Chapters 10 & 11

Identify and explain the functions of the male and female reproductive anatomy

Knowledge of hormone function and its affect on reproductive success

Understanding of the process of parturition Describe the process of semen collection

and processing Influence of AI on the livestock industries Knowledge of the use of embryo transfer

and its place in reproductive management

Ovary◦ Produces the ova & female sex hormones

(estrogen & progesterone) Folliculogenesis

◦ Each follicle contains an ovum◦ Development starts from deep within the ovary

with primordial follicles◦ As a follicle develops, it produces more estrogen,

which continues its maturation

◦ Each follicle goes through stages of recruitment, selection, and dominance.

◦ As a follicle develops it can become: Primary Secondary Tertiary Graafian Degenerative (atresia)

◦ Only the Graafian follicle can be ovulated◦ Ovulation occurs when the follicle ruptures,

releasing the ovum◦ After ovulation, follicular cells form the Corpus

Luteum The Corpus Luteum

◦ “yellow body” or callous on the ovary◦ Produces progesterone (maintains pregnancy)

http://www.cvm.okstate.edu/instruction/mm_curr/histology/fr/HiFRp09.htm

The Oviduct◦ Collects the ovulated ovum in the Infundibulum

which guides the egg into the oviduct◦ The site of fertilization◦ A fertilized embryo migrates to the uterus within

3-5 d Uterus

◦ Embryo attaches to the uterine wall to begin development

◦ Some attach in the uterine horn (sow), others in the uterine body (cow/mare)

◦ Guarded by the cervix (gatekeeper)

The Vagina◦ The “passageway” to the reproductive tract◦ Female organ of copulation◦ Environment changes depending on the stage of

reproductive cycle◦ Also include the urethra

Testicles◦ Suspended from the body◦ Produce testosterone

Leydig or Interstitial cells◦ Site of spermatogenesis

Sperm begin development within the seminiferous tubules

The Epididymis◦ Stores sperm for maturation◦ Acquire the potential for fertilization◦ Most mature spermatozoa are nearest the Vas

Deferens, while least mature are nearer the testicles

◦ Some degenerate and are reabsorbed

Vas Deferens◦ Transport tube for sperm from epididymis to

urethra.◦ Spermatozoa are stored in the ampulla of the V.D.

until the time of ejaculation◦ Some species deposit sperm very quickly, and

some slowly (8-12 min.) Bull, horse, ram Boar, dog

Urethra◦ Canal extending from the bladder through the

pelvis to the end of the penis◦ Carries both urinary waste and sperm

The Penis◦ Male organ of copulation◦ Virtually every species is different in form and

function

Hormones stimulated and produced from the Anterior Pituitary of the brain1. Luteinizing Hormone (LH)-causes Leydig cells

to produce testosterone2. Follicle-Stimulating Hormone (FSH)-stimulates

the seminiferous tubules to nourish developing spermatozoa

Hormone function can be influenced by photoperiod (day length)

Originate in the Hypothalamus and the Anterior Pituitary◦ Gonadotropin Releasing Hormone◦ LH◦ FSH

Some Hormones also released from the female reproductive organs◦ Estrogen-follicle◦ Progesterone-CL◦ Prostaglandin-uterus

All these activities make up the estrous cycle◦ Estrous cycles range from 14-29d and can last

anywhere from 12 hrs. to 9d Hormone function can be altered or

stimulated with hormone therapy treatments

Onset of gestation following fertilization Embryonic cell division every 20 hrs. The period of attachment in the uterus is

critical (20-30d cattle, 14-21d swine)-if no attachment-embryonic death occurs

Embryonic stage ends around 45d after period of formation of major organs

Fetal stage from 46d to birth

Placenta is responsible for protecting the fetus and exchanging nutrients and waste with the mother

Birthing is initiated with the release of cortisol

Cortisol release causes progesterone to decrease and estrogen, PGF2a, and oxytocin to spike initiating uterine contractions

Relaxin also released from the CL-stimulates the pelvis

What has it done for the livestock industry?◦ How does it fit?◦ What are the drawbacks?◦ Is it prominent in all of animal agriculture?

