animal, plant & soil science lesson c4-4 animal reproduction technology

Animal, Plant & Soil Science

Lesson C4-4

Animal Reproduction Technology

Interest Approach

Place some of the equipment needed to perform artificial insemination in the front of the classroom. Ask students if they can identify the uses of the various tools. Lead the discussion into the first objective of the lesson.

Objectives

Describe the process of artificial insemination in common agricultural animals, including the collection, evaluation, extension, and storage of semen.

Recognize signs of estrus, and identify methods or technology used to detect estrus in common agricultural animals.

Objectives

Determine the optimal breeding times and optimal placement of semen deposition in common agricultural animals.

Discuss the advantages and disadvantages of artificial insemination and natural breeding.

Define the process of estrous synchronization, semen sexing, embryo transfer, cloning, and genetic engineering.

Terms

artificial insemination

cloning donor female embryo transfer estrous

synchronization genetic engineering progestin

prostaglandin recipient female semen collection semen evaluation semen extension semen storage sexed semen standing heat superovulation

What are the steps involved in artificial insemination?

Artificial insemination is the placing of semen in the female reproductive tract by artificial techniques.

The use of this technique has increased over the past several years due to advancements in technology.

The process varies by species, but it typically involves specialized equipment and a trained technician.


The technician deposits a prepared unit of semen into the reproductive tract of the female at a predetermined time.

The objective of artificial insemination is to deposit the semen at the appropriate time to achieve fertilization.

Timing varies by species of animal and should be closely studied prior to implementing artificial insemination.


There are several different segments that support the process of artificial insemination.

Some of the major segments include: A. Semen collection—Artificial insemination

requires that semen be collected from the male. Semen may be collected

via manual stimulation or the use of an artificial vagina.

The technique used depends on the species from which the semen is being collected.


Manual stimulation involves the use of an electronic probe to encourage ejaculation.

While this process produces a semen sample, it has been determined that a more appropriate sample can be collected if the male is stimulated.

This can be achieved by utilizing an artificial vagina.

It involves allowing the male to mount a dummy animal and inserting the penis into an artificial vagina.

This process more closely simulates naturally breeding, resulting in a higher quality semen sample.


B. Semen evaluation—After semen is collected from the male, it is evaluated for quality. Only the highest quality

semen is utilized for artificial insemination.

The semen must be evaluated under a microscope to verify that it contains an appropriate number of living sperm cells.

If approved for use, the sperm is then processed to increase utilization.

What are the steps involved in artificial insemination? C. Semen extension—Semen is extended

during the processing phase, which allows for a single collection to be divided into many units. Only one unit is required for

artificial insemination; by extending it, the semen can be used for several breedings.

To extend semen, specialized compounds are added to enhance the viability and storage of the sperm cells.

Depending on the species, often nutrients are added to expand the mass of each semen unit.


D. Semen storage—Semen is stored in one of two ways. It is either frozen to extremely low

temperatures or maintained fresh until use. How semen is stored depends on the species. For example, cattle semen is slowly cooled

and frozen at a temperature of –320°F (–196°C).

Liquid nitrogen is used to obtain these extreme temperatures.


Properly frozen and stored semen can remain viable and be used 30 to 40 years later.

The frozen semen is thawed prior to use in a 95 to 98°F (33 to 34°C) water bath.

It is then ready to be deposited in the female. Fresh semen cannot be stored for such long

periods of time. For example, collections from pigs are kept at

approximately 60°F (16°C) for two to four days. Fresh semen becomes less fertile over time,

so immediate use improves the chances of successful insemination.

What are some signs of estrus, and how is estrus detected?

Estrus detection is a crucial part of a successful artificial insemination program.

Producers must be able to determine when females are at the appropriate reproductive stage to be inseminated.

Proper estrus detection results in a higher success rate for pregnancies and increases the efficiency of artificial insemination.

