Change and genetic aspects of body condition score (BCS) in Italian Brown cattle

Body condition score (BCS) at approximately four-week intervals were taken during over 2 years (from 2001 to 2002) on 1,323 Italian Brown cattle reared in 50 farms. The aims of this study were to investigate the pattern of changes during lactation of BCS and to estimate heritability value of BCS and its genetic correlations with daily milk yield, using a test-day model. A total of 10,460 records of BCS were available for statistical analysis. Only cows with at least two records were analyzed and repeated observations per cows were considered repeated measurements of the same trait. Data were analyzed using ANOVA according to a time-dependent model based on days in milk. R_ accounted for 72% of total variation of test-day BCS. The pattern of change in BCS appeared closely related to stage of lactation. Body reserves decreased from calving until first 3 months of lactation and were restored in mid and late lactation. Variance and covariance components and related parameters were estimated using a REML bi-trait procedure (unequal design) for BCS and milk yield. Heritability estimates for BCS and daily milk yield were 0.31 and 0.19, respectively. Condition score was negatively correlated (-0.32) with daily milk yield.