Animal Science REPRO

Why is reproduction the trait of greatest economic importance?

It controls the number of offspring. More offspring = more profit. No reproduction = no production of meat, milk, or fiber.

What are the 3 primary functions of the male in the reproductive process?

• Produce sperm

• Deliver sperm to female

• Produce male hormones (like testosterone)

What are the two main functions of the testes?

• Produce sperm

• Produce testosterone

What are the two main functions of the epididymis?

• Store sperm

• Mature sperm

What are the two main functions of the scrotum?

• Protect testes

• Regulate testes temperature (keeps sperm healthy)

Why is scrotal circumference a widely used selection tool for reproductive management?

Bigger scrotal circumference = more sperm production and earlier puberty in offspring.

What is the vas deferens?

A tube that carries sperm from the epididymis to the urethra.

What is the primary function of the accessory sex glands?

Produce fluids that protect, feed, and transport sperm (part of semen).

Major reproductive anatomy of a male?

• Testes

• Epididymis

• Vas deferens

• Accessory glands

• Penis

• Scrotum

What is the relationship between semen volume and concentration?

More volume usually = lower concentration.
Important for AI to make sure enough sperm per insemination dose.

What are the primary functions of the female in the reproductive process?

• Produce eggs

• Provide the environment for fertilization, pregnancy, and birth

• Nurse the young

Functions of the ovaries, oviducts, uterus, cervix, and vagina?

• Ovaries: Make eggs and hormones

• Oviducts: Fertilization site

• Uterus: Pregnancy support

• Cervix: Barrier to infection; pathway for sperm

• Vagina: Birth canal and mating organ

Describe the anatomical differences of the uterus among species.

• Cattle, pigs, sheep: Bicornuate (two horns)

• Horses: Shorter horns, larger body

• Humans: Simple uterus (no horns)

Define "standing heat."

When a female will stand still and allow mating — best sign of ovulation.

What is the follicle, where is it found, and what hormone does it secrete?

• Follicle: Structure on the ovary

• Secretes estrogen

• Holds the egg

What is the CL, where and when is it found, and what is the primary hormone it secretes?

• Corpus luteum (CL) forms after ovulation

• Found on the ovary

• Secretes progesterone

Primary function of FSH and LH in the female?

• FSH: Stimulates follicle (egg) growth

• LH: Causes ovulation and CL formation

What hormone is the "pregnancy hormone"? What structure secretes it?

• Hormone: Progesterone

• Secreted by: Corpus luteum (CL)

What organ secretes prostaglandin? What does it do?

• Uterus secretes it

• Destroys the CL

• Causes a return to heat if no pregnancy

How do structures and hormones relate throughout the estrous cycle?

Follicles grow → Estrogen rises → Ovulation (LH surge) → CL forms → Progesterone rises → If no pregnancy, prostaglandin destroys CL → Cycle repeats.

What is the major hormonal difference if pregnancy happens?

Progesterone stays high to maintain pregnancy.

What are the advantages of estrus synchronization?

• Shortens breeding/calving seasons

• Easier to manage labor and feeding

• Makes AI easier

Two hormones used in estrus synchronization programs?

• Prostaglandin (regress CL)

• Progesterone (hold off heat, then remove to cause heat)

Average estrous cycle length for livestock species?

• Cow: 21 days

• Sow: 21 days

• Ewe: 17 days

• Mare: 21 days

Which species are seasonal breeders? Which are polyestrus?

• Seasonal: Sheep, goats, horses

• Polyestrus: Cattle, pigs (cycle year-round)

What is the most reliable evidence of a female being in heat?

Standing still for mounting (standing heat).

What is teasing?

Using a male to detect females in heat (no breeding happens during teasing).

Main advantages of artificial insemination (AI)?

• Access to top genetics

• Disease control

• Lower cost vs. owning many bulls

• Used a lot in cattle, pigs, horses, and dairy goats

What is the AM/PM rule for AI?

• If a cow shows heat in the morning → Breed in the evening.

• If in the evening → Breed next morning.
  Allows sperm to meet the egg at the right time

What is the main advantage of embryo transfer?

Multiply genetics of superior females quickly.

Gestation lengths of livestock species?

• Cow: ~283 days

• Ewe: ~150 days

• Sow: ~114 days (3 months, 3 weeks, 3 days)

• Mare: ~340 days

• Goat: ~150 days

Two main functions of oxytocin?

• Causes uterine contractions during birth

• Causes milk let-down for nursing

Normal presentation for delivery of a fetus?

Front feet first, head between the legs ("diving" position).

Why is colostrum critical for a newborn?

• Provides antibodies (immunity)

• Gives energy and nutrients

• Must be received quickly (gut can absorb it for only ~24 hours)

What is dystocia? What causes it

• Dystocia = difficult birth

• Causes: big baby, small pelvis, wrong position of baby

How long after parturition do females return to estrus?

• Cows: 30-60 days

• Sheep and goats: Next breeding season

• Sows: 4-7 days after weaning

• Mares: 5-15 days after foaling ("foal heat")