BASIC PRINCIPLES OF ANIMAL SCIENCE
A Reference Unit for Teaching Basic Principles
Vocational Agriculture Courses
W, B. Howell, Jro, Assistant Teacher-Educator
Department of Agricultural Education
University of Florida
Division of Vocational, Technical, and Adult Education
Walter R. Williams, Jr., Director
Agricultural Education Section
Harry E. Wood, Supervisor
Go C. Norman, Program Specialist
R. W. Scull, Assistant
FORE W 0 RD
In view of the broadened program in agricultural education to include "any
occupation involving knowledge and skills in agriculture subjects", it is evident
that basic principles must be taught during the first two or more years in the
high school agriculture curriculum,
References that are concerned primarily with production practices are pre-
sently available to vocational agriculture teachers. This reference titled "Basic
Principles of Animal Science" represents a different approach, and is designed
to fulfill the need for organized subject matter dealing with basic principles.
Much of the organized body of animal husbandry is deeply rooted in the basic prin-
ciples of animal science. By bringing the two together -- the WHY and the HOW
learning will be expedited and interest in performance will be increased.' A
comprehensive understanding of the basic principles underlying a procedure or
practice, in connection with a problem, increases the efficiency of the individ-
ual, and equips him to make decisions on other problems involving the same or
similar principles. Indeed, a practice taught without the understandings of the
underlying basic principles will certainly not equip the students to adjust to
a rapidly changing agriculture.
A The best use of the basic principles seem to be this: Select and incorporate
into the course of study those principles that are truly basic to agriculture and
Then "round out" the instruction by including productive enterprise jobs, improve-
ment projects, supplementary practices, and other activities which can be worked
,9 into a supervised experience program to develop understandings and skills involved.
7"" As already implied, it is not intended that basic principles be used to re-
place or de-emphasize the student's supervised experience program. Indeed, it
Sis highly doubtful that basic principles can be effectively taught unless they
are put into actual practice, Numerous experiences with the applications of
these basic principles should result in the permanent and productive vocational
education of our students,
Teachers are urged to supplement this reference with additional basic referen-
ces, as long as they are reliable, and to use pictorials, specimens, films, film-
strips, and other visuals to make the information more meaningful.
We are greatly indebted to the Agricultural Education Department of Mississippi
State University, and Mr. L. P, Jacks, Subject Matter Specialist, for permission
to reproduce some of the materials in this publication.
Subject Matter Specialist
TABLE OF CONTENTS
I. Anatomy and Physiology of Farm Animals
A. Skeletal System . ... . . . 3
B. Muscular System . . ..... . . .. . . 3
C. Nervous System . ....... ...... .. 4
D. Circulatory System .... ........ . ... 4
E. Respiratory System ........ . . . 7
F. Excretory System ............ .. .. 7
G. Digestive System ........... . . 8
H. Sense Organs and Common Integument ....... .... 10
I. Reproductive System ........... .... 10
II. Nutrition of Farm Animals .. ...... . .... .. 23
III. Environmental Factors That Affect Physiology . . . 34
IV. Diseases of Farm Animals ............ ... ... 36
V. Common Parasites of Farm Animals (Economics) . . . . 43
BASIC PRINCIPLES OF ANIMAL SCIENCE
I. Anatomy and Physiology of Farm Animals
The animal body is a highly complex structure which may be defined
as: the living mechanism composed of systems of organs working harmon-
iously under the control of the nervous system, and capable of transform-
ing, storing, and releasing energy. Each system is composed of a group
of organs that perform a particular function. The organ systems of the
A. Skeletal D. Circulatory G. Digestive
B. Muscular E. Respiratory H. Sense Organs and
C. Nervous F. Excretory Common Integument
A. Skeletal System
1. What are the types of skeletal systems?
The animal kingdom is divided into two sub-kingdoms the verte-
brates, and the invertebrates. Vertebrates, are animals having a strong
internal framework, or endo-skeleton. Invertebrates, are animals hav-
ing an exo-skeleton type framework, such as insects, crayfish and a
host of others. Our interest in this publication will deal only with
the vertebrate sub-kingdom, which includes human beings, farm livestock,
2. What are the functions of the skeletal system and how is it related
to animal quality?
This system is composed of the bony and cartilage structures of
an animal's body. It serves to support the other body systems, for pro-
tection, and acts as levers of motion. In addition, the bones through
the medium of their red marrow manufacture the red-blood corpuscles,
some forms of white blood corpuscles, and serve as a store house for
minerals that is drawn upon when the body needs demand a supply.
The quality of the skeleton is closely related to an animal's
health and quality. It should be well-developed and maintained through
proper management of the animal in order that it can best serve the
needs of the animal. Poorly developed skeletal systems are unable to
support the heavy loads of the other body systems, and will result in
an animal of lower quality and less monetary value.
B. Muscular System
1. What is the function of the muscular system, and how does it relate to
quality in an animal?
This is the largest of all the body systems from the standpoint
of weight. In meat-producing animals it is the most important from an
economic viewpoint. Composed of a great many separate muscles, the sys-
tem is concerned with all body movements, both voluntary and involuntary,
such as walking and jumping, blood circulation, digestion, respiration
Muscles are of two types, Visceral and skeletal. The visceral mus-
cles are located in the walls of the heart, digestive system, blood ves-
sels and other hollow organs. Skeletal muscles comprise all the flesh
or lean meat of the body and represent approximately 45 percent of body
weight. This edible meat is for the most part connected directly or in-
directly with the skeleton. The connective tissues of the edible por-
tions of the meat are far less tender than their lean meat contents. It
follows that their presence in large quantities characterize the less
tender cuts. The amount of connective tissues varies with age (greater
in older animals), and within a given age animal, are more numerous in
those areas where there are the greatest number of small muscles. For
example, in beef there are the less tender cuts such as the shank and
neck- heavily exercised parts. Since the inside muscle of the round
(top round), the strip muscle of the loin and the eye muscle of the rib
receive a minimum of exercise and are in themselves large muscles con-
taining little connective tissue, they are the most tender cuts.
C. Nervous System
1. What is the function of the nervous system, and its relation to animal
behavior and production?
This is the most highly developed system of a vertebrate. It is
the system which enables animals to find food, fight enemies, and to
guard against danger. Its function is to coordinate all activities of
the body. Impulses are transmitted by nerves from the body tissues and
organs to nerve centers, and in turn are sent from these centers to the
tissues and organs.
This system may be conveniently divided into three main parts: (a)
he, nJtral system, comprising the brain and spinal cord, which com-
municates with all parts of the body by means of (b) th.-le.tL r_)LI
ystem and (c) the autonromic or ympatheti s.ytJJsj which regulates
certain involuntary functions almost independently of the central
system. These three divisions have intimate relations with each other
by means of connecting fibers. They are not to be considered as sepa-
rate systems but as parts of the nervous system as a whole.
It is a well known fact that the temperament of an animal affects
its behavior and production. For instance, anything which frightens
the dairy cow or annoys her can interfere with the "milk let-down" pro-
cess, and there may also be a decrease in the egg production of the
laying flock during stress periods.
D. Circulatory System
1. What is the function of the circulatory system, and its relation to
animal health, quality and value?
It consists of the heart and blood vessels which function as the
transportation system of the body.
The heart is the central organ of this system, corresponding to
the pump of a farm water supply station in that it pumps the blood
through the vessels by strong muscular contractions, yet it differs
somewhat in that the blood is eventually returned to it, afterwards
Distributed oy -
MISSISSIPPI STATE UNIVERSIlY
Agricultural Education Department
Subject Matter Service
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being pumped out again into the vessels- a continuous circulating pro-
cess. Blood is pumped from the heart into arteries, which are the tubes
that transmit the blood from the heart to the lungs and on to the body
cells. The artery branches again and again until the branches are too
small in size to be seen with the naked eye. Veins, companion vessels
of the arteries, conduct the blood back to the heart from the tissues.
Blood is a fluid tissue which travels through the circulatory sys-
tem. transporting digested food, cell wastes, oxygen, water, heat and se-
cretions. Its function is to aid in growth and repair of cells, supply
energy, regulate body processes, etc. It is composed of plasma and
solid components, known as red corpuscles, white corpuscles, and plate-
lets. Plasma contains digested food going to the body cells, and waste
products on their way to the kidneys, lungs and skin. The red corpus-
cles carry oxygen from the lungs to the body cells. The white corpus-
cles, fewer in number and larger than the red, are known as "scavengers"
or "soldiers" of the blood and aid in defending the body against infec-
tion. It is believed that platelets aid in the clotting of the blood.
A healthy, properly functioning circulatory system is important to
the farm animal in that it has much to do with the animal's general
health and quality and these in turn affect the value of the animal.
E. Resplratory System
1. What are the functions of the respiratory system, and its relation to
This is the system through which animals supply oxygen to the body
cells and excrete carbon dioxide wastes.
Oxygen being fed to the body cells, in the form of air, normally
enters the respiratory system through the nostrils where it comes in con-
tact with a mucous membrane which warms, moistens and filters it. It
then passes through the pharnyx (back of the throat) into the larnyx
(voice box) which is commonly known as the "adams apple". It then pass-
es into the trachea, or windpipe, the tube that connects the larnyx
with the lungs. From there it enters the lungs by the way of the bron-
chi, two tubes at the entrance to the lungs.
Oxygen from the inhaled air is absorbed into the bloodstream
which supplies it to the body cells and excess carbon dioxide is ex-
haled as a waste product for use by plants.
Huge quantities of oxygen are demanded by the body cells. The
oxygen, as mentioned previously, must be filtered and warmed and wastes
in the form of excess amounts of carbon dioxide must be excreted. An
improperly functioning respiratory system will prevent these functions
from being carried out and may result in an unhealthy condition.
F. Excretory System
1. What is the function of the excretory system?
This system includes the skin, kidneys, lungs, large intestine,
and the liver, several of which also function as part of other systems.
Various wastes that result from body metabolism are excreted from
the body by the organs of this system. The major roles played by each
of the organs of this system are:
a. Sj -- The skin assists the kidneys in removing large quanti-
ties of water, "salts", and urea, in the form of perspiration. Its
most important function is that of serving as a "radiator" in regu-
lating body temperature. In addition, to its excretory functions,
the skin protects the inner tissues from drying out, and has other
b. Kiady~ -- They serve as blood filters, purifying the blood by
removing most of the nitrogenous wastes, excess water, minerals and
c.' igSS -- In addition to their respiratory role, they excrete
carbon dioxide and considerable water in the form of vapor.
d.* IS.g intestine -- It plays a dual role as a part of both the
excretory and digestive systems. Its excretory function is to excrete
e. Liver -- The liver, also an organ of the digestive system,
assists in ridding.the body of waste materials by forming urea which is
discharged by other excretory organs.
G. Digestive System
1. What is the function of the digestive system, and how are the systems
Digestive systems are comprised of organs which prepare food for
use by the body. They may be classified as follows: (a) ruminating or
"cud chewing" system of cattle, sheep, and goats, and (b) the non-rumi-
nating system of hogs, horses, and poultry.
