The Safety of Consuming
Animal Products Produced
under Conventional Systems
ANSC 3404
Presentation formulated with contributions from:
Michael A. Ballou, PhD, US Foodservice Seminar 2009,
The American Farm Bureau “Addressing Misconceptions
About Agriculture,” and
The American Meat Institute Fact Sheets
LEARNING OUTCOMES
• After attending the presentation the participant will
know more about: (1) the need to adapt safe and
sustainable technologies to feed the increasing global
population and (2) the safety of current technologies
used in the livestock industry.
• This presentation will focus on the current uses of
growth promotants and antibiotics
For the first time in human history, the majority of people will
have no contact with the source of their food….
…other than buying or eating it.
We know this population shift has occurred in the United States
since the end of World War II.
 It will soon be true across the globe.
By 2050, the majority of the world’s population will be
disconnected from the earth.
 In 1950, more than 75 percent of world’s population was rural.
 By 2050, almost 75 percent of world’s population will be
urban.
The average U.S. citizen is three or more generations removed
from the farm.
Food is taken for granted.
 Issue has no personal relevance.
 Sentimentality persists, but far less than in past.
 More questioning of farmers’ competency
The ignorant are very easily misled.
 We believe that we understand subjects that we do not.
 We fear the wrong things.
 We don’t fear the right things.
The U.S. public has many misconceptions about agriculture.
 Many we are taught!
 Others come from superficial reporting by media or through
advertising.
 Once something is in print, it is repeated, endlessly, as factual.
 Malthus
 1798 Prediction
Population Growth
256%
Food
Production
9%
1798
1998
6
An Inconvenient Truth
 The world population is predicted to continue increasing
 World population is growing at a rate of 1.7% each year
 Therefore by 2050 the population will have nearly doubled
An Inconvenient Truth
 Central question is……how are we going to feed everyone?
 This is not a new question.
 In 1798 Thomas Malthus published an essay on the Principle of
Population that suggested population growth exceeded the
growth of resources
 This was at a time when population growth wasn’t growing quickly by
current standards
 Thomas predicted that famine, disease, and war would
ultimately be the causative force driving population
stabilization.
 This presentation will not discuss philosophies on how to
control population growth, but will focus on the safety of
current technologies that can feed, at least in the immediate
future, an inevitable increase in the population.
56.3
Grazing
Land
16.9
Ice Covered
15
Deserts
2.5
Rock and
Tundra
5.2
Wetlands
15.1
Cropland
4.7
Urban Land
33.2
Dense
Forests
World’s Agricultural Land
 Approximately 2/3 is permanent pasture, range, or meadow
 Of which 60 % is unsuitable for producing crops
 This land produces cellulosic roughages – grass, and other
vegetation
 Digestible by ruminant grazing animals (cattle, sheep, goats, deer, and
bison)
 Not digestible by humans
Diet of Cattle:
 Cattle graze and eat forages that humans cannot digest due to
the fiber content.
 Much of the grain milling and food processing waste is turned
into feeds that cattle can eat and convert into high quality
protein.
Milling and Food Processing Waste:
 For every 100 pounds of human food produced by processing
crops, 37 pounds of waste products are produced.
 These waste products can be turned into animal feed or will
enter the waste stream to be disposed.
Diet of Cattle:
 50 – 70 percent of a beef animal’s feedlot diet is human-
inedible forages and feed.
 In U.S., 2.6 pounds of grain are used to produce 1 pound of
beef.
 Globally, 0.3 pound of grain is used to produce 1 pound of
beef.
An Inconvenient Truth
 How are we going to feed the various populations
 (1) Increase land devoted to food production
 Or (2) Increase efficiency of yields
 Most of earth’s productive land is already cultivated for food
production
 Some deforestation and use of rangeland will be transitioned
into cultivated land
 The focus of this presentation will be on technologies used to
increase efficiencies of yields in livestock.
 Central Goal:
 Adopt SAFE technologies that promote INCREASED
UTILIZATION of available resources in a SUSTAINABLE
manner.
Growth Promotants
Growth Promotants
 Why use growth promotants in livestock?
