Reproductive Technologies – SS3 Livestock Farming Lesson Note (First Term)

Reproductive technology is the use of science to assist animal breeding so that the best traits, such as high milk yield or fast growth, pass to offspring quickly. The main methods are artificial insemination, embryo transfer and cloning.

Behavioural objectives

By the end of the lesson, students should be able to:

1. Define artificial insemination, embryo transfer and cloning.
2. State the benefits of artificial insemination.
3. Explain why embryo transfer is used.
4. State the purpose and the limitations of cloning.
5. Compare the three technologies by focus, main goal and complexity.
6. Explain how these technologies can help Nigeria’s food security.

Why are we changing how animals breed?

Reproductive technology makes sure the best traits pass to the next generation faster than natural mating can.

• Natural mating: a bull and a cow are kept together and mate on their own.
• Problem 1: it is slow, because a cow usually has one calf a year.
• Problem 2: it is unpredictable, because the calf may not inherit the best traits.
• Solution: assisted breeding lets farmers choose the parents and spread their genes widely.

What are the types of reproductive technology?

There are three main types of reproductive technology: artificial insemination, embryo transfer and cloning.

• Artificial insemination (AI): semen from a chosen male is placed in the female by hand.
• Embryo transfer (ET): embryos from a top female are placed in other females to carry.
• Cloning: an exact genetic copy of an animal is made.

What is artificial insemination (AI)?

Artificial insemination is the placing of semen from a chosen male into the female’s reproductive tract by hand, without natural mating.

• It is the most common of the three technologies.
• The semen is often frozen and stored in small straws.

What are the steps of artificial insemination?

1. Select a high-quality male with the traits wanted.
2. Collect semen from the male.
3. Check the semen, dilute it and freeze it for storage.
4. Watch the female to find out when she is on heat.
5. Thaw the semen and place it in her reproductive tract at the right time.
6. Confirm later that she is pregnant.

What are the benefits of artificial insemination?

• The “Super Dad” effect: one elite bull can father thousands of calves without leaving his farm.
• Safety: a large bull can hurt a smaller cow during natural mating, and AI removes that risk.
• Disease control: it reduces the spread of diseases passed on during mating.
• Cost: a straw of frozen semen is cheaper than buying, feeding and housing a large bull.

What are the limitations of artificial insemination?

• Skill: a trained person is needed to do it correctly.
• Heat detection: the farmer must spot the right time, or the female will not conceive.
• Storage: frozen semen needs proper equipment and careful handling.

What is embryo transfer (ET)?

Embryo transfer is the removal of embryos from a top female (the donor) and their placement in other females (surrogates or recipients) to carry to birth.

• If AI focuses on the father, ET focuses on the mother.
• The donor is the “Super Mom”: a very healthy and productive cow.
• The surrogates are average cows that carry the calves to term.

What are the steps of embryo transfer?

1. Select a top donor cow.
2. Give her a hormone so that she produces many eggs at once.
3. Mate or inseminate her so that the eggs are fertilised and become embryos.
4. “Flush” the embryos out of her reproductive tract.
5. Examine the embryos and keep the healthy ones, fresh or frozen.
6. Place each embryo in a surrogate cow.
7. The surrogate carries the calf to term and gives birth.

Why do we use embryo transfer?

• Speeding up progress: a cow normally has one calf a year, but with ET one “Super Mom” can have many of her own calves born in a year through host mothers.
• International trade: it is easier and cheaper to ship a small container of frozen embryos than to fly live cows.
• Spreading good female genes: the best cow is no longer limited by how many calves she can carry.

What is cloning?

Cloning is the making of an exact genetic copy of an animal.

• It is the most complex of the three technologies.
• A clone is like an identical twin of the original, born at a different time.
• A clone is not the son or daughter of the original animal.
• A cell is taken from a high-performing animal (the “original”) and used to make an embryo with the same DNA.

What are the steps of cloning?

1. Take a body cell from the animal to be copied.
2. Take an egg cell from a female and remove its nucleus.
3. Put the body cell, with its DNA, into the empty egg cell.
4. Stimulate the egg so that it divides and forms an embryo.
5. Place the embryo in a surrogate female.
6. The surrogate gives birth to the clone.

What is the purpose of cloning?

• Preserving “the best”: if a prize-winning bull dies unexpectedly, a clone can replace him in the breeding programme.
• Consistency: a cow that gives the ideal amount of milk and never falls sick can be copied to make a uniform herd.

What are the limitations of cloning?

• Cost: it is very expensive.
• Difficulty: it needs advanced laboratory skill and equipment.
• Success rate: it often fails, so many attempts may be needed.
• Result: few cloned animals are found on regular farms yet.

How do the three technologies compare?

AI uses the male’s semen, ET uses the female’s embryos and cloning copies one whole animal. The table compares them.

How can reproductive technology help Nigeria’s food security?

Reproductive technology can raise meat and milk output so that food supply keeps pace with a growing population.

• The need: a growing population needs more meat and milk.
• Local cattle: breeds such as the White Fulani are hardy and cope with heat, but give less milk than European breeds.
• Crossbreeding: AI or ET can cross local cows with high-yielding breeds.
• Result: the offspring can tolerate the Nigerian climate and give more milk than the local parent.
• Wide reach: AI lets many farmers use one good bull’s semen without owning the bull.

Evaluation

1. True or False: In artificial insemination, the male and female animals must meet face-to-face.
2. What do we call the “average” cow that carries the baby for a “Super Mom” in embryo transfer?
3. Which technology creates a “genetic twin” of an existing animal?
4. State two limitations of cloning.
5. Why is it cheaper to ship frozen embryos than live cows?

Assignment

Explain how artificial insemination or embryo transfer can help Nigerian farmers improve milk production from local cows such as the White Fulani. In your answer, state two benefits of artificial insemination.