A controlled trial assessing the effect of gradual cessation of milking prior to dry-off on the risk of new intramammary infection and wellbeing in dairy cows
The importance of the end of lactation and the dry period in the dynamics of intramammary infection (IMI) in dairy cattle has long been recognized. In previous studies, gradual cessation of milking has been shown to decrease daily milk production during the last week of lactation and reduce risk of new IMI during the dry period. Although these results support the use of gradual cessation of milking to end lactation as an aid to improve udder health, only a limited number of recent studies have investigated its suitability in high-producing dairy cows. Consequently, gradual cessation has not been implemented widely in the field and no definite regimen has been recommended to dairy producers. However, due to increased intramammary pressure and subsequent tissue damage, abrupt cessation has been shown to be associated with elevated fecal stress hormones and is therefore subject to increasing concerns regarding animal well-being. The objective of this study, therefore, was to investigate the effect of 2 different drying-off protocols (gradual vs abrupt cessation) on the risk of new IMI, milk production, and somatic cell count (SCC) in the subsequent lactation, as well as concentration of fecal glucocorticoid metabolites in dairy cows. We hypothesized that cows that are enrolled in an intermittent milking schedule (i.e., gradual cessation) for the final week of lactation would have a lower risk of new IMI during the dry period, higher milk production, and lower SCC in the subsequent lactation, as well as lower fecal glucocorticoid concentration compared with their herd mates that are milked 3 times daily and dried-off by abrupt cessation.