1. Reproductive Structures and Cycles in Livestock

2. 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

3. 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

4. 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

5. The Female Reproductive System
Objective: Identify the parts of the female reproductive system of livestock

6. Female Reproductive Anatomy

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

9. Suspensory Ligaments
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10. 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

11. Ovaries Continued Suspended by mesovarium Shape varies by species
Cattle-almond shaped
Horses- bean shaped
Sheep- round
Swine- lobular

12. 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

13. 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

14. Oviducts (Fallopian Tubes)
Functions:
Ovum transport
Sperm storage and capacitation
Fertilization
Early embryo development

15. Female Reproductive System
infundibulum
ovary
uterus
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16. 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)

17. Female Reproductive System

18. Uterus Functions Sustains sperm and aids in its transport
Maternal placenta - supports embryo and fetus during gestation
Expels fetus at parturition
Control of cyclicity

19. Cervix Area between the uterus and vagina
Normally closed; opens at estrus and parturition
Functions:
Lubrication
Flushing
Barrier to foreign material or bacteria

20. Cervix – Species Differences
Cow and ewe - annular rings
Sow - corkscrew
Mare - longitudinal folds
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Cow -
Sow -

21. 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
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22. Reproductive Tract of Cow

23. Sow

24. Reproductive Tract of the Ewe

25. Reproductive Tract of the Mare

26. 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

27. Ovulation Rates by Species
Cow
1 egg/estrus
Ewe
1 - 3 eggs/estrus
Sow
eggs/estrus
Mare
Hen
~ 28 eggs/month

28. 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

29. 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

30. 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

31. Reproductive Functions (Female)
3. Gestation
Fertilization to parturition
Develop embryo in uterus
4. Parturition
Expel fully developed young at birth
5. Lactation
Milk production

32. Reproductive Terminology
Species
Act
Offspring
Cow
calving
calf
Ewe
lambing
lamb
Sow
farrowing
piglet
Hen
hatching
chick
Mare
foaling
foal
Goat
kidding
kid

33. Gestation and Lactation Periods
Species
Gestation Period (days)
Lactation Period (days)
Cow
beef
dairy
Ewe
Sow
Mare
Woman
270
? (years)

34. Reproductive Functions (Female)

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

36. Male Reproductive Tract

37. Male Reproductive Tract

38. 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

39. 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

40. Testicle Anatomy

41. 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

42. 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

43. 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

44. 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

45. 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

46. Male Reproductive Tract
Cowper’s gland
Also called the Bulbourethral gland
Paired organs
cleans the urethra prior to semen passage

47. Male Reproductive Tract

48. 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

49. Bull Reproductive Tract

50. Ram Reproductive Tract

51. Boar Reproductive Tract

52. Stallion Reproductive Tract

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

55. 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

58. 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