Genetic analysis of body condition score of lactating Dutch Holstein and Red-and-White heifers.

The aim of this study was to estimate phenotypic and genetic parameters for body condition scores (BCS) from the Dutch type classification system. Data included 108,809 Holstein (H) and 26,208 Red-and-White (R) heifers from 9701 herds that were scored once during lactation on a 1 to 9 scale (1 = emaciated and 9 = obese). Mean BCS for H and R data were 4.50 and 4.94, respectively. The BCS decreased as the percentage of Holstein genes increased. For both breeds, BCS after calving was about 5.6 and BCS was lowest around wk 11. For H heifers, mean BCS at drying off was about 0.8 lower than BCS at calving, whereas for R heifers BCS was at about the same level as at calving. Variance components were estimated using an animal model including the effects of herd x visit, classifier, age at calving, DIM, and genetic group. The random herd x visit effect explained about 10 to 15% of the phenotypic variation. Heritabilities ranged from 0.24 to 0.38, depending on breed and lactation period. Genetic correlations between BCS observations in bimonthly lactation periods were close to unity, especially for H. It was concluded that BCS data collected by type classifiers can well be used for genetic evaluation and that genetic variation between animals for BCS-change patterns is a small component of the overall variation in BCS.