Young Scientists 1 BREEDING FOR BODY CONDITION SCORE IN DAIRY COWS

Body condition score has been proposed as an additional trait in New Zealand’s national breeding objective. To be considered for inclusion, genetic parameters and an economic value are required. We propose genetic evaluation of body condition score using a random regression model that includes 2 order orthogonal Legendre polynomials fitted to the genetic variance and a link function to account for heterogeneity of error variance over time. Multivariate analyses have shown that in New Zealand, body condition score is not genetically correlated with first lactation milksolids yield traits (when projected to a single common lactation length of 270 days). Moderate genetic correlations with fertility, survival and live weight were estimated. The economic value for body condition score is likely to include feed demands required to replenish lost body condition in a typical New Zealand farm. The relationship between body condition score and fertility will be accounted for in the breeding value for fertility.