GENETIC CORRELATIONS BETWEEN LINEAR TYPE TRAITS, FOOD-INTAKE, LIVE WEIGHT AND CONDITION SCORE IN HOLSTEIN-FRIESIAN DAIRY-CATTLE

Variance components were estimated from an animal model using a restri cted maximum likelihood procedure which allowed for unequal design mat rices and missing observations (VCE). Data sets containing: (i) 15 275 records of lineal type classifications on heifers, (ii) 3399 live wei ght and condition scores measured at calving and (iii) 1157 records of yield, dry-matter intake, average live weight and condition score dur ing the first 26 weeks of lactation; were analysed jointly. Heritabili ty estimates for dry-matter intake, live weight and condition score in tile largest data set were 0.44, 0.44 and 0.35 respectively and the g enetic correlation between condition score and the yield traits ranged from -0.29 to -0.46. The genetic correlation between milk yield and a verage live weight ions negative (-0.09) but after adjusting for the g enetic variation in condition score this correlation was positive (0.2 9). Genetic correlations between live weight and stature, chest width, body depth and rump width were consistently high (0.52 to 0.64; 0.75 to 0.86; 0.59 to 0.81; 0.56 to 0.74, respectively). Chest width and bo dy depth were little to moderately correlated with dry-matter intake ( 0.25 to 0.28 and 0.20 to 0.34 respectively), and angularity (-0.47 to -0.77) and chest width (0.32 to 0.73) appeared to be good predictors o f condition score. These correlations showed that (i) the relative val ue of live weight compared with food intake capacity determines the op timum direction of selection for stature, chest width, body depth and angularity, and consequently the optimum size of tile dairy cow, and t hat (ii) live weight, condition score and food intake can be predicted from the type traits with little loss in accuracy. A restricted index which maintains condition score at its current level was predicted to reduce overall (economic) genetic gain by 5%.