Reproduction Flashcards
Scrotum
-skin sac that surrounds, supports, and protects testes
-Thermoregulation=temperatures 3-5 Celsius less than body temperature required for spermatogenesis
-Has smooth muscle layer that can contract to draw testes closer to abdomen when cold and relax when warm
What are the functions of a scrotum
-protective sac
-radiator (sweating)
-Thermosensor (nerves in skin)
Testicles
-Tubular glands
-primary male reproductive organs
-Cryptorchid=retention of one or both testicles within the body cavity
What are the major products of the testicles?
-Spermatozoa
-Hormones (testosterone) and proteins
-Fluids
Sperm production and maturation
-Testes
-Epididymis
Testes
-Seminiferous tubules (FSH)=where sperm are
-Cells of Leydig (LH)=Testosterone
Epididymis
-Sperm storage and maturation
-3 distinct section
-maturity progresses from head to tail
Sperm
-head contains genetic material
-haploid has 1/2 total number of chromosomes of other body cells
-tail controls movement
Semen
combination of sperm and associated fluid
Semen Evaluation
-Sperm concentration
-Motility
-Morphology=primary abnormalities, the head (DNA)
=secondary abnormalities, tail
Spermatic cord and accessory glands
-Vas deferens
-accessory sex glands
-seminal plasma
Vas deferens
tube to transport mature sperm from epididymis and into the urethra
Accessory sex glands
-add specific secretions to the semen including nutrients and liquid (add volume)
-Ampulla
-Prostate
-Vesicular glands (seminal vesicles)
-Bulbourethral glans (Cowper’s glands)
Seminal Plasma
a non-cellular portion of semen
Penis
-is a copulatory organ
-The three main parts are the base, shaft, and glans penis
-The shaft is the main portion of the penis
-The glans penis is the specialized distal end, has sensory nerves, and stimulation initiates ejaculation
What are the two main types of Penises
-Vascular= fills with blood to become erect; human, stallion, dog, tom cat
-Fibroelastic= uses muscles to become erect’ bull, boar, ram, buck (male goat)
Factors influencing sperm production
-Heredity= low heritability, crossbreeding widely used
-Nutrition= Vitamin A, Protein level
-Management= heat and cold stress
Avian anatomy
-Testes= same as mammals, but internal
-Vas deferens= opens into papillae located in cloaca
-Papillae= mating organ, transfers sperm to hen’s oviduct, sperm stored in sperm-host glands in the oviduct, 30 days for turkeys, 10 days for chickens
Function of female reproductive tract
-Hormonal control of organs= estrus, myometrial contraction
-Transport sperm= myometrial contraction
-Produce oocyte= female gamete
-provide environment for embryo and fetus
-give birth to fetus
-recycle to become pregnant again
-provide nutrients to young
Oocyte
-egg; female’s DNA contribution
-haploid (secondary oocyte)
-DNA in nucleus
-Zona pellucida= membrane surrounding oocyte
-Meiosis= type of cell division that reduces the number of chromosomes by half; produces four gamete cells
Ovary
-produce oocytes; produces estrogen and progesterone
Oviduct
-connects ovary to uterus
-site of fertilization
-After fertilization, oocyte=embryo
Uterus
-generally “Y-shaped”
-Horns=branches at top, larger in species that have more offspring
-Body= stem
-Growing site of embryo and fetus
Cervix
protects opening of uterus’ semen deposition in pig and horse
Vagina
connects uterus to outside of body; site of semen deposition in most species
Vulva
external opening
Female Avian System
-only left side develops
-ovary
-oviduct= infundibulum, magnum, isthmus, sperm host glands
-uterus
-vagina
-cloaca
Hormones
chemical messenger that travels in the blood to affect other cells
Gonadotropin
-releasing hormone (GnRH)
-produced by the hypothalamus, targets the anterior pituitary
What hormones does the anterior pituitary release?
