Authors : N.B. Russi, A.I. Molineri, M.L. Signorini, A.L. Cuatrín, V.R. Canavesio, V.E. Neder, J.C. Bonazza and L.F. Calvinho
Abstract: The objective of this work was to determine on-farm risk factors for psychrotrophs counts in bulk tank milk of dairy farms from Argentina. Raw milk from bulk tank was sampled and Total Psychrotrophics bacteria Count (TPC), Proteolitic Psychrotrophic bacteria Count (PPC) and Lipolitic Psychrotrophic bacteria Count (LPC) were used to assess the bacteriological quality of bulk tank milk (dependent or outcome variables). At the same time, a survey was performed asking about infrastructure conditions, equipment and milking management (independent variables). Bivariate association proofs and logistic regression was used to find association between independent variables and psychrotrophic bacteria counts. Milk cooled in plate heat exchangers or barrel tanks had 16.39 and 10.52 times more likely to have elevated TPC and PPC (up to the level established for high quality milk) than bulk milk cooling tank, respectively. When the milking man does not wash his hands while milking there were 7.81 times more likely to have higher PPC. There was not possible to find association between LPC with any of the independent variables. The only variable associated with TPC and PPC was the type of refrigeration system used at the farm being bulk milk cooling tanks the best to avoid bacterial growth. The results of this study highlight the importance of the type of cooling system used at farm being bulk milk cooling tank the equipment that generates the best microbiological quality. The election of the cooling system to be used at farm and the correct sizing of it are fundamental factors to guarantee a correct microbiological quality of the milk obtained.
N.B. Russi, A.I. Molineri, M.L. Signorini, A.L. Cuatrín, V.R. Canavesio, V.E. Neder, J.C. Bonazza and L.F. Calvinho, 2014. Association Between Milking Practices and Psychrotrophic Bacteria Counts on Bulk Tank Milk. Research Journal of Dairy Sciences, 8: 13-18.