Swine production Exam 3

Zygote

the fertilized eggs (one cell)

Embryo

Stage of cevelopment prior to complete differentiation and organ formation

Morula

An early staged embryo consisting

Blastocysr

Stage of embryo development before implanation (12-20 days) into the sows uterus

Zona pellucida

Thick membrane that prevents embryo from interacting with sperm prior to implantation

Ectoderm

External tissues, nervous tissue and mammary glands

Endoderm

Internal organs, digestive system and liver

Mesoderm (Mesenchyme)

Structural tissues,muscles, reproductive organs, and vascular tissue

Fetus

A developing pig after complete differentiation of tissue and organs

When do male boar reproductive organs develop during gestation?

They develop between 20–90 days after fertilization.

What marks the end of the early fetal period in boars?

The descent of the testicles from the body cavity into the scrotum (around 85–90 days of pregnancy).

What is Cryptorchidism?

Failure for the testicle to drop results in unilateral or bilateral

How can hormonal deficiencies cause cryptorchidism?

Low testosterone production from Leydig cells can prevent normal testicular descent.

What genetic factors are associated with cryptorchidism?

Mutations in genes for insulin-like growth factor 3 (INSL3), its receptor, or the androgen receptor can interfere with testicular descent.

What genetic factors are associated with cryptorchidism?

Mutations in genes for insulin-like growth factor 3 (INSL3), its receptor, or the androgen receptor can interfere with testicular descent.

What are the primary endocrine cells of the testes?

The Leydig cells and Sertoli cells.

What is the main function of Leydig cells?

They produce testosterone.

What is the main function of Sertoli cells?

They support and nourish developing sperm cells and help regulate spermatogenesis.

What is the function of the seminiferous tubules in the testes?

They are the sites of spermatogenesis (sperm production).

Where are Leydig cells located in relation to the seminiferous tubules?

They are located outside the seminiferous tubules.

Where are Sertoli cells found in the testes?

They are located inside the seminiferous tubules.

Where are Leydig cells located in the testes?

In the testicular interstitium (between the seminiferous tubules)

What hormone stimulates Leydig cells, and where is it produced?

Luteinizing hormone (LH), produced and secreted by the pituitary gland.

What do Leydig cells produce?

They synthesize and secrete androgens, mainly testosterone.

What are the main functions of testosterone in males?

It stimulates maturity, development of sperm, and development of secondary sex glands.

How does testosterone affect sperm development?

It supports and promotes spermatogenesis in the testes.

What hormone stimulates Sertoli cells, and what do they produce in response?

FSH stimulates Sertoli cells to produce testosterone-binding proteins, inhibin, and enzymes.

What is the role of testosterone-binding proteins in the testes?

They help transport and concentrate testosterone near developing spermatogonia.

What is the function of inhibin?

It enters the bloodstream and inhibits FSH secretion from the pituitary gland.

What happens during the perinatal period in boar development?

Germ cell numbers increase and Leydig cells begin to differentiate.

What changes occur during the pubertal period?

Sertoli cell proliferation slows, cell junctions form, and germ cells begin differentiating into spermatocytes and spermatids.

When are Leydig cells fully developed and when does puberty begin?

Leydig cells are developed by about 120 days of age, and puberty begins around 160 days.

What is the pathway sperm take before ejaculation?

From the seminiferous tubules → rete testis → epididymis.

Where do sperm go after leaving the epididymis?

They travel through the vas deferens to the ejaculatory duct.

What is the role of the epididymis in spermatogenesis?

It stores and allows sperm to mature before ejaculation.

After leaving the epididymis, where do sperm travel?

Through the vas deferens to the ejaculatory duct.

What is added to sperm before entering the urethra?

Seminal fluid from the seminal vesicles and Cowper’s (bulbourethral) glands.

What is the purpose of seminal fluid?

It nourishes, protects, and helps transport sperm.

Why is semen often collected fresh from boars instead of frozen?

Freezing reduces the fertility of swine semen more than it does in cattle.

