Dynamics of milk quality indicators in raw milk stored in collective bulk tanks

Abstract

Somatic Cell Count (SCC) and Total Bacterial Count (TBC) are reference methods to assess the quality of raw milk stored in collective bulk tanks. One of the issues resulting from the use of collective bulk tanks is the mixture of milks of different qualities within the same tank. Producers who deliver low quality milk negatively influence the quality of the bulk milk, leading to payment penalties to all producers. The overall objective of this study is to generate knowledge that can be used to improve the bacteriological quality of raw milk stored in collective bulk tanks. Milk samples will be collected daily from four collective tanks during two ten-day periods, in summer and winter. Samples will be collected shortly after delivery of milk from all properties to the tank, and at the time of pick up. In addition, milk samples will be collected from each milk can brought by producers before pouring into the tank, to make a composite sample that will represent the milk quality of each farm prior to delivery to the tank. After delivery of milk by all producers, an additional milk sample will be collected from the tank. The data collected will allow the following objectives to be achieved: to quantify the contribution of somatic cells and total bacteria from individual properties to the tank, to compare the TBC in the milk between the initial and final storage times, to develop a SCC and TBC sampling scheme to identify, using as few samples as possible, producers that negatively contribute to the quality of the milk of the collective tank, and to transfer knowledge to farmers by means of extension activities. Results of this study will help producers improve the quality and safety of the milk marketed to the dairy industry. (AU)