1. Animal Reproduction and Genetics

2. Terminology Objective:
Define terminology related to reproductive management and breeding systems including castration, colustrum, estrus, gestation, lactation and parturition.

3. Terminology Castration
Removing the testicles of the male to prevent breeding
Colostrum
First milk produced after a mammal gives birth that contains antibodies needed for immunity.
Gestation
Time an animal is pregnant
Puberty
Age at which animals reach sexual maturity

4. Terminology Estrus (Estrus Cycle)
When a female is receptive to be bred (also called ‘in heat’)
Ovulation
Release of an egg from the ovary
Lactation
Period of time that milk is secreted by the mammary glands
Parturition
The act of giving birth

5. Breeding Systems Objective
Discuss crossbreeding, grading-up, inbreeding, linebreeding, and purebreeding

6. Breeding Systems X Pure Breeding Registered male and female animals
Angus X Angus X

7. Breeding Systems X Cross Breeding
Mating a male and female of different breeds
Angus X Charolais = Crossbreed X

8. Breeding Systems Inbreeding Mating closely related animals
Brother X Sister
Son X Mother
Father X Daughter

9. Breeding Systems Linebreeding
Breeding more distant relatives than inbreeding
Cousin X Cousin

10. Breeding Systems Grading-Up
Mating purebred male (sires) to unregistered or crossbred females (dams)
Yorkshire bore X Yorkshire/Hampshire sow
Hybrid Vigor
Superior traits from crossbreeding
Offspring are better than parents

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

12. Reproductive Traits Species Age Range at Puberty
Average Length of Estrus Cycle
Average Length of Estrus
Average Length of Gestation
Cow
6-8 months
21 days
16-18 hours
283 days
Swine
4-7 months
3 days
114 days
Sheep
4-8 months
22 days
30 hours
148 days
Goat
1st autumn
2.5 days
151 days
Horse
12-15 months
3-7 days
345 days

13. Female Tract

14. Female Reproductive System
Ovary
Function  Produce ova called eggs.
Description  Two oval shaped organs located near the end of the reproductive tract inside the body cavity.
the ovary is comparable to the male testicle and is the site of gamete production.

15. Female Reproductive System
3 Major Functions of Ovaries
Gamete Production
Estrogen Secretion
Corpus Luteum Formation
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

16. Female Reproductive System
Infundibulum
Function  Picks up eggs at ovulation and directs eggs to oviduct
Description  - the funnel shaped portion of the fallopian tube near the ovary
Oviducts
Function  Carry the eggs from the ovary to the uterus. Also called fallopian tubes.
Description  Small tubes that are near but not attached to ovaries and have a funnel-shaped end near the ovary.

17. Female Reproductive System
Uterus - Muscular sac connecting fallopian tubes and cervix
1. Sustains the sperm and aids in its transport
2. Supports embryo and fetus during gestation
3. Expels fetus at parturition

18. Female Reproductive System
Cervix - Area between the uterus and vagina
Normally closed
Opens at estrus and parturition
Shape will match penis of male
Vagina – the female organ of copulation
1. Admits penis
2. Receives semen
3. Passageway for fetus at parturition
Vulva - external genitalia
opening for both urinary and genital tracts

19. 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
Estrus (heat, estrous period)
Gestation
Fertilization to parturition
Embryo developing in uterus
Parturition
Expel fetus/give birth
Lactation
Milk production

20. Ovulation Rates by Species Cow- 1 egg per estrus Ewe- 1 to 3 eggs per estrus Sow- 10 to 20 eggs per estrus Mare- 1 egg per estrus Hen- Approx. 28 eggs per month

21. Gestation and Lactation Periods:
Species Gestation Period Lactation(Milking)
Cow days beef days dairy days
Ewe days days
Sow days days
Mare days days
Woman days ? years

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

23. Male Reproductive Tract

24. Male Reproductive Tract
Scrotum
Holds and protects the testicles
keeps sperm 4-5oF cooler than the body temperature
Testicles
the primary male organs of reproduction inside scrotum
produces sperm
secretes testosterone
Epididymis
Long coiled tube that is a path for sperm out of seminiferous tubules
Storage for sperm while they mature
Fluid secretion to nourish sperm

25. Male Reproductive Tract
Vas Deferens
slender tube from epididymis to urethra
moves sperm to the urethra
Urethra
long tube from bladder to penis
passageway for urine and sperm out of the body
Penis
male organ of copulation
deposits semen into female (same as papilla in poultry)
Shape will match cervix of female
Sheath
- Skin that covers and protects penis from injury

26. Accessory Glands Seminal Vesicles
add fructose and citric acid to nourishes, protects and transports sperm
Prostate Gland
located at the neck of the bladder
produces fluid that is mixed with seminal fluid, the medium for sperm transport
Cowper’s Gland
Also called Bulbourethral gland
Paired organs
Cleans and neutralizes the urethra prior to semen passage

27. Male Reproductive Tract

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

30. 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

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

33. Parturition of Animals
Objective: Understand animal reproduction and parturition.

34. First Steps of Development
After fertilization, the embryo begins to develop
After a period of embryological development, the developing animal is referred to as a fetus.
During gestation, the fetus develops in the uterus.
At the end of the gestation period, parturition begins.

35. Fetus Position at Birth
Normal Position:
Front feet first with legs slightly offset from each other to allow for shoulders to pass through birth canal.
Nose tucked between front legs.
Shoulders.
Body or middle of animal.
Hips.
Back legs and feet.
Any else is abnormal and could cause problems as severe as death of the newborn animal and/or the mother.

