Factors Influencing Total Bacterial Count in Tanks: An Application of Linear Mixed-Effect Models

Abstract

The objective of this research was to evaluate the influence of procedures for hygienic milking and cleaning of dairy equipment and milk cooling tanks on the levels of total bacterial count (TBC). Mixed-effect models were used in order to model the structure of dependence between and within dairy farms. To this end, four bulk samples of milk were collected from each tank in eight properties for TBC analysis, employing the flow cytometry method. A questionnaire was applied in each property to assess the current situation of milking procedures on each production system that took part on this research, followed by training of employees in good agricultural practices in the production of milk and monitoring of the TBC measurements. Analysis of longitudinal data was the method employed, which focused on random effects models. The results showed that the handling procedures for milking and the cleanliness of the cooling tanks contributed to a further reduction in the levels of total bacterial count in raw milk cooling tanks.

Composition and properties of bovine milk: A study from dairy farms in northern Sweden; Part II. Effect of monthly variation

“…Total bacteria count was not influenced by the sampling month in this study, indicating uniform and good hygienic conditions on the participating farms throughout the year. Low numbers of bacteria result from proper handling of the raw milk, as well as good hygiene and cleaning routines on-farm (Guerra et al, 2013). The trend for slightly higher numerical values during the outdoor period in this study was possibly related to higher contamination from the environment when the cows were out on pasture, which has also been reported by Doyle et al (2016).…”