Feed Additives
Pages 319 – 325 (Chapter 6)
Why use them?
• Cause a desired response/benefit
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Alter metabolism
affect growth
change pH
manipulate microflora
improve digestion
increase yield
Reduce acidosis
Improve immune response
Increase palatability
Reduce fecal odor
Reduce joint pain
Major Classes
• Growth Promotion and Feed Efficiency
– Antibiotics
• Medicinal Uses
– Coccidiostats, worming agents
• Others
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Buffers and Neutralizers
Antioxidants
Preservatives
Binders
Direct Fed Microbials
Coloring Agents
Flavorings
• Hormonelike products
– Feed Additives
– Implants
Examples
• Antibiotics: disease prevention
• Coccidiostats: control parasites
• Xanthophyll: makes egg yolks yellow
– Cantaxanthin
• Hormones (hormone like): increases growth
• Yeast, Fungi, Direct fed microbials:
• Buffers: HCO3 etc.. Prevent rumen acidosis
• Antioxidants: prevents feed from getting rancid
• Pellet Binders: keeps feed in pellet form
• Flavoring Agents: makes feed taste better
• Surfactants: lipid digestion, increase milk production, yield
• Anionic salts: acidify diet to increase Ca absorption
FEED ADDITIVES
• Use of feed additives is strictly regulated in the
developed countries, and many others, to ensure:
– Human food safety
– Animal safety
– Additive efficacy
– Minimal environmental impact
• Dramatic increase in globalization of marketing
of animal products has led to more uniformity in
regulations among countries.
– Animal products must comply with the laws of
the countries to which they are being sold.
FEED ADDITIVES
• AAFCO (Association of American Feed Control
Officials) provides the U.S. mechanism for
developing/implementing uniform & equitable
laws, regulations, standards, and enforcement
policies.
– Regulating manufacture, distribution, and sale of
safe and effective animal feeds.
• AAFCO defines a feed additive as…
– "an ingredient or combination of ingredients added
to the basic feed mix …to fulfill a specific need."
– " …usually used in micro quantities and requires
careful handling and mixing"
FEED ADDITIVES
• In practice, feed additives are defined as feed
ingredients of a nonnutritive nature that…
– Stimulate growth or other types of performance.
– Improve the efficiency of feed utilization.
– Are beneficial in some manner to health or
metabolism of the animal.
FEED ADDITIVES
• Of the groups of additives classed as drugs, the major
groups include many different compounds:
– Antibiotics, nitrofurans and sulfa compounds.
– Coccidiostats, wormers (antihelminthics & others),
and hormone-like compounds.
• Feed additives have been used extensively in the U.S.
and many other countries since the discovery &
commercial production of antibiotics and sulfa drugs in
the late 1940s.
– The European Union recently banned feeding of antibiotics
to animals meant for human consumption.
FEED ADDITIVES
• Animal products are routinely tested to ensure
that feed additives are being used correctly.
– Use of feed additives has been beneficial to livestock
producers under our modern methods of production.
• Development of intense systems of management
and concentration of animals has been made
possible only because additives could be used to
help control various diseases and/or parasites.
– Broilers, laying hens, growing-finishing pigs, and
fattening cattle and sheep.
ADDITIVES CLASSED AS DRUGS
• In the U.S., use & regulation of additives classed as
drugs is controlled by the Center for Veterinary
Medicine, within the FDA.
– To determine that drugs & medicated feed are properly
labeled for intended use and that animal feeds and
food derived from animals are safe to eat.
• Federal law states no animal drug can be used
in feed until adequate research submitted to the
FDA proves the drug is both safe and effective.
– In developing a new drug for use with animals,
manufacturers must go through extensive testing.
ADDITIVES CLASSED AS DRUGS
Requirements for Medicated Feed
• FDA requirements for medicated feed focus on
mixers who use human-risk drug sources.
– Mixers who do not use human-risk drug sources
are subject to less demanding regulation.
ADDITIVES CLASSED AS DRUGS
Antibiotics
• Antibiotics are compounds produced by
microorganisms.
– inhibit growth/metabolism of some (not all) other
microorganisms.
– In some instances, they may be toxic to warmblooded animals.
– Most antibiotic names end in -cin or -mycin.
• All antibiotics used commercially for growth
promotion are produced by fermentation processes
using fungi or bacteria.
ADDITIVES CLASSED AS DRUGS
Antibiotics
• Antibiotics are effective at improving production
when fed at low levels to young, growing
animals.
ADDITIVES CLASSED AS DRUGS
Antibiotics
• Improve feed efficiency.
– Growth is nearly always increased, particularly with
animals exposed to adverse environmental conditions.
– Feed intake usually decreases in ruminants.
– Varies by animal species.
– Antibiotic-fed animals are less apt to go off feed.
– Can control a wide variety of diseases.
– As a rule, reduce the incidence or severity of several types
of diarrhea
ADDITIVES CLASSED AS DRUGS
Antibiotics
• Some are approved at low levels of continuous use for
reducing the incidence of…
– Enterotoxemia (overeating disease) in lambs.