 Increase performance by 5 – 25%
 Increase efficiency of performance (kg feed required for a kg of
product produced) by 5 – 15%
 Types of growth promotants currently used:
 Recombinant growth hormones
 Estrogenic and Androgenic implants
 β-agonists (not discussed in this presentation)
Growth Promotants - rBST
 Types of growth promotants currently used:
- Recombinant growth hormones:
 Commonly used in the dairy cattle industry under the name
recombinant bovine somatotropin (rBST)
 rBST is a Protein hormone that is naturally secreted from the
pituitary of all cattle.
 Using recombinant technology a synthetic form almost identical
to the natural analog is produced (An extra amino acid at the
terminal region of the protein – confers no biological activity)
 Circulating rBST binds to receptors in the liver and increases
the secretion of insulin-like growth factor-1 (IGF-1).
 IGF-1 regulates many cell functions including stimulating cell
growth and inhibiting programmed cell death
Growth Promotants - rBST
 Types of growth promotants currently used:
- rBST:
80
70
Milk / cow / day (lbs)
The increase in IGF-1
decreases mammary cell
death and extends the
lactation curve: (1)
improving milk production
& (2) improving feed
efficiency
60
50
40
30
No rBST
rBST - treated
20
10
0
100
200
Days in milk
300
400
Growth Promotants - rBST
Does rBST pose any health risk to humans?
 All milk contains small amounts (ppb) of BST
 Cows treated with rBST also have very low levels of BST in milk and
meat, comparable to naturally occurring concentrations
 rBST is not active in humans because the protein is about 35%
different than human somatotropin (Juskevich & Guyer, 1990)
 Therefore when rBST is injected into humans, even at
pharmacological doses, the rBST cannot bind to the somatotropin
receptors in the liver.
 Even if rBST was active in humans, since it is a protein it is
digested in the gastrointestinal tract of humans to amino acids
 Rats are responsive to injections of rBST; however when given
pharmacological oral doses of rBST there is no growth response
(Seaman et al., 1988).
Growth Promotants - rBST
Does rBST pose any health risk to humans?
 IGF-1 in meat and milk from rBST-treated cattle are
increased (30 – 60%). (Hammond et al., 1990)
 However, the amount of IGF-1 consumed in 1 glass of milk is
equal to approximately 0.03% of the IGF-1 produced naturally
in our bodies each day (Dale Bauman, Cornell University)
 Require 12,000 cups of milk per day to equal the amount of IGF-1
produced in our bodies daily
 Additionally, IGF-1 is a protein, so oral IGF-1 is digested in
the small intestines to amino acids
Growth Promotants - rBST
 The European Union, Japan, Australia, New Zealand, and Canada







have not approved rBST for use.
Tillamook Cheese (Oregon) rBST free in 2005.
Safeway (NE US) stopped buying milk from dairy farmers that
used rBST in Jan. 2007.
California Dairies Inc (15 billion lbs annually or 8% of the US
milk produced) rBST free since Aug. 2007.
Kroger has banned all rBST-derived milk products from it’s stores.
Starbucks all dairy is from rBST free animals in Jan. 2008
Wal-Mart and Sam’s Club now sells milk from rBST free animals
Mostly citing consumer demand for hormone-free milk
 Education of safe technologies is needed
Growth Promotants - rBST
Does rBST pose any health risks to the cow?
 One meta-analysis suggested that rBST-treated cattle are
more likely to develop clinical mastitis and foot problems and
less likely to conceive. (Dohoo et al., 2003)
 However in cows that conceived there was no difference in
number of days it took for them to conceive.
 More data is needed to accurately assess the impact of rBST
on health of cattle.
 Use immune, reproductive, and welfare parameters to assess.
 If health is adversely affected the industry will need to design
preventative management strategies.
Growth Promotants – Estrogenic &
Androgenic Implants
 Types of growth promotants currently used:
- Estrogenic and Androgenic Implants:
 Commonly used in the beef cattle industry
 Estrogenic implants increase circulating levels of somatotropin
and IGF-1
 Androgenic implants increase circulating levels of IGF-1
Growth Promotants – Estrogenic &
Androgenic Implants
Do Estrogenic or Androgenic implants pose any
health risk to humans?
 Estrogen and Androgen are lipid hormones
 Unlike protein hormones (rBST and IGF-1) they are not
digested in the gastrointestinal tract; therefore they can be
absorbed intact.
