Terminology
• Reproductive cyclicity– Provides females with repeated
opportunities to become pregnant• Estrous Cycle
– Physiologic events that occur between periods of sexual receptivity and/or ovulations
• Estrus– Period of female sexual receptivity
Terminology
• Castration– Removing the testicles of the male to
prevent breeding
• Anestrus– Condition when females do not
exhibit regular estrous cycles
• Gestation– Time an animal is pregnant
Terminology
• Parturition– The act of giving birth
• Lactation– Period of time that milk is secreted
by the mammary glands
• Colustrum– First milk containing a high content
of antibodies providing temporary immunity to the offspring
The Female Reproductive System
Objective: Identify the parts of the female reproductive system of livestock
Suspensory Ligaments
• Broad Ligament– Supports and suspends tract– Provides vascular supply– Lymphatic drainage– Nerves
• Composed of:– Mesometrium (Body)– Mesosalpinx (oviduct)– Mesovarium (ovary)
Ovary
• Female gonad comparable to the male testicle – Site of gamete production– Bovine have 20,000 potential eggs (ova)
per ovary, humans have 400,000 potential eggs per ovary
– Ova are fully developed at puberty and are not continuously produced as in the male
– The hen has only a left functioning ovary
Ovaries Continued
• Suspended by mesovarium• Shape varies by species
– Cattle-almond shaped– Horses- bean shaped– Sheep- round– Swine- lobular
Functions of the Ovaries
• Gamete production• Secrete estrogen (hormone)
• absence of muscle development • development of mammary glands • development of reproductive
systems and external genitalia • fat deposition on hips and stomach
(source of energy) • triggering of heat
• Form the corpus luteum
Oviducts (Fallopian Tubes)
• Pair of small tubes leading from the ovaries to the horns of the uterus– Site of fertilization– Supported by mesosalpinx– 3 to 4 days for egg to travel down
oviducts• Infundibulum - funnel shaped portion of
the fallopian tube that catches the ovulated egg
Oviducts (Fallopian Tubes)
• Functions:– Ovum transport– Sperm storage and capacitation– Fertilization – Early embryo development
Uterus
• Muscular sac connecting fallopian tubes and cervix
• Consists of a body and two horns– Cow, ewe, and mare (bicornuate)– Sow has only horns, no body– Woman has no horns (simplex)
Uterus Functions
• Sustains sperm and aids in its transport
• Maternal placenta - supports embryo and fetus during gestation
• Expels fetus at parturition • Control of cyclicity
Cervix
• Area between the uterus and vagina• Normally closed; opens at estrus and
parturition • Functions:
– Lubrication– Flushing– Barrier to foreign material or bacteria
Cervix – Species Differences
• Cow and ewe - annular rings
• Sow - corkscrew• Mare - longitudinal
folds
Vagina and Vulva
• Vagina: connects the cervix to the external genitalia and serves as the female copulatory organ
• Vulva: external tissue of the female reproductive tract, receives penis during copulation
Reproductive Functions (Female)
• Steps in the female reproductive process:
1. Ovulation — Produce gamete (ova or ovum)— Release of egg(s)— Infundibulum pushes the ovum into the
fallopian tube
Ovulation Rates by Species
Species Ovulation Rate
Cow 1 egg/estrus
Ewe 1 - 3 eggs/estrus
Sow 10 - 20 eggs/estrus
Mare 1 egg/estrus
Hen ~ 28 eggs/month
Reproductive Functions (Female)
2. Estrus (heat) – Period of time when a female will accept a
male in copulation– The female must stand (standing heat)
to be mounted before the reproductive process can begin
– Estrus detection methods: visual inspection, teaser animals, marker aids
Types of Cyclicity
• Polyestrus - uniform distribution of estrous cycles occurring regularly throughout the year– Cow, sow
