US Food and Drug Administration
Center for Food Safety and Applied Nutrition
FDA Prime Connection
David Barbano, Department of Food Science Cornell University
Are milk and meat from bST-supplemented cows safe?
YES! Extensive studies of the safety of bST have
been conducted world-wide and reviewed by the Food and Drug Administration
(FDA). The FDA concluded that both milk and meat are safe. A separate
review of the data has been conducted by the National Institute
of Health, the World Health Organization, the Office of the Inspector
General of the Department of Health and Human Services, and reviews
by the Journal of the American Medical Association, Pediatrics,
and the Journal of
the American Dietetic Association all independently have arrived
at the same conclusion, milk and meat from bST supplemented cows
are safe. In addition, regulatory agencies from countries around
the world have reached the same conclusion, milk and meat from bST
supplemented cows are safe. In addition, regulatory agencies from
countries around the world have reached the same conclusion.
What is bST?
bST is an abbreviation for bovine somatotropin or what is also
called bovine growth hormone. The term rbST has been used to refer
to bST that is produced using fermentation technology and injected
into dairy cows to increase efficiency of milk production.
Is bST a hormone?
Yes. However, there are two types of hormones: steroids and proteins.
bST is a protein hormone. Protein hormones have no activity when
taken by mouth, while steroid hormones do have activity. For example,
insulin is a protein hormone.
Insulin has no activity if taken orally. Therefore, a diabetic
has to have injections of insulin. Like insulin, the protein hormone
bST has no activity when taken by mouth. In contrast, hormones used
in birth control pills are steroids and therefore are effective
when taken by mouth. Again, bST has no effect when taken by mouth.
Furthermore, studies were conducted in the 1950's to determine
if children suffering from dwarfism could be given direct injections
of high levels of bST to stimulate growth. The conclusion of the
study was that somatotropin from cows is not active in humans even
if injected. Why? The structure of human somatotropin is so different
from bovine somatotropin, that injections of high levels of bovine
somatotropin into children have no influence on growth and development.
How does bST work?
The pituitary gland of the dairy cow normally produces bST. bST
is one of a group of hormones produced naturally in the cow that
controls milk production. Supplemental rbST can be injected into
a dairy cow. Both sources of bST (that produced by the cow herself
and supplemental) are carried to the liver of the cow via the blood
stream. bST in the liver stimulates this organ to produce insulin-like
growth factor (IGF-1), another protein hormone that plays an important
role in helping regulate the conversion of dietary nutrients into
Supplement bST helps direct nutrients to the milk production process
within the cow's body. It has been shown that to support increased
milk production, a cow supplemented with rbST automatically consumes
more feed. The amount of nutrients required for the cow's body maintenance
remain unchanged, therefore, the cow's increased nutrient intake
is used primarily for milk production. bST is found in trace amounts
in milk from all cows, unsupplemented and supplemented.
Milk from cows given supplemental bST contains no more bST than
milk from cows not given the supplement.
Is there any difference between milk from bST supplemented cows
and unsupplemented cows?"
For all practical purposes no. There are no differences in nutrient
content (i.e., fat, protein, calcium, vitamins, etc.) or sensory
characteristics (flavor, color, etc.). There is no difference in
The concentration of IGF-1 in milk from supplemented cows is slightly
higher than from unsupplemented cows. However, the average increase
in concentration in milk is small compared to normal variations
in concentration of this compound from cow-to-cow in milk from unsupplemented
animals. The average increase of IGF-1
in milk produced by supplemented cows is also small compared to
the variation in amounts that occur normally from the beginning
to end of the cow's lactation period.
Should I be concerned about the small difference in concentration
of IGF-1 in milk?
No. IGF-1 is normally present in milk. It is a protein
hormone and is digested just like any other protein in milk, meat,
or other foods that you eat. IGF-1 is not active when consumed by
mouth. IGF-1 is a normal component in human milk. The average amount
of IGF-1 in human milk is higher than that found in milk from bST
supplemented cows. IGF-1 is also present in human saliva and the
average person consumes IGF-1 from this source each day that is
equivalent to the amount consumed from any source of milk.
How much more milk does a bST supplemented cow produce?
On average about 10%. After having a calf, a cow produces milk
for about 300 days. The highest daily milk production will occur
at about 8 weeks after calving and then the level of milk production
per day gradually declines during the rest of the lactation period.
Not all cows give the same amount of milk. Cows that produce the
highest amounts of milk generally have about the same peak milk
production per day as lower producing cows. However, the rate of
decline in daily production of milk during the rest of lactation
is slower in these high-producing cows.
Administration of supplemental bST is started after the peak of
milk production occurs and causes the cow to maintain a higher level
milk production per day during the period when milk production is
normally declining. Therefore, a cow supplemented with bST will
not be producing more milk per day than it produced per day at peak
production prior to the start of bST supplements.
Won't higher milk production trigger mastitis in cows?
The question of animal health has been reviewed extensively by
the FDA and was the subject of a special FDA Expert Advisory Panel
hearing on March 31, 1993. The Panel reported that based on extensive
research results, any increase in mastitis that may result from
use of bST is insignificant compared to the increase in mastitis
that occurs normally for other reasons, such as seasonal variation,
extremes of weather conditions, age of the cow, and stage of lactation.
The influence of season of the year changes the incidence of mastitis
9 times more that the influence of bST.
Doesn't treating mastitis require antibiotics which might find their
way into milk and affect milk safety?
