Compliments of the Canine Chronicle...by DR. Carmen Battaglia..interesting math formula...anyone have any thoughts with bulldogs?
there is a chart I can post later on how this is done...Susan

By Dr. Carmen Battaglia



Predicting the traits, characteristics and qualities most likely to occur in a planned breeding is not a science, nor is it a matter of statistics. It is a task for those willing to learn how to use the right tools. It begins with the sire and dam, and an analysis of their pedigrees. Unless this is done, a prediction of expected traits is nothing more than speculation. But for those willing to study pedigrees for their strengths and weaknesses (conformation, health, temperament, drive, etc.) predictions can take on a more meaningful purpose. The process always begins with the brood bitch. Since no one sire is ideal for all bitches, finding the right sire means knowing what strengths and weaknesses are carried in the pedigree of the bitch to be bred.


There are many reasons to explain why there is a wide range of success among breeders and their abilities to predict the traits that might occur in their litters. For example, those who breed for only one or two traits are more likely to be successful than those that breed to improve several characteristics. Differences can also be found between the individuals being bred. Some have pedigrees with more serious problems than others. Then there are levels of difficulty. Those who attempt to improve coat quality; pigment and expression will find their problems easier to solve than those who attempt to improve structure or life-threatening diseases. Some breeders simply have more access and knowledge about the sires that have the demonstrated abilities to produce. But perhaps the most notable differences are those that can be found between the breeds themselves. Comparisons show that the average number of defects in some breeds may be as low as seven or as high as fifty or sixty. For example, the German Shepherd Dog has at least 7 defects, the Pekingese 14, Beagles 31 and the Bulldogs 44, which is more than twice the average, but significantly less than the highest, which are Cocker Spaniels with 52, and Rhodesian Ridgebacks with 58.


But even if all of these differences could be made equal and breeders were given total control over all of the genes, the key to predicating outcomes would still depend on knowing the modes of inheritance for each trait and disease. For example, traits caused by simple recessives are easier to correct and control than those caused by polygenes. The former involves both parents; the latter involves one or both of the parents.


Heritability Estimates


Once a breeder has analyzed the pedigree of the sire and dam for their strengths and weaknesses, predicting the traits to be expected can begin. To aid in this process researchers developed a tool called the heritability estimate(s) (HE). The HE was calculated using mathematics as a means to forecast the chances that certain traits will occur in the next generation. The HE is a useful tool because it shows how closely a dog's phenotype resembles its genotype. The higher the HE for a particular trait the more closely the offspring are likely to resemble that trait. HE are typically expressed as a range in values, such as 50% - 70%. The lower percentage is used for outcrossed dogs, the higher percentage is used for line and inbred dogs. Breeders unable to determine if their dogs are line bred or the result of an outcross should use the average of the two percentages.


PREDICTING TRAITS


Every breeder expects good traits to occur in their litters. Those who use the HE to predict traits have an advantage over those who don't. This is particularly true if they take into consideration and use the following six principles. First, improvements occur faster when the desired trait has a high HE. For example, the estimate for chest width is 80 % which is higher than the HE for litter size, which are only 10 – 20%. Second, when the HE is low, it should be taken to mean that factors other than genetics will influence the occurrence of the trait. For example, the health and condition of the bitch are factors known to influence litter size, which has low heritability. Bitches that are obese or in poor condition tend to have smaller litters than those in good physical condition. Another factor known to influence litter size is the nutrition fed a bitch during the gestation period. Those fed a commercial dry food that has been mixed with supplements tend to have smaller litters that those not fed any supplements (Kelley). Third, traits are more likely to occur in the offspring when both parents exhibit the trait or have produced it. For example, traits are more likely to occur in the offspring if the parents have breadth of pedigree, meaning that the littermates of the parents exhibited or produced the desired trait(s). Sires and dams that have several littermates with the desired traits are better candidates than another pair that has no littermates with the desired traits. The fourth principle involves the sire-dam relationship. Breeding partners that are unrelated are less likely to have a concentration of similar genes that complement each other. The breeding of unrelated dogs whose littermates have not exhibited or produced the desired traits are least likely to produce the desired traits. In this regard, many breeders use dogs that have not produced the trait(s) they desire in the belief that because the sire and dam have phenotypes that complement each other, the desired traits will occur.