In order to detect estrus, producers must be able to identify physical signs expressed by animals. Some producers may utilize new technology to aid in

the process.


A. Detecting estrus—To insure high conception rates, the artificial insemination technician must be able to detect when the female is in estrus (heat). Estrus signs vary between species. The best indication of estrus for most species is

standing heat, which is the stage of estrus when a female stands when mounted by another animal.

By standing to be mounted, the female is expressing that she is at the appropriate stage of her reproductive cycle and is prepared to be inseminated at a predetermined time.


Many times the female will not stand for the first few hours, will try to mount other animals, and will be very active among a group of animals.

It is important to view the animals every few hours to determine if they are experiencing a standing heat.

Many times prior to standing or shortly after standing, heat animals will express the same characteristics.

Frequent observations can help to determine if the female is coming in or going out of the standing heat phase.


Many animals display extra mucus and redness in the vulva when experiencing estrus, which can be visually evaluated and used as indicators of when to artificially inseminate animals.

Estrus characteristics should be studied for specific animals when utilizing artificial insemination.

It will aid producers in identifying which characteristics should be observed prior to breeding.


B. Technology in estrus detection—One of the disadvantages of using artificial insemination is that it requires estrus detection. The most common method used to detect

estrus is observing the animals several times throughout the day.

It is very time consuming and can lack consistency, especially in poor weather conditions.

Recently there have been technology advancements to detect estrus.


1. Paint markers have been designed to place marks on an animal when she is experiencing estrus. The paint marker is placed on an

accompanying animal in the pen. When the companion animal

mounts the animal in estrus, the marker leaves identifying marks on the animal’s back, sides, and rump region.


2. Specialized pressure patches have been developed to identify when an animal is in a standing heat. The patch changes color

when an accompanying animal mounts the animal in estrus for a period of time.


3. Advanced computer technology has been developed to detect estrus. The use of specialized radio transmitters can

help producers. Animals are fitted with patches that transmit a

radio signal when the animal is mounted. The computer program records the date, time,

and duration of the mounting. It then sorts the data recorded and identifies

when the animal is experiencing a standing estrus.


4. The newest and developing means of estrus detection is through the use of blood, milk, and bodily fluid tests. These tests measure certain

levels of hormones in the fluid to determine the reproductive cycle stage.

The test is performed over several days and can be used to determine when the female is approaching a standing heat.

What are the various optimal breeding times and placement of semen in common agricultural animals? To have a successful artificial insemination

program, a technician must deposit semen in the reproductive tract of a female at the appropriate time.

The female must be experiencing estrus. In addition, the female must have displayed a

standing heat. Then the technician must place the semen at

the appropriate location for the sperm cells to fertilize the female’s egg.

The optimal breeding time and placement of the semen varies by species.

What are the various optimal breeding times and placement of semen in common agricultural animals? A. The use of artificial insemination is

common in beef and dairy cattle. The process of determining

when to inseminate cattle has been tweaked over time, but it is typically agreed that artificial insemination should occur approximately 12 hours after a standing heat is detected.

What are the various optimal breeding times and placement of semen in common agricultural animals?

The semen is deposited in the uterine body of the cow by passing a pipette through the vagina and cervix.

The technician must palpate the cow rectally and be able to feel the tip of the pipette in the uterine body.

Cattle are usually inseminated once with a single unit of semen.

What are the various optimal breeding times and placement of semen in common agricultural animals? B. The swine industry also frequently utilizes

artificial insemination in breeding programs. Sows and gilts will experience a standing heat

for up to three days. During this time, frame

technicians will inseminate the female daily for two or three days.

Ideally, insemination will occur 10 to 12 hours prior to ovulation.


The semen is deposited in the uterine body of the female by passing a specialized catheter through the vagina into the cervix.

The catheter is ribbed to simulate the boar penis and allow for the female’s cervix to grip the catheter.

Once the semen unit is deposited, the female will relax the cervix and release the catheter.

