Weighting factors for the international genetic evaluation
The following is a procedure to compute new weighting factors for the international genetic evaluation of Interbull, and has to be implemented separately by each individual organisation participating in Interbull evaluations. The procedure is based on information used in the national genetic evaluation in each country, and how a country considers such information depends on the genetic evaluation model.
The procedure consists of two steps. In the first step, for each animal with own performance records used in the national genetic evaluation, the reliability due to its own performance, R(o), is estimated using selection index methodology. R(o) is computed separately per trait (milk, fat or protein yield) and information from the other traits in a multiple trait national genetic evaluation is ignored. The second step combines the R(o) from the daughter and her dam, expressed in effective daughter contributions (EDC), which are subsequently accumulated over all daughters of a sire.
Step 1: Estimation of reliability based on own performance (R(o)):
For each animal with own performance records in the national genetic evaluation, Ri(o) is estimated. Estimation of Ri(o) depends on the genetic evaluation model.
a) Single trait (repeatability) model for the national genetic evaluation (where individual lactations are considered as the same trait):
b) Multiple trait model for the genetic evaluation (where each lactation, part of lactation or test day observation are treated as different traits):
Let k’EBV be the estimated breeding value or transmitting ability of the bull for the trait of interest (milk, fat or protein yield), i.e. the one submitted in the 010 file to Interbull, where EBV is a vector with multiple trait (lactation, part-lactation, test day) estimates of breeding value or transmitting ability, and k a vector with weights given to each estimate.