2. How does digestion take place in ruminants?
The digestive systems of ruminants are comprised of the mouth,
gullet, and the four-compartment compound stomach, which is divided as
1st compartment Rumen, or paunch
2nd compartment Reticulum
rd comrartioent Cmasum, or many-plies
th compartment Abomasum, or "true stomach".
Other parts of the digestive system are the small intestine and the
large intestine, mouth, teeth, and esophagus.
During the eating process, these animals chew their solid food
just enough to make swallowing possible. When mature animals swallow
their food it:passes through the gullet (esophagus) into the first com-
partment:(rumen), which is the largest of the four compartments. The
rumen contains billions of bacteria that have the ability to break down
high-cellulose content feeds, thus accounting for their ability to uti-
lize large quantities of roughage. They also have the ability to pro-
duce protein from nitrogen in the consumed feed. This synthesized pro-
tein contains all the necessary amino-acids for proper nutrition. The
micro-organisms, also, produce practically all the needed vitamins.
When a ruminant has eaten enough food .to satisfy its appetite, it
seeks a quiet place, if possible, and proceeds to ruminate, or "chew
its cud". During this process food is regurgitated, or "belched",
from the rumen into the mouth where it is rechewed. (Only that por-
tion of grain that becomes entwined in the bolus of roughage is regurgi-
tated. Consequently, kernals of whole grain that have escaped mastica-
tion will pass through the rest of the digestion system in an unbroken
condition.) After rechewing, the food is again swallowed into the rumen
where further digestive action takes place.
It then passes into the second compartment of the stomach, the
reticulum, whose major function is to furnish additional storage space
and to sort out and retain most foreign materials such as wire and nails.
Food then passes into the third stomach compartment, the omasum,
which consists of strong muscular walls that aid in further breaking up
the food material. The omasum and reticulum have common openings with
the rumen from the gullet.
The food then passes into the last compartment of the stomach, the
abomasum, where it mixes with gastric juice which is necessary in pro-
When the food leaves the abomasum it goes into the small intestine
where pancreatic, bile, and intestinal juices are mixed with it. The
digestible portion is then absorbed into the bloodstream and the un-
digested or waste portion is passed into the large intestine and elimi-
(Note: The rumen increases in size as the animal matures and
eats increasing amounts of grain and roughage. In the case
of young calves consuming milk the slit-like esophageal groove
closes to prevent the milk from entering the rumen, causing
it to flow directly into the third and fourth compartments
of the stomach.)
3. How does the digestive process take place in non-ruminating farm
The type of digestive systems of non-ruminating farm animals are
less complicated than those in ruminants.
a. The digestieresgin swine and horses.
The major difference in the make-up of the digestive system of
these animals from that of the ruminants is that swine and horses
have a simple stomach, consisting of a single compartment. The di-
gestive process is generally the same as that of ruminants, with the
exceptions that the simple stomach of these animals performs the func-
tions of the complicated four compartment stomach in ruminants, and
that regurgitative action is absent.
This type system consists of the mouth, gullet or crop, proven-
triculus (glandular stomach), and the gizzard ventriculuss). It is
usually classified as a simple-type system, as compared to the more
complicated system in ruminants, even though it varies somewhat from
the simple system of the hog and the horse.
Food taken into the mouth is mixed with saliva and forced down
the throat, or gullet, into the crop, or craw, a pouch-like enlarge-
ment of the gullet, which acts as a "hopper" for the gizzard. Here
the food is temporarily stored, partially softened, and some bacterial
action takes place. It then passes from the crop into the proventriculus
where gastric juices are mixed with it. The food remains here only a
short time before it passes on into the gizzard, or muscular stomach,
where it is thoroughly crushed and ground. From here on the digestive
process is very similar to that in cattle, hogs, etc. However, the
undigested portion of food and urine are excreted together.
(Mote: Refer to Dr. Salsbury's Manual of Poultry Diseases",
1962, PP 24-25, for a diagram of the digestive system of
An excellent 16mm color film on digestion entitled,
"The Rumen Story" may be obtained from the Purina Company,
Checkerboard Square, St. Louis, Missouri.
H. Sense Organs and Commron Integ lent
1. What are the functions of the sense organs and common integument?
The sense organs are the organs of the senses that receive extern-
al stimuli and conduct impulses to the brain that result in the abili-
ty of the animal to see, hear, taste, smell, and feel.
The common integument consists of the skin with its appendages
of hair, hoof, feathers, etc., and serves primarily as the protective
covering of the body.
I. Reproductive Systems (and Reproduction)
Perhaps no phase of physiology creates a greater interest than the
study of the mystery of reproduction.
1. What is meant reproduction?
Reproduction in animals is the process whereby new animals are
produced. It begins after copulation (mating) when the sperm, the male
germ cell, unites with and fertilizes the egg, or ovum, which is the fe-
male germ cell. The union of sperm and egg takes place within the body
of the female, where the offspring is nourished and protected until
2, What are the parts and functions of the reproductive systems of:
(1). The female.
(a) OvarLes -- two glandular organs located near the posterior
end of the reproductive tract. They have a two-fold purpose, in that
they produce eggs, or ovum, and have an endocrine function. Each
ovary contains many follicles, in which the eggs are produced.
(b) Oviducts (Fallopian tubes) -- two funnel-like tubes leading
from the ovaries to the horns of the uterus. Fertilization of the
egg usually takes place near the upper end of the oviduct.
(c) Uterus (Womb) -- a hollow organ, containing two horns, which
are connected with the oviducts. Place of fetal development.
(d) Cervix -- the neck of the uterus, that separates it from the
vagina. It is known as the valve of the tubular genital tract.
(e) Vagina_(female copulatory organ) -- a passage way connect-
ing the Vulva and the cervix.
(f) Vulva -- the reproductive and urinary organs of the female
(2). The male.
(a) Testicles -- where sperm cells are produced.
(b) Sperum ducts (vas deferens) -- two tubes connecting the testi-
FIGURE 2. Generative and Urinary Organs of Cow.
FIGURE 3. Generative and Urinary Organs of Bull.
Agricultural Education Service
cles with the urethra. Sperms pass through these ducts and may be
stored at the upper ends of these tubes.
(c) Semal vesicl -- glands opening to the urethra. They se-
crete a fluid.
(d) Erosiat -- produces a fluid that mixes with the seminal
fluid. It is located near the urethra and bladder.
(e) Cowgergs ane. -- secretes a fluid that precedes the passage
of the sperm cells down the urethra.
(f) Urethra -- a long tube that carries both semen and urine. It
extends from the bladder to the end of the penis.
(g) Eelg -- the organ which deposits the sperm cells within the fe-
male reproductive system.
3. How does the reproductive process take place?
Each animal has its origin when the male germ cell, or sperm, unites
with the female germ cell, known as ovum or egg.
The reproductive process begins with the heat period or estrus. The
estrus cycle is the chain of events dealing with reproduction, and occur-
ring in the non-pregnant female between heat periods. During the heat
period the female animal is receptive to the male. It begins by the ripen-
ing of the ovaries in the female. These eggs, when ripe, rupture the
ovary walls and drop into the upper parts of the oviduct, or Fallopian
tubes. They travel by gravity and motion to the uterus or womb.
During the processes of natural mating or artificial insemination
the male sperm are deposited within the uterus of the female. These
minute-size "wiggle-tale" sperm immediately begin to seek-out an egg.
If no uniting takes place the female fails to conceive and the germ cells
are absorbed by the body and the heat period is repeated. If, however,
a sperm is successful in fertilizing an egg then the female conceived and
a new individual begins to develop. Normally only one sperm unites with
After being fertilized, the egg soon passes down the tube into the
uterus or womb. Here it finds nourishment and quickly develops by the
process of cell division. The embryo becomes attached to the mucous mem-
brane of the uterus, where it has direct contact with the functioning
organ systems of the mother, remaining dependent throughout the entire
gestation, or pregnancy period. Then, as soon as the development of the
new individual is complete, the individual breaks contact with the body
of the mother and is born.
(Note: If more than one egg becomes fertilized and develops,
multiple births occur. However, twins, triplets, etc. origi-
nated in this manner are fraternally related and are no more
alike than other brothers or sisters. On the other hand,
when multiple births occur from the division of a single egg
that has been fertilized by a single sperm, these individuals
are identical. Identical individuals closely resemble each
other in physical traits and mental characteristics, and are al-
ways of the same sex.
When a bull and heifer calf are born twins, the heifer
is often sterile, and is known as a free-martin. This sterili-
ty is due to the hormones of the male being dominant to those
of the female, which results in imperfect development of the
heifers reproductive system. Most cattlemen, for instance, pre-
fer single births due to the above reason, the increased
mortality rate of twins, and the tendency of the dam of
twins to have a decreased conception rate.)
4. What is the reproductive cycle in domestic animals?
"I --- -- ----- -
Aver- Varia- in relation
age tion to heat period
I I _ I _
3-5 mo. All
ning of heat
1/ Age when animal becomes of breeding
age. Varies with breeds and indi-
2/ Period when egg is released from the ovary and is capable of being
/ Period of pregnancy. Varies with breeds, individual, etc.
/ If unbred during this period, season extends to late December or early
Dorset Horn and Merino breeds may breed any time of the year.
If unbred may continue heat periods for a variable period.
* Even though these species of animals are not of economic importance on
the farm this information is included here, due to the many requests for
2 or morph
I CrS--~ Cr
,~ . . .. , .. H I-
- -- --
FIGURE 4. Obstetrical Chart, -Cow.
A. Foetal Membranes of the Cow at
Mid-Term--Uterus Open on its Left
C. Foeti No's 1 &2 --Normal Position,
Foetus No. 2 --Normal Position,
B. Beginning of Act of Parturition.
D. Anterior Presentation: Lateral Devi-
ation of the Head Towards the Abdo-
men (Abnormal Position).
E. Posterior Position of the Foetus (Ab-
F. Fore-Limbs Flexed at the Knees, in
the Anterior Presentation. (Abnormal)
The reproductive process of the young in poultry differs con-
siderably from that in livestock.
During the formative process of the egg within the reproductive
tract of the hen the germ-cell deposited by the male fertilizes the
female germ cell, which is located on the outer edge of the yolk of the
egg. This marks the beginning of a new chick. If after the egg is
laid proper temperature is maintained the embryo continues to develop.
Proper humidity is also necessary for successful development. During
the development period the embryo receives its nourishment from the egg
contents, which are completely consumed at the end of the twenty-one
day hatching period.
(Note: It is not necessary for the male to deposit sperm
within the reproductive tract of the fenrale between the
laying of each egg since the sperm retains its full fertili-
ty for approximately six days. The fertilizing ability of
the sperm decreases thereafter to approximately fifty percent
on the tenth day, and to.approximately fifteen percent on the
19th day. Occasionally eggs may be fertilized up to twenty-
six days after a single insemination.)
Days Chick Development in an Egg During Incubation
1 3 Development is continued during the incubation period after
the egg has been laid.
