Expert opinion on ranking risk factors for subclinical mastitis using a modified Delphi technique

To collate the expert opinion of Australian dairy practitioners on the relative importance of risk factors for subclinical mastitis in dairy cattle.

A modified Delphi technique was used to collect the data over two rounds. First, participants were asked to complete a survey involving ranking the level of importance of 42 risk factors on the incidence of subclinical mastitis on a scale from 1 to 10 for two categories of subclinical mastitis; contagious and environmental. After presenting and discussing the results of the first survey, the participants were asked to complete the same survey a second time. To rank the risk factors and identify the consensus amongst the participants, the median and total variation of answers were calculated and compared between the two surveys.

The most important factors identified by the respondents after the second survey for contagious subclinical mastitis were: Teat Disinfection Post-milking, Management of High Cell Count Cows and Presence of Chronically Infected Mastitis Cows in the Herd. The most important factors for environmental subclinical mastitis were Cleanliness of the Environment and Technique of Teat Disinfection Post-milking.

A movement toward consensus for the more important factors and a movement away from consensus for the less important factors in the second survey were observed. The most important factors for subclinical mastitis were found to be: teat disinfection post-milking, management of high cell count cows, presence of chronically infected mastitis cows in the herd and cleanliness of the environment.