Animal Science Exam 3 Book Notes

testes

produce sperm and testosterone

epididymis

passageway of sperm from testes to vas deferents, long, coiled tube attached to the testis, maturation of sperm. sperm travels through head, body, tail.

head sperm

sperm not capable of fertilization (useless)

body sperm

sperm gains motility, gains ability to swim

tail sperm

storage site until ejaculation; sperm fertile & mobile

vas deferens

transport sperm from testes to penis, tube that carries sperm from the epididymis to the urethra

accessory sex glands

secrete components of seminal fluid, male reproductive system that produce fluids added to sperm to make semen

pathway of sperm

Testes → Epididymis → Vas deferens → Ampullae → Seminal vesicles → Prostate → Cowper’s (bulbourethral) glands → Urethra → Outside (TEVASPCUO)

seminiferous tubule

sperm producing cells. are tiny coiled tubes in the testes where sperm are produced

structure of testes

seminiferous tubule. a bunch of tubes

LC (leydig cells)

source of testosterone

ST (seminiferous tubules)

source of sperm. structures in the testes where sperm are made

Rectum

last part of the large intestine where feces are stored before leaving the body

who has a fibroelastic penis

boar, bull, ram, goats. straightening an S-shaped bend instead of getting much bigger.

who has a vascular penis

stallion. filling with blood and increasing in size

flehmen response

exposure of nasopalatine duct to absorb pheromones. behavior where an animal lifts its upper lip and inhales to better detect smells (especially reproductive hormones)

semen and ejaculation characteristics of farm species

they’re all different

cryptorchidism

one or both testicles fail to descend into the scrotum. common boars and stallions

thermo-regulation of the testis

4-6 degrees celsius

insulation

keeping heat in or out to control temperature

sweat glands

glands in the skin that produce sweat to help cool the body

blood supply to testis

warm arterial blood is cooled before entering testis by crossing over cooler veins that are leaving testis

pampiniform plexus

temperature regulation. network of veins around the testicular artery that cools blood going to the testes

estrous

no shedding. the reproductive cycle in females that are of an estrual species. is the time in the female reproductive cycle when the animal is in heat and can get pregnant.

A.I.

artificial insemination, common technique used in reproductive biology that involves placing semen into the reproductive tract of the female by artificial techniques rather than natural mating

E.T.

embryo transfer, which is a procedure used to transfer embryos from a donor female to a group of recipient females

copulatory organ

reproductive organ used to transfer sperm from the male to the female during mating

sow uterine body

VERY SMALL uterine body, long uterine horns

mare uterine body

LARGE uterine body, shorter uterine horns

uterus

where a fertilized egg implants and develops into a fetus. whom. home for fetus

sow uterus

different because of piglets. has extremely long uterine horns and a very small uterine body.

difference in uterus among animals

pig is different. cow, ewe, doe, and mare are similar

functions of the uterus: muscle contractions

after ovulation, the corpus luteum produces progesterone to maintain pregnancy and keep the uterus relaxed; near birth, progesterone decreases as the CL regresses, allowing prostaglandin and oxytocin to stimulate uterine contractions that dilate the cervix and expel the fetus and placenta

uterus provides environment for embryo

the uterus provides a safe and supportive environment where the embryo can implant, grow, and develop

if not pregnant…

uterine endometrium releases Prostaglandin (PGF) to cause the CL(Corpus Luteum) to regress(breakdown)

if pregnant…

embryo provides a chemical signal (interferon tau) which allows the CL to be maintained

oviduct

is the site of fertilization. where the sperm meets the egg.

ovary

produces the female gamete (eggcell/ovum or oocyte) and produces hormones

how many ovaries do farm animals have

two

Graafian follicle

mature follicle, contains an egg ready for ovulation, produces estrogen, will release the egg (goes to ovulation)

Atretic follicle

deteriorated follicle, will not ovulate, gets reabsorbed by the body (dies)

corpus luteum

produces progesterone which is important for maintaining pregnancy

corpus luteum

keeps pregnancy, produces progesterone, helps maintain pregnancy, keeps the uterus ready for an embryo

Follicle is filled with what

fluid

Mare ovary

has a reversed cortex and medulla with an ovulation fossa and typically releases one egg

Sow ovary

has a normal structure without an ovulation fossa and releases multiple eggs, popcorn.

feedback mechanisms

Negative Feedback (turns things OFF)

• A hormone reduces or stops another hormone

• Example:

  • Progesterone ↓ GnRH

  • Prevents another ovulation

Keeps the system stable

Positive Feedback (turns things ON more)

• A hormone increases another hormone

• Example:

  • High estrogen → ↑ GnRH → ↑ LH → ovulation

  • Oxytocin → more contractions → more oxytocin (during birth)

👉 Amplifies a process until it finishes

gonadotropin releasing hormone

secreted by hypothalamus, acts upon anterior pituitary(small gland in the brain that releases hormones controlling reproduction), stimulates release of FSH(follicle growth)

GnRH

Stimulates the pituitary gland to release: FSH (follicle growth) LH (ovulation) to control reproduction

Luteinizing hormone

secreted by anterior pituitary, acts upon ovary, causes ovulation(release of the egg) and development of the CL

FSH: Follicle stimulating hormone

secreted by anterior pituitary, acts upon ovary, stimulates follicles in the ovary to grow, needed in very small amounts

estrogen

secreted by follicle, follicular hormone responsible for estrus(time when a female is in heat and willing to mate)

Progesterone

often called “the hormone of pregnancy” is responsible to maintain of pregnancy and keep the uterus ready for an embryo

oxytocin

uterine contractions during parturition,

prostaglandin

secreted upon uterine lining, acts upon corpus luteum, causes the regression of the CL, causes uterine contractions

interferon tau

pregnancy recognition signal in cattle and sheep

parturition

parturition is initiated by the release of the hormone, cortisol(helps the body respond to stress), from the fetal adrenal cortex(large inner layer of the fetal adrenal gland that helps produce hormones needed for the baby’s growth and for maintaining pregnancy)

causes of dystocia

fetus is too large, females that are too young, abnormal pregnancy, small pelvis in the female

timing of estrus and ovulation

the animals have different durations

why synchronize estrus

scheduled calving, problem cows are identified(many cows show heat at once, which can make it hard to correctly identify which cows are actually in estrus), early conception(higher weaning weights and more uniform calf crop)

ram & swine effect

natural synchronization method. The ram effect is when introducing a ram (male sheep) to a group of ewes (female sheep) causes the ewes to start cycling and come into estrus (heat)—even if they weren’t cycling before.

common signs of estrus

stands to be mounted by other animals, persistent trailing of other animals, licking other animals, nervous and restless behavior, red and swollen vulva, mounting other animals, clear mucus discharge

estrus detection

many estrus section aids: computer sensor, K-mar, bovine beacon, estrus alert, paint stick, former bull, pedometer

method of artificial insemination for cow

rectocervical: hand in rectum guiding through the cervix

method of artificial insemination for sow

cervical: insert tool (pipet) into vigina. no visual aid, you insert the AI tool and feel/estimate where the cervix is

method of artificial insemination for mare

vaginocervical: uses a speculum (tool to open the vagina), you can see the cervix directly, more accurate than cervical because it’s visual

method of artificial insemination for sheep, goats, deer

laparoscopy: surgical introduction of semen directly into uterine horns

objectives for embryo transfer

to increase the number of offspring from genetically valuable females

collection of embryos

an epidural block is given to prevent rectal contractions by the donor

testicular location and orientation

board=inverted testes

stallion=horizontal testes

bull, sheep, goat=pendulous testes