4 A network of bloodcells are visible.
7 The head, limbs, eyes and abdomen are evident.
8 The legs and wings are well-formed. Toes are noticeable.
9 Down appears on parts of the body. Beak is fairly well-
19 Embryo is well-covered with down. Yolk sack is being drawn
into the abdomen as the last of the food is utilized.
21 The embryonic development is complete and the chick frees
itself from the egg shell.
5. What effect does pregnancy have on lactation?
The period of lactation in milk producing females is the period of
secreting and yielding milk by the mannary glands. In dairy cows, the
yield of milk after calving usually increases for a period of time and
then gradually decreases as lactation advances. Pregnancy has no appre-
ciable effect on the milk yield until after about 5 months, after which
it hastens the decline.
6. What is the relation of an animal's reproductive capacity to profit?
Fertility and sterility are two terms that relate to the reproduc-
tive capacity of an animal. Fertility refers to the ability of the male
or female to produce viable germ cells that are capable of uniting with
the germ cells of the opposite sex and of producing vigorous, living
offspring. Fertility is lacking in very young animals. It first mani-
fests itself at puberty, increases for a time, levels out, and then de-
creases in very old animals.
Sterility, on the other hand, means exactly the opposite of fertili-
ty-infertility or barrenness. It may be defined as the inability of an
animal to reproduce, and may be temporary or permanent. The incidence of
sterility varies considerably from herd to herd, and from year to year with-
in the same herd, Fortunately, very few barren cows or sterile bulls are
permanently and totally infertile. It is believed by authorities that
approximately 10% of the infertile or sterile cases are due to inherent
traits while the remainder are due to environmental conditions such as
genital infections, diseases, silent heat periods, failure to come into
heat, excessive inbreeding, poor feeding practices, poor management, etc.
The possibility for profit in a given livestock enterprise is prac-
tically dependent upon the breeding efficiency of the animals within the
herd. In fact most beef cattlemen, acknowledge that the calf crop per-
centage is the largest single factor affecting profit in beef cattle pro-
7. What are the methods of breeding animals?
Two methods are commonly practiced: (a) natural breeding controlled
and uncontrolled, and (b) artificial breeding.
a. Natural breeding -- Controlled natural breeding, one of the two
natural types, consists of confining the male and bringing the female to
him. This manner is very commonly used by purebred breeders because
registration requires specific breeding information that would not be ob-
tainable under the uncontrolled method. Uncontrolled natural breeding, or
pasture breeding, is simply allowing the male animal to run with the fe-
males in the pasture,
b. Artificial breeding -- This method consists of a practice in
which semen Tspermatazoa is collected from the male artificially and
inserted into the reproductive tract of the female. This method of mat-
ing farm animals is very common with dairy cattle, but to a lesser degree
with other animals.
8. What are the different systems of animal breeding?
A breeding system is a system of mating animals in order to produce
a given result. Successful breeders follow a breeding system, the purpose
of which is to give greater control of heredity than if selection alone
is used. Therefore, breeders need to know about the different breeding
systems. The various systems of breeding are (a) inbreeding, (b) line-
breeding, (c) outcrossing, (d) crossbreeding, and (e) upgrading. These
systems may be practiced with either grades or purebreds. There is no
one best system. Each has its advantages and disadvantages depending
upon the situation of individual livestock-men. In determining the sys-
tem of breeding to use, careful consideration should be given to such
factors as the size and quality of the herd, skill and experience of the
farmer, operating capital, and the purpose of the production program.
a. Inbreeding -- This system of breeding involves the mating of
closely related animals such as sire to daughter, brother to sister, or
son to mother. This system if often referred to as closebreeding. It was
widely used in foundation stock in the establishment of practically all
of the beef breeds in order to intensify the production of animals uni-
form in type and other characteristics. The use of this system is now
limited to a comparatively few breeders who have purebred herds of such
highly developed type and quality they feel that no further improvement
could be made by getting breeding stock outside their own herds.
Just as inbreeding intensifies desirable traits, by the same token,
it intensifies undesirable characteristics or weaknesses. Therein lies
the danger of inbreeding for all livestockmen with herds of no more than
average quality. The use of this system requires very rigid culling to
eliminate the "fixing" of undesirable traits, and hence is rather expen-
b. S^gA~p g -- Actually, this is almost the same system as in-
breeding, just less intense. It consists of mating animals not closely
related such as half brother to half sister, cousins, grandparents to
their offspring, etc., all of which trace in pedigree to an outstanding
ancestor. This system of breeding was widely used in developing family
lines or bloodlines that have been so popular during recent years.
This system of breeding does not offer the possibilities for improve-
ment as does inbreeding, nor does it offer the possibilities for regression
or the intensifying of undesirable characteristics as inbreeding does. It
is more nearly adapted for improvement in the herds of larger purebred
operations. It is never used in grade or commercial herds.
c. Outrossing -- This system of breeding consists of the mating of
animals of the same breed which have no close-up relationship in the pedi-
gree. For practical purposes they might be considered as unrelated ani-
mals. This system is probably the most widely used among the purebred
breeders, except in the largest and most highly advertised herds. Out-
crossing is sometimes referred to as linecrossing and is a very practi-
cal and relatively safe breeding program because it is very unlikely
that two unrelated breeding animals would transmit the same undesirable
traits to their offspring. In fact, many purebred breeders often remedy
a weakness or undesirable trait that occurs in their herd by outcross-
ing with an animal known to be especially strong.in such trait.
d. Crossbreeding -- This system consists of the mating of purebred
animals of different breeds. It is the system of breeding that has been
used to develop many comparatively new American breeds of livestock.
In broad terms, crossbreeding also includes the mating of purebred
sires of one breed with high grade animals of a different breed. This is
the practical application of crossbreeding made by most commercial
livestock-men with grade herds. Crossbreeding gives the offspring the
advantage of hybrid vigor, and often an increase in rate of growth and
efficiency of production. When a good selection is made of breeding
animals, particularly the males, used in crossbreeding, the desirable
traits in both parents seem to be strengthened and the undesirable traits
seem to become recessive or overshadowed. The limitation of this system
of course lies in the female replacement program, for in a very few
generations one most likely would have a herd lacking uniformity size,
color, and conformation if he attempted to save replacement females from
his own herd.
e. Up~gragdS -- This is the system of breeding where purebred
males of any pure breed are mated to native, nondescript grade females.
The purposes are to develop uniformity, improve quality, and increase
performance in the offspring. Naturally, the greatest progress is made
in the first cross because 50 percent of the inheritance of the offspring
comes from the sire. Progress will continue to be made by following this
system. By the fourth generation cross, the animals will be carrying
about 94 percent pure blood.
This is the breeding system followed by nearly all commercial beef
cattle producers in Mississippi and wonderful progress has been made dur-
ing the past decade or more in improving the quality of our cattle. The
big problem is getting farmers to select really good purebred bulls to
use in this system.
(Note: ePu.r.eAis.e.is.no .. s .ein.a..
jTe_ ved. The production of purebreds is a system of pro-
duction or type of operation. For example, within beef
cattle farming several of the types of operations, or sys-
tems of production, are (a) purebred, (b) baby beef, (c) cow
and calf, (d) stocker, and (e) fattening.
The words "purebred" and "thoroughbred" are not synon-
omous and should not be confused. A purebred animal may be
defined as a member of a breed, the animals of which possess
a common ancestry and distinctive characteristics; also, he
is registered or eligible for registry in the herd book of
that breed. Thoroughbred is a breed of horses.)
9. What is meant b_ a "breed of livestock"?
A breed may be defined as a group of animals having a common origin,
and possessing certain well-fixed and distinctive inherent characteris-
tics not common to other members of the same species. For example, there
is the Hereford beef cattle breed, the Jersey dairy cattle breed, and the
Poland China breed of hogs.
10. What is meant ] bloodline, or "strain"?
The term bloodline, or "strain", as used here might be considered to
be synonymous with families or family lines of breeding. In the develop-
ment of various breeds within the various species of animals, individuals
often use unrelated animals in their breeding program; thus separate fami-
lies, or bloodlines (sometimes called "strains"), soon take on significance
of certain characteristics of the breeds. These breeders have done this
in an effort to improve certain characteristics within their breed.
11. What is meant b_ "typiness" in livestock?
Typiness in animals may be defined as an ideal combining all the
characters that contribute to the animals usefulness for a given purpose.
There are several distinct types of animal within each species of
livestock. Within the cattle species there are the following types:
a. Beef -te -- These are animals fed for the purpose of converting
feed into maximum meat. Examples are the Hereford, and Aberdeen-Angus
b. BB1 .1ry g -- In contrast to the beef-type, these animals are
bred in such a way that their major purpose is the production of milk.
Examples are, Jersey, Guernsey, and the Holstein-Friesian breeds.
c. Dualpurp22eSye -- Animals of this type are combination meat-
milk producing animals that are intermediate between the beef and dairy
types. Examples are, the Milking Shorthorns and the Red Poll breeds.
In addition, there is another known as the Draft-type. Even though
very few of their type exist in this country, they are an important source
of power in some parts of the world. They are characterized by their
ruggedness, vast size and length of leg.
Within the swine species there was for years the (1) Lard-type, and
(2) Bacon-type of hogs. The demands of the consumer have long since
changed and is today for a meat-type hog. Today, an animal of this type
is neither lard or bacon-type, nor a cross between these types. The meat-
type hog is characterized by its ability to yield a high percentage of
high quality lean meat. The ability of this type hog to do just that is
due to the fact that it is a bred-in characteristic, and not the result
of reduced amounts of feed. There is no one breed of meat-type hogs, but
rather there are meat-type hogs within many different breeds. Some of the
more recently developed breeds have been developed specifically toward
producing only meat-type hogs, and many breeders of long established hog
breeds have made much progress along this line.
Within the poultry species the types are classified as (1) Egg, and
(2) Meat types.
12. How does tyje, beed, and bloodline (family line or "strain") affect
quality and value of farm animals?
As implied in the above question, type, breed, and bloodline
influence the quality and value of an animal.
Type, as previously discussed, refers to the various types of animals
within the several species of livestock and poultry -- beef, dairy, and
dual-purpose types among cattle, and the various types among other species.
"Typiness", also previously discussed, refers to the ideal type combining
all the characteristics that contribute to the animals usefulness for a
given purpose -- beef type for beef, dairy-type for milk, etc.
When the housewife goes to market she is usually looking for, and
willing to pay for, good meat. To meet this demand it is, of course,
necessary for the producer to grow the type of meat that meets her require-
ments. If she is looking for good beef, then she will more likely get it
from carcasses of beef-type cattle rather than from those of dairy-type or
beef-dairy crosses, because dairy and beef-dairy crosses do not have the
conformation and quality, and generally do not have the finish, afforded
by beef-type animals. If she is looking for good pork, she will be more
likely to find it in carcasses produced by meat-type hogs, which produce
a high proportion of lean to fat. Likewise, she will find that the best
broilers come from the broiler-type strains rather than from those of the
egg type. When the milk producer goes to market to buy an addition to his
dairy herd he is looking for a true dairy-type animal because it will pro-
duce him more milk and do so more profitably than an animal of beef or
dairy-beef cross. Consequently, type does affect the quality and value
of an animal.
