Estimated Breeding Values
What are breeding values?
A breeding value is an estimation of the genetic predisposition of a dog for a certain trait.
A trait is usually determined by genes and environmental factors. The hereditary predisposition of an animal for a certain trait, not taking into account the environmental effects, is estimated by way of mathematical models and modern computer programmes.
In other words: estimated breeding values try to estimate what is encrypted in the dog’s manual as well as possible. Everything in that manual is hereditary.
The effects of environmental factors are not hereditary. A combination of what is written in father’s and mother’s manuals will determine what the descendants will be like.
Estimating Breeding Values can be calculated for all traits/qualities of a dog (wanted and unwanted) which are more or less hereditary. Hence, it is possible to calculate estimating breeding values both for afflictions and behaviour as well as breed traits, provided those are hereditary. For years, estimating breeding values have been calculated for production traits such as milk production in cows, number of piglets per sow, number of puppies per dog.
For each trait, it is possible to express the estimating breeding values in a number per dog. A breeding value reflects the genetic predisposition of the animal and not what you can see on the animal for that certain trait! It may be that you believe that the breeding value is incorrect, since you cannot see what is hidden in the dog (= its manual).
|Name of the dog||Dysplasia||Coat||Temperament|
BONNO has a breeding value of 87 for hip dysplasia, 102 for coat and 98 for temperament in the above example. That means that he will produce more puppies which suffer hip dysplasia than Max and Figo. His descendants have the nicest coat, but are a bit sharper in temperament.
How do we calculate breeding values?
We do not mean to explain the complicated mathematical formulas, but intend to explain the schedule on how breeding values are calculated in practice.
It is very important to collect as many data as possible of the dogs (pedigrees, exams, judging’s…) in one central database. Breed clubs, studbooks, breeders, but also dog owners and veterinarians play a crucial part in that respect. Those data are put into a specifically designed computer programme in a standardized manner, paying special attention to the fact that individual data remain INVISIBLE to the outside world.
That step in the process is of the utmost importance, since the estimating breeding values are based on those data. If the central database lacks or does not have enough individual information on achievements, diseases and origins, it is not possible to calculate correct breeding values.
The collected data are processed afterwards (often in research centres such as universities) and estimating breeding values are calculated. After the necessary analyses and study of the data, the breeding values are estimated.
It is important to know that the animal model is central in the entire system. Whenever the computer calculates the estimating breeding values for a dog, that will be done based on all results of the dog itself, its ancestors, brothers and sisters, offspring etc. In addition, all those results will be compared to those of the entire population. That is why it is most useful to also store data from dogs of the past in that database.
Hence, the computer will be able to make a correct estimation of how the dog will pass certain traits to its puppies. The environmental factors are almost entirely eliminated thanks to that system.
In the end, the calculated estimating breeding values can be consulted by breeders.
How are we to interpret those breeding values?
Estimating breeding values are always calculated for the entire population. So also for the dogs, of which there are no results known. 100 is always the average of the population for each trait for which estimating breeding values are calculated.
Dogs which have a number higher than 100 will have a better genetic predisposition for some traits. Hence, their puppies will be better than the average. 100 is the ideal value for other traits, in which case higher or lower numbers are less wanted. The ideal value is always mentioned in the legend.
How to use breeding values in practice?
That is the most important thing for breeders. Even if you do not really understand what breeding values stand for, you must simply rely on the professional geneticists since they really know what they are doing and accept that they offer you a tool that you can use as a breeder to improve the exterior and working capacities of your dogs. It is also a practical tool that will avoid a great deal of unnecessary pain and problems.
Let’s discuss the following example to improve the tracking capacity of gundogs and working dogs by way of estimating breeding values. Properly tracking and looking for game are highly influenced by correctly learning and a lot of practice. However, one dog is more apt/talented (= better genes) than the other. That is what we aim to map, since we would like to have more puppies of that talented dog which, in turn, are also apt at tracking properly.
|Males||Breeding values – tracking capacity|
Breeding values can also be used to control the less pleasant traits in dogs. A second example deals with two hereditary afflictions: hip dysplasia and destructiveness. The breeding values of all dogs are reflected in the tables below.
Which dogs can be mated?
It is important to know that a puppy is automatically attributed a breeding value from the moment it is born. That value is the average of the breeding value of both parents (50% from the father, 50% from the mother).
The goal of breeding is to improve every new generation. In other words, we try to lift the breeding value of the puppies above that of the current breed average.
This table shows the breeding value of the combination of all four males with a certain female (Fleur).
|MALE + FEMALE||BREEDING VALUES|
|BONNO + FLEUR||(104+100):2 = 102||(102+102):2 =102|
|RICKY + FLEUR||(112+100):2 =106||(88+102):2 =95|
|TOM + FLEUR||(106+100):2 =103||(98+102):2 =100|
|BAS + FLEUR||(90+100):2 =95||(90+102):2 =96|
Only the combinations of Bonno and Fleur and Tom and Fleur meet our demand of surpassing the breed average for every trait. Only those two combinations fill the demands for both traits, the other two combinations only result in improvement for one or neither of both traits.
In short, using breeding values is very simple. When you would like to have your female mated, a little bit of calculation suffices to find the best combination. Breeding values can be freely consulted on the internet for several animal species.
Breeding values change as time progresses. Even when there are no new exams done of a certain dog, its breeding values can still change in time, since we know that the breeding value of a dog is influenced by measuring the dog’s relatives. If something changes there, it affects the breeding value of the dog itself. Even calculating the entire population can influence the dog’s breeding value.
That is why breeding values are calculated a few times a year in practice. In some cases every 3 months, in others 2 times a year.
If a certain dog’s breeding value deteriorates in time, it means that the accomplishments and the health of the breed population improve!
The danger of individual breeding values
In theory, breeding by way of breeding values is an excellent system to improve the breed traits and repress hereditary diseases within a population. We only need to make sure that the genetic diversity of a population is not reduced by abusing those breeding values.
There is a danger that breeders will only use the males with the best breeding values. That will only result in the same problems as with the culture of champion described earlier on in this brochure.
Furthermore, we risk that stud owners will refuse a mating with females which have worse breeding values, for – ungrounded – fear that the puppies from that combination might negatively influence the estimating breeding values of the stud in the long term.
A breeding value is an estimation of the genetic predisposition of a dog for a complex trait.
Dogs with a higher breeding value have a better genetic predisposition, which means that their puppies will be better than the average.
Using individual breeding values can lead to exaggerated and uncontrolled use of the same studs.