D. High somatic cell counts Mastitis, both subclinical and clinical, may depress fat test. This may be a factor in low testing herds. Freezing or churning of milk in the bulk tank lowers the tank test. Clumps of milkfat seen after emptying the tank indicate such a problem. Freezing can occur if there is a malfunction in the controls and refrigeration unit or if milk is excessively agitated.
Problems can also occur if the temperature is too high.
This can happen when old and raw milk is blended and the temperature exceeds 45 degrees F. Excessive agitation in the pipeline or a malfunctioning pump may reduce milkfat due to churning the milk. F. Improper milk handling Milk samples must be collected and handled properly to give accurate results. F. This usually requires ice or water-cooling. Completely fill sample bags or bottles to prevent churning if samples are not kept below 40 degrees F. Samples should not be frozen. The bulk tank should be agitated for at least five minutes and larger tanks require a longer agitation time before sampling.