animal reproduction by: soccer mom

AG-ASB-13 The student demonstrates an understanding of the reproductive anatomy and biological processes involved in the reproduction of agricultural animals. a. Distinguishes between asexual and sexual reproduction. b. Explains the process by which gametes are produced in both the male and female. c. Diagrams and explains the steps involved in meiosis and mitosis. d. Describes the parts and functions of the male and female reproductive system. e. Analyzes the functions of the hormones that control reproduction. f. Describes the phases of the female reproductive cycle. g. Explains the process by which fertilization takes place. h. Compares the size and shape of sperm cells and egg cells. i. Demonstrates the procedures used in artificial insemination. j. Explains the use and procedures of embryo transfer and evaluates its economic importance. k. Describes the process and advantages of estrus synchronization. l. Researches and predicts new scientific technology that will be of benefit to livestock producers.

Animal Reproduction by:Soccer mom

Distinguishes between asexual and sexual reproduction.

» Two basic means of reproduction˃ Asexual reproduction- another organism produced from only one

parent˃ Sexual reproduction- union of sperm and egg; requires male and

female

Explains the process by which gametes are produced in both the male and female.

» Male and female parent produce reproductive cells called gametes˃ Male gamete- sperm

+ Production of sperm is called spermatogenesis+ The testes produced spermatogonia which develop into

spermatozoa.+ Four new sperm cells are created through meiosis

˃ Female gamete- egg+ Production of eggs is called oogenesis.+ Only one egg cell is produced through meiosis. Other newly divided

cells become the polar bodies to provide sustenance for the egg until conception.

˃ Uniting of sperm and egg is beginning of a new animal similar to the parents. This new cell is called a zygote.

Diagrams and explains the steps involved in meiosis and mitosis/ Compares the size and shape of sperm cells and egg cells.

Describes the parts and functions of the male reproductive system.

» Testicles˃ Most males have 2 testicles suspended away from the body (except

poultry) that produce sperm+ Enclosed in a sac called the scrotum which protects the testicles

and acts to regulate the temperature of the testicles+ For sperm production to occur, the testicles must have a

temperature lower than animal’s body.– In Winter, the scrotum pulls the testicles closer to the body– In Summer, the scrotum hangs away from the body to lower

the temp.˃ Also produce testosterone

– Controls libido and stimulates the development of sex characteristics (like muscling or tusks or odor)

˃ Sperm production is constant


» Epididymis˃ Small tube leading from the testicles where sperm mature and are stored

» Vas deferens˃ Tube leading from the epididymis to the seminal vesicles located at the

upper end of the urethra; serves as the transportation route for the sperm

» Seminal vesicles˃ Gland attached to the urethra that produces fluids to carry and nourish

the sperm; also act as a holding place for the sperm

» Cowper’s gland˃ Secretes fluid that helps cleanse the urethra before the sperm passes

through; also acts to thicken the sperm


» Prostate gland˃ Secretes fluid that is added to the semen mixture to provide nutrients

for the sperm and to expel the sperm during mating

» Penis˃ Male organ that deposits sperm in the female tract˃ Also expels urine from body˃ Boar, bull, and ram penis is made of high concentration of connective

tissue+ Upper end is S-shaped and flexes outward during mating

˃ Horse penis is made up of a high concentration of vascular tissue that becomes engorged with blood, caused the penis to become erect to penetrate the female

˃ Covered by the sheath or prepuce to protect it from injury

Describes the parts and functions of the female reproductive system.

» Ovaries˃ Produces an egg only once during an estrus cycle

+ Cycle produces the egg, places the egg in the proper places, causes the female to accept the male for mating (heat)

+ Cycle lengths differ for various animals (21d for hogs, cattle, and horses; 17d in sheep)

˃ Site of oogenesis˃ Produces estrogen, the hormone that stimulates the female sex drive

and controls the development of female characteristics+ Secreted by follicle on ovary

˃ Produces progesterone, the hormone that functions in preparing the uterus for pregnancy and maintaining it if it occurs

+ Secreted by corpus luteum (yellow body) left after follicle ruptures and releases egg


» Fallopian tubes˃ Transport the egg from the ovaries to the uterus˃ Site of fertilization of egg by sperm

» Uterus˃ Chamber in which the zygote develops into an embryo, then into fetus

» Cervix˃ Seals the uterus by its circular-shaped muscles˃ Keeps foreign matter from entering the uterus˃ Glands in cervix secrete a waxlike material that serves as a seal ˃ Dilates or opens when female is in heat to let sperm pass through and

when baby is born


» Vagina˃ Canal that connects the uterus to the outside of the body˃ Accepts the male’s penis during mating˃ Site where semen is deposited during copulation˃ Also serves as the birth canal during parturition

» Vulva˃ Exterior part of the female repro system˃ Provides a closing for the vagina and serves as the end of the urinary

tract that expels urine˃ Contains the clitoris that provides stimulation during the mating

process

Analyzes the functions of the hormones that control reproduction/ Describes the phases of the female reproductive cycle.

» Entire reproductive cycle is controlled by hormones˃ Produced by the endocrine system and serve to stimulate or inhibit the

operation of body functions+ System includes the pituitary gland (at base of brain)

» Follicle˃ Growth caused by the follicle stimulating hormone (FSH) released by

pituitary gland˃ Causes ovary to produce the follicle (looks like a clear blister on the ovary)

that secretes estrogen which tells the rest of the repro system to prepare for the egg

˃ Follicle also provide place for the egg to grow and mature and site of oogenesis

˃ When follicle ruptures releasing egg, it is called ovulation. At this time, the estrogen causes the animal to go into heat and be receptive to copulation.

