Freezing Point of Bulk Milk in Ontario - An Observational Study

The objective of this study is to describe the trends and variation in freezing point of milk in recent years. The data were obtained from the Central Milk Testing Laboratory and the Ontario Milk Marketing Board. For each of the approximately 10,000 Ontario farms, there were monthly data from January, 1985 through September, 1991. A slight upward trend is present in the Ontario data (.005 degrees Hortvet in 7 years). The analysis of seasonality revealed a very significant and strong seasonal component present in the freezing point data. The freezing point was high in the summer (June and July) and low in the winter (December and January). There seems to be a regional difference in freezing point. Counties located in central Ontario appear to have a freezing point below the mean, and counties on the periphery of Ontario seem to have a somewhat higher freezing point. The regression of the monthly freezing point against milk solids showed a significant effect of % lactose, and % protein on the freezing point of milk. The % fat had very little influence. The information on seasonality and components of milk at ≤-0.510 degrees Hortvert. This normal range was compared to the current standards. The differences between these two ranges are important.