First recorded in dogs in 1780, cattle & horses in the early 1900’s

Can increase the number of offspring from one male◦ Bulls – 30-50 females/yr natural, 200-400 units/wk

for AI (avg. 1 calf/1.5 units semen) Success of AI dependent on success of

estrus detection, quality semen, semen handling, high fertility

Semen Collection & Processing◦ Collection of semen w/ and artificial vagina◦ Male mounts a female in estrus, or trained to

mount an object◦ May also collect semen manually (boar, dog), or

by electroejaculation◦ Collection timing

Bulls – 2x/d, 2d/wk Boars – every other day Shortening or extending the schedule may decrease

number of sperm/ejaculate

Evaluated for:◦ Volume, sperm concentration, motility,

abnormalities Mixed w/ an extender to dilute for more

volume (milk, egg yolk, buffer) 1 unit of cattle semen should contain 10m

normal, motile spermatozoa Can be stored and used fresh for only 24-48

hrs.

Freezing semen◦ What is it frozen in?◦ Bull semen – can be frozen and stored for

indefinite time without loss of fertility◦ Boars, stallions, rams – only modest success w/

frozen semen Inseminating the Female

◦ Conception rates depend on: Estrus detection, properly managed semen, timing of

insemination, insemination techniques, avoiding stress

Estrus Detection◦ Signals time of ovulation, timing of insemination◦ What is the best indicator?◦ What are some other indicators of estrus?◦ What are some technologies that might be used

to detect estrus?◦ What strategies might we use to detect estrus?

Timing of Insemination◦ Duration of estrus and timing of insemination

varies w/ species◦ Exhibition of estrus doesn’t necessarily include

ovulation Sows at 3-5d after farrowing

Why use estrous synchronization? Where is it the most appropriate and cost

effective? Prostaglandins

◦ Causes regression of a CL◦ Cows will be in estrus ~3d after injection◦ Only effective in the presence of a functional CL◦ Heifers/cows must be in d 5 – 18 of estrous cycle

One-injection system◦ Observe heats for first 5d of breeding season and

AI all that exhibit heat◦ Inject those not exhibiting heat on day 6◦ All animals bred by day 11◦ Can increase P.R. from 30-40% to 50-60%

Two-injection system◦ Inject all cows at day 1 and day 14◦ All cows should exhibit estrus by day 19, or breed

76-80 hrs. after second shot Can be a good tool in well-managed herds What is a major risk w/ using Prostaglandin?

MGA & Prostaglandin◦ MGA – feed additive that suppresses estrus in

heifers◦ Feed MGA for 14d, give Prostaglandin 19d after

last MGA feeding Most heifers should show estrus in 48-72 hrs Conception rate may be >80%

Select-Synch◦ Injection of GnRH 7d following Prostaglandin

Heat detect 24-36 hrs to 5d after injection Should have ~70% exhibit estrus

Co-Synch◦ GnRH on day 0, Prostaglandin on day 7, second

GnRH on day 9 and breed◦ Initiates ovulation◦ May not exhibit estrus

CIDR-B◦ Use of intravaginal progesterone implant for 7d◦ Inject prostaglandin on day 6◦ Breed upon estrus detection from days 3-6 after

injection

PG 600◦ Pregnant mare serum gonadotropin◦ Enhances fertility efficiency in swine◦ Helps lower days returning to estrus after

farrowing, schedule breeding Natural estrus synchronization

◦ Most females will suppress estrous while nursing young

◦ Removal of calf/piglet will help bring the cow into heat

What is ET? Why use ET? Can be costly - ~$1000/hd Superovulation

◦ Increase the number of ovulated ova◦ May increase the number of harvested embryos

How is ET performed? What components are essential?

What are the advantages/disadvantages? Reliability of 85-90%