It is sometimes believed that there is very little difference between
the quality and value of breeds, but a great deal of difference between
individual animals within a breed. It is true that a great deal of differ-
ence exists among individuals. And it is usually true that not a great
deal of difference exists between some breeds, but this does not necessari-
ly hold true for all breeds. Actually there are differences between the
breeds of the various species of animals, differences between the various
bloodlines (family lines or "strains") within each breed, and differences
between individuals themselves within these bloodlines.
(Note: Many factors should be considered when selecting
breeds, bloodlines and individuals; however, since the
intent of this publication is to furnish information
dealing with certain basic principles, these factors are
not being listed here but are to be listed and consider-
ed when the student is actually in the process of select-
ing a breed, bloodline and an individual animal.)
The following are merely a few pointers to show that differences
exist between breeds, between bloodlines within a breed, and between in-
dividuals within a bloodline:
a. Dwarfism in cattle, while probably appearing in all breeds,
appears more often within some breeds than others, and within
these breeds it appears more often in some bloodlines than in
b. Within a given specie of meat animals there is little dif-
ference in the dressing percentage of most breeds. Yet, several
breeds within each specie tend to yield a higher dressing percent-
age than others, and tend to produce a higher grade of meat in
a shorter period of time. Likewise, there is a variation between
the dressing percent of animals from the different bloodlines,
as well as between individual animals within these bloodlines.
c. Calves of some breeds consistently outgain calves of other
breeds when they are marketed as milk-fed calves. There are al-
so variations among the bloodlines, and between individuals with-
in these bloodlines.
d. Some breeds of beef cattle are often harder to handle as live
animals- thus influencing in an indirect manner their market
e. Animals of some breeds of beef cattle are more susceptible
to pinkeye, and to cancer eye than are animals of the other breeds.
f. Breeds of dairy cattle vary in their milk-producing charac-
g. Breeds, varieties and strains of poultry vary in their abili-
ty to produce eggs and meat. Some breeds, for instance, produce
white eggs, while others produce brown eggs. These colors in
some instances affect the salability' of the eggs on the market.
Even though some breeds vary in their abilities, keep in mind that
different strains within each of these breeds often vary considerably and
that within each strain of each breed there are often considerable differ-
ences among individuals.
II. Nutrition of Farm Animals
1. How are feeds utilized by animals?
Approximately one-half of the nutritive content of feeds are used
merely to maintain the necessary life processes, such as providing energy
for body movements, food digestion, maintaining and regulating body tem-
perature, etc. The remaining nutrients provide for growth, fattening, and
2. Ug are the following terms defined?
a. t. i..t~ -- This term is applied to any food constituent, or
group of foods of the same general composition, that nourishes and pro-
motes growth. Proteins, carbohydrates, fats, minerals, and vitamins are
the classes of nutrients. Although not actually a nutrient, water is
usually listed with them because it is essential for most body functions,
including the digestion of food.
b.D JW;tEkeJ-a Jtrbj ejt -- This term, usually applying only to pro-
tein, carbohydrates, and fats, means that portion of a nutrient which may
be digested and utilized by the body.
c. Pation -- A ration is the total feed allowed for a given animal
during a twenty-four hour period.
d. Balanced ration -- This is one which furnishes over the twenty-
four hour 'perfoj afi: of the feed nutrients in the necessary proportion and
amounts to provide proper nourishment.
3. What Is the relationship of nutrients in feed to the animal's body
a. rrjSjD -- are necessary for growth, reproduction, and maintenance.
They build muscles and new tissues (including lean meat), and repair worn-
out or damaged tissue. Protein not needed as protein may be used to supply
energy. They are very essential in the production of animal products such
as meat, milk, eggs, and wool. Protein constitutes the greater part of
muscles (including lean meat), internal organs, cartilage and connective
tissues, skin, hair, horns, and hoofs. Some of the feeds high in protein
content are cottonseed meal, soybean oil meal, tankage, skim milk, legum-
inous hays, etc.
b. SaOgBydrates -- furnishes energy required for body functions. Ex-
cessive amounts above maintenance requirements are stored throughout the
body in the form of fat. They are the chief sources of body fat, and are
found in large quantities in corn, oats, hay, cottonseed meal, cottonseed
hulls, soybean oil meal, etc.
c. Eatg -- perform practically the same function as carbohydrates,
but are a concentrated source of energy providing pound for pound 2- times
as much energy as carbohydrates, Examples of feeds high in fat content are
meatscraps, tankage, and cottonseed. (Whole cottonseed contain approxi-
mately 3 times as much fat as cottonseed meal. This is due to most of the
fat being extracted during the meal-manufacturing process.)
d. iI2DralJ.-- give strength to the bone, helps manufacture red pig-
ment in blood, and are essential in all body processes. Feeds, especially
legumes, grown on well-mineralized land are usually higher in mineral con-
tent than are feeds grown on land that has not been well-mineralized. The
major mineral needs of the animal are usually supplied in the form of
steam bone meal and common table salt, plus ground limestone in some
instances. Minor elements usually are provided in ample quantities in
the feed; however, deficiency systems resulting from a shortage of these
minor elements may show up, necessitating the providing of them.
e. VitWmDS -- regulate body functions, helps keep the body in a
healthy condition, and aids in developing resistance to infections and
diseases. Most of the animal's body needs of vitamins are provided by
feeds such as silage, well-cured hay (especially legumes), well fertilized
pasture plants, and by sunshine.
Synthetic vitamin pre-mixes are available as a commercial mix. These
pre-mixes will supply all the vitamins needed at a sufficient level to
fortify the ration being fed. Commercially-mixed rations supply the necessa-
ry vitamins, also.
f. Yater -- softens feed, aids in digestion, assimilation of nutrients,
helps regulate body temperature, and is essential in the elimination of
4. What value to the.livestock producer is there in knowing the nutritive
content of animal bodies and products?
Feeds represent by far the greatest cost item in animal production.
Because of this and other reasons, it is important that the livestock pro-
ducer have a basic understanding of the nutritive requirements of animals.
Knowing the nutritive content of an animal's body and animal products
will be helpful to the producer in determining the kind and quantity of the
various nutrients needed by animals of various species during their various
stages in life.
The composition of an animal's body varies considerably, depending on
their age, degree of fatness, etc. By studying the contents of the follow-
ing table a producer can readily understand why some species require high-
er protein content feeds than are required by others, why young growing
animals need rations of higher protein content than older, mature animals,
and why other nutritive needs vary.
Approximate Nutritive Content -- Anima3 Bodies and Products
Animal bodies* Protein Fat Carbohydrates Mineral Water
P e r c e n t age
Dairy calf, 19 3 ** 4 74
Dairy cow, 18 18 ** 559
4 yrs. old
Beef calf, 20 4 ** 4 72
100 lbs. net
Steer (med. fat) 16 32 ** 4 48
1,200 lbs. net
Young chicken 21 4 ** 4 71
1/2 lb. net
Older chicken 20 20 4 56
4 Ibs. net
Pig, 100 lbs. 15 16 3 67
Hog (Med. fat) 14 29 ** 3 54
200 lbs. net
Fluid Whole Milk 3.5 4 5 1.7 85.8
Egg (Including shell) 11.8 11 ** 11.7 65.5
Not including contents of digestive system.
** Usually less than 1%. To get total energy producing values and needs,
multiply precent fat by 2.25. Add this to percent carbohydrates if given.
5. yi is the quality of protein important in feeding swine and poultry?
Protein is a very complex nutrient made up of at least 24 amino acids.
Yet, 10 of these amino acids, known as the essential ones, cannot be manufac-
tured in the digestive systems of simple stomach animals at a sufficient rate
to meet their body needs. Protein having the proper proportions of all the
essential amino acids is said to be protein of high quality, while protein
furnished by feeds or rations in insufficient amounts of these essential amino
acids is said to be protein of low quality. Many common feeds contain inade-
quate amounts of one or more of the essential amino acids. For example, all
the grais are low in one or more of these amino acids -- corn is deficient
in two of them. It is fortunate, however, that all of these are not deficient
in the same ones. In general, animal source feeds such as meat scraps, skim
milk, etc.4,are high in protein quality. Consequently, whenever necessary,
the proper combination of these feeds can be made to provide all the essential
Low quality protein presents no problem in rations of ruminants and
horses, since their digestive systems are capable of taking even low quality
protein or urea and manufacturing sufficient amounts of the essential amino
acids from it. This means simply that it is not necessary that rations of
these animals contain feeds high in protein quality. It does not imply, how-
ever, that the amount of protein needed by the animal is not important.
On the other hand, the quality of protein may be just as important as
the quantity of protein in swine and poultry rations. The simple stomachs
of these animals are unable to produce all of the essential amino acids in
sufficient amounts from feeds low in protein quality. The high quality pro-
tein must be provided in their rations, or they will fail to properly utilize
the other feed nutrients.
6. How are feedstuffs classified?
Feedstuffs making up a ration are generally classified according to their
fiber content or bulk- as concentrates, and roughages. Some authorities list
succulent feeds (silage, green pasture grasses, etc.) as another class of feed-
stuff. However, since plants classifying as succulent feeds are feeds that
are usually high in fiber, they are classed herein as roughages.
Concentrates are feeds that are high in total digestible nutrients
(T.D.N.) and low in fiber. (Fiber is cellulose materials in feedstuffs
that are hard to digest.) All the common feed grains, which are low in
protein content, are classified as concentrates. Concentrates are added
to the roughages fed ruminants and horses in order to increase the nutri-
tional value of the ration to the desired level. Concentrates form the
greater part of the ration for poultry (approximately 97%) and swine (approxi-
Roughages include hay, pasture, and silage materials. These plants
are high in fiber content, and usually low in T.D.N. Beef cattle and
other ruminants, as well as horses, are efficient utilizers of good rough-
ages. Because of this fact and the fact that roughages yield more nutrients
per acre than grain crops, roughages are the basic part of the rations of
7. What are the characteristics of concentrates?
a. Grains (corn, oats, wheat, barley, grain sorghums, and rye.)
-- are nutritionally unbalanced for any kind of livestock.
(A good rule of thumb- never feed grain alone.) They are
low in protein quality, also. To correct this deficiency
provide leguminous plants or protein supplements as part of
-- are high in T.D.N. content- since it is a concentrate feed,
-- vary in mineral content, but are all low in calcium- especial-
ly corn. Most are high in phosphorous- even higher than
common grasses and legumes.
-- are palatable in most instances. Corn is probably the most
palatable- rye the least.
-- are not usually considered good sources of vitamins; how-
ever, yellow corn is a fair source of vitamin A activity.
(By "vitamin A activity" we mean that vitamin A is not con-
tained in feeds in the form of a vitamin, but in the form
of carotene, which is converted into vitamin A.) Yet, these
deficiencies may be corrected by providing good quality le-
gume hay or pasture. A well-balanced ration and sunlight
will supply adequate vitamins. (Sunlight does not supply
vitamin D but it converts a compound which exists in the skin
into vitamin D.)
