SIRE EVALUATION STANDARDS AND BREEDING STRATEGIES FOR LIMITING DYSTOCIA AND STILLBIRTH - REPORT OF AN EEC-EAAP WORKING GROUP

In most European countries, calving problems exert a significant influence on the economics of cattle breeding. In order to reduce the incidence of dystocia and stillbirth, a variety of breeding schemes are in use. Sampling techniques and definitions differ between countries and organizations as do methods of calculation, publishing and utilization of results. An E.E.C. working group was therefore set up with the task of establishing standards which should lead to a greater uniformity in this field of breeding work. The most important recommendations of the group can be summarized as follows. To characterize calving problems the two traits, dystocia and stillbirth, should both be used. Definitions for the criteria are given. In order to minimize the expense of testing programs, already existing information from milk recording or A.I. should be utilized. Additional information necessary for progeny testing is described. For sire evaluation it is recommended that heifer results be used when possible, as the heritability of cow results is extremely low and also because the genetic correlations with heifer results are so moderate. As sires of the calves (direct effect) as well as sires of dams (whole maternal and half of the direct effect), bulls exert an appreciable effect on the incidence of dystocia and stillbirth. Consequently, breeding values should be estimated for both types of effect. The accuracy of progeny tests is discussed in relation to heritability level and number of calvings required. The genetic merit of a bull should be stated as breeding values, either absolute, relative or in five classes, according to an earlier E.A.A.P. recommendation. If more than one character is recorded it may be worthwhile constructing a selection index. The types of effect which should be combined into a total index for a bull, depend on the breeding goal and the breeding strategy applied. Finally the advantages and disadvantages of three possible breeding strategies are discussed and the possible expected gains are illustrated. © 1979.