Development of a breeding value for Mastitis based on SCS-results

Aim of this study was to develop a trait for the breeding value estimation of direct mastitis based on results of the national routine evaluation for SCS. Two traits were chosen based on their impact on direct mastitis. Standard deviation of residual SCS-scores (STD) and number of excessive SCS-values during a lactation (N_SCS). STD was analysed having largest influence on mastitis. Heritabilities for the two traits were estimated with .09 (STD) and .04 (N_SCS) with a genetic correlation of 0.76 between both traits. Although validation data with direct mastitis was quite small the two traits derived from SCS routine estimation showed promising results to become indicator traits for a routine evaluation for mastitis in Germany. Advantage of the new traits is the availability for all bulls and cows in the actual routine evaluation. Genomic breeding values can easily be derived because all bulls in the actual reference population will get proofs for the new traits immediately without new performance recording.