37. Parturition Process
Increased estrogen causes the uterus muscles to contract.
Water bag appears, enlarges and breaks open.
Second water bag containing the fetus breaks open and the presentation of the fetus begins.
Several hours later, the placenta and other membranes (afterbirth) are expelled.
If afterbirth is not expelled, the animal will become sick (Retained placenta or Septicemia)  

38. Parturition in Action
Mare Foaling
Cow Calving
Birth Process of Pigs

39. Animal Reproduction and Genetics
Objective: Describe the cell and process involved in cell division including how genes affect the transmission of characteristics

40. Animal Cell The body is made up of millions of tiny cells
Most of the cell is made up of protoplasm
Cell parts:
Nucleus
Cytoplasm
Cell membrane

41. Animal Cell
Nucleus/Nucleolus - gives cell ability to grow, to digest food and to divide, contains chromosomes composed of genes
Cytoplasm - gives the cell shape and contains components necessary for cell functions
Cell Membrane – outside of cell; allows passage of some materials
Centrosome - The centrosome divides during mitosis
Nuclear Membrane – membrane that surrounds nucleus
Ribosome – site of protein synthesis
Endoplasmic Reticulum – transports material throughout the cell
Golgi Body – produces membrane that surrounds lysosome
Lysosome - round shaped organelles that contain digestive enzymes that allow for digestion of cell nutrients
Mitochondria - rod-shaped organelles that convert the energy stored in glucose into ATP (adenosine triphosphate)

42. Cell Division Mitosis Meiosis Increases total number of cells
Results in animal growth
Chromosomes pairs are duplicated
Meiosis
Produces gametes
Sperm/Eggs
Only have one-half the chromosomes of normal cells

43. Fertilization When the sperm from a male reaches the egg from a female
Two cells join to form a complete cell
Pairs of chromosomes are formed again
Many different combinations of traits are formed

44. Chromosomes Rod shaped bodies Made of protein
Found in the cell nucleus
Exist in pairs except for gamete cells
The number of chromosome pairs differ for various animals
Cattle 30
Swine 19
Horses 32
Chickens 39
Humans 23

45. Genes Located on chromosomes Thousands found in each animal
Control inherited characteristics
Carcass traits
Growth rate
Feed efficiency
Two types of inherited traits
Dominant
Recessive

46. Genes Dominant gene Hides the effect of another gene
Polled condition in cattle is dominant
The gene is represented by a capital letter
Recessive
Gene that is hidden by another
The gene is represented by a lower case letter

47. Genes
Example: The dominant gene is written- P The recessive gene is written-p P= Polled p= horned

48. Homozygous and Heterozygous
Homozygous gene pair
Carries two genes for a trait
Polled cow might carry the gene PP
Heterozygous
Carries two different genes that affect a trait
Polled cows might carry a recessive gene with the dominant Pp

49. Predicting Genotype Genotype-kind of gene pairs possessed
Phenotype- the physical appearance of an animal
Punnett squares are used to predict genotypes and phenotypes of animals

50. Genotypes Three class genotypes Homozygous Dominant = PP
Homozygous Recessive = pp
Heterozygous = Pp
P = Polled & p = horned
Six possible crosses:
PP x PP, PP x Pp, PP x pp, Pp x Pp, Pp x pp, pp x pp

51. Punnett Square P= Polled p= horned P Example:
Polled Dam
P= Polled
p= horned
Example:
Two polled cattle that are homozygous for the polled trait
Genotypic Ratio: 4PP : 0
Phenotypic Ratio:4 polled animals
Polled Sire
Polled Dam P PP
Polled Sire

52. Punnett Square N= Normal size n= Dwarfism Example:
Normal Dam
N= Normal size
n= Dwarfism
Example:
Normal size in cattle is dominant to dwarfism
Genotypic Ratio:
Phenotypic Ratio:
Sire Carrier
Normal Dam N NN n Nn
Sire Carrier

53. Punnett Square N= Normal size n= Dwarfism Example:
Normal Dam
N= Normal size
n= Dwarfism
Example:
What if both parents are carriers for a trait or disorder?
Genotype:
Phenotype:
Sire Carrier
Normal Dam N n NN Nn nn
Sire Carrier

54. Assignment
Complete a Punnett Square for two animals that are heterozygous for two traits:
Polled=P
Black= B
(Alternatives are horned and red)
Dam
Sire

55. Answer
A Punnett Square for two animals that are heterozygous for two traits:
Polled=P
Black= B
(Alternatives are horned and red)
Dam PB Pb pB pb
PPBB
PPBb
PpBB
PpBb
PPbb
Ppbb
ppBB
ppBb
ppbb
Sire

56. Heritability Objective:
Discuss hertability estimates for beef and swine

57. Heritability
Estimated the likelihood of a trait being passes on from the parent to the offspring
Low heritability
slow herd improvement
High heritability
faster improvement

58. Heritability Swine rates are usually lower than cattle
Heritiability for carcass traits are higher than reproductive traits
Estimates vary from 0 to 70%

59. Heritability Estimates
Birth weight 40%
Weaning Weight %
Yearling Weight 60%
Fertility 10%
Tenderness 60%

60. Heritability Review Herd improvement slow for low heritability
faster for high heritability
Estimates are higher for:
beef compared to swine
carcass traits compared to repro