Feed Additives & Hormone Implants
Animal Science II
Unit 7
Objectives
 Discuss the general use and purpose of feed additives and





hormone implants
Describe the proper method of hormone implantation
Discuss the proper use of feed additives for various species of
animals
Discuss labeling and regulation of feed additives
Discuss the proper mixing of feed additives in complete rations
Discuss health issues and concerns relating to the use of feed
additives.
Feed Additives
 Used to
 Improve feed efficiency
 Promote faster gains
 Improve health
 Increase production of animal products
 Not considered nutrients
 Used in small amounts
 Require careful handling and mixing
 Came into use in the early 1950’s
Hormone Implants
 Pelleted, Synthetic compounds
 Placed under the skin or in the muscle
 Used to lower production costs by improving both rate and
efficiency of gain
 Mainly used in beef cattle
Hormone Implants and Feed Additives
 Sometimes called performance stimulants
 Wide variety have been developed, tested and approved for
use
 Some have been discontinued due to toxicity, cost, lack of
proven benefit or excessive residues in meat
Types
 Antimicrobial compounds
 Antibiotics and chemoanticacterials
 Hormones
 Hormone like substances
 Anthelmintics
 Dewormers
 Buffering agents
 Feed flavors
 Bloat preventatives
Antimicrobial Drugs
 Kill or slow down the growth of some kinds of
microorganisms
 Often used as feed additives for livestock and poultry
 Used at a subtherapeutic level of use to keep harmful
microbes under control
Difference Between the Antibiotics and
Chemoantibacterial Compounds
 Major difference is in the way they are produced
 Antibiotics are produced from living microorganisms
 Chemoantibacterial compounds are made from
chemicals
 An antibiotic and antibacterial are combined into one
compound called a chemobiotic
 They are combined to combat a problem that is not susceptible
to either one individually
Common Antibiotics Used in Livestock
Production
 Chlortetracycline (Aueromycin)
 Neomycin
 Oxytetracycline (Terramycin)
 Penicillin
 Streptomycin
 Tylosin
 Polyether antibiotics are called ionophores and are usually used in
the production of ruminant animals
 Monensin (Rumensin)
 Lasalocid sodium (Bovatec)
Common chemoantibacterial
Compounds
 Carbadox
 Furazolidone
 Nitrofurazone
 Sulfamethazine
Use of Antibiotics
 Response varies among species and feeding conditions
 Little or no benefit gained from the feeding of antibiotics
in conditions that are free of harmful microorganisms
 Research in livestock nutrition shows several factors that
explain why antibiotics increase rate of gain, improve
feed efficiency or improve the general health of the
animal
Nutrient Sparing Substances
 The substance allows animals to use available nutrients more
effectively
 Some antibiotics stimulate microbes in the digestive tract to
produce more nutrients than they would without the
antibiotic
Metabolic Rate in Young Growing
Animals
 When fed at low levels in the ration
 Increase daily feed intake
 Conversion of feed to meat is faster and more efficient
 This is compared to animals that are not fed antibiotics
in their ration
Subclinical Diseases
 Disease that is present in the animal’s body at levels too
low to cause visible effects
 Antibiotics can control these disease continuously
 Result is a more vigorous and healthy animal
 Also results in a more uniform rate of gain
Broad and Narrow Spectrum Antibiotics
 Broad Spectrum- control many different microorganisms
 Preferred for use as feed additives
 Generally give better results in terms of rate of gain, feed
efficiency, improved animal health
 Narrow spectrum- control only a few microorganisms
 Used to control specific disease problems that may be present in
the group
Hormones
 Produced in the animals body
 Natural hormones are secreted into body fluids such as
the bloodstream by various glands in the body
 Regulate body functions such as growth, metabolism,
reproductive cycle
Hormone like Compounds
 Synthetic substances that act like hormones
 Both hormones and hormone like compounds are produced
commercially for use as feed additives, primarily in beef
nutrition
Androgen, Progestogens, Estrogens
 Produced by sex glands of the body
 Increase rate of protein synthesis and muscle
development
 Used in rations to improve feed efficiency and rate of
growth
 Beef cattle have shown the greatest response to these as
feed additives and implants
The Controversy Over Hormone Use
 DES
 Approved in 1954
 Disapproved in 1972
 Reapproved
 Banned in 1979
 European Union (EU)
 Banned importation of meat for human consumption
that has been treated with anabolic agents
 1988 WTO ruled that the EU ban was in violation of
trade laws
 As of summer 1999 the issue was not resolved
Anthelmintics
 Dewormers
 May be provided in either feed or water
 Worms reduce feed efficiency and rate of gain
 Good management practices can also help keep worm
infestations to a minimum.
Other Feed Additives
 Coccidiostats
 Used in poultry rations to prevent coccidiosis
 Iodinated casein (Thyropotein)
 Used to increase the amount of hormone thyroxin
 Poloxalene (Bloat Guard)
 Bloat preventative
 Breaks up the foam and slime layer and allows gases to escape the rumen
 Others
 Tranquilizers
 Antioxidants
 Copper compounds
 Probiotics
 Organic acids