– Liver abscesses in fattening cattle.
– Diarrhea in young mammals deprived of colostrum.
• In poultry, some claims include…
– Reduction in respiratory disease.
– Nonspecific enteritis (blue comb) & infectious sinusitis.
– Improved egg production and hatchability.
ADDITIVES CLASSED AS DRUGS
Antibiotics
• At higher levels for therapeutic treatments, antibiotics
have been very useful for…
– Cattle - treating or preventing stresses associated with
transportation and adjustment to new conditions.
– Treatment of diseases such as anaplasmosis in cattle and
bacterial enteritis in swine.
– Respiratory diseases, diarrhea, fowl cholera, fowl typhoid,
and breast blisters in poultry.
• In most instances, the higher levels are not approved
for long-term additive feeding usage.
ADDITIVES CLASSED AS DRUGS
Antibiotics
• Two antibiotics for use in cattle, monensin and
lasalocid, are unusual in that they give a good
response in both growing and mature animals.
– Approval was first received for use as coccidiostats
with poultry.
– Both of these antibiotics are quite toxic to horses.
ADDITIVES CLASSED AS DRUGS
Antibiotics
• Obtaining approval for new feed additive drugs has become
more difficult in recent years.
– More investigative effort & expense are involved.
– As a result, not many new additives have been approved in
recent years.
• Very few antibiotic additives are approved for horses,
rabbits, sheep, goats, ducks, pheasants & quail.
– No approvals are given for geese, dogs, cats, exotics.
• The primary reason is the cost of obtaining approval in
relation to potential sales volumes.
ADDITIVES CLASSED AS DRUGS
Antibiotics
• In poultry, the trend is to use one or more
antibiotics in nearly all broiler feeds.
– Most can be used for layers, except high levels
of chlortetracycline and erythromycin.
• Manufacturer approval must be obtained for
using different combinations of antibiotics.
– Or combinations of antibiotics & other controlled drugs.
• Far more drug combinations have been approved for chickens &
turkeys than all other animals combined.
– It is illegal to feed antibiotics at different levels or in
different combinations from those previously approved.
CLASSED AS DRUGS
Arsenicals
• Arsenicals are all synthetic compounds
(chemotherapeutic agent) & include a number of
drugs used in turkey, chicken, and swine rations.
– Developed as a means of controlling parasites.
– Some compounds stimulate growth in the same
manner as antibiotics.
– The effect can be additive to antibiotic stimulation.
• Several arsenicals have claims of improved growth
production as well as improved feed efficiency for
chickens, turkeys, or swine.
– And control of blackhead in poultry & diarrhea in
swine.
ADDITIVES CLASSED AS DRUGS
Arsenicals
• Arsenicals have the disadvantage that they may
accumulate in body tissues, particularly the liver.
– At the levels fed, they are not considered to be toxic.
– All have a minimum 5-day withdrawal period before
animals are to be slaughtered for human food.
ADDITIVES CLASSED AS DRUGS
Coccidiostats
• Coccidia are microscopic parasites.
– Coccidiostats include a wide variety of compounds,
ranging from a number of synthetic drugs to several
of the antibiotics.
• These drugs are of considerable importance to the
poultry producer because close confinement
methods used in modern facilities accentuate the
possibility of coccidiosis outbreaks.
– Evidence suggests coccidiosis is becoming a greater
problem with sheep & cattle in close confinement.
ADDITIVES CLASSED AS DRUGS
Nitrofurans
• The nitrofurans are antibacterial compounds
and are effective against a relatively large
number of microbial diseases.
– Continued use of nitrofurans has not as yet
developed bacterial resistance, as is the
case for some antibiotics.
ADDITIVES CLASSED AS DRUGS
Sulfas
• Reduction in use
– Problems with tissue residues
• Most of problems alleviated by sulfas can be
managed with other additives.
ADDITIVES CLASSED AS DRUGS
Hormone-like Production Improvers
• Melengestrol acetate (MGA) is the only
hormone-like production improver remaining
on the approved list.
– Extensively used with beef heifers; it acts to
suppress estrus, resulting in more efficient and
more rapid gain.
ADDITIVES CLASSED AS DRUGS
Hormone-like Production Improvers
• Although not feed additives, several products
are available for use as subcutaneous implants.
– Hexestrol, (outside the U.S.)
– Zeranol (Ralgro™), said to be an anabolic agent.
– Synovex™, a combination of estrogen & progesterone.
– Rapid Gain™, a combination of testosterone & estrogen
– Steer-oid™, a combination of progesterone and
estradiol.
• A high percentage of growing- finishing cattle are
treated with one or another of these implants.
ADDITIVES CLASSED AS DRUGS
Hormone-like Production Improvers
• In ruminants, natural or synthetic hormones
produce a response that results from increased
nitrogen retention accompanied by an
increased intake of feed.
– Increased growth rate; Improvement in feed
efficiency.
