The genetic evaluations for the dairy breeds are sent to Interbull and pooled with breeds from other countries that participate with Interbull. Then the data is brought back to the CDCB (Council on Dairy Cattle Breeding) where it is evaluated by breeds. Holstein, Jersey, Brown Swiss, Ayrshire, Milking Shorthorn, Guernsey have their own breed bases.
If an animal is crossbred then she is evaluated based on the breed of her sire.
With our breeds the Viking Reds (Red Dane, Finnish Ayrshire and Swedish Red), Norwegian Red, and the North American Red are all evaluated on the Ayrshire base. The Fleckvieh and Montbeliarde are sent to Interbull on the Simmental base, but when their data comes back to the US they are put on the Holstein base.
The way the data flows is thru DHIA (Dairy Herd Improvement Association). Herds that are enrolled have a person that comes to the farm once a month to collect milk weights and milk samples on each milking cow. The samples are sent to a lab and processed for butterfat and protein. The milk, fat and protein are used to calculate the cows estimated production for her current lactation. From the central lab is goes to a DRPC (Dairy Record Processing Center) of which there are 4 in the US. The data is processed for the dairy and reports are sent back to the dairy. Information from the DRPC's are then sent to the CDCB.