Breeding Value Estimation

In order to select the best animals for breeding, genetic evaluation is performed every day by using BLUP (Best Linear Unbiased Prediction). BLUP is a statistical method that effectively corrects the environmental effects and estimates the animal’s value in breeding. This is called breeding value and is given for each animal and each trait. The breeding value is not only based on the individual animal’s results but also by its relative’s results. When new information about the animal or its relatives is registered the breeding value is changed. The more information the animal has, the safer (reflect reality better) is the breeding value.

The breeding values for the included traits are multiplied with an economic weight that reflects its importance in pig production. This is summed in a Total Merit Index in Swedish crowns that reflects the pigs’ genetic value and is used for ranking of breeding boars and sows.

By constantly selecting the best animals for breeding a genetic progress is obtained, and the next generation is will be better than the parents’ generation. How high the genetic gain will be depends on:
- Accuracy of prediction of animals breeding value (depends on the heritability and the extent of available information about the animals)
- Selection intensity (the number of animals used in breeding, few selected animals for breeding gives high
genetic gain but the risk of inbreeding increases)
- Additive genetic standard deviation of the trait (greater genetic variation leads to faster progress)
- Generation interval, how rapidly better younger animals can replace their parents (shorter interval gives faster progress)

The formula for genetic progress: