Bacteriologic Testing Offered
Procedures that assess the bacteriological quality of raw milk are of value in identifying current or potential problems on the farm that could relate to milk quality and herd health. Tests available through Dairy Bacterial Testing, LLC are 1) total aerobic count, 2) total coliform count, and 3) Herd Health Screen.
Total Aerobic Count: The total aerobic count is also known as the Standard Plate Count or Raw Count. This test is an estimate of the total number of viable aerobic bacteria present in one milliliter of raw milk. Milk samples are incubated for 48 hours. Consistent use of proper milking practices, udder hygiene and good mastitis prevention and control practices should allow dairy producers to produce milk with total aerobic counts of ≤5,000cfu/mL. High bacterial counts (>10,000 cfu/mL) suggest that bacteria are entering milk from a variety of possible sources. The most frequent cause of high counts is poor cleaning of milking equipment. Milk residues on equipment surfaces provide nutrients for growth and multiplication of bacteria that can contaminate milk. Cows with mastitis, soiled cows, unclean milking practices, and failure to rapidly cool milk to less than 40°F can also contribute to high bacterial counts in raw milk.
Coliform Count: The coliform count estimates the number of bacteria that originate from manure or a contaminated environment. Milk samples are incubated for 24 hours. Coliform counts reflect hygiene and sanitation practices on the farm. Coliforms may enter the milk as a consequence of milking soiled cows or dropping the milking claw into manure during milking. Coliform counts of >50cfu/mL suggest poor milking practices, dirty equipment, contaminated water, dirty milking facilities or cows with subclinical or clinical coliform mastitis.
Herd Health Screen: The herd health screen is offered for the producer who wishes to investigate possible mastitis issues on the farm. Samples can be collected from the bulk tank,
milk can, or individual cow or quarter. Milk samples are plated on differential media in the laboratory to screen for common causes of mastitis such as Eschericia coli, Staphylococcus aureus, Streptococcus agalactaie, Klebsiella species and Pseudomonas species. Samples are incubated for 24 to 48 hours. Preliminary results may be available at 24 hours after plating.