What is used during semen collection to separate components?

A clean filter, such as cheesecloth.

What is removed during filtering of boar semen?

The gel-like pre-ejaculation fraction is separated from the seminal fluid and sperm.

What is the average volume of semen a boar ejaculates?

About 200 mL (range: 50–500 mL).

How many sperm cells are in a fertile boar ejaculate?

Approximately 10–200 billion sperm cells.

What is the recommended composition of an insemination dose?

2–5 billion sperm cells in 80–100 mL of semen, with 70–90% motile sperm (stored 3–7 days).

What roles do estrogen and LH play in gilt reproduction?

Estrogen stimulates follicle growth, and LH triggers ovulation.

What happens to the eggs after ovulation?

They are released in a burst and captured by the infundibulum of the oviduct.

What occurs after fertilization of the egg?

The fertilized egg implants into the uterine wall.

What is the M-shaped structure connected to the oviduct, and what is its function?

The uterus; it provides a large area for implantation and fetal growth.

What is the cervix and what are its functions?

It is a braided structure caudal to the uterine body that connects to the vagina, protects the uterus from infection, and is the site of semen deposition.

What is the function of the vagina?

It serves as the birth canal.

How often does the estrous cycle occur in healthy adult female pigs?

About every 21 days.

What are the two phases of the estrous cycle?

The follicular phase and the luteal phase.

How long does each phase last?

Follicular phase ≈ 5 days; luteal phase ≈ 16 days.

What hormonal changes occur during the follicular phase?

FSH declines, LH is released in pulses, and estrogen gradually rises.

What triggers ovulation at the end of the follicular phase?

A surge (spike) in LH.

What happens to estrogen levels after ovulation?

Estrogen levels drop to very low levels.

What structures work together to maintain pregnancy in pigs?

The corpus luteum (CL), ovaries, placenta, and uterus.

How are embryos distributed in the uterus?.

They evenly spread throughout the uterine horns, averaging about 12 embryos

What hormonal and uterine changes lead to the end of pregnancy?

The uterus produces prostaglandins and glucocorticoids, causing CL regression and initiating parturition.

What is the role of lactation in the sow after birth?

It promotes repair and rejuvenation of the uterus.

What is prolactin and where is it produced?

Prolactin is a hormone produced by the pituitary gland.

What is the function of prolactin?

It initiates and maintains milk production (lactation).

Why is teat number important when selecting replacement gilts?

Because it is directly correlated with litter size and lactation ability.

What is the average and preferred number of teats in female pigs?

The average is about 10 teats, but breeders prefer at least 14.

What genetic factors are associated with teat number?

QTLs (quantitative trait loci) on SSC1 and SSC14.

What happens during the hypergonadotrophic phase?

The CL regresses, progesterone is low, and FSH and LH increase, allowing follicular development to resume.

What characterizes the transitional phase?

FSH and LH are suppressed while the uterus is involuting (about 2–14 days after farrowing).

What occurs during the normalization phase?

FSH and LH increase, the uterus is fully involuted, follicles grow, and estrogen levels rise (15–21 days postpartum).

What is estrus in female pigs?

It is the period when the female is receptive to mating.

What are common behavioral signs of estrus in sows?

Boar seeking, reduced feed intake, pacing, mounting other sows, allowing mounting, and vocalization.

What physical signs indicate a sow is in estrus?

Ears perked, feet firmly planted, swollen/red vulva, swollen clitoris, and mucus discharge.

What behaviors are involved in boar courtship?

Vocalization, smelling the sow’s snout, and physical contact with the snout.

What is intromission in boar mating behavior?

It is the insertion of the penis into the vagina.

What happens during ejaculation?

Semen is propelled through the urethra and out of the penis.

How can handlers mimic natural mating during artificial insemination?

By applying pressure to simulate mounting.

Why is oxytocin given to sows during AI?

It mimics natural release during courtship and improves farrowing rate and litter size.

What method gives the best results for improving AI success?

Exposure to a live boar.