Risk Factors of Forced Take-Off in Dairy Cows Milked Three Times per Day in A Rotary Milking Parlor: A Case Control Study

SIMPLE SUMMARY: To remain competitive on the global market in the presence of shrinking profit margins, dairy producers continuously seek to increase the efficiency of their operations. One way to increase the operating efficiency in rotary milking parlors is to enhance the rotational speed of the platform. However, increasing the rotational speed reduces the maximum milking duration that is possible during a single rotation. This can increase the number of cows that have not finished milking and milk remaining in the mammary gland if the milking unit is removed early by means of a forced take-off, a practice that is typical for dairy herds in North America and some European countries. To provide a means for monitoring these cows, we described a protocol for the identification of cows that repeatedly are subjected to a forced take-off (RFTO) at the end of milking. Using this protocol, we then investigated cow characteristics that were associated with RFTO. The associations found suggested that the developed protocol could serve as a useful tool to identify cows at risk of RFTO. Through modification of the case definition, dairy producers will be able to adjust their monitoring protocol according to their individual farm-goals. ABSTRACT: The aims of the research were to: (1) describe a protocol for the identification of cows that are subjected repeatedly to a forced retraction event at the end of milking; (2) study risk factors of repeated forced take-off (RFTO); and (3) assess the average milk flow rate at which the forced retraction event occurred. In a retrospective study, we collected milk flow data over a 1-week period from a 4300-cow dairy with a rotary milking parlor and a thrice-daily milking schedule. We identified 109 cases of RFTO and 2467 controls. A multivariable logistic regression model revealed associations of parity, stage of lactation, average daily milk production, and milking speed with RFTO. Cows in parity 3 or greater, animals ≤100 days in milk, high-producing animals, and cows with low milking speed had higher odds of RFTO. The average (least squares means (95% CI)) milk flow rates at the time of removal of the milking unit were 2.1 (2.0–2.1) kg/min in milking observations that were terminated with the forced retract and 1.5 (1.4–1.5) kg/min when milking units were removed with the automatic cluster remover. Future research to better understand the effect of RFTO on milk production, udder health, and animal well-being is warranted.