Reproductive Structures and Cycles in Livestock

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 Anestrus Gestation 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 Lactation Colustrum The act of giving birth 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

Female Reproductive Anatomy

Female Tract Image from: http://www.ca.uky.edu/agripedia/agmania/IAS/ASC106/REPRFEMA.asp

Suspensory Ligaments Broad Ligament Supports and suspends tract Provides vascular supply Lymphatic drainage Nerves Composed of: Mesometrium (Body) Mesosalpinx (oviduct) Mesovarium (ovary)

Suspensory Ligaments Image from: http://medical-dictionary.thefreedictionary.com/_/viewer.aspx?path=dorland&name=ligamentum_latum-uteri.jpg

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

Female Reproductive System infundibulum ovary uterus Image from: http://www.selectsires.com/resources/fertilitydocs/reproductive_anatomy.pdf

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)

Female Reproductive System

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 Images from: Cow - http://www.ansci.wisc.edu/jjp1/ansci_repro/lab/female_anatomy/cow_2011/cow_tract_750_cut.html Sow - http://www.ansc.purdue.edu/swine/porkpage/repro/physiol/reppaper.html

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 Image from: http://www.thehorse.com/images/content/0703/repro.html

Reproductive Tract of Cow

Sow

Reproductive Tract of the Ewe

Reproductive Tract of the Mare

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 Cow 1 egg/estrus Ewe 1 - 3 eggs/estrus Sow 10 - 20 eggs/estrus Mare 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 48-72 hours 35-45 hrs from estrus onset Cow 18-19 hours 10-11 hrs after onset of estrus Mare 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)

Reproductive Functions (Female) http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CB8QFjAA&url=http%3A%2F%2Fmail.clevelandcountyschools.org%2F~kharris%2FFOV1-000341D9%2FS03C1AC2A-03C1AC2A.9%2FAnimal%2520Reproduction%2520and%2520Genetics.ppt&ei=eZdYUOXZNcS-2AW52oHIBw&usg=AFQjCNG44DGlnvwCMu-TsjVfr2HyJsnJeQ

The Male Reproductive Tract Objective: Identify the parts of the male reproductive system of livestock and poultry

Male Reproductive Tract

Male Reproductive Tract

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

Testicle Anatomy

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

Male Reproductive Tract http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CB8QFjAA&url=http%3A%2F%2Fmail.clevelandcountyschools.org%2F~kharris%2FFOV1-000341D9%2FS03C1AC2A-03C1AC2A.9%2FAnimal%2520Reproduction%2520and%2520Genetics.ppt&ei=eZdYUOXZNcS-2AW52oHIBw&usg=AFQjCNG44DGlnvwCMu-TsjVfr2HyJsnJeQ

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

Bull Reproductive Tract

Ram Reproductive Tract

Boar Reproductive Tract

Stallion Reproductive Tract

Reproduction in Poultry Objective: Specify how the reproductive system for poultry functions

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

Reproduction in Poultry Major difference: Embryo of livestock develop inside the female’s body while the embryo of poultry develops inside the egg. Poultry only have the left ovary and oviduct when mature The yoke is the ovum Chicken Incubation 21 days