Application of decision-tree technique to assess herd specific risk factors for coliform mastitis in sows

The aim of the study was to investigate factors associated with coliform mastitis in sows, determined at herd level, by applying the decision-tree technique. Coliform mastitis represents an economically important disease in sows after farrowing that also affects the health, welfare and performance of the piglets. The decision-tree technique, a data mining method, may be an effective tool for making large datasets accessible and different sow herd information comparable. It is based on the C4.5-algorithm which generates trees in a top-down recursive strategy. The technique can be used to detect weak points in farm management. Two datasets of two farms in Germany, consisting of sow-related parameters, were analysed and compared by decision-tree algorithms. Data were collected over the period of April 2007 to August 2010 from 987 sows (499 CM-positive sows and 488 CM-negative sows) and 596 sows (322 CM-positive sows and 274 CM-negative sows), respectively. Depending on the dataset, different graphical trees were built showing relevant factors at the herd level which may lead to coliform mastitis. To our understanding, this is the first time decision-tree modeling was used to assess risk factors for coliform mastitis. Herd specific risk factors for the disease were illustrated what could prove beneficial in disease and herd management.