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METHODS OF
ANIMAL BREEDING
Agriscience 332
Animal Science
#8407
TEKS: (c)(4)(C)
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Introduction
Nearly every successful livestock
breeding operation considers the
environmental, economical, and
technological factors that affect the
choices made concerning breeding
systems, breeding seasons, times of
breeding, and methods of breeding.
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Producers must be prepared to
successfully breed livestock by
using the appropriate technology
and by applying a thorough
working knowledge of animal
nutrition, as well as, animal
reproduction and physiology.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Breeding Systems
Breeding systems are a set of
management practices that are
used by producers to ensure the
transmission of certain traits from
parents to offspring; particularly
those traits that the producer
desires to be inherited.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
No one breeding system or
method of breeding livestock will
fit all producers.
Some systems may include
grading-up, crossbreeding,
purebred breeding, line-breeding,
and inbreeding.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Factors to consider when determining
which breeding system to use:
1. Climatic conditions,
2. Types of markets,
3. Knowledge of genetics,
4. Size of operation,
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5. Personal preferences,
6. Available resources, and
7. Goals of the breeder.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Crossbreeding
Crossbreeding involves the mating
of two animals of different breeds.
Usually, both animals are purebreds.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
However, commercial breeders will
often mate purebred sires to females
that are considered grade animals
(animal having non-purebred
ancestors) with the resulting offspring
also considered “crossbreds” or F1s.
This system may be referred to as
indiscriminate crossbreeding.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Crossbreeding is done to improve the
overall performance of offspring that
result from mating individuals with
different, but complementary, breed
values.
Another reason for crossbreeding is to
produce hybrid vigor or heterosis for
traits such as fertility and survivability.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Advantages of crossbreeding are
1. Weaknesses can be improved
upon or eliminated by breeding an
animal “strong” in a particular trait
to an animal that is considered to
be lacking or “weak” in that trait;
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2. The average productivity of the
offspring is increased over either
parent;
3. Crossbreds are more fertile than
their purebred parents;
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4. Crossbreds wean heavier
offspring than purebreds; and
5. Crossbreds are more vigorous
than purebreds.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
With several crossbreeding
methods in use, crossbreeding is
the most popular breeding
system practiced by commercial
livestock operations.
However, some methods work
better for certain species than
others.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Three types of crossbreeding
discussed in this topic are:
• Grading up,
• Backcrossing, and
• Three-breed rotational crossing.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Grading-Up
Grading-up is the process of mating
purebred males to commercial
females, with the ultimate goal of
eventually creating a purebred herd
or flock.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
The purpose of grading-up is to
improve quality, develop uniformity,
and increase performance in the
offspring.
Breeding replacement females from
within a commercial herd back to
purebred sires results in offspring
that are more genetically similar to
the purebred sire.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
A noticeable improvement through
the fourth generation can be
expected; however, progress is
much slower for proceeding
generations.
The purebred sires should be
products of different productiontested herds.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Backcrossing
Backcrossing is the mating of an
individual to any other individual
with which it has one or more
ancestral breeds or lines in common.
The backcross method is popular in
commercial cattle operations.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
With the backcrossing method,
two purebreds are crossed and
then the resulting offspring is
bred back to one of the original
parental breeds, but not the
same parent animal.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
This method of breeding
productive female offspring to
related breeds of superior males
can be continued for several
generations.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Repeated backcrossing is used to
incorporate a specific trait found in
one population into a different
population, while maintaining selective
traits found in the second population.
However, when using this system, the
breeder may risk losing some hybrid
vigor in later generations.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Three-breed Rotational Crossing
The three-breed rotational cross
method is a type of crossbreeding
that is popular with swine breeders.
This system involves breeding
crossbred females to purebred
males.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
The rotation of purebred males
from three breeds on subsequent
generations of selected crossbred
females can be continued for
several generations.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Inbreeding
Inbreeding is the mating of individuals
over several generations that are
more closely related than average
for the population they represent.
Inbreeding is used more in purebred
operations than in commercial
operations.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
When inbreeding is practiced for
several generations it is called
intensive breeding.
When “overused,” this form of
breeding gives inbreeding a
negative connotation.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
When used appropriately, the purposes
for inbreeding are to concentrate the
inheritance of desirable traits and
eliminate undesirable traits for a given
group of animals.
If starting with a desirable group of
animals, a breeder can make further
improvements by inbreeding.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Ways inbreeding can improve
livestock are:
• to develop outstanding herds,
• to form families,
• to produce breeding stock,
• to develop lines for crossing, and
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
• to determine the genetic value
of an individual.
