American Pit Bull Terrier Gazette Volume 45 Issue 1 | Page 4

A Look at Prepotent Brood Stock in ADBA History ~ Part V by Amy Greenwood-Dudar Thanks to all of our readers who sent in suggestions of prepotent brood stock to include in our retroactive study. Those dogs will be featured in this issue with perhaps a few left over for the next issue. We will add these individuals to the 30 previous dogs featured to expand our sample size. As a general rule, the bigger the sample size, the more validity in a study. As a recap for first time readers of the Gazette, what I am doing in this series of articles is looking at the breeding strategy in the pedigrees of select prepotent stud dogs and brood matrons in APBT history. I have always enjoyed looking at pedigrees and identifying the breeding strategies used by breeders in the development of their bloodline. My father, Ralph Greenwood, was a pedigree connoisseur. As a teenager, he would have me write out a seven generation pedigree by hand on every new dog that he would get into his kennel. My brother, Hank, had made up the pedigree template in drafting class in high school and Ralph made good use of these forms researching extensive backgrounds on his dogs as well as those of his friends. Because of the influence of my father and other breeders that he respected, I developed my passion for pedigrees. Identifying the breeding strategy contained within each generation is akin to solving a mystery. It is something I have the opportunity do weekly in my role doing pedigree analysis and bloodline identification with the American Dog Breeders Association. After the breeding strategy is identified on each dog featured, I can then evaluate how they measure up to the genetic basis of prepotency as proposed in the Cynologist article that I have referenced in my previous article in the August 2019 issue of the Gazette. At the conclusion, we will look at the tally of the dogs we have highlighted and the statistics up to that point in our study. First some background: The term ‘prepotent’, by definition, is having ex- 4 ceptional power, authority or influence. Applied to dog breeding, prepotency is when a stud dog stamps his likeness upon his offspring to a marked degree and passes on his traits to an especially large number of his offspring, or produce puppies that resembles each other more closely than usual. The term prepotent can also apply to a brood matron and having a dam with this quality is valuable also. The far reaching effects of a prepotent stud dog to the breed as a whole is considerable, since he can produce a larger number of offspring over his lifetime compared to that of a dam. Every dog breeder knows the importance of a great sire that “throws himself” in an individual breeding program, as well as the far reaching influence in the betterment of the breed as a whole. There are three major questions with regard to prepotency that may be of interest to breeders. • What is the genetic basis of prepotency? • How can prepotency be measured? • How can prepotent animals be produced? The book Animal Breeding Plans by Lush answers these questions. Lush states that the most important genetic basis of prepotence to a high degree depends first upon homozygosity and second upon dominance, linkage and epistasis. A homozygous animal is one which possesses the gene for a given trait from both his sire and dam and is genetically pure for that characteristic. A homozygous animal can only produce one type of germ cell (sperm or egg) and he would pass on exactly the same genes to all of his offspring. A dominant gene is described as one of a pair of alleles (alternate forms of the same gene influencing the same trait but in different ways) whose effect is expressed to the exclusion of the effect of the other alleles. Every puppy receiving the dominant gene will show the effect of the gene. If the gene is dominant and the parent is homozygous for it, the offspring will appear exactly alike for the trait expressed by the gene, regardless of the genetic material that they received from the other parent. “When a parent having many dominant genes is also highly homozygous, it prepotency is maximum”. (Lush) Linked genes are those that are located closely on the same chromosome. Two or more characteristics are transmitted together instead of randomly in the usual manner. Epistasis is believed to contribute to prepotency in some cases. “When a gene of one pair of allelic genes masks the expression of the genes of another pair of allelic genes, it is said to be epistatic to the other pair. (Snyder, The Principals of Heredity.) Epistasis is similar to dominance except the relationship is between different genes, instead of alleles on the same gene. Measuring prepotency: One way to measure prepotency is to note the resemblance of sire and puppies as compared to the resemblance ordinarily found between parents and offspring. When a prepotent sire is used, the resemblance of their traits will be greater no matter which dam is used. I am not only talking about physical resemblance but more importantly athleticism, temperament and performance. Production of prepotent animals: Even though we see prepotent sires in lines that are not inbred, the breeder’s chief aid in producing a prepotent animal is through the use of inbreeding. The reason for this is that while dominance, linkage and epistasis of genes are not within the power of the breeder to control, he can control the homozygosity of his stock. The more closely related the more rapid will be the increase in homozygosity. Mating like to like without inbreeding does little to increase prepotency. “The broad scientific definition is that inbreeding is the mating of animals