 Estrogen and Androgen produced in cattle are active in
humans
Growth Promotants – Estrogenic &
Androgenic Implants
Do Estrogenic or Androgenic implants pose any health risk to
humans?
 Concentrations of estrogen and androgens increase ~ 4 fold
relative to untreated cattle (Daxenberger et al., 2001)
 4.3 vs 20 ng/500g
 Obviously varies among tissue because lipid hormones are
stored with fat
 500 g = daily consumption of 300 g muscle, 50 g fat, 100 g of
liver, and 50 g of kidney (Worldwide Regulatory Organization)
Growth Promotants – Estrogenic &
Androgenic Implants
Do Estrogenic or Androgenic implants pose any health risk to
humans?
 Is the increase in estrogen a risk to humans?
 Assessment by the Food and Drug Administration (FDA)
 Natural hormones regulated through Allowable Incremental
Increase
 No harmful effects will occur if individuals chronically ingest meat that
contains an daily incremental increase of ≤ 1% of what is naturally
produced in the segment of the population with the lowest daily
production (ie: prepubertal boys).
Growth Promotants – Estrogenic &
Androgenic Implants
Do Estrogenic or Androgenic implants pose any health risk to
humans?
 Is the increase in estrogen a risk to humans?
 Previous reports suggested serum concentrations of ~ 8 pg/mL
in prepubertal children based on RIA methods.
 Recent bioassay suggested much lower concentrations, 1.4 and
3.5 pg/mL in prepubertal boys and girls, respectively. (Paris et
al., 2002)
 Corresponds to 7 and 17.5 μg / d in prepubertal boys and girls,
respectively.
Growth Promotants – Estrogenic &
Androgenic Implants
Do Estrogenic or Androgenic implants pose any health risk to
humans?
 Is the increase in estrogen a risk to humans?
 Using 7 µg / d naturally produced in prepubertal boys
 Equal to 7,000 ng
 Hormone-treated beef having 20 ng / 500 g
 Amount of estrogen in a day’s serving of hormone-treated beef is only
0.29% of the amount naturally produced in prepubertal boys
 0.11% for prepubertal girls
 0.014% for men and 0.0032% for women (calculations based on data
from Hartmann et al., 1998)
 Also most prepubertal boys and girls will not consume the 500 g / d as
established by worldwide regulatory organizations
 Ie: ~ 75 g protein (> twice their protein requirement) and 50 g fat
(450 kcal) from animal products / day
Growth Promotants – Estrogenic &
Androgenic Implants
Do Estrogenic or Androgenic implants pose any health risk to
humans?
 All implants are administered in the middle third of the back
side of the ear
 The ear is removed and discarded at harvest, reducing any risk
of estrogen or androgen from entering the food supply.
 Greater risk of your child eating your birth control pills or hormone
replacement therapies.
Growth Promotants – Estrogenic &
Androgenic Implants
 European Commission has agreed that both naturally
occurring and synthetic hormones are safe when used
according to label directions in food producing animals.
 FDA has concluded that there is essentially no difference
between beef from animals raised using hormones and those
raised without their use. The miniscule amount in beef is
well below any level that would have a known effect on
humans.
Conclusions on Growth Promotants
 Increase growth and efficiency of nutrient utilization
 Increased utilization of available resources – land and feed.
 Making them more “Green”?!
 rBST treatment of cows posses absolutely NO risk for human
health
 More research is needed on the health risks to the cow when
treated with rBST.
 Industry will have to respond if there is an effect.
 Although the amount of estrogenic and androgenic hormones
increases by ~ 4 fold in hormonally implanted cattle it posses
no risk to the human population because consumptions is far
less than naturally synthesized in the body.
Antibiotics
Antibiotics
 Why use antibiotics and antimicrobials in livestock
industries?
 Used to treat bacterial infections
 Also used to prevent bacterial infections
 Disease due to bacterial infections decreases performance in animals due
to the nutrient and energy costs of an immune response
 If the growing phase is short this can have tremendous impacts on the
efficiency and subsequent profitability of a producer
 Broiler chicken industry has almost completely bred out the immune
response because the cost of the response is too great relative to the
pay off (extremely short growing period).
 Prevent and control epidemic diseases
 Improve animal welfare
Antibiotics
 Do meat and milk products from livestock contain
antibiotics?