Some potential disadvantages of
inbreeding may be decreases in
reproductive efficiency, vigor,
survival rate, and growth rate.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Line-breeding
Line-breeding is a “milder” form of
inbreeding designed to maintain a
degree of relationship to highly
regarded ancestors, without
resulting in a level of inbreeding
that is harmful.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Similar to inbreeding, line-breeding
is more often used in purebred
operations.
Animals are never mated that are
closer than half-brothers or halfsisters.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
A breeder using the line-breeding
system should recognize its
potential and limitations.
Line-breeding is only successful in
herds that have a high degree of
excellence and possess outstanding
individuals as indicated by progeny
tests.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Purebred Breeding
Inbred lines are established breeds.
Rather than referring to the process
of mating purebred individuals of
the same breed as “inbreeding,” it
is known as purebreeding or
straightbreeding.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Purebreeding is the mating of animals
within the same breed that are either
registered in a breed association or
are eligible for registry.
A purebred animal’s lineage can be
traced to the original foundation
animals of the breed, which were
those animals first accepted for
registry.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Being a purebred does not
necessarily guarantee that an
animal is superior.
Yet, purebred animals may be
preferable in many respects when
compared to grade animals.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Methods of Breeding
Livestock species can be bred
naturally or through assisted
reproductive (artificial)
technologies.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
The method of breeding a producer
uses depends on several factors:
• Type and size of the operation,
• Available labor,
• Number of males and females in
the herd or flock,
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
• Facilities,
• Financial resources,
• Breed registry policies, and
• Personal preference.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Natural Breeding
As the name suggests, natural
breeding allows animals to breed
naturally.
However, there are ways of
controlling the natural breeding
process.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Hand Mating
Hand mating, where the male is
kept separate from the female
except during the act of breeding,
is used primarily by purebred
breeders to control mating.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Under the hand mating system,
when the female comes into heat
(estrus) she is brought to the male
and mated individually.
Advantages of this system are that
the male can service more females,
the act of mating is controlled, and
accurate records (breeding dates,
etc.) are easier to keep.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Hand mating requires additional
labor because the female must be
checked for heat twice daily during
the breeding season and also
brought to the male when mating
is to occur.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Pasture Mating
The pasture mating system, used
with most commercial herds, allows
the male to be with the females
throughout the breeding season or
for the entire year.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
If uniformity in size of offspring and
time of parturition are important
production factors, exposure to
males must be limited to only the
breeding season.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
The pasture mating system may be
used for all species of livestock.
It requires less labor because it
involves less handling of the animals.
A disadvantage is that records are
more difficult to keep, especially
when more than one male is used
for pasture mating.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
When exact records are desired,
place the recommended number of
females per male and keep them in
separate pastures.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Corral Mating
Corral mating is used mostly by
horse breeders and involves
putting the mare and stallion
together in a strongly fenced
corral.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
There is no human assistance
required, other than transporting
the animals to the corral.
Both mare and stallion are returned
to their respective pens after
service.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Flock Mating
Flock mating, popular with poultry
breeders, allows a number of
males to be placed with an entire
flock of females.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
On average, a placement ratio of
12 to 15 males per 100 females is
practiced in poultry breeding
flocks.
There tends to be high fertility
rates with this system and it
requires less labor.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Pen Mating
Pen mating, a breeding method
practiced primarily by poultry
breeders, places one male with 8
to 20 females in a single pen.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
The pen mating system makes it
easier for a producer to know the
parents of every chick and to
evaluate a male’s reproductive
performance.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Fertility is generally not as good in
pen mating as compared to flock
mating because the females cannot
choose their mate, and there is no
competition occurring between
males for mates.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Assisted Reproductive
Technology
Technology offers new approaches
for the artificial breeding of animals
and can assist in addressing
problems of infertility.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Modern reproductive technologies
include artificial insemination,
semen freezing, embryo transfer,
and cloning.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
In recent years, these techniques
have been applied to produce
animals with new genes, which has
benefited not only the production
of food and fiber, but animal and
human health as well.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Artificial Insemination (A.I.)
Artificial insemination is a
reproductive technology in which
semen is collected from males and
then used to breed females.
Artificial insemination is discussed in-depth in lesson 8818-A.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Advantages of Artificial Insemination
1. It allows the use of superior,
performance-tested sires;
2. Records for production (such as
sire identification) can be
improved;
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
3. The number of females that can
be bred to one superior male
increases;
4. The chance of spreading disease
is reduced; and
5. The chances of breeding-related
injuries are reduced.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Disadvantages of Artificial Insemination
1. A trained inseminator is required;
2. More time and supervision of the
female is required, thus more labor
is needed;
3. Special handling facilities and
sterile equipment are required; and
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
4. The cost may be a problem for
some producers.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Embryo Transfer
Embryo transfer is the process of
removing an embryo from a female’s
reproductive tract, during the early
stages of embryonic development, and
transferring the embryo to another
female’s reproductive tract for further
development and subsequent birth.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Embryo transfer procedures are
more expensive and labor intensive
than other methods and are used
more often in cattle than in other
species of livestock.
