families is valid. Highly competitive crosses made up of similar families like the Bullyson and Alligator dogs prove that crossing families that have similar attributes is also effective. The success and failure of any cross is dependent upon the compatibility of the genes and the only way of knowing if the dog will be a "hit” is to breed them together and test their progeny.

While some might think that breeding outcrossed and cross-bred dogs as foundations of a yard is unsound, some two-way or 50-50 crosses nick with a third or even a fourth bloodline. Example, some of the best dogs I have ever raised were out of a JD  x Scud-Señorita stud and a JD x Linear-Señorita bitch.  Since all four of the original parent dogs are from inbred families, this 4-way cross was very consistent in appearance and style. This is something you may want to try if you have four inbred families.

All modern breeders acknowledge that the dogs used to develop today’s bloodlines were crosses. However, the successful bloodlines the great breeders in the past developed from these crosses were refined over many years through selection of superior individuals, inbreeding, testing and extensive culling.

Yours In Sport