-- are used as a supplement to pasture plants and roughagea,
which are high in fiber and low in T.D.N. and compose the
bulk of the feed for beef and dairy cattle, and sheep. Cattle
and sheep are ruminants and are equipped with a digestive
system that can handle large quantities of roughage. Con-
sequently, they do not need large quantities 'of concentrates.
On the other hand, swine and poultry digestive systems are
unable to handle large quantities of roughage, so they need
a greater portion of concentrates in their rations. Most
rations should vary in protein Content from 12 to 20 percent,
depending upon the purpose for which fed, age, etc. This
usually necessitates the use of a protein supplement in a
ration, since roughages range in protein content from 2 to
(2) SPecificech staceristics.
-- is the basic feed for livestock, ranking ahead of other
cereal grains in importance for livestock feeding.
-- is usually cheaper per pound of T.D.N. than other grains.
-- is very palatable to all livestock.
-- is low in protein, but high in carbohydrates. Yellow corn
is high in vitamin A activity.
-- is a good grain for fattening purposes.
-- may be fed whole to swine, poultry, and horses; but it should
be ground for dairy cattle and cracked for young chicken
are approximately 80 to 85% as efficient as corn (pound for
-* are good for young animals and breeding stock since they are
high in bulk and minerals.
-- are important in "fitting" content.
-- are low in vitamin content.
-- should be crimped or ground for dairy, beef, and swine, but do
not have to be for sheep or calves less than one year old.
-- has approximately the same feeding value as corn.
-- is very palatable.
-- is usually too expensive to feed.
-- cannot be fed in large quantities due to chances of diges-
tional disturbances occurring.
-- has approximately 90% of the feeding value of corn.
-- may bloat cattle when fed in large amounts.
-- is good in a mixture of feeding rations.
-- should be ground for all livestock except sheep.
(e) Grain sorghums:
-- are approximately 90 to 95% as efficient as corn. They are
slightly higher than corn in protein, but lower in fat.
-- should be ground for dairy, beef, and poultry mashes. How-
ever, it is not necessary to grind them for swine, sheep, and
horses, and for poultry scratch feed.
-- has about the same feeding value as corn.
-- is unpalatable to all animals they will not eat much of it.
It should compose only 20 to 30% of a ration.
-- may cause digestive disturbances when fed in large amounts.
-- should not be fed until it has passed through a sweat or is
conditioned when stored after threshing.
-- should be coarsely ground or rolled for feeding all live-
stock and poultry.
NUTRITIVE VALUE OF GRAINS
GRAIN DIGESTIVE TOTAL TOTAL FIBER
PROTEIN DIGESTIBLE DRY
(D. P.) NUTRIENTS MATTER
Corn 6.9 82.5 88.2 2.4
Oats 9.0 68.5 89.8 12.1
Wheat 11.1 80.0 89.5 2.6
Barley 9.2 75.6 89.3 6.2
Grain Sorghum 8.4 79.9 89.6 2.3
Rye 10.0 76.5 89.5 2.4
b. Protein Supplements.
Protein supplements are high in T.D.N. and especially high in pro-
tein, with the exception of urea, which contains no energy producing nu-
trients. Supplements are classified into three categories according to
Plant Cottonseed, soybean, linseed, and peanut oil
meals; alfalfa leaf meal, corn gluten meal, brew-
er's dried grains, etc.
Animal Meat scraps, tankage, skim milk, fish meal, blood
Cattle, sheep, and horses do well
Swine and poultry do better on rations
mal sources as well as some from plant
protein of the supplements from animal
to this rule is soybean oil meal which
protein supplement in hog rations.
on supplements from plant sources.
that contain some protein from ani-
sources, due to the higher quality
sources. However, one exception
has proven satisfactory as the only
(1) Animal Sources.
(a) Meat scraps and tankage:
-- are primarily used as protein supplements in swine and poultry
-- generally range in protein from 40 to 60 percent.
-- correct the grain protein deficiencies, but are less effective
single supplements to the grain than are soybean meal or fish
-- may be used in poultry rations, but meat scraps and bone meal
(b) Blood meal (dried blood):
is made from blood meal collected at the packing plant.
-- is used primarily in rations for young calves, poultry, and
occasionally young pigs.
-- is usually low in digestibility, palatability, calcium, and
phosphorous, and the protein content is lower than that of meat
scraps and tankage.
(c) Fish meal:
-- is made chiefly from the wastes of fish.
-- is high in protein- approximately 60 percent.
-- usually is not palatable other than to swine and poultry, and
therefore is not recommended in rations other than these.
(d) Skim milk:
-- is slightly higher in protein, milk sugar, and minerals than
whole milk, due to the removal of most of the fat.
-- is low in vitamin A activity (carotene).
-- is fed chiefly to pigs, poultry, and dairy calves.
-- one gallon replaces one pound of linseed oil meal.
(2) Plant Sources.
l(a Cottonseed meal:
-- has protein of high quality- good for correcting protein de-
ficiency of cereal grains for cattle and sheep.
-- is high in T.D.N.- approximately 74 percent.
-- is high in phosphorous.
-- should be fed lightly to swine and poultry, due to possible
danger from gossypol poisoning when fed in large amounts.
(b) Soybean oil meal:
-- is one of the best protein supplements for all animals, es-
pecially if its cost is favorable.
-- is a high quality supplement, ranking ahead of other plant pro-
tein supplements in swine and poultry rations.
-- is lower in calcium and phosphorous than cottonseed meal or lin-
seed oil meal.
(c) Linseed oil meal:
-- is a by-product of flaxseed.
-- is a very popular protein supplement.
-- is high in protein and palatability.
-- is slightly laxative in effect.
-- is excellent as the only protein supplement for cattle, sheep,
-- should be mixed with animal source proteins if fed to swine and
-- gives a sheen to animal hair, which is valuable to show ani-
(d) Peanut oil meal:
-- is a good protein supplement for livestock, but should be mixed
with other protein supplements when fed to simple stomach ani-
mals, because its protein is only fair in quality.
-- is very palatable.
-- is low in calcium and phosphorous.
-- is high in T.D.N.
(e) Alfalfa leaf meal:
-- is low in fiber, and high in vitamin A activity.
-- contains approximately 20 percent protein.
-- is very good in poultry rations.
(f) Corn gluten meal:
-- is a by-product of the manufacture of corn starch and sugar.
-- is high in protein content- averages approximately 43 percent.
-- is mainly used in dairy rations and should be fed in combina-
tion with other protein supplements.
(g) Brewer's grain:
-- is a by-product of barley used in the beer-making process.
-- is not very palatable, but may be made tastier by mixing it
with more palatable feeds.
-- is fed chiefly to dairy cattle, but may be fed as part of the
concentrate mixture in beef and sheep rations.
(3) SD i2,2S
In addition to protein supplements being available from animal and
plant sources, a synthetic source is also available. Protein substitutes
in the form of simple nitrogenous compounds are available. Urea is the
form that has proven most successful.
Urea is the chief nitrogenous waste product in the urine of most
animals, and is now manufactured synthetically on a large scale from the
nitrogen in the air. Our supply of protein supplements from animal and
plant sources is insufficient to balance properly the rations of our fast
growing animal population. Thus, urea is filling a great need.
Urea is suitable only as a replacement of a portion of the protein
requirements of ruminating animals. It cannot replace all of the protein
supplement, and is not suitable as a supplement for non-ruminants, or dairy
calves whose rumen is not well-developed. The principle involved here
is that bacteria in the rumen, the first compartment in the compound
stomach of ruminants, convert the nitrogenous urea into protein that can
be utilized by the body. Non-ruminants, or dairy calves with little
developed rumens, are unable to make the conversion.
When feeding urea, the animal's ration must contain sufficient
energy-producing nutrients for the bacteria to efficiently convert the
urea into protein. Since urea provides only protein, sufficient energy
must be provided from the other feed materials to furnish the bacteria
with the necessary amount of energy. The conversion of urea into protein
is also inefficient when it is added (1) to a mixture that is already
fairly high in protein, (2) to hay alone, without any concentrates, (3) to
molasses and such roughage as grass hay. However, it can be converted
into protein effectively when the concentrate mixture contains a good sup-
ply of grain, along with some molasses.
Too much urea in a concentrate mixture may render it unpalatable, and
excessive amounts may poison animals.
8. What are the characteristics of roughages?
Good quality stored roughage is second in line as a low cost live-
stock feed- pasture is first, silage is third, and concentrates are the
highest. One of the greatest needs in a good feed program for ruminants
are adequate amounts of high quality hay and silage. More high quality
legume hay and corn silage are highly needed- especially.in dairy feed
programs. A good roughage program can be built around high-yielding
There may be considerable variations in the feeding value of any
specific kind of roughage. Pasture plants grown on well-fertilized land
are more nutritious and palatable than pasture plants growing on unferti-
lized or poorly fertilized soils. Plant maturity and the method of har-
vesting and curing also affect the nutritive value and palatability of
(a) Hay (legumes):
-- leads in yield of palatable hay per acre.
-- contains more protein than any of the common forages.
-- vitamins excels in A; is high in D and riboflavin and other B
-- minerals highest in calcium of all the homegrown fields; re-
latively low in phosphorous.
-- T.D.N. content approximately 50%; fiber content usually 25-30%.
(b) Hay (grasses):
-- lower in protein, calcium and vitamins than legume hay.
-- usually less palatable than legume hay.
-- quality affected more by cutting stage than legumes.
-- requires more protein supplement to balance a ration than does le-
gume hay or grass-legume mixtures.
-- is highly palatable, thus it increases feed consumption.
-- is slightly laxative.
-- from corn usually provides 1/3 more T.D.N. per acre than alfalfa
hay and up to twice as much as some grass hays.
-- from corn is worth 30 to 40% as much as good hay for dairy cows,
and 50% as much as good hay for beef cattle.
(d) Cottonseed hulls:
-- are low in T.D.N. 43.7%, or approximately the same amount as
furnished by oatstraw.
-- contain no digestible protein.
-- are low in calcium, very low in phosphorous, and lacking in vita-
min A activity (carotene).
-- when properly fed are worth more per ton than corn stover, straw,
or poor hay.
-- are a good source of energy when price is favorable.
(e) Corn stover, straw, etc.:
-- is high in fiber, extremely low in proteins and T.D.N.
-- is low in calcium and phosphorous.
-- is low in vitamins except for straw which has considerable vitamin
9. What are the characteristics of a good ration for animals?
A satisfactory ration for animals, in addition to supplying the re-
quired nutrients, must be made up of feeds that will give it the follow-
ing desirable characteristics:
(a) Palatability -- A good ration must be palatable, or "tasty"; in
other words, the animal must like it. Like man, these animals differ in
the feeds they like and those they dislike. In general, the animals tend
to like the feeds they are used to; therefore, if changes in the ration are
to be made, these changes should be gradual. Some of the more palatable
feeds are pasture plants (especially young ones), high quality hay, corn
silage, corn, oats, wheat bran, molasses, and cotton seed meal.
