top of page
Search

FROM THE FARM REPORT: FREE FATTY ACIDS IN BULK TANK MILK

  • Writer: Heather Dann
    Heather Dann
  • Apr 14
  • 3 min read

An elevated concentration of free fatty acids (FFA; ≥ 1.2 mmol FFA/100 g of milk fat) in bulk tank milk is a concern for dairy farmers and their milk processors as it can lead to poor milk quality such as off-flavor, rancidity, reduced foaming ability, and problems with cheese coagulation. “What causes FFA in milk?” “What can I do about it?” These are some of the common questions that we have received in our milk lab over the years. Most of the research on high milk FFA has been done in Europe and not surprisingly is multifactorial. To provide a North America perspective, University of Guelph researchers have recently evaluated the associations of bulk tank milk FFA with farm type, facility and management factors, and time of year and reported their findings in the Journal of Dairy Science and JDS Communications.


Types of Lipolysis that Increase Milk FFA

Free fatty acids in milk are the result of the “breakdown” of milk fat (i.e., triglyceride). A milk fat globule membrane (MFGM) protects the triglyceride. However, if the membrane is damaged for some reason, a lipoprotein lipase, an enzyme, will cleave the triglyceride into 3 FFA and a glycerol molecule. There are 3 types of lipolysis that can occur:

  • Induced lipolysis – Physical stress on the MFGM during milking and transport can lead to FFA. For example, pipelines with smaller diameters, long lengths, many turns, or elevated sections can increase the risk of MFGM damage.

  • Spontaneous lipolysis – A higher concentration of endogenous lipoprotein lipase occurs in milk increase the risk of lipolysis. This is more common in cows that are later lactation, are lower producers, have greater somatic cell counts, are feed-restricted, or experience a sudden feed change.

  • Bacterial lipolysis – Psychotropic bacteria grow in warmer or dirty environments and produce lipolytic enzymes that increase the risk of FFA. This is more common when milk is cooled to slowly or improperly cleaned equipment.


Farm Type Related to Milk FFA

A study with 3,771 farms in Ontario over 53 months from 2018 to 2022 found that milk FFA varies among farm type, months, and years. Conventional farms had the lowest FFA (0.83 mmol/100 g milk fat) with 7% of monthly averages ≥ 1.2 mmol FFA/100 g milk fat. Farms with grass-fed herds had the highest FFA (1.10 mmol/100 g milk fat) with 23% of months with elevated FFA. Organic farms were intermediate with an average FFA of 0.89 mmol/100 g milk fat and 12% of months with elevated FFA. Interestingly, FFA varied during the year with the lowest FFA occurring in May for all farm types. Additionally, monthly FFA values varied year to year.


Facility and Management Factors Related to Milk FFA

A study involved 293 dairy farms in Ontario and British Columbia. Researchers visited the farms to survey milking systems, assess cow diets, and gather 30-day average bulk tank FFA values. The overall average was 0.84 mmol FFA/100 g milk fat with 10% of farms having elevated FFA.

  • Milking system – Farms with nonparlor milking systems (e.g., AMS and pipelines) had higher FFA

  • Milking frequency – Farms with milking frequencies of ≥ 3 times per day had higher FFA particularly in AMS and tiestall milking systems. Parlor farms did not have elevated FFA regardless of milking frequency

  • Milk filter change frequency – Not changing the milk filter as least 2 times per day was associated with higher FFA in farms milking ≥ 3 times per day.

  • Pre-cooling milk – The absence of pre-cooling milk was associated with higher FFA.

  • Fat supplements – The use of fat supplements in lactating diets was not associated with FFA; incomplete diet reporting was a limitation of the study suggesting further study of dietary factors with FFA is appropriate

The researchers suggested that spontaneous lipolysis affected by milking frequency and bacterial lipolysis affected by milk pre-cooling and milk filter change frequency did affect milk FFA more than induced lipolysis. However, these factors didn’t explain all the FFA variation so the researchers suggested that there are likely more risk factors such as nutrition, bulk tank cooling and agitation settings, and individual cow factors. Looks like there are still a few more questions to be answered.

— Heather Dann

bottom of page