Mate selection may be aimed at compensating specific shortcomings. For example, a mare may have superb gaits, but her legs are not of superior quality. The stallion of choice would need to have perfect legs, preferably with evidence that his offspring also have good legs. His legs would be considered more important that a strong trot, as the mare should bring that into the offspring. Another mare may have perfect legs but could have a somewhat stronger gallop, then the stallion should have an excellent gallop but is allowed to have somewhat lesser leg quality. At least, that is the idea. Specific mate choice for each female so that the offspring is of the best possible quality. A practical advice for breeding organisations would be to first select the parents as that defines the genetic improvement, and then define a compensation mating scheme as potential advisory serviceA crucial moment in the real world of animal breeding is the mating of dams and sires to produce the next generation of animals. Before mating, the owner of the breeding females has evaluated his animals and selected the females with a view to his breeding goal. And, he has selected a few males which comply to his breeding goal and are expected to improve the average genetic and phenotypic level of his animals. Then, still the question exists: which female to mate with which male?
In practice, breeders often use(d) compensatory matings. The shortcomings in certain traits of a selected female are compensated by the choice of a selected male that is outstanding for these traits. The offspring is expected not to have the shortcomings of the female.
However, even though this sounds very logical, there is no guarantee for success! It is clear that with compensatory mating breeders will have different breeding goals that they base their mate choice on. Aspects of lesser quality in one female may be the stronger point in another female. Obviously, the additive effects of all mate decisions in a population is not likely to point in a certain direction. In other words, mating decisions will result in extra genetic gain. Also at individual level all matings will result in a success! At individual level, there are a number of factors that may influence the expected result of mate choice:
Mendelian sampling. The fact that a sire and a dam transmit 50 percent of their alleles to their offspring and you cannot predict which 50 percent. This introduces a chance factor, even if you know the EBV for father and mother very accurately.
Pleiotropic (one gene affects multiple traits) and epistatic effects (gene-gene interactions). It is possible that a trait, for example
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leg quality
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, is affected by a gene that interacts with another gene. If one of those genes has the wrong allele in the offspring then the
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legs won’t be improved.
What is the accuracy of the information that the selection decision is based on? For example,
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is genetics or management responsible for the performance? You should especially ask yourself such questions in the absence of an accurate EBV.
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Thus: compensatory mating involves finding the best mate for male for individual females to compensate her shortcomings.
Compensatory mating may have an effect on individual mating results, but has not effect at population levelselection determines the increase in herd and in population level .
An example of a mating system for dairy, dual purpose breeds of cattle and dairy goats aAa®with compensatory elementswas created in 1950 by U.S. Holstein breeder and classifier Bill Weeks and is outlined in chapter 10.2.1. In 10.2.2 CRV’s SAP mating system for dairy cows outlined that is developed to compensate in planned matings the weak characteristics of a cow with strong characteristics of a bull.