GENETIC-PARAMETERS FOR AND BLAD EFFECTS ON BEEF-PRODUCTION TRAITS ANDDISEASE FREQUENCY

Beef production traits measured on 6292 performance tested Danish Frie sian bulls from 1973 to 1992 were analysed together with disease recor ds for 4621 bulls performance tested from 1981 to 1992 using a thresho ld model. Univariate Gaussian and polychotomous and bivariate Gaussian -binary mixed models with Bovine Leukocyte Adhesion Deficiency (BLAD) test information were used. Danish Friesians were found to have a larg er ultrasonic muscle area than North American Holstein-Friesians and f avourable heterosis was observed for daily gain and feed utilization. Carriers of BLAD were observed to have poorer feed utilization than no n-carriers and tended to grow slower and to have a lower incidence of disease treatments; Estimated heritabilities for beef production trait s ranged from 0.29 to 0.39. For disease frequency analysed as polychot omous and as binary, the estimated heritabilities ranged from 0.08 to 0.19 and from 0.12 to 0.33, respectively. Simulation showed that herit ability estimates tended to be biased with increasing number of pooled categories. Phenotypic and genetic correlations between disease frequ ency and beef production traits ranged from -0.32 to 0.10 and from -0. 43 to 0.23, respectively.