-Luteinizing hormone (LH)
-Follicle stimulating hormone (FSH)
-these act on the gonads
Males Hormones
-Testosterone produced in testes in response to LH
-Testosterone is responsible for secondary sex characteristics (larger, more muscle, thicker neck)
-FSH role in sperm development and maturation
Females Hormones
-FSH promotes follicle growth
LH promotes release of oocyte from ovary
-After oocyte released, ovary produces progesterone
-Progesterone functions to support and maintain pregnancy, also produced by placenta
-Estrogen produced by ovary, mating behavior
Estrous Cycle
-hormonally controlled cycle of events from one heat period to the next
1. FSH primes follicle development
2. LH surge includes ovulation and development of corpus luteum(CL), maturation of follicle and spermatozoa
3. estrogen (E2) causes signs of estrus (heat)
4. Progesterone (P4) maintains CL
5. Prostaglandin regresses the CL
Corpus Luteum
-“yellow body,” mass of cells at site of ovulated follicle
-produces estrogen and progesterone
Length of estrous cycle
-Heifer, cow=21 days
-Ewe= 17 days
-Mare= 21 days
-Gilt, sow=21 days
-Queen= 18 days
-Bitch= 6 months
Types of estrous
-polyestrous
-seasonally polyestrous= short and long day breeders
-Anestrous
Polyestrous
-continue to cycle until they become pregnant
-humans, cows, sows, bitches
Seasonally polyestrous
-cycle only during certain times of the years
-Short day breeders= cyclic when days get shorter (ewe, doe(goat))
-Long day breeders= cyclic when day length is increasing (mare, hen, jenny, queen)
Anestrous
time period when female is not cycling, such as out of season or after giving birth
Mating
-females receptive to mating during estrus
-“estrous” the cycle vs “estrus”
-breed near ovulation=gametes have short lifespan
-conception=egg fertilized by sperm
-pregnancy check= rectal palpation, ultrasound, blood test
-females that are not pregnant= “open”
Artificial insemination
-semen deposited in female reproductive tract by artificial techniques rather than by the male
-pros= fewer animals, safer, better genetics, disease barrier, can use old/dead sires
-cons= startup costs, collecting males, techniques, estrus detection, lower conception rates
AI use across the industries
-beef cattle= 8-10%
-dairy cattle= 80-90%
-Horses= 40-50%
-Swine= 80-85%
-sheep= less than 5%
-Turkeys= 95%
Estrus synchronization
-“Natural”= weaning in pigs, transport phenomenon
-“Artificial”= manipulates estrous cycle in some way, cycling animals (regress corpus luteum and/or extend corpus luteum), non-cycling (jump start ovulation, follow with other hormones)
Embryo transfer
-implant embryo into surrogate or recipient female
-produce many offspring from elite females
-must have synchronized donors and recipients
-donor animals super ovulated and bred
-embryos flushed and implanted into recipient females
In vitro fertilization
-similar to embryo transfer
-oocytes collected from ovary
-fertilized in a petri dish and developed into embryos
-week old embryos transferred into recipients
Conception
-fertilization of egg marks beginning of gestation
-embryo implants in uterus
-placentation= attachment of chorion (membrane around fetus) to uterus (serval types)
-placentomes= caruncles (dam) and cotyledons (fetus)
Gestation 1st trimester
-placentation
-formation of brain, heart, reproductive organs
-first heartbeat
Gestation 2nd trimester
-development of organ systems
-muscle development
Gestation 3rd trimester
-lung development
-75% weight gain
Signs of parturition: 1-2 weeks prior
-mammary gland development
-“waxing” of teats
-Vulva swelling
Signs of parturition: 12-24 hours prios
-frequent defecation and urination
-Nesting
-Isolate from herd
-Turn head toward flank
-Mucus
-Off feed
Signs of parturition: “Immediately” prior
-milk dripping
-Amniotic sac may break and be partially expulsed
-cow getting up and down frequently
-restlessness, pawing
-appearance of feet
What is parturition and how many stages does it have?
-act of giving birth
-3 stages
Parturition Stage 1
-Uterus contracts, fetus into birth canal
-1-6 hours
Parturition Stage 2
-begins with fetus entering birth canal, ends with birth of fetus
-Multiples 15-30 minutes in between each
-Takes about 20 minutes to 2 hours
Parturition Stage 3
expulsion of placenta
Dystocia
-difficult birth
-typically caused by abnormal presentation
-normal position front feet fist, head in between legs
-breech= butt first
-another breech is butt first and upside down
-abnormal head backwards, front feet first or back feet first
Lacatation
-Colostrum= first milk, high in antibodies, consumed within 1st 24 hours of life
-Hormones associated with lactation are oxytocin and proactin
oxytocin
-released due to manual stimulation (suckling)
-causes milk release
Proactin
-produced when milk is removed
-stimulates milk production
Early Life Management
-Identification
-Iodine applied to umbilical cord
-some vaccinations/injection
-Castration= all species but poultry, males in livestock species, neutering/spaying, several options, benefits are males are less aggressive, no reproduction, better meat quality, disadvantages are some pain and bleeding, public perception
Modification to animals
-Dehorning= removing horn tissue, uses local anesthetic, benefits are safety, bruises on carcasses, easier to feed and transport, disadvantages are pain and infection
-Tail docking= sheep, pig, dogs, dairy
-beak trimming= avoid pecking injury
-trimming needle teeth= pigs
-ear cropping= dogs
-declawing = cats
