Preliminary results from a genetic analysis of clinical mastitis data

First lactation clinical mastitis records from Norwegian health recording were analysed. These preliminary analyses utilised data on 70,861 daughters from 2 annual batches of a total of 257 young bulls. Genetic parameters of mastitis resistance were estimated with both a threshold and a traditional linear model analysis, resulting in heritability estimates of 0.09 and 0.05 respectively. Mastitis information from the period 10 days prior to 90 days after calving resulted in the highest heritability estimate. Estimated breeding values and ranking of bulls were compared for the threshold and linear models. Correlations using either criterion were both greater than 0.99. ___________________________________________________________________________________