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
Colustrum
First milk produced after a mammal gives birth that contains antibodies needed for immunity.
Gestation
Time an animal is pregnant

4. Terminology
Estrus
When a female is receptive to be bred (also called ‘in heat’)
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. Female Tract

13. Female Reproductive System
Ovary - the ovary is comparable to the male testicle and is the site of gamete production.
A bovine animal has 20,000 potential eggs per ovary, while a human female has 400,000 potential eggs per ovary.
Ova are fully developed at puberty and are not continuously produced as in the male.
All species contain two functional ovaries except for the hen which has only a left functioning ovary.

14. Female Reproductive System
The ovaries have three major functions:
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

15. Female Reproductive System
Infundibulum - the funnel shaped portion of the fallopian tube near the ovary that catches the ovulated egg.
Oviducts- pair of small tubes leading from the ovaries to the horns of the uterus (5 - 6 inches).
Fertilization occurs in the oviduct.
Egg travels from ovary to uterine horn in days.

16. 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

17. Female Reproductive System
Cervix
Area between the uterus and vagina
Normally closed
Opens at estrus and parturition
(2 -3 inches)

18. Female Reproductive System
Vagina - the female organ of copulation
1. admits penis
2. receives semen
3. passageway for fetus at parturition
Vulva - extended 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

20. Reproductive Functions (Female)

21. Reproductive Functions (Female)
Estrus (heat, estrous period)
Period of time when a female will accept a male in copulation

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

23. Ovulation Rates
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

24. Reproductive Terminology
Species Act Offspring
Cows
Ewes
Sows
Hens hatching chick
Mares
Goats

25. Species Act Offspring
Cows calving calf
Ewes lambing lamb
Sows farrowing pig
Hens hatching chick
Mares foaling foal
Goats kidding kid

26. Reproductive Functions (Female)
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

27. Reproductive Functions (Female)
Estrous period length by species: Cow hours Ewe hours Sow hours Mare hours Hens & Women none

28. Reproductive Functions of the Female
Estrous cycle - time from one heat period (or menstrual cycle) to the next. Length of estrous cycle by species: Cow days Ewe days Sow days Mare days Woman 28 days Hen none

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

30. Male Reproductive Tract

31. Male Reproductive Tract
Scrotum - external sac that holds testicles outside of the body to keep sperm at 4-5oF cooler than the body temperature
Testicles - the primary male organs of reproduction
to produce sperm
to secrete testosterone

32. 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

33. Male Reproductive Tract
Vas Deferens - slender tube from epididymis to urethra which moves sperm to the urethra
Urethra - long tube from bladder to penis; passageway for urine and sperm out of the body

34. Male Reproductive Tract
Penis - male organ of copulation which conveys semen and urine out of the body

35. 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
provides the characteristic odor of semen

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

37. Male Reproductive Tract

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

40. 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

43. 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 yolk is the ovum
Chicken Incubation
21 days

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

45. 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

46. Animal Cell
Nucleus
Cytoplasm
Cell Membrane

47. Animal Cell
nucleus – 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 wall – outside of cell

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

49. 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

50. Fertilization

51. 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

52. 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

53. 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

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

55. 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

56. 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

57. 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

58. 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

59. 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

60. 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

61. 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

62. 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

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

64. 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

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

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

67. 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