Variation in the actual preferences for AI bull traits among Finnish dairy herds

Changing production circumstances, a wide range of traits and the international bull market enable dairy farmers to make increasingly specific choices concerning artificial insemination (AI) bulls. Finland is part of the joint Nordic dairy cattle breeding programme where in addition to yield, high emphasis is given to health, fertility, conformation and longevity. The aims of our study were (a) to investigate whether Finnish dairy farmers differ in their selection preferences for AI bull traits and can be clustered into herd groups, (b) to determine whether AI bull selection in different herd groups is in line with the Nordic Total Merit index (NTM) and (c) to analyse how the herd groups are related to herd characteristics. We used a statistical cluster analysis to analyse AI bull usage and to group herds according to each herd's bull selection profile determined by the traits' estimated breeding value (EBV) mean weighted by the number of inseminations for the various traits. We identified four herd groups in both Ayrshire (AY) and Holstein (HOL) breeds: Production, Fertility, All-rounders, and Conformation. The herds' bull selection profiles were mostly close to the NTM except in the Conformation herd groups where traits other than conformation were nearly neglected. This led to poorer expected genetic and economic outcomes than with the NTM selection. Conformation herds were a minority, but they were larger in herd size and investments had recently been made. The data suggest that either fine-tuning the weights in the NTM, forming alternative indices or developing a herd-specific total merit index (TMI) could fulfil the needs of very diverse herds.