Animal cleanliness in dairy herds is essential to ensure hygienic milk production, high microbial quality of carcasses, good hide quality, and animal welfare. The objective of this study was to identify on-farm factors associated with dairy cattle cleanliness. The study also examined differences in risk factors and preventive factors between contrasting herds regarding cattle cleanliness. In total, 60 dairy herds, selected from a national database, were visited by 2 trained assessors during the indoor feeding period in February and March 2009. In Norwegian abattoirs, cattle are assessed and categorized according to hide cleanliness, based on national guidelines, using a 3-category scale. Dirty animals result in deductions in payment to farmers. "Dirty" herds (n=30) were defined as those that had most deductions in payment registered due to dirty animals slaughtered in 2007 and 2008. "Clean" herds (n=30) were those that had similar farm characteristics, but slaughtered only clean animals during 2007 and 2008, and thus had no deductions in payments registered. The dairy farms were located in 4 different areas of Norway. Relevant information, such as housing, bedding, feeding, and management practices concerning cleaning animals and floors, was collected during farm visits. In addition, the cleanliness of each animal over 1 yr of age (4,991 animals) was assessed and scored on a 5-point scale, and later changed to a dichotomous variable during statistical analysis. Milk data (milk yield and somatic cell counts) were obtained from the Norwegian Dairy Herd Recording System. Factors associated with dirty animals in all 60 herds were, in ranked order, high air humidity, many dirty animals slaughtered during the previous 2 yr, lack of preslaughter management practices toward cleaning animals, animal type (heifers and bulls/steers), housing (freestalls and pens without bedding), manure consistency, and lack of efforts directed toward cleaning the animals throughout the year. Additional factors associated with dirty animals in the dirty herds were water leakage from drinking nipples/troughs into lying areas, bedding type, and feed type. In the clean herds, additional risk factors were water leakage from drinking nipples/troughs and low milk yield.