• Seasonal Polyestrus - “periods” of estrous cycles occurring only during certain seasons of the year– Sheep, goat, deer, mare
• Monoestrus - only one cycle per year, often lasting several days– Dogs, wolves, bear, fox
Timing of Events in the Reproductive Cycle
Species Length of Estrous Cycle
Duration of Estrus
Time of ovulation
Ewe 17 days 24-36 hours 24-30 hrs from estrus onset
Goat 21 days 32-40 hours 30-36 hrs from estrus onset
Sow 21 days 48-72 hours 35-45 hrs from estrus onset
Cow 21 days 18-19 hours 10-11 hrs after onset of estrus
Mare 21 days 4-8 days 1-2 days before end of estrus
Reproductive Functions (Female)
3. Gestation— Fertilization to parturition— Develop embryo in uterus
4. Parturition— Expel fully developed young at birth
5. Lactation— Milk production
Reproductive Terminology
Species Act Offspring
Cow calving calf
Ewe lambing lamb
Sow farrowing piglet
Hen hatching chick
Mare foaling foal
Goat kidding kid
Gestation and Lactation Periods
Species Gestation Period (days)
Lactation Period (days)
Cow 275 - 285 beef 180 - 270 dairy 305 - 365
Ewe 115 - 142 60 - 90 - 120
Sow 112 - 115 21 - 42
Mare 330 - 345 90 - 150
Woman 270 ? (years)
The Male Reproductive Tract
Objective: Identify the parts of the male reproductive system of livestock and poultry
Male Reproductive Tract
• Scrotum - external sac that holds testicles outside of the body – Maintains sperm 4-5oF cooler than
the body temperature • Testicles - primary male organs of
reproduction – Produce sperm – Secrete testosterone
Cryptorchidism
• Failure of one or both testes to descend into the scrotum– Unilateral: one testis does not
descend •testis that descends is fertile;
reduced sperm concentrations
– Bilateral- neither testes descend into scrotum•Results in sterility due to elevated
temperature of both testes
Male Reproductive Tract
• Epididymis: long coiled tube that is a path for sperm
– Provide passageway for sperm out of the seminiferous tubules
– Storage for sperm – Fluid secretion to nourish sperm – Place for sperm maturation
Male Reproductive Tract
• Vas Deferens - slender tube from epididymis to urethra– Moves sperm to the urethra at
ejaculation • Urethra - long tube from bladder to
penis– Passageway for urine and sperm
out of the body
Male Reproductive Tract
• Penis - male organ of copulation which conveys semen and urine out of the body
• Penis retractor muscle - allows extension and retraction of the penis; sigmoid flexure extends in copulation
Fibroelastic vs. Vascular Penis
• Fibroelastic: erection extends the length of penis rather than diameter– Bull, Ram, Boar
• Vascular: composed of specialized tissues that fill with blood causing the penis to become turgid during erection – Stallion
Male Reproductive Tract
Accessory Glands: • Seminal vesicles- add fructose and
citric acid to nourish the sperm • Prostate Gland - located at the neck of
the bladder– Cleans the urethra prior to and
during ejaculation – Provides minerals for sperm – Provides the medium for sperm
transport – Gives semen it’s characteristic odor
Male Reproductive Tract
• Cowper’s gland•Also called the Bulbourethral
gland•Paired organs •cleans the urethra prior to semen
passage
Differences in Tracts
• Bulls- Pendulous, perpendicular testes• Ram- Pendulous, perpendicular testes;
Filiform appendage• Boar- Inverted testes; No ampulla;
corkscrew penis; much larger bulbourethral gland
• Stallion-Horizontal testis; loosely attached tail of epididymis; Smooth seminal vesicles; no sigmoid flexure
Reproduction in Poultry
The poultry oviduct has five parts:1) Vagina
– Holds the egg until laid
2) Uterus– Secretes the shell
3) Isthmus– Adds the two shell membranes
4) Magnum– Secretes the albumen
5) Infundibulum– Where fertilization takes place
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