Is intersucking in dairy cows the continuation of a habit developed in early life?

Intersucking, i.e., cattle sucking the udder of heifers or cows, is a frequent problem in dairy herds and may lead to udder damage, mastitis, milk loss, and culling of breeding animals. Using epidemiological methods, we conducted an observational cross-sectional study to investigate risk factors for intersucking in Swiss dairy cows. We asked 114 randomly selected dairy farmers about a broad spectrum of environmental factors possibly associated with intersucking, such as housing conditions, management, and feeding of calves, heifers, and cows. Thirty of the 114 farms were confronted with intersucking in cows. The mean proportion of intersucking cows per farm was 1.6%. From a total of 3077 cows (Swiss Brown Cattle, Simmental, and Holstein Friesian) we recorded 49 cows that had performed or were currently intersucking. In 69% of these cows, intersucking had been observed as heifers. Using path analysis and multivariable stepwise backward logistic and linear regression analyses, we revealed that the most important risk factor for intersucking cows was the presence of intersucking heifers on a farm (odds ratio = 7.8). The results suggest that intersucking in cows is the continuation of a habit that was already established in a cow's subadult life. This emphasizes the importance of looking not only at the animal's current environmental situation but also considering its entire life history for the prevention of behavioral problems.