The animals studied were loose-housed dairy cows held for education and milk production and Vreta Farm School (Linköping). 

The cows were milked in a milking parlour three times per day and handling and milking was carried out by students from the farm school and by two altering animal keepers.

Animals were of two different breeds, Holstein (n=35) and Swedish Red and White cattle (SRB, n=34) and in different lactations. The animals also differed in the number of months since they had their last calving and number of month during pregnancy.