Breeding progress

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Under breeding progress is defined as the difference between the average performance of a genetic population over the previous generation.

In breeding , breeding progress is achieved in that individuals (animals, plants, etc.) are crossed with one another that have a particular expression of certain, desirable properties. These properties are based on the breeding objectives (e.g. milk yield in cows , egg yield in chickens or the efficiency of N utilization in grasses ). Breeding goals can contradict each other (for example lean meat content and stress resistance in pigs) if the corresponding genes are coupled unfavorably.

Breeding progress is achieved in that only that part of a population is further bred whose expression shows a minimum deviation from the mean of the population (= selection intensity ): the more sharply selected, the greater the difference between the mean expression of the characteristic of the F1 generation compared to the parent generation , but the fewer individuals are available for further breeding and therefore the generation interval is also lengthened - the breeding progress results from these two parameters.
For breeding, it is therefore imperative that the expression of the desired trait has the highest possible variance in order to be able to select enough individuals for further breeding (i.e. if they all looked the same, no breeding progress would be possible).
On the other hand, repeated crossings of such animals with the desired properties (theoretically) lead to increasing inbreeding depression , which is expressed, among other things, by a reduction in the genetic pool of the population, which ultimately reduces the variance. It can therefore be necessary to violate the breeding goals by using individuals who are actually not suitable for breeding due to the characteristic expression in order to increase the variance of the characteristic expression.

Characteristics that are particularly suitable for breeding are those that have high heritability , that is, heredity. Heterosis is usually used to express traits with low heredity .

See also: Breeding ,