What are the various optimal breeding times and placement of semen in common agricultural animals? C. The use of artificial insemination in horses

is increasing rapidly. Much like cattle and swine,

the semen is deposited in the uterine body by using a specialized pipette.

The technician guides the pipette through the vagina and into the cervix to deposit the semen.


The timing of insemination is determined by palpating the horse’s ovaries to determine the stage of the reproductive cycle when the mare is experiencing estrus.

Once all indicators determine that the mare is ready for breeding, she may be injected with a synthetic hormone to enhance ovulation.

Ideally, insemination will occur 12 to 16 hours prior to ovulation.

What are the various optimal breeding times and placement of semen in common agricultural animals? D. The sheep industry has not adopted

artificial insemination at a high rate. Therefore, sheep producers rely

on nature for proper timing and placement of semen in the reproductive process through natural breeding.

Researchers continue to explore options for use, but they have been unable to create a practice that is as successful or as simple to apply as in other species.

What are the various optimal breeding times and placement of semen in common agricultural animals? E. Nearly 100 percent of all

commercial turkeys are inseminated artificially. This is due to breeding

practices and the limitations that have developed to prevent natural mating.

Fortunately, the timing and placement is much simpler than that of other species.


During the laying season, hens are inseminated with semen every 10 to 14 days.

Because turkeys do not experience estrus, the only requirement is that the hen is frequently laying eggs.

The semen is deposited in the oviduct with a small straw and is stored there as needed to fertilize eggs.

What are the advantages and disadvantages of artificialinsemination and natural breeding?

As with all management practices in livestock production, there are several advantages and disadvantages of using artificial insemination.

The same is true in the case of natural breeding.

Both should be evaluated to determine which fits best in a breeding program.

A. Some of the advantages of utilizing artificial insemination are:


1. Increases the use of outstanding sires—Through artificial insemination, many producers can use an outstanding sire to breed their females. The actual sire does not need to be present.

2. Eliminates the danger of keeping a sire—Some hazards are usually involved in keeping a sire on site. Also sires, when not breeding, are typically

kept in separate facilities. This need is eliminated with the use of artificial

insemination.


3. Reduce sire costs—In smaller herds, artificial insemination is usually less expensive than the ownership of a quality sire due to building, feed, and labor costs.

4. Increase the number of different sires in the herd— Through artificial insemination, it is possible to introduce several different genetic lines into the herd through the use of different sires.


B. Some of the disadvantages or limitations of artificial insemination are:

1. Requires skilled technician—To be successful, artificial insemination must be carried out by a person who has received training and has experience.

2. High initial investment—Considerable money is necessary to begin an artificial insemination operation.


3. Equipment costs can be high in addition to the training needed to conduct the procedure.

4. Increase management—To be successful, the level of observation and management by the producer must increase in an artificial-insemination operation.


C. Some of the advantages of utilizing natural breeding include:

1. Lower management requirements—Allowing animals to breed naturally requires little management input outside of exposing male and female animals.

2. Uniformity among offspring—By utilizing a limited number of sires through natural breeding, offspring will share similar genetic traits, which typically results in the offspring growing at the same rate.


3. Maximizing the investment of breeding animals—Purchasing sires is expensive. Allowing them to breed

more animals naturally aids in better utilizing the animals in a herd.

4. Higher success rate of breeding—Higher conception rates can be expected by allowing animals to breed naturally.


D. Some of the disadvantages of utilizing natural breeding include:

1. Danger of aggressive sires— Male animals can become extremely aggressive during the breeding season, resulting in a dangerous situation for the producers who work with the animals during this time.


2. Slow genetic improvement—Natural breeding only allows for the use of genetics from the sires owned, which slows genetic improvement unless new sires are purchased each breeding season.

3. Cost of maintaining sires—To use natural breeding, the sires must be fed and maintained year around, which increases costs due to the expense of feed and health management.