– Reduced deposition of body fat, which may, at
times, result in a lower carcass grade for animals
fed to the same weight as nontreated animals.
-agonists
• Molecules that structurally resemble epinephrine
– Caffeine, ephedrine, aspirin
• Easily made in the lab
• Muscle:
– Increase in muscle synthesis
– Decrease in muscle breakdown
• Fat
– Decrease in lipogenesis
– Increase in lipolysis
• Ractopamine (Paylean)
 Agonist summary
• Structurally resembles epinephrine
• Increases muscle synthesis
– Need to increase the protein % of diet
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Decreases fat content
Orally active
Desensitization
Recently approved for pigs and beef cattle
Antioxidants
• Used to prevent rancidity of unsaturated fatty
acids
• Inclusion rates up to 0.25 Lb per ton
• BHA/BHT (Butylated hydroxyanisole or
toluene)
• Ethyoxiquin
• Vitamin E
• Rosemary
Preservatives
• Used to prevent feed deterioration
(mold/bacteria inhibitors)
– Vitamin C
– Calcium sorbate
– Citric acid
– Phosphoric acid
– Propylene glycol (toxic in cats)
– Sodium propionate
– Sodium metabisulfate
Buffers and Neutralizers
– Buffers & Neutralizers
• Lessen the decrease in pH caused by VFA production
• Valuable for use in high concentrate diets to ruminants
but not high forage diets
• Examples
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Sodium bicarbonate (most effective and most common)
Potassium bicarbonate
Calcium carbonate
Mag oxide
Mag carbonate
DFMs and Yeast
www.microbialcompendium.com
– Bacteria, Enzymes, Mold, Oligosaccharides, Yeast
– Lactobacillus, streptococcus, fungi, aspergillus, bacillus
– Probiotics
• Scientifically inconsistent
• Consist of microbial cultures
– Can stimulate cultural growth
• Reasons for use
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Increase/balance beneficial bacteria
Reduce toxic byproducts of digestion
Support rate of gain and feed efficiency
Alleviate/minimize stress
• Various times for use
– When do you use them?
• Available forms
– Feed additives
– Water dispensing
– Bolus/gel form
Microorganisms found to be appropriate for use n animal feeds
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Aspergillus niger
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Aspergillus oryzae
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Bacillus coagulans
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Bacillus lentus
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Bacillus licheniformis
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Bacillus pumilus
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Bacillus subtilis
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Bacteroides amylophilus
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Bacteroides capillosus
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Bacteroides ruminocola
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Bacteroides suis
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Bifidobacterium adolescentis •
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Bifidobacterium animalis
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Bifidobacterium bifidum
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Bifidobacterium infantis
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Bifidobacterium longum
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Bifidobacterium thermophilum•
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Lactobacillus acidophilus
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Lactobacillus brevis
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Lactobacillus buchneri (cattle only) •
Lactobacillus bulgaricus
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Lactobacillus casei
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Lactobacillus cellobiosus
Lactobacillus curvatus
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Lactobacillus delbruekii
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Lactobacillus farciminis (swine only) •
Lactobacillus fermentum
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Lactobacillus helveticus
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Lactobacillus lactis
Lactobacillus plantarum
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Lactobacillus reuterii
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Leuconostoc mesenteroides
Pediococcus acidilacticii
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Pediococcus cerevisiae (damnosus)
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Pediococcus pentosaceus
Propionibacterium acidpropionici •
(cattle only)
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Propionibacterium freudenreichii •
Propionibacterium shermanii
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Saccharomyces cerevisiae
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*Enterococcus cremoris
*Enterococcus diacetylactis
*Enterococcus faecium
*Enterococcus intermedius
*Enterococcus lactis
*Enterococcus thermophilus
Yeast
Aspergillus niger
Leuconostoc mesenteroides
Pediococcus acidilacticii
Pediococcus cerevisiae (damnosus)
Pediococcus pentosaceus
Propionibacterium acidpropionici
(cattle only)
Propionibacterium freudenreichii
Propionibacterium shermanii
Saccharomyces cerevisiae
*Enterococcus cremoris
*Enterococcus diacetylactis
*Enterococcus faecium
*Enterococcus intermedius
*Enterococcus lactis
*Enterococcus thermophilus
Yeast
Pet Food
• Pet food, including dry and canned food and pet treats, is
considered to be animal feed. Like other animal feed, FDA
regulates pet food and establishes standards for labeling.
• Pet food labeling is regulated at two levels: federal and state.
The federal regulations, enforced by FDA’s Center for
Veterinary Medicine, establish standards that apply to all
animal feeds:
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proper identification of the product
net quantity statement
manufacturer’s address
proper listing of ingredients
• FDA carries out its animal feed regulatory responsibilities in
cooperation with state and local partners, and works together
with AAFCO on uniform feed ingredient definitions and
proper labeling.
Lab Assignment
• Find a research article (journals only) –
additive
• Cite the study
• Indicate species, number animals used,
treatments (doses/inclusion rates)
• Intended benefit
• Outcome