rBST: Fact Sheet

S.A. Modena maildrop maildrop at csemail.cropsci.ncsu.edu
Thu Feb 24 07:46:18 EST 1994

>From:           "Basil R. Eastwood" <BEASTWOOD at cite.esusda.gov>
Organization:   Extension Service, USDA
>To:             DAIRY at ESUSDA.GOV
Date sent:      Wed, 23 Feb 1994 13:20:28 EST
Subject:        DAIRY UPDATE-BST FACTSHEET-2/23/94

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The following fact sheet was written by Professor David Barbano, 
Department of Food Science, Cornell University.  

                       BST Fact Sheet

**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 

**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 milk.

Supplemental bST helps increase the efficiency of conversion of feed 
to milk in 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 

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 bST 

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 identify 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 year). 

**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 rbSTS 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 

**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 

**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 tha  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 after pasteurization. 

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. Barbano
      Department of Food Science
      Cornell University
      (607) 255-5482
BASIL R. EASTWOOD      USDA-Ext. Service      Ph. (202) 720-6486
Prog. Leader-Dairy     3334 South Bldg.       Fax (202) 720-7714
                       Washington DC 20250    BEASTWOOD at ESUSDA.GOV

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