Embryo transfer technologies are discussed in-depth in
lesson # 8818-B.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
However, through the use of
artificial insemination and embryo
transfer, there can be a greater
number of offspring produced from
genetically superior sires and
dams.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Estrous Synchronization
Estrous synchronization is a process
that uses chemically manipulated
hormones to bring females into
heat at or near the same time.
Estrous synchronization can be
used in any breeding program.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Estrous synchronization of several
females can be economical for
producers.
It reduces the number of days
needed to inseminate or transfer a
herd, thus concentrating labor
needs to specific breeding and
birthing times.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Cloning
Cloning is a reproductive technology
that may be used to produce
genetically identical individuals.
There are several methods of
cloning such as embryo splitting and
nuclear transfer.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Embryo Splitting
Embryo splitting, or bisection,
involves mechanically cutting an
embryo in half to produce twin
embryos, which are then
transferred to recipient females.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Embryo splitting is
possible because the
young embryonic cells
are totipotent; that is,
the cells have not yet begun to
differentiate into specialized cells
and have the potential to become
any type of cell.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Embryo splitting occurs naturally in
the case of identical twins.
Embryo splitting is designed to
increase the efficiency of the embryo
transfer rather than producing
multiple clones.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Nuclear Transfer
The process of nuclear transfer
takes the genetic material from the
nucleus of a donor cell and transfers
it into an immature recipient egg
cell, one whose own nuclear
material was removed.
This process is discussed in-depth in lesson #8518.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Advantages of Cloning
1. Individuals with outstanding
genetics can be replicated;
2. Cloning allows for mass
production of outstanding animals;
3. Sex selection of an animal can be
predetermined; and
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
4. Records of evaluation become
more accurate.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Disadvantages of Cloning
1. The rate of success is lower;
2. More labor and other expenses
are required;
3. The potential for genetic variation
is decreased;
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
4. Selection of outstanding animals
from a cloned herd becomes
more difficult; and
5. A highly-skilled technician is
needed to perform procedures.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Factors to Consider When
Selecting a Method of
Animal Breeding
When selecting a method of animal
breeding, producers should consider
the following factors.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
• Breeding season;
• Age of puberty and breeding ages
of livestock;
• Reproductive cycles of livestock;
and
• Preparation of animals for breeding.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Selecting a Breeding Season
When establishing breeding systems
and methods of breeding, producers
must decide on a breeding season.
The time and duration of the
breeding season affects the birthing
season and the uniformity of the
offspring.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
While some producers may choose
to have a year-long breeding
season, many producers prefer to
have offspring born in the spring or
fall and have offspring that are
similar in age and weight.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Ideally, offspring for a given
livestock enterprise should be born
within a specified number of days;
for example, 40 to 60 days is a
common time frame for cattle.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Factors to consider:
• Climatic conditions will affect the
amount of equipment, feed, and
housing needed;
• The availability of labor should
determine the system of mating
to use, as well as, the time of
year the offspring will be born;
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
• Usually, prices for market animals
are better during certain times of
the year than others, so “target”
dates for marketing the offspring
need to be set;
• In certain areas, availability of
equipment and housing are factors
that affect the choice of breeding
season. For example, …
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
some species of livestock will
have to be placed in a barn and
provided heat during the winter
months.
• If the females and offspring are to be
provided grazing, then its availability
may be of great importance (usually
grazing is best during late spring and
early summer);
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
• Livestock show rules may require
that animals be classed based on
their ages (Frequently, animals
that are the maximum allowable
age for a particular class have a
competitive advantage); and
• The purpose for which livestock are
produced (For example, …
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
the birth of offspring for
replacement purposes determines
the season in which they will reach
a desirable breeding age and thus
the length of time required to
bring them into production).
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Age of Puberty and Breeding
Ages of Livestock
Season of birth, temperature,
nutrition, rate of maturity, and
heredity affect the age at which
animals reach puberty.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
The age of puberty (age at which
animal reaches sexual maturity
and is capable of reproducing) and
breeding age are two distinct
benchmarks of physical
development.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Because an animal has reached sexual
maturity does not always mean that it
is capable of reproducing efficiently.
