Herd level risk factors for elevated total bacterial count in bulk tank milk of dairy herds

Abstract EN

The aim of this study was to determine the risk factors associated with high total bacterial count of bulk tank milk.

Bulk tank milk samples were collected from all Prince Edward Island dairy herds (n = 235) from March 2005 to March 2007.

Biweekly total bacterial count was conducted using a Petrifilm culture system.

Data for on-farm risk factors were collected via a mail-out survey which consisted of 4 main sections : 1) general farm demographics and management, 2) cow cleanliness and hygiene, 3) milking procedures and mastitis control, and 4) equipment maintenance and cleaning.

The total bacterial count was positively associated with the amount of soiling on the teats prior to udder preparation, manual cleaning of the bulk tank, and the use of a certain type of detergent.

Additionally, various methods of prebilling udder preparation were important, with predip followed by drying being superior to other methods in reducing bacterial count.

Season was a strong predictor, with the lowest count tending to occur in winter.

The results of this study highlight the importance of total bacterial count as indicator of on-farm management practices, which influence bacteriological quality of milk.