Fifth, no one factor is sufficient to predict litter qualities, it always involves a combination of factors. Sixth, the mode of inheritance must be considered.

Traits that are produced by simple recessives are easier to control or produce than those produced by the polygenes.


In order to minimize the number of mistakes and the amount of error that can be made when selecting sires and dams the above principles have been condensed in the format of a guideline:


1. Frequency of desired traits among the ancestors in the first 3 generations (depth of pedigree)


2. Number of littermates of the sire and dam that have the desired traits (breadth pedigree)


3. Number of carriers or affected ancestors in the first


3 generations (depth of pedigree)


4. Number of offspring produced by the sire and dam with the desired traits


5. The heritability estimate of the trait desired


6. Mode of inheritance


When taken together these six principles are useful when planning a breeding and predicting outcomes. They are most useful to those who wish to produce traits by direction rather than by chance. It is well to remember that when a pup turns out as expected or becomes a good performer, the breeder is sure to take credit. This reinforces what they believe about their pedigrees, breeding methods and their ability to produce quality pups. But when one or more pups turn out poorly, most are left wondering what went wrong. Some will place blame on the stud dog or the person who recommended the breeding. Others will switch to a different breeding method or abandon their own ideas or the guidelines listed above. In each instance it is well to remember that problems and improvements always involve some combination of genetics, training, management and nutrition. Whatever the improvement one expects, it usually will occur in small steps. Rarely will all the pups show the same change at once. Sometimes the breeder will notice that a few pups show the desired change or that some begin to show a slight improvement. This is said to be progress because the offspring show the improvements. When offspring are of such quality that they can begin to replace their parents in the breeding program, progress has occurred. Each time a breeding takes place and the litter has been evaluated, the sire and dam should also be evaluated to ensure that the best combinations of parents are being used. Breeding-up is a concept that requires a plan that builds on each breeding. It is one of the best ways to make improvements.


Finally, the prediction of desired qualities and traits is a matter that belongs to those who are committed to principles stated above because they are the known ways to produce results by direction rather than by chance.

Reference:


Battaglia, Carmelo, “Punnett Squares”, Canine Chronicle, September 2003.
Battaglia, C. L. – Breeding Better Dogs, BEI Publications, Atlanta, GA 1986.
Bell, Jerold S. "Choosing Wisely", AKC Gazette, August 2000, Vol. 117, Number 8, p-51.
Bell, Jerold, S. “The Search for Defective Genes”, AKC Gazette, January 2003, Vol. 120, No.1, P-26.
Kelley, Russ, Recent Advances in Canine and Feline Nutrition, Iams Nutrition symposium proceedings; “Canine reproduction: What should we expect?” Vol. III, 2000.Orange Frazer Press, Wilmington, OH 2000, p. 225-239.
Padgett, George, “Genetics I Introduction”, Beagle Review, Darcroft Publishing, Wilmington, VT, Vol. 1, No. 1, Winter 1991, pg. 14-16.
Seranne, Ann, The Joy of Breeding Your Own Show Dog, published by Howell House, 1980, P 51.
Willis, Malcolm, Genetics of the Dog, Howell Book House, New York, New York, 1989



If you would care to express your ideas on this subject, forward them to me in care of the editor at K9CHRON@aol.com.



ABOUT THE AUTHOR

Carmen L. Battaglia holds a Ph.D. and Masters Degree from Florida State University. As an AKC judge, researcher and writer, he has been a leader in promoting ways to breed better dogs. The author of many articles and several books, he is a popular TV and radio talk show speaker. His seminars on breeding dogs, selecting sires and choosing puppies have been well-received by breed clubs all over the country.

Dr. Battaglia is also a popular TV and radio talk show speaker. His seminars on breeding dogs, selecting sires and choosing puppies have been well received by the breed clubs throughout the dog world. Those interested in learning more about his seminars should contact him directly or visit his website for breeders at: http://www.breedingbetterdogs.com.