For example, research reveals that
stage of body development is
frequently more important than age in
determining when animals will reach
puberty.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Usually, it is advisable to allow
livestock to continue to develop and
mature after reaching puberty.
Proper breeding age may vary
widely, depending on body growth
and development of individual
animals, within a breed and species.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Often, it may appear advantageous to
breed at an early age to reduce
production expenses.
Sometimes it is to the producer’s
advantage to delay breeding to avoid
the possibility of physical injury
occurring and to reduce the incidence
of birthing problems associated with
physically underdeveloped females.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Puberty Age
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Breeding Ages of Females
Mating females for the first time at
a mature breeding age offers certain
advantages to the producer, such as
a physiological advantage and
increasing a heifer’s rate of milk
production.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Early breeding can potentially
increase the lifetime production of a
female.
Supplemental feeding of heifers or
providing them with good pastures
can cause heifers to develop and
mature faster and thus breed earlier.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Although early breeding may offer
some advantages, more often than
not, it is body development that
determines when producers will
mate females for the first time.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Breeding Age of Males
The principal consideration for the
breeding age of males is the
number and quality of offspring
that a male can sire in a given
season.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
The total number of services
possible will vary according to a
male’s age, physical development,
health, temperament, and
condition, as well as, the breeding
system (hand or pasture mating)
used and the distribution of
services.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Mating Guide
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If pasture mating is practiced,
several other important factors,
such as range carrying capacity,
size of pasture, and herd size, will
influence the number of females
that can be serviced by one male.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
One bull to about 25 cows is the
standard ratio recommendation for
cattle under range conditions.
A ratio of one ram to 25 – 30 ewes
is recommended for sheep under
range conditions.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Pasture mating is not recommended
for stallions, due to the possibility of
injury.
As a general rule, mature males of
all species are capable of breeding
considerably more females than are
young males.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Reproductive Cycles of Livestock
Factors that control reproductive
cycles of female livestock:
• Estrus,
• Estrous cycle,
• Time of ovulation, and
• Gestation period.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Estrous (or heat interval) – includes
the reproductive and hormonal
changes a female undergoes on a
“scheduled-basis” after reaching
puberty.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Estrus (or heat period) – is the
portion of the heat interval during
which hormones are secreted by
female and outward signs of
receptivity to mating are
displayed.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Ovulation is the expelling of an
egg (ovum) from the ovary.
Ovulation occurs during the heat
period (estrus) and signals that
the egg is ready to be fertilized by
a sperm cell.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Once an egg is successfully
fertilized, the female’s body
undergoes physical changes as
the fetus develops.
Gestation period – the period of
time required for the fetus to
develop.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Reproductive Cycles of Livestock
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Preparing Animals for Breeding
The percentage of females giving
birth greatly affects the success of a
livestock enterprise.
The fastest means of increasing
profit is to increase the number of
females giving birth, which impacts
the production costs per pound.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
To ensure a high conception rate,
males and females of most species
of livestock should be prepared for
breeding.
Elements that influence when female
livestock will begin a heat period are
age, post-birthing interval, nutrition,
physical condition, and disease.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Age – mainly refers to those females
that are too young for breeding.
Post-birthing interval – refers to the
period of time needed by the female
reproductive tract to return to its
original shape and condition
following parturition.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Physical condition – refers to the body
condition of the animal and is based
on nutrition; females and males that
are too fat or too thin frequently do
not reproduce efficiently.
Diseases – affect fertility and the
ability of an animal maintain
pregnancy for full term.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
Cattle
The ultimate goal of most cattle
producers is to achieve a 100% calf
crop.
Calf crop refers to the ratio of calves
produced to the number of cows in
the herd.
Photo by Keith Weller courtesy of USDA Agricultural Research Service.
If producers want their cows to
calve annually, they must plan for
them to calve at least 45 days
before the beginning of the next
breeding season, so they may be
rebred in a timely fashion.
Photo by Keith Weller courtesy of USDA Agricultural Research Service.
The age of the cow influences the
number of days after calving that will
pass before she will come into heat.
Usually, older cows come into heat
sooner than younger cows.
Photo by Keith Weller courtesy of USDA Agricultural Research Service.
First-calf heifers have to perform
all the bodily functions of a mature
cow, while at the same time
continue to grow.
The stress related to producing
milk affects the rate of recycling of
first-calf heifers.
Photo by Keith Weller courtesy of USDA Agricultural Research Service.
Research has shown that a 90%
conception rate for first-calf heifers
can be achieved, if they are handled
properly following the birth of their
first calf.
Photo by Keith Weller courtesy of USDA Agricultural Research Service.
The most common problem
affecting early breeding is a
retained placenta, which can
cause the cow’s uterus to
become infected and delay her
next estrous cycle.