No. Federal and state milk safety and quality assurance
programs, as well as testing by farmers and processors, ensure the
safety and wholesomeness of milk. When a farmer treats a cow with
an antibiotic, the milk from that cow is discarded by the farmer
for several days as defined on the label of the antibiotic. In many
cases today, a concerned farmer sends a sample of milk from that
cow to the dairy plant to be tested for antibiotics before the milk
from that cow is allowed to go in with the milk to be sold.
When milk is picked up at dairy farms, the truck driver must take
a sample of milk from the farm bulk tank at every farm before the
milk is pumped into the truck. When every truck arrives at a milk
processing plant, a milk sample is taken from the milk in the truck
and tested for antibiotics. If the load is positive, the truck is
not unloaded. Another sample is taken and the positive test is confirmed.
If the load of milk is positive for antibiotics, then all of the
individual farm samples that the driver collected are tested to
which farm's milk contained the antibiotics. In addition, the dairy
plant must notify the local regulatory agency that milk is being
discarded and they need to document the manner in which is was discarded.
There are very large financial penalties imposed on dairy farmers
that contaminate a truck load of milk with antibiotics. Many processing
plants have offered incentives to their farmers to avoid contamination
of tank trucks of milk with antibiotics. If a farmer thinks a mistake
has been made and his/her milk is contaminated, he/she can call
the plant and have a milk sample picked up and tested. If the tank
of milk is positive and the farmer prevented it from contaminating
a full truck load, then some plants have a program to pay the farmer
for one tank of milk during some period of time (for instance, 1
What impact will the approval of bST have on the economy and
the environment in the US?
The US Office of Management and Budget recently reported that
the use of bST will likely have a small but positive impact on the
US economy and environment. Use of bST will reduce the amount of
animal waste per unit of milk produced and will reduce the amount
of feed required to produce a unit of milk. This will be an environmental
Will some dairy products be labeled as "from cows not
treated with rbST" and what does it mean?
This type of label will be allowed by the US FDA. FDA also requires
that all statements on food product labels must be truthful and
not misleading. The FDA recommends that the company also put
information on the label to inform the consumer that "no
significant difference has been shown between milk derived from
rbST-treated cows and non-rbST-treated cows". FDA says
that this will put the statement "from cows not treated with
rbST in proper perspective so it is not misleading. The FDA recommends
that firms that make such claims establish a plan and maintain records
to substantiate their claims, and make those records available for
inspection by regulatory agencies responsible to verify the accuracy
of the label claim.
Will the commercialization of bST hurt the small dairy farmer?
The effective use of bST has nothing to do with farm
size. Unlike many new technologies, there is no up-front capital
costs before a farmer starts using this technology. Thus, small
farms will have equal access to this technology. The Office of Technology
Assessment has concluded that "quality of management"
on the dairy farm, not farm size, will be the major factor affecting
the magnitude of milk production response from bST. Better farm
managers will benefit most from bST, regardless of farm size. Milk
price is derived from many factors including consumer demand, business
costs, and government regulations.
Will bST create a large surplus of dairy products?
No. The signal to a dairy farmer that triggers the production
of more or less milk is the difference between the price of milk
paid to the dairy farmer and the cost of producing that milk. Farmers
will continue to respond to these signals. The larger the spread
between cost of production and price paid to the farmer for milk,
the greater the incentive for dairy farmers to produce more milk.
Prior to the introduction of bST there have been times of short
and surplus milk supply and times of high and low milk prices. This
will continue with or without bST use.
Use of supplemental bST will provide dairy farmers with a production
management tool to produce the same amount of milk that would have
been produced without bST with fewer cows and at lower cost. The
signal to the dairy farmer to produce more or less milk will continue
to be based on the difference between the price paid for milk and
the cost of milk production. For the well-managed dairy farm that
adopts bST technology (just like any other technology that improves
efficiency), profitability should be enhanced.
Over the period from 1982 to 1992 (when most of the research on
bST has taken place), new technology and better dairy farm management
without supplemental bST has increased the annual milk production
per cow from 12,306 to 15,423 pounds per year (25% increase in productivity
per cow), while the number of cows has decreased.
Increased production efficiency has kept the rate of increase
of dairy product prices to consumers lower than increases in prices
of other foods. Thus, excellent food value for the price, new product
offerings (such as low fat products) developed through dairy product
research that meet changing consumer needs, and promotion of dairy
products have increased total sales of milk for commercial use from
122 billion pounds to 142 billion pounds over the same 10 year period.
Should I buy raw milk from a local farmer and pasteurize it
at home to be sure I don't drink milk from bST supplemented cows?
While it is possible to do this, there are several risks involved
that a consumer should be aware of before they begin this practice.
About 2 to 10% of raw milk contains harmful bacteria (such as, Salmonella,
Listeria, Campylobacter, E. coli 0157:H7 and possibly other pathogens).
These disease causing bacteria are all killed by commercial pasteurization.
There is very strict regulatory inspection, control, and testing
of milk processing equipment and personnel to ensure that commercially
pasteurized milk does not contain pathogenic bacteria and that milk
is not recontaminated after it is pasteurized. When pasteurization
of milk is done at home, there is always a possibility that the
milk will not be fully pasteurized or that it will be contaminated
In addition, all milk from commercial processing plants is tested
for the presence of antibiotics prior to processing and bottling.
If a consumer buys raw milk directly from a dairy farmer, that consumer
has abandoned the dairy industry's quality and safety assurance
system designed to protect them from antibiotic contaminated milk.
The food safety risks of home pasteurization could be large compared
with the low level of risk that has been enjoyed by consumers of
commercially pasteurized milk.
For answers to additional questions, contact Professor David M.
Department of Food Science Cornell University, (607) 255-5482.