(b) Protein quality -- An important consideration in feeds for swine
and poultry. (Refer to Unit II Nutrition of Farm Animals, question 5
on page 25 for additional information.)
(c) Yzriety -- while important in the rations of all animals, is
more important in the rations for simple-stomach animals, particularly
hogs and poultry. However, other factors such as cost being equal, a
variety of feed is desirable. Variety improves palatability, enabling
the animals to eat more. It also provides a greater variety of nutrients,
especially vitamins and minerals.
(d) Bulkiueaa -- while not desirable in large amounts in rations
for poultry and hogs, is desirable in rations for cattle, sheep and horses.
The digestive systems of poultry and hogs are unable to handle the bulky
feeds that can be handled by ruminants and horses.
(e) PEQGQmy -- is important in all rations, but the cheapest ration
fed is not always the most economical ration in the long run.. The ration
must be well-balanced to provide the required quantity and quality of
In addition, the ration should be slightly laxative, plenty of good
clean water should be provided, and succulent feed should be supplied.
10. What effects do common nutritional deficiencies have on farm animals?
Nutritional deficiencies in livestock result in great losses, not
only to the owner but to the entire livestock industry. These deficien-
cies are not due only to the feeding of rations too low in one or more nu-
trients, but also due to insufficient feed. The latter, often called the
"hollow-belly" deficiency, actually causes greater damage than the former.
Forced high production, and the feeding of grains and forages produced
on nutrient depleted soils, have also created many nutritional problems.
The increased confinement of livestock has further aggravated this condi-
tion. Under these unnatural conditions nutritional diseases and ailments
have been on the increase.
The cause, prevention, and treatment of many of these results of
nutritional deficiencies are known, but they continue to reduce profits
because this knowledge is too seldom placed into practice. Often these
deficiencies are of insufficient proportions to be easily recognized-
they do not produce clear-cut deficiency symptoms. Therefore, they go
unnoticed and unattended to, causing even greater economic losses.
Some of the most important nutritional diseases and ailments among
farm livestock are rickets, bbloat, vitamin A deficiency (example: nu-
tritional blindness in cattle), iodine deficiency, phosphorous deficien-
cy, X-disease, anemia, acetonemia, milk fever, grass tetany, founder,
and salt deficiency.
11. What are the meanings, functions, uses, precautions and dangers of feed
In recent years the use of feed additives in rations for various
kinds of livestock has increased tremendously. These additives are
generally classified into four groups:
(a) Eormones~ -- Many years ago scientists determined that many of
the body processes of animals are controlled and regulated in varying de-
grees by substances called hormones. Certain hormones are produced by the
ductless glands of the body as internal secretions which are discharged
into the blood and distributed to the various parts of the body where
they perform their functions.
Hormones are administered to animals as feed additives or body im-
plants. They haven't yet generally proven to be of value in feeding live-
stock except in the case of beef cattle being fed for market. However,
when administered to breeding stock, breeding difficulties may occur. Stil-
bestrol and Thyroprotein are two hormones being used.
(b)_.Pgg igQc, B -- are chemical compounds that have the ability to
inhibit the growth of, or even destroy, certain micro-organisms which
may cause diseases. They also increase feed consumption of livestock by
increasing the appetite. The following includes additional information
(1) SiUing e, antibiotic feed supplements will generally
increase appreciably the rate of gain in pigs, dairy calves,
chicks, broilers, and poults, until about 3 months of age.
(2) In most cases, antibiotics will reduce very slightly
the feed required per pound of gain (with the animals men-
tioned in No. 1).
(3) The feeding of antibiotics to sheep and beef cattle is
still in the experimental stage, with considerable disagree-
ment to date as to their value.
(4) It is usually unprofitable to add antibiotics to feed
for brood sows, or for dairy cows, and dairy heifers 4 months
(5) Many antibiotic supplements also contain B-complex vita-
mins. Some of the benefits may be due to these vitamins.
(6) Antibiotics probably stimulate growth primarily by (a)
reducing the number of detrimental bacteria in the digestive
tract of animals, and (b) increasing the appetite, and thus
feed consumption, of farm animals.
(7) Some antibiotics have produced good results, and some
have not. The reputation of the feed manufacturer is prob-
ably the best guide in purchasing formula feeds which contain
antibiotic additives or supplements.
(c) Tranauis, -- have been used for years in human medicine for
the treatment of certain mental disorders, high blood pressure, nervous
tension, etc., but during recent years some research has been devoted to
determining their value in livestock production. However, at the present
time, results are primarily in the experimental stage.
(d) UaXgga -- are organic catalysts whose function is to break
down food so that it can be absorbed and used. The more efficiently
food is broken down the greater the value of the feed. Enzymes are al-
ready present in an animal's digestive tract, but scientists are trying
to determine if the addition of various enzymes to the ration will in-
crease the efficiency of the ration. Different enzymes act upon carbohy-
drates, fat and proteins, to break them down.
Extreme care should be exercised in the use of feed additives. Their
effect as of the present time are largely speculative. (This is especially
true with tranquilizers.) Strict adherence to recommendations should be
followed when they are used.
III. Environmental Factors That Affect Physiol
1. ggha d.o agors hav2. os animal production?
a. -THttEB& t -- All animals suffer when the temperature becomes
excessively high or low. The different species of animals, as well as
individual animals within these species, vary in their ability to with-
stand these extremes. Within the beef cattle breeds, the Brahaman and
Santa Gertrudis withstand extremely hot weather better than do many of
the other breeds. Among the European breeds of cattle the Brown Swiss,
and Jerseys tolerate heat better than Holsteins, Ayrshires, Herefords,
Aberdeen-Angus, or Shorthorns.
Extremely high temperatures may be a predisposing influence that
results in lowered resistance to bronchial infection, reduction in
appetite, an increased work load upon the heart, and otherwise directly
or indirectly affect the health of an animal. There is good evidence that
summer heat combines with heavy lactation to produce breeding problems.
Likewise, when the temperature becomes extremely low it can become
a predisposing influence to lowered health. As the temperature becomes
lower and lower, the production of heat within an animal's body must be
increased. On cold days animals eat more heartily and usually exercise
more than in warm weather, resulting in the production of more heat with-
in the body. When an animal becomes too cold it begins to shiver. Actual-
ly, what is taking place is that the muscles are contracting involuntarily
in order to produce more heat.
Well-fed animals can withstand lower temperatures than can poorly-fed
animals, due to the greater fat content in the bodies of the better fed
animals. And naturally, on the other hand, fat animals experience greater
difficulty during extremely high temperatures than do animals that are not
so fat. Artificially heated quarters are not needed for dairy cattle- at
least in the Southern section of these United States. Similarly, cattle
and sheep fattened in the winter in cold climates make economic gains when
housed in open sheds, or even canebrakes- where quarters are fairly dry
and free from excessive drafts.
Normally, very young animals need warmer quarters in colder weather
than older ones. This is especially true with very young pigs and very
young artificially raised chickens, who need artificially heated brooders.
Very young calves, too, need reasonable warm quarters; however, young
dairy calves, for instance, are successfully raised in Mississippi in in-
dividual calf pens. Under these conditions, unless extremely cold and ex-
tremely young animals are being dealt with, there is no need for artificial
heat- only protection from rain, snow and cold drafts, and warm bedding are
During extended periods of extreme temperatures, especially high ones,
milk yields are likely to be reduced, growing or fattening animals tend to
make less rapid gains, and egg production among hens is lowered.
b. .LiJT -- It is believed that bright sunlight may have some predis-
posing influence upon the incidence of cancer eye, pinkeye, and photosyn-
thesisation in cattle. The length of the daylight period has an effect
upon the egg production of laying flocks, and the production of broilers.
For example, during seasons of short daylight hours, artificial lights are
turned on during the pre-daylight hours in laying houses, and broiler
houses. These light rays activate the pituitary glands of the chickens,
causing hormones to be released into the bloodstream. This additional
supply of hormones results, if the bird is not already performing at full
capacity- according to its ability- in increased production.
In addition, the value of light in aiding in the control of some di-
seases and parasites should not be under estimated.
c. S&tSUrg -- Moisture content in the air can affect an animal's
health, and its production. For instance, high moisture-laden air (high
humidity) does not cool an animal as rapidly as does air containing normal
or low amounts of moisture. During high-temperature high-humidity periods
perspiration from the body is not absorbed by the surrounding air to the
extent that it is during periods when high-temperature low-humidity condi-
tions prevail. Consequently, body temperature increases. Deaths from heat
strokes have resulted from such conditions.
Air containing excessive amounts of moisture is capable of transmitting
more contagious disease germs than can be carried by drier air. Diseases
and parasites thrive better under damp, dark, warm surroundings. Likewise,
damp air during cold weather predisposes the animal to respiratory ailments.
IV. Diseases of Farm Animals
1. What is a disease and how are diseases classified?
a. Disease defined.*
A disease may be defined as a disorder of mind or body marked by
definite symptoms. It may be further defined as an alteration in the
condition of the body or any of its organs that interferes with the
normal functioning of the body or any of its parts.
b. Diseases classified.*
The classification of diseases, and examples of diseases coming
under each classification are:
(1) CQg~g ig. ieC iO .p.2s8r- These diseases are caused by germs or
microscpoic living organisms that can be spread by direct or indirect
contact from animal to animal. Blackleg, anthrax, brucellosis (Bang's
disease), and leptospirosis come under this category.
(2) Qa:E0Q!.~i~ t S E q:Q taglgi~ -. These are diseases usually
caused by something other than germs, such as traumatisms, poisons, dis-
turbances of metabolism, and faulty nutrition. Examples of non-com-
municable, non-contagious diseases are:
Traumatisms Poisons disturbances nutrition
Broken bones Prussic acid Milk fever Vitamin A
Bruises Chemical(insecticides, deficiency
Lacerations(barb- amm. nitrate, etc.) Acetonemia
wire injuries, Calcium
A few infectious diseases such as tetanus (lockjaw) and botulism
(food poisoning) are non-contagious.
The definition of a disease as given here is rather
broad in its meaning. Even though it may vary some-
what from a person's idea of the definition of a dis-
ease this definition is one given and agreed on by
2. What causes diseases in farm animals?
a. _Jacgera -- Bacteria, or germs, are microscopic organisms of various
types and shapes found everywhere in nature. Some are beneficial or
non-pathoghnic types, such as bacteria that aid in the cheese ripen-
ing process, the vinegar fermenting process, the decaying of plant
materials, etc. Some are disease producers, and are known as patho-
Pathogenic bacteria produce toxins, which are poisons produced by
action within animal or plant tissue. These toxins are produced by two
different types of processes: (a) Toxins produced within the bodies of
pathogenic bacteria are known as endotoxin. These toxins are released
with deadly effect when the pathogenic bacteria die and disintegrate.