Photo by Keith Weller courtesy of USDA Agricultural Research Service.
The post-calving interval influences
recycling and conception rate.
About one-third of cows having a
rest period shorter than 45 days
experience serious reproductive
problems.
Photo by Keith Weller courtesy of USDA Agricultural Research Service.
An effective means of increasing overall
breeding efficiency is to select females
based on breeding performance, which
is genetically influenced.
This may be done by palpating females
about 45 days after bulls are removed
and culling cows that are not pregnant.
Photo by Keith Weller courtesy of USDA Agricultural Research Service.
The most important environmental
factor affecting reproduction is
nutrition.
Most breeding failures and late
calving incidents can be related to
a lack of adequate nutrition.
Photo by Keith Weller courtesy of USDA Agricultural Research Service.
Nutrition is important for gestation,
lactation, and rebreeding.
If extra feed or grazing is not provided,
the cow will mobilize body fats to
compensate for the deficiency and will
suffer a weight loss, which could
prevent her from cycling and rebreeding
in a timely fashion.
Photo by Keith Weller courtesy of USDA Agricultural Research Service.
It has often been said that a bull is
one-half the cow herd.
Factors such as general health,
condition of feet and legs, age, teeth,
and abnormalities of reproductive
organs should be check during a bull’s
breeding soundness evaluation.
Photo by Keith Weller courtesy of USDA Agricultural Research Service.
Bulls should be fertility-tested prior
to the breeding season to determine
semen quality.
The bull’s libido should be evaluated
when the bull is placed with cows
that are in heat; at this time the
bull should become sexually aroused
and eager to mate.
Photo by Keith Weller courtesy of USDA Agricultural Research Service.
Sheep
For most sheep producers, the goal
set for their lambing crop is 200%,
since most ewes are physically capable
of giving birth to twin lambs.
Producers tend to select and keep ewes
that consistently deliver healthy twins.
Photo by Ron Nichols courtesy of USDA Natural Conservation Resource Services.
Flushing, a practice of feeding ewes
good high-quality green pasture or
additional concentrates four to eight
weeks before breeding, increases the
rate of conception and influences the
rate of twinning.
Photo by Ron Nichols courtesy of USDA Natural Conservation Resource Services.
Rams should be fertility-tested prior
to each breeding season.
Factors such as quality and quantity
of feed nutrients are very important
at time of breeding, during gestation,
and while lactating.
Photo by Ron Nichols courtesy of USDA Natural Conservation Resource Services.
Since most ewes go through a
period of anestrous, they tend to
only lamb in the late winter and
spring.
Most breeds of sheep will experience
17-day estrous cycles beginning in
mid-fall and ending in early spring.
Photo by Ron Nichols courtesy of USDA Natural Conservation Resource Services.
Swine
Most swine producers want their
breeding stock to produce eight to
fifteen pigs per litter.
Female swine are
selected based on
the number of pigs
born and weaned,
as well as, their
overall mothering ability.
As with sheep and cattle, female
swine productivity is affected by
nutrition prior to breeding (flushing),
during gestation, and during
lactation.
Boars exposed to stress or high
temperature conditions may stop
producing sperm.
Boars should be kept in a cool, wellventilated area and should have feed
intake increased during times of active
breeding.
Ideally, boars should be purchased
several months prior to the
breeding season so that they can
become accustomed to their new
environment.
Boars should be fertility tested
once they are established.
Horses
Most authorities agree that mares
are the most difficult of all livestock
species to “settle” or conceive.
Before breeding, mares should be
checked for signs of venereal
disease, general sickness, and other
types of unsoundness.
Photo courtesy of USDA Photography Center.
Plenty of exercise and adequate
feed should be provided during
the mating season.
Photo courtesy of USDA Photography Center.
If possible, a mare should be taken
to the stallion for service.
Allow the mare to become quiet
and cooled prior to breeding.
Permit the stallion to mount the
mare only when he is ready for
service, then return him to his stall.
Photo courtesy of USDA Photography Center.
Allow the mare to remain quiet for
a short period of time after service,
then return her to her quarters.
During gestation, a mare should
receive the same ration as before
breeding.
Photo courtesy of USDA Photography Center.
Summary
Producers should carefully consider
factors that affect the reproductive
efficiency of livestock and use
sound management practices to
increase production and profitability
of enterprises.
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
ALL RIGHTS RESERVED
Reproduction or redistribution of all, or
part, of this presentation without
written permission is prohibited.
Instructional Materials Service
Texas A&M University
2588 TAMUS
College Station, Texas 77843-2588
http://www-ims.tamu.edu
2006
Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.
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