4. Higher probability of poor traits—If a sire is utilized to breed several animals naturally in a herd, there is a chance that poor traits could be passed to all offspring. For example, high birth

weight could be a trait of a sire, resulting in birthing problems for all females.

What are the processes of estrous synchronization, semen sexing, embryo transfer, cloning, and genetic engineering? Several other techniques are used in animal

reproduction in addition to artificial insemination.

Some of the more common techniques are:

A. Estrous synchronization—Estrous synchronization is bringing a group of animals into heat simultaneously, which is done to assist the producer in scheduling animal breeding and birthing.

What are the processes of estrous synchronization, semen sexing, embryo transfer, cloning, and genetic engineering?

Synchronization usually involves the use of prostaglandin, progestin, or a combination of the two.

The hormone prostaglandin causes the corpus luteum to stop producing progesterone, which allows the animal to come into estrus.

The hormone progestin has the effect of keeping progesterone levels high, holding animals in an extended diestrus.

When the progestin source is removed, the animal quickly comes into estrus.

What are the processes of estrous synchronization, semen sexing, embryo transfer, cloning, and genetic engineering? B. Sexed semen—The sex of the offspring

produced through artificial insemination can be controlled by the producer through the use of sexed semen. Sexed semen is semen that has

been prepared to produce all male or all female offspring.

It is collected in the same manner as other semen used in artificial insemination.

Once collected, the semen is processed using sophisticated equipment that sorts the X chromosomes from the Y chromosomes.


It is then packaged as either all X chromosome semen to produce female offspring or all Y chromosome semen to produce male offspring.

Generally sexed semen will predict sex with approximately 90 percent accuracy.

The cost of sexed semen is normally about four times higher than the cost of unsexed semen.

What are the processes of estrous synchronization, semen sexing, embryo transfer, cloning, and genetic engineering? C. Embryo transfer—Embryo transfer is

moving embryos from one female, called the donor female, to the reproductive tract of another female called the recipient female. Donor females usually carry

extraordinary genetics. Recipient animals have far

less worth and are used as surrogate mothers.

Embryo transfer is used following superovulation.


Superovulation involves getting a female to release more than the usual number of eggs during a single estrous cycle.

Embryos can be frozen in liquid nitrogen and transferred later; however, the success rate is higher when transferring fresh embryos.

What are the processes of estrous synchronization, semen sexing, embryo transfer, cloning, and genetic engineering? D. Cloning—Cloning is the production of one

or more exact genetic copies of an animal. There are several methods of cloning animals.

1. One method of cloning involves letting embryos grow to the 32-cell stage before splitting into two identical embryos.

What are the processes of estrous synchronization, semen sexing, embryo transfer, cloning, and genetic engineering? 2. Another method involves taking the DNA

from an adult animal and transferring it to an embryo that has had its DNA information removed. The embryo is then stimulated through

chemicals and other techniques to encourage division.

After a period of time, it is transferred to a recipient mother to continue to grow and develop until birth.

This method was used in creation of the famous sheep named Dolly.

What are the processes of estrous synchronization, semen sexing, embryo transfer, cloning, and genetic engineering? 3. A third technique involves taking cells from

primordial germ cells during fetal development. These are more stable

cells and can be cultured and frozen for indefinite periods of time.

The germ cells can be stimulated to divide rapidly and can grow to create identical cells.

What are the processes of estrous synchronization, semen sexing, embryo transfer, cloning, and genetic engineering? E. Genetic engineering—Genetic

engineering is removing, modifying, or adding genes to DNA. Genetic engineering

using gene-splicing or recombinant DNA, along with other reproductive technology, will have a great deal of impact on future animal production.

Review




Review

What are the advantages and disadvantages of artificial insemination and natural breeding?


animal, plant & soil science lesson c4-4 animal reproduction technology

Documents

semen evaluationafter

storage of semen

semen sexing

placing of semen

artificial vagina

artificial techniques

highest quality semen

prepared unit of semen