An example of an endotoxin disease is tuberculosis; and (b) the most
powerful type of toxin, known as exotoxin (or soluble toxin) are pro-
S' duced in the mediums in which they grow. The powerful, virulent tox-
ins produced in this manner enter the body and cause enfterotoxemia, tet-
anus (lockjaw), etc.
Certain types of bacteria produce localized inflammatory changes
in tissues. An example is the abcess. These infections may remain lo-
calized or may enter the bloodstream and cause a serious general dis-
turbance, and sometimes death from septecemia- "blood poisoning".
b. *~9.S a -- Protozoa, one celled animals, cause such diseases as anaplas-
mosis and coccidiosis.
c. Y~lass -- Filterable viruses also cause diseases. A virus is an in-
fectious agent too small to be retained by filters that retain bacteria,
and also too small to be seen under an ordinary high power microscope.
Among the animal diseases caused by viruses are rabies, hog cholera, and
foot and mouth disease. (Some virus diseases in man are small pox, in-
fluenza, infantile paralysis, and mumps.)
Viruses must be propagated through a host organism- media containing
living cells. Many are propagated in growing chicken embryos.
Some of the virus diseases are complicated by the action of second-
ary bacterial invaders. A vicious cycle may be established by the vir-
us and the secondary bacterial infection- the action of one increases
the virulence or power'of the other. This sometimes occurs in hog
cholera, swine influenza, and distemper in dogs.
d. MQ .dad.Qlal,1ik.Elai -- Fungi, which are non-green plants, cause
athletes foot, ringworm, and some ear and eye infections. Moat fungus
diseases are confined to the covering of the animal's body, and are
*e.. aitic.i iQia -- Internal parasitic diseases are caused by tapeworms,
hookworms, roundworms, etc. Internal parasites are a universal hazard
to livestock production. They are abundant in kinds and numbers, and
losses are often unrecognized because animals often do not exhibit ex-
treme signs of infestation.
f. Qthta.Gauaaa -- Other causes are foreign bodies and nutritional defi-
ciencies. Foreign bodies such as nails, wire, etc., are taken into the
digestive tract. Ruminating animals retain many such objects in their
reticulum, or second compartment of their compound stomach. However,
sharp objects may still endanger the animal's life. In non-ruminating
animals the danger of swallowing these objects is greater than in rumi-
nating animals, due to their not having a compartment in their digest-
ive tract that has the function of the reticulum in the digestive tract
Nutritional deficiencies, whether the result of too little feed or
unbalanced rations, are a great detriment to an animal's health.
(Refer to II Nutrition of Farm Animals- in this publication for in-
formation concerning nutritional deficiencies.)
Some people 'believe that heredity plays a minor role in pathology.
Such reasoning is not based on facts, but there may be some indirect in-
fluence. Animals may have inherent resistance or a susceptibility to spe-
cific diseases; in other words, an animal may have a predisposing influence
to some diseases.
Lethal, or deadly characters are heritable. Lethal traits bring
about the early death of the young individuals. Some lethal diseases are
the "bull dog" calf, which has a round vaulted skull, swollen tongue,
swollen body, and short legs. They are born dead and are not to be con-
fused with "Acorn" calves, who resemble "bull dog" calves. "Acorn" calves
are born alive, and the cause of their condition is not hereditary. Hair-
lessness, in some dairy calves at birth, is another example.of many lethal
traits affecting livestock.
Inherited conditions in livestock that do not necessarily result in
death of the individual are very numerous. However, such conditions do
result in economic loss to the producer. Some of these conditions are
dwarfism in cattle, extra or rudimentary teats, fused teats, blindness,
3. What physiological changes indicate disease?
Physiological changes vary somewhat from disease to disease. However,
any marked and persistent deviations from normal temperature, pulse rate,
and breathing rate may be considered as possible signs of ill health.
In general, an increase in the body temperature of an animal ushers
in an infectious disease. However, it must be remembered that normal tem-
peratures may vary among animals slightly. Temperature is also affected by
exercise, excitement, outside temperature, age, feed, etc. It is lower in
cold weather, higher in extremely hot weather, lower at night, and in old-
er animals. Temperature is even affected by inadequate supplies of water.
The normal pulse rate also varies from animal to animal. It will also
vary with excitement, exercise, digestion and outside temperature.
The breathing rate is accelerated when the animal is suffering from
pain or discomfort. Increases are also due to excitement, exercise, high
temperature or poorly ventilated buildings.
Even though these physiological changes may be signs of ill health,
they may also be due to the other reasons mentioned. Changes due to excite-
ment, exercise, etc., should not be confused with disease,
In addition, other changes may consist of a decreased appetite, an un-
due thirst for water, a listless appearance, etc.
The following table gives the normal temperature, pulse rate, and
breathing rate for several species of farm animals.
Animal Normal Temperature* Normal Pulse Normal
Average Range Rate Breathing
Degrees E. Bat er Mjnute
Cattle 101.5 100.4 102.8 60 70 10 30
Swine 102.6 102.0 103.6 60 80 8 18
Sheep 102.3 100.9 103.8 70 80 12 20
Goats 103.8 101.7 105.3 70 80 12 20
Horses 100.5 99.0 100.8 32 44 8 16
Fowl 106.0 105.0 107.0 200 400 15 30
4. What natural defenses do bodies have against disease?
An animal's body may be considered a battle ground in which the invad-
ing forces seek to overcome the defense. The body is equipped by nature to
fight against disease. Three lines of defense aid in the fight.
a. UgfggtJgyU!'.bu s one -- The function of this line is to prevent
disease germs from entLjrin the body. Skin, covering all exterior parts of
the body, is bacteria-proof unless it becomes broken. However, it is not
virus-proof, so we have very little protection agi.i~t this gro l of disease
germs entering the body. The body openings, lined with mucous membranes,
serve as a protective lining. Other first line defenlss include the acid of
the stomach, and the tears of the eyes.
b. DefeIDsli tA'.D.I'JV --" If the first line of defense is unsuccess-
ful in preventing entry of the disease germs into the body, then the second
line of defense, the white blood corpuscles of the bloodstream, go into
action. If, for instance, disease germs enter through a break in the skin,
these corpuscles immediately leave the blood vessels and proceed through the
tissue fluids to the site of infection. They completely surround the invad-
ing germs and begin to engulf them. A race starts between the multiplica-
tion of the invading bacteria and their destruction by the white corpuscles.
During this period of infection the involved tissues usually become swollen
and inflamed. This inflamed, or red condition is the result of the increased
flow of blood to the area to promote healing. The lymph also aid in this
fight by carrying disease germs to nodes when they are filtered out and
destroyed by white blood cells. Pus, which is dead bacteria and white cor-
puscles, collects at the site of infection. It is later discharged extern-
ally, or transmitted to the excretionary organs and discharged. During this
struggle fever may arise. Fever is a body reaction against infection, and
actually is beneficial unless it is too high during too long a period of
c. J i JJ eJLuJiL-aJT 2 -- If the second line of the body's de-
fense is unsuccessful in destroying the pathogenic organisms then they enter
the bloodstream. The infection then becomes general and the patient begins
fighting for his life. The infection becomes a battle between bacteria and
their products and antibodies produced by the blood to destroy the bacteria,
or at least to neutralize the effect of their poisons.
Another factor, general resistance, seems to play a vital role in main-
taining the body defenses against disease. It performs a role in all three
lines. A general healthy condition strengthens the body's resistance to
pathogenic organisms, while a general unhealthy condition weakens its resist-
ance to them.
5. What principles are involved in controlling diseases?
One or more of the principles of immunization, sanitation, and isolation
may be involved in controlling diseases.
6. What is immunity and how is it acquired?
Immunity from a disease refers to the power of the body to resist a
disease by natural or artificial means. Immunity may be natural, or it may
be acquired. Some species of animals are immune to diseases of other species.
In other words, they have natural immunity. For example, cattle are not sus-
ceptible to hog cholera. Acquired irmminity is established during the life
time of the individual. It may be permanent (active), or it may be tem-
porary (passive), depending on the manner in which it is acquired. Permanent
mmunity from a disease results from having had that disease, or it may also
be acquired artificially by using biological preparations such as vaccines,
I~TE0.orari,..m.un.t is acquired artificially through the injection of
antibodies contained in serums and toxoids. For example, tetanus antitoxin
(or antiserum) is taken from the blood of the horse, processed, and in-
jected into the blood of man or other animals to give immunity in the case
of deep wounds. These antibodies remain only temporarily and when des-
troyed no longer make the inoculated individual immune.
In many instances serums, vaccines, and other immunizing agents (bio-
logical preparations) aid in the treatment and'prevention of infectious
diseases by bolstering the natural defenses of the body. (Refer to ques-
tion number 4 on page 38.)
7. What are the characteristics of immunizing agents?
(a) ccAQLg -- Vaccines contain modified, live or killed pathogenic
(disease producing) virus or bacterial organisms in suitable media. Under
certain conditions they are capable of producing the disease for which im-
munity. is. intended. 'Vaccines require 7 to 21 days after injection for the
stimulation of satisfactory immunity, which lasts from 4 months to life.
Repeated injections may be necessary. Rabies, distemper, anthrax and
bang's vaccines are several of the well-known ones.
(b) QgEum -- Serums contain no pathogenic organisms. They are the
fluid part of the blood of hyper-immunized animals containing antibodies
that will overcome neutralized, or destroy, disease producing organisms
which stimulate their development. Immunity lasts from a few days to 3
weeks at most. Hog cholera serum is widely used.
(c) 2Baterins -- Bacterins are suspensions of killed pathogenic bac-
terial organisms. Seven to twenty-one days are required to produce im-
munity that lasts from 4 months to life. Repeated injections may be
necessary. Blackleg bacterin is one of the most widely used.
(d) Toxoids -- Toxoids are detoxified poisons. They were previously
produced b7y pathogenic bacterial organisms. Toxoids require from seven
to twenty-one days for the production of immunity that usually lasts for
one year. Tetanus toxoid and Enterotoxemia toxoid are examples of this
type of immunizing agent.
(Note: There are combination immunizing agents that
can be administered. For example, there are combi-
nations which can be given in one injection to stimu-
late immunity against one, two, or three diseases.
The blackleg-hemorrhagic septecemia- malignant
edema bacteria is a well known three-way combina-
tion. DO NOT COMBINE ANY IMMUNIZING AGENT WITHOUT
THE ADVICE AND PRESCRIPTION OF A LICENSED GRADUATE
8. How does sanitation relate to the spread and control of diseases?
Sanitation is synonomous with cleanliness, and cleanliness is basic
in any program of disease or parasite control- both preventive and cura-
tive. The old adage "an ounce of prevention is worth a pound of cure"
still holds true. Unclean, unsanitary premises breeds filth, and filth
breeds disease and parasites. Sanitation involves general cleanliness
including keeping the premises well drained, free of infected animals,
animal body discharges, disinfection, pasture rotation, etc. No disease
or parasite control is very effective that does not involve the con-
tinued use of sanitary measures. Sanitation plays an important role in
the prevention of diseases by reducing the number of disease bacteria
on the premises where livestock are kept. It is especially important
that strict sanitary measures be used on premises where contagious di-
seases are present, because sanitation plays an important part in pre-
venting the spread of any infectious disease. It should be remembered
that the number of disease germs gaining entrance to an animal's body de-
termines to a large extent whether or not that animal contracts the di-
sease, and if it does, the degree of mildness or severity of the disease.