 There is an extremely small chance: Most meat segments will have <
0.5% chance of an animal with an antibiotic residue above safe
tolerable limits.
 Why is important to limit antibiotic contamination of
food?
 Public health issue
 Allergies to certain antibiotics (ie: penicillin)
 Toxicities to certain antibiotics (ie: nitrofurans & chloramphenicol)
 Would increase the likelihood of antibiotic resistance bacterial strains
emerging in the human populations
 Dairy industry issue
 Many dairy products are fermented by specific bacteria added to the milk;
antibiotics in milk could inhibit the growth of the added bacteria
Antibiotics
 How does the FDA assure there is no antibiotics in
animal products for human consumption?
 FDA’s approval process for food animal antibiotics
 FDA audited studies to ensure the meat, milk, and eggs from
animals treated with a specific antibiotic are safe for human
consumption
 Free of antibiotics - Data used to determine withdrawl periods
Specifies the number of days required after the last antibiotic
treatment before the animal can enter the food supply
 They use large margins of safety for establishing withdrawl periods
 As of 2003, determine relative risk of the antibiotic causing antibiotic
resistance in the human population. (Guidance 152; FDA).

Antibiotics
 FDA approved studies to ensure the meat, milk, and eggs from
animals treated with a specific antibiotic are safe for human
consumption
 Determine relative risk of the antibiotic causing antibiotic resistance
in the human population.
 Part 1: Determine the probability that a resistant bacteria will be present as a
result of the antibiotic.
 Part 2: Exposure – determines the likelihood that a human would come in
contact with the resistant bacteria.
 Part 3: Consequence – determines the health consequences if ANY following
human exposure
 If the assessment indicates a high risk the FDA could deny the
application or put restrictions on its use.
 Even medium or low risk could have restrictions regarding its use
Antibiotics
 FDA approved studies to ensure the meat, milk, and eggs
from animals treated with a specific antibiotic are safe for
human consumption
 In addition, the FDA in cooperation with the USDA and CDC
monitor antimicrobial resistant foodborne pathogens in animal
carcasses at slaughter, retail meats, and in human clinical cases
to help provide insight into emerging resistance.
 Can be used to help make future decisions on antibiotic use in livestock.
Antibiotics
 How do we know that producers follow the
appropriate withdrawl times for each antibiotic.
 The FDA and USDA have coordinated surveillance programs
for meat and milk to help ensure that antibiotic residues found
in the products are below safe tolerable limits.
 Monitoring Plan: designed to provide statistical information regarding
the prevalence and concentrations of residues.
 Identifies an emerging problem
 Recent data has indicated a problem in the veal calf industry, which
will now be addressed.
Antibiotics
 How do we know that producers follow the appropriate
withdrawl times for each antibiotic.
 The FDA and USDA have coordinated surveillance programs
for meat and milk to help ensure that antibiotic residues found
in the products are below safe tolerable limits.
 Surveillance: Investigates classes of animals suspect because of a
previous residue.
 Enforcement Testing: Samples collected by USDA in-plant personnel
on suspect animals because of previous residue or antemortem or
postmortem evaluation (ie: does the animal appear sick).
 Unlike monitoring the goal here is to prevent violative products from
entering food supply
Conclusions on Antibiotics
 Antibiotics are used to prevent and treat bacterial infections
 Improve growth
 Prevent and control epidemic diseases
 Improve animal welfare
 USDA & FDA determine the “safety” of a new and approved
antibiotics.
 Since 2003, now consider the “risk” of causing antibiotic resistance in
human population
 USDA monitors and reports the incidence of violative residues
 Identifies problem areas that need to be addressed
 In house USDA personnel test all “suspect” carcasses for antibiotic
residues
 Producer history, or ante- or postmortem animal evaluation
Concluding Remarks
 Population growth is expected and if stabilization doesn’t occur
the population will nearly double by 2050.
 Resources: solar energy, land and water will limit how much food can
be produced
 Technologies that improve utilization of resources in a
sustainable manner need to be implemented.
 Furthermore, the food produced using these technologies needs to be
safe for human consumption.
 Use of growth promotants and antibiotics in livestock have little
or no risk to human health
 In addition to the evaluating human health, the environmental
implications of each new and existing technology needs to be
identified because sustainability = future.
Questions or Comments?