Analyzes the functions of the hormones that control reproduction/ Describes the phases of the female reproductive cycle.

» Corpus Luteum˃ The yellow body the develops at the follicle after ovulation˃ Development caused by luteinizing hormone (LH)˃ Secretes progesterone that causes the walls of the uterus to thicken in

preparation for receiving the fertilized egg˃ Continues production of progesterone during pregnancy˃ If conception does not occur, the corpus luteum goes away and the

ovary starts the cycle again

Explains the process by which fertilization takes place.

» Fertilization is the process by which the sperm is joined with the egg˃ Sperm may only live 20-30 hours in the female body so mating must take

place at a time when the egg is ovulated

» During mating, sperm are ejaculated into the vagina˃ Each ejaculation contains million of sperm that contain a tail that allows

the sperm to swim˃ Sperm able to move freely are said to be motile

» Sperm swim up through the cervix, uterus and into the fallopian tubes where fertilization occurs

Explains the process by which fertilization takes place.

» In fallopian tube, sperm swim around the egg releasing an enzyme that breaks down the coating surrounding the egg˃ Then one sperm forms a tubelike connection with the egg allowing the

nuclear material in the head of the sperm to enter the egg˃ The egg then releases CHOs and protein to form a layer around the egg

to prevent any more sperm from entering (fertilization membrane)

» Fertilization complete when the nucleus of sperm and nucleus of egg fuse together

» Very soon after, the zygote begins to divide through mitosis (cleavage)

Demonstrates the procedures used in artificial insemination.

» Artificial Insemination˃ First recorded use is in 1780 by Lazarro Spallanzani, an Italian scientist,

who was successful in AI-ing dogs˃ First large-scale use was in Russia in early 1900s to replenish horse

population after WWI˃ First used in US in 1930s, but did not reach its full potential until the

technique of freezing semen was perfected in 1950s.+ Glycerin is added to semen to protect it and then semen is frozen

at a steady rate until it reaches -320°F and can be kept for years– Bull, stallion and ram semen can be frozen while boar semen

is shipped immediately and used fresh b/c of problems with sperm viability

˃ Most widely used in the dairy industry, but also used extensively for beef and to a lesser degree with horses, sheep and swine

» Advantages of AI˃ Producers may use sires of higher quality than they could normally

afford to purchase; cost of semen is lower that purchase price of live animal

˃ The EPDs and Performance Data on AI sires is much more accurate and available

˃ Allows the producer to select the type of sire needed for a particular female to increase performance of the offspring

˃ Producers don’t have to keep male animals which can be expensive and a safety hazard

˃ Less likelihood of passing STDs among animals˃ Can use sires from all over the world˃ Sires can be easily changed or replaced whereas the live animals

would have to be sold and a new animal purchased


» Semen Collection and Processing˃ Collected through the use of an artificial vagina˃ Semen is then examined under the microscope for foreign material

and quality+ Number of sperm in ml of semen- ↑+ Motility (activity) of sperm- ↑+ Morphology (shape) of sperm- irregular heads or tails

˃ Extenders (milk, egg yolk, glycerine, antibiotics) are then added to dilute the semen to divide into units and to protect the sperm during freezing

˃ Semen then packaged into straws, sealed and labeled with the name of company, date and name of sire

˃ Straws are frozen to -320°F and stored in liquid nitrogen tanks


» AI Lab


Describes the process and advantages of estrus synchronization.

» Estrus Synchronization˃ Uses artificial hormones administered to the female to control the

estrus cycle˃ Give FSH to cause follicle to rise on ovary, prostaglandin to cause heat˃ Advantages

+ Can bring groups of animals into heat at one time for breeding+ Saves time in breeding+ Creates tight calving or farrowing seasons to better market

uniform offspring

Explains the use and procedures of embryo transfer and evaluates its economic importance.

» Embryo Transfer˃ Transfer embryo of one cow to another cow˃ Increases the reproductive capacity of superior females˃ Allows for the rapid advancement of genetics from the dam since the

superior dam can produce many more offspring in her lifetime than naturally

˃ Allows the for more accurate performance data and EPDs on females since more offspring are produced

˃ Permits the import and export of quality animals˃ Allows the use of a dual production system. Ex. Dairy cows could carry

and birth beef calves, but still produce the milk need for sale˃ Can get mothers to carry twins˃ A producer can quickly their herd from commercial animals to

registered animals

» Process of ET˃ Select donor (superior) cows and recipient (inferior) cows

+ Donors chosen based on high milking ability, growthability or reproductive ability or phenotype

+ Recipients chosen based on health, reproductive efficiency, ability to maintain pregnancy, and deliver a healthy calf and produce enough milk

˃ Synchronize donor and recip heats so that they are in the same phase of estrus cycle at the same time

+ Donors are superovulated to release several eggs instead of just one by giving FSH+ Give prostaglandin to cause the animals to come into heat+ When in heat, then AI donors

˃ Fertilized eggs are allowed to grow for one week before they are collected from the donor cows by flushing

+ About six fertilized eggs are collected with each flush+ Then a solution is put into the uterus to kills any embryos that were missed

˃ Fertilized eggs are then examined under microscope to determine their quality and high quality eggs are frozen and stored like semen

˃ Bring recipient cow into heat by giving prostaglandins and then when CL is at right stage, implant embryo into uterus

Explains the use and procedures of embryo transfer and evaluates its economic importance.

Researches and predicts new scientific technology that will be of benefit to livestock producers.

» Sexing embryos to produce desired offspring,˃ ex. Heifers in dairy cows

» Sexing sperm to chose to either get male offspring or female offspring

» Cloning˃ Split embryos into two or more parts to produce genetically identical

offspring

animal reproduction by: soccer mom

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