9. How do isolation measures aid in controlling diseases?
Isolation, or quarantine, involves the separation of non-diseased ani-
mals from diseased ones, or disease exposed animals from unexposed ones.
The principle governing effective isolation is that there must be no direct
or indirect contact between the animal in isolation and those not so re-
strained. Isolation, of course, is an essential aid in preventing the
spread of diseases or parasites.
Isolation has its variations depending upon the degree of contagious-
ness of a disease. For example, hog cholera spreads very rapidly, making
isolation of considerable value in its control.
Isolation of newly purchased animals before they are placed with
other animals already on hand is also an important phase of disease con-
In its wider application animals are isolated or quarantined, by law,
to keep a disease from spreading to other counties, states, etc.
10. How are the various medications used in disease control applied?
Medications are applied by injecting them into the body by several
injection methods. Other methods are also used, such as oral, topical (ex-
terior surface), inhalation, and rectal.
Injections into an individual's body are made in several different
ways- subcutaneously, intramuscularly, intravenously, and intraperitoneally.
A g anggg njeQJUa is an injection made beneath the skin. The
areas of injection are places where the skin is loose, particularly on the
sides of the neck, behind the shoulder, and in the axilliary spaces be-
tween the foreleg (armpit).
ratuiaculMa injections are made through the skin and subcutaneous
tissue, directly into the muscle. Heavily muscled parts of the body such
as the neck, shoulder and hindquarters are good areas for this type of in-
ntrayenou InjGltctQS are made directly into the veins. This method
is generally used when quick and effective action is necessary to save life.
raE1eritos; l n ic~tl~t-Qt G are made through the belly wall. This area
is the center of the area known as the "hollow of the flank". This type
of injection is made in lieu of intravenous injections.
Oral administrations. of drugs are given by the mouth and are absorbed
in the stomach and intestines. Absorption is more rapid when drugs are
given in solution into an empty stomach. They are absorbed slower when
administered in powder, pill, or ball form, and on a full stomach.
The inhalation method is used when volatile drugs are administered for
their local action in the respiratory tract.
Rectal administration is used when oral administration is impossible
or inadvisable, due to paralysis of the throat, or other conditions. The
absorption rate is slower.
To-cical (external surface).jgsyatQa.n are local applications made
to external surfaces of the body. Absorption by this method is extremely
slow. The effects of the drug are also limited to the local area.
(Note: For additional information including detailed
sketches of administering drugs by various injection
methods, refer to pp. 9-15 and pp. 76-77, 1961 issue
of "The Globe Blue Book", published by the Globe
Laboratories, Inc., 116 Commerce Street, Fort Worth 2,
V. Common PiaraflLtes of Farm Animals (Economics)
1. What are araites and how are they classified?
As used in this publication, the term "parasites" refers to low
forms of animal life that live on or in other animals (hosts) larger than
themselves- and at the expense of the host.
Parasites are classified as external and internal types. External
parasites, such as fleas, ticks, and lice, live on the skin or in its lay-
ers. Internal parafiites, such as cattle grubs, roundworms, etc., live in
the digestive tract, the liver, the lungs, the kidneys, and elsewhere in
2. What is the nature of the life-cycles of parasites?
Each of the many kinds of parasites have a relatively fixed life-
cycle and rate of development, despite the abundance of different species,
each of which has its own forms, habits, modes of life, and potentialities
for causing disease and injury. This cycle involves a series of stages in
the life history of parasites. In many parasites, the development from
egg..to adult includes several more or less distinct states. This series of
stages in a life history is called metamorphosis. Among insects there are
basically six types of metamorphosis. However, most insects are classified
into two of these types- complete metamorphosis and simple metamorphosis.
Even though all species of parasites are not classed as insects, many of
them are. Therefore, many common parasites of farm animals fall into one
or the other of these two major metamorphosis types. (These two types,
however, do not include such parasites as tapeworms, roundworms, etc.
whose life cycles are not as well-defined as are the life cycles of para-
sites classified in the two major groups. Intermediate hosts are re-
quired for the completion of their life-cycles.)
Parasites having life cycles in which the young are not at all like
the adults, as in the case of cattle grubs, are said to have complete meta-
morphosis. There are four stages in their lives: (1) the egg; (2~ the
larva; (3) the pupa, or resting stage; and (4) the adult. In others, the
differences between their immature and adult forms are slight- as in the
case of lice. Their life-cycle is one of simple metamorphosis, and there
are only three stages: (1) the egg; (2) the nymph; and (3) the adult.
The nymph usually looks like the adult, except for a few minor features
such as being smaller in size, having no wings, and no reproductive struc-
tures at the time. In some instances the entire life cycle is spent in or
on the host animal. In other instances, one or more stages of the life
cycle is spent outside of the host animal, and in some instances a stage
in the life cycle is spent in the bodies of intermediate hosts, thus com-
plicating the problem of control. The latter, for example, is true with
the stomach worms of swine. Stomach worm eggs are excretbd with the
droppings of swine. Insects feeding on these droppings eat the eggs, the
eggs hatch, and then the tiny larvae bore through the intestine into the
body cavity of the insect, where in the course of about a month they de-
velop to a stage infective to swine. Hogs feeding on contaminated ground
swallow the beetles. In the stomach of the hog, these parasites are then
freed from the bodies of the beetles by the action of the digestive juices.
The young worms then make their way into the mucous membrane of the stomach
where they grow to maturity.
3. What is the economic importance of livestock parasites?
Parasites have played an important role in the history of civiliza-
tion, because they cause many of the ills to which human beings and ani-
mals are subject.
The value of livestock and poultry lost per year is approximately
one billion dollars. Diseases and parasites alone are responsible for
approximately one-half of these losses. All these losses are not confined
strictly to farm operations, although losses discovered after livestock
and poultry leave the farm have a way of being reflected in prices re-
ceived by farmers. Hidden losses from disease and parasites in meat, hides,
edible offal, and by-products, because of condemnation or lowered quality,
when added to the economic loss from death and sickness on the farm, and
between the farms and the processor, reach a staggering total.
4. What are the principles involved in the control of common parasites?
Parasites, and parasitic diseases as well, are of a nature that sets
them apart and is the basis of special principles that determine and ex-
plain the measures used to control them.
Parasites are a universal hazard to livestock and livestock produc-
tion. Climate, the kind of animals- susceptible to specific parasites,
and other factors, determine their distribution.
Control of parasites usually means establishing control within an
individual or within an individual herd or flock. Yet, in its broad
meaning, control actually means complete eradication. However, as used
in this publication, these two terms infer two different degrees of con-
trol. In other words, control, as used herein, refers to control in the
individual animal or herd, while eradication refers to stamping out the
infestation within a given state, or nation. If control measures are
applied strongly enough, eradication of specific parasites can be achieved,
however remote the possibilities.
The development of control measures requires the knowledge of cer-
tain facts relative to:
a. the manner in which a parasite propagates
b. the stage at which it is infective to its host (livestock
c. the ability of the parasite to maintain itself for periods
of time away from the host- on pastures, etc.
d. the condition under which the hosts become infected
e. the behavior of the parasite in the body of the animal,
and the damage it inflicts,
f. the stage or stages during the life cycle of the parasite
that are most vulnerable to attack.
Unless the farmer has a knowledge of these facts he can do little to over-
come such pests.
Control methods are based on two keystones- sanitation and medication.
The adage "an ounce of prevention is worth a pound of cure" holds
a lot of truthful meaning in a livestock and poultry parasite control pro-
gram. That "ounce of prevention" actually refers to sanitation- the
really basic measure of the two keystones. In other words, the key to
prevention is sanitation.
Sanitation is a two-fold problem. There is, first of all, the
problem of providing facilities and surroundings which can be made sani-
tary. Then there is the problem of keeping animals and their surround-
wings in a sanitary condition. Sanitation is, of course, dependent upon
the solution of both of these problems.
Sanitation means cleanliness, and cleanliness, in a parasite control
program, is the result when the following practices, among others, are
a. The premises are kept free of general filth, trash, drop-
b. Dead animals are properly destroyed.
c. Premises, and animals when necessary, have been disinfect-
d. The animals have been moved to clean pastures as the old
pastures became infected.
Few parasites have been controlled by medication alone, but in
many instances medication, or the use of antiparasitic chemicals (includ-
ing insecticides in some instances) are powerful aids to control. They
are not synonymous with control or substitutes for it. Chemical measures
generally are immediate in their effects, economical and simple. Some
efficient measures of control do not depend for their success on the use
of medication. For example, this is true in the case where the sanita-
tion systems are used to control worm parasites in swine. Parasitism is
essentially a herd or flock problem, rather than one of individual ani-
mals. The urgency of treating all animals of a flock or herd is dictat-
ed by the fact that parasitism is recognized first on one, or a few, ani-
mals when actually all the animals are probably infected. Measures of
control, whether medication or sanitation, are really less effective un-
less they are applied to an entire herd or flock as if they were only one
individual. Actually, in most instances both medication and sanitation
are needed for control.
The concept of control of a parasite embraces all measures, the
two basic ones as well as others, aimed at the weakest link(s) or stages)
in the life cycle of the parasite. In other words, during certain stages)
in the life cycle of a parasite, the parasite can be destroyed easier
than in other stage(a). This is known as the "life-cycle approach". A con-
certed attack on all fronts achieves best results, but the strongest
attack must be made on the parasite's stages) of development that is most
vulnerable- "the weakest link", whether it be the larva stage, the adult
stage, or some other stage.
The common roundworm, for example, is more vulnerable to attack
during its adult stage in life, where-as the very effective control of screw-
worms has been accomplished by a radiobiological attack on the egg stage
and also on the reproductive potential of adult flies.
Time factors have a great significance in determining when, how
often, and at what intervals medication can best destroy the parasite.
For instance, swine are treated twice at an interval of 10 weeks to com-
bat large roundworms. The first treatment kills most of the worms pres-
ent, while the second treatment destroys the worms that later hatch from
eggs present at the time of the first treatment. Temperature, precipi-
tation, and the other factors of climate determine the distribution,
seasonal occurrence, and abundance of many parasites. Warmth and mois-
ture generally favor their development. Many internal worm.parasites
must overwinter in animals because the free-living infective stages can-
not survive the cold winter on pastures. They can be destroyed by medi-
cation during this winter period. External parasites, however, usually
exhibit the opposite pattern. Lice, for example, survive in small numbers
in the summer, but become abundant in the winter. It is quite easy to
control them by efficient treatment of animals in early fall.
Improper feeding and grazing, overstocking, unsanitary conditions,
and inattention to illnesses in early stages favor parasitism. On the
other hand, good feeding and the removal of adverse influences increase
the resistance to the invasion and establishment of parasites.