In the modern breeding work, most breeding value estimates are calculated by means of the BLUP-method. The Animal Model is an example of a BLUP model.
BLUP is an abbreviation of Best Linear Unbiased Prediction. ‘Best’ is a reference to the method which gives the best estimates for the breeding value, or to put it more precisely, this minimizes the variance of difference between the estimates and the true breeding values.
‘Linear’ means that there is a linear relation between parameters in the statistical model.
‘Unbiased’ means that the breeding value estimates are central, that they are expected to be normally distributed with the true breeding value as mean value.
‘Prediction’ normally refers to the future. But prediction also refers to the estimation of realized values of a random variable drawn from a population with known variance- and co-variance-structure.
A simpler and less precise formulation: ‘prediction’ is estimation of a given value of a random variable. It is better to use the expression ‘prediction of breeding values’, but ‘breeding value estimates’ are commonly used.
With BLUP the breeding values are calculated for all animals simultaneously, and at the same time environmental effects can be corrected for.
The theory behind BLUP is comparatively complex, and the BLUP method demands a lot of calculations.
All the earlier simple methods for breeding value estimation have the properties of the BLUP method, but especially when dealing with animals with scarce information, it is a great advantage that all information can be utilized by using BLUP.
