Simplified equations for evaluations of bulls in the Interbull international evaluation system

The Interbull Centre is responsible for the production of international bull evaluations. From the mixed model equations used by the Interbull Centre for the Multi-trait Across Country Evaluations (MACE), simple equations explaining the contribution of various sources of information to the Interbull proof of a bull under various situations are derived. When a bull has little or no information in an importing country, the parent average in the importing country and Mendelian sampling effect in the foreign country are the major sources of information contributing to the proof of the bull in the importing country. It is shown that the contribution of the parent average in the importing country could be very substantial and explains much of the variance of the proof. It is demonstrated that as more information accumulates in terms of increases in the number of daughters ( greater than or equal to 300), the influence of the de-regressed national proof dominates the Interbull proof of the bull. The various general equations presented are useful in understanding the contribution of several sources of information to the MACE proof of a bull. (C) 1999 Elsevier Science B.V. All rights reserved.