Animal Science Midterm

Crops Grown in California

Almonds, Raisins,Prunes (dried plums)Persimmons, OlivesCling Peaches, PomegranatesArtichokes, Kiwifruit, Figs, Pistachios, Dates, Walnuts, Almonds

IN 2012 the U.S. was still a major producer of

Peaches, hay, vegetables, dried onions

Propogation

increase in animal numbers

breeding

Increase in quality of each generation

Phenotype

Actual performance of the animal

Genotype

genetic makeup of the animal

What is Dna?

Genetic blueprint

All DNA is carried in genes

Is California the top state for cow numbers?

Yes

Why do animals need a pair of chromosomes?

to express traits like black hair

What cells in the body are not a pair?

Haploids

What is cell division?

It replaces older cells

Where does meiosis occur?

In the reproductive organs

What is the purpose of Mitosis?

Cell divison for growth and repair

What is the purpose of meiosis?

production of gametes (sperm and ovum)

Mitosis- Chromosome count

Diploid (pair of chromosomes)

Meiosis- Chromosome Count

Haploid (single set of chromosomes)

Where does mitosis occur?

in somatic cells (body cells)

Where does meiosis occur? pt.2

in germ cells (reproductive cells

What is the result of mitosis?

two identical daughter cells

What is the result of meiosis?

four genetically diverse gametes

Mitosis

Cell division resulting in two identical diploid cells

Meiosis

cell division resulting in haploid gametes (sperm and ova)

Dominant vs Recessive

Dominant alleles mask the expression of recessive alleles in phenotypes.

Number of chromosomes in a Chicken

78

Number of chromosomes in a Goat

60

Number of chromosomes in a Rabbit

44

Number of chromosomes in a Pig

38

Number of chromosomes in a Sheep

54

Number of chromosomes in a Dairy Cow

60

Number of chromosomes in a Dog

60

Number of chromosomes in a Cat

38

Number of chromosomes in a Beef Cow

60

Number of chromosomes in a Mare

64

Number of chromosomes in a Llama

74

Number of chromosomes in a Stallion

64

Number of chromosomes in a Human

46

How are traits expressed?

Genes on the chromosomes code for traits

What are homologous chromosomes?

Two genetically similar chromosomes, one from each parent

Homozygous

same alleles

Heterozygous

different alleles

Dominant Gene

A gene whose effect masks the phenotypic expression of its allele.

Recessive Gene

A gene whose expression is hidden when a dominant allele is present.

Codominance

A genetic scenario where both alleles in a heterozygote are fully expressed, resulting in a phenotype that is neither dominant nor recessive.

What is HYPP(Hyperkalemic periodic paralysis)?

A hereditary genetic defect affecting muscle function in horses and humans, caused by a mutation in a sodium ion channel protein. This leads to uncontrolled sodium influxes, resulting in muscle twitching and weakness.

HYPP Genetic Inheritance

HYPP is inherited as a dominant trait. Homozygous horses (H/H) exhibit more severe symptoms than heterozygous horses (N/H).

HYPP Breeding Implications

Selective breeding strategies can help eliminate HYPP by mating affected horses with normal horses (N/N), leading to a 50% chance of normal offspring.

HYPP Regulatory Measures

The AQHA has implemented rules requiring testing for HYPP in descendants of affected horses, banning registration of homozygous individuals born after January 1, 2007.

How is sex determined in mammals?

Females have two X chromosomes (XX), while males have one X and one Y chromosome (XY). The female ovum carries only X chromosomes, while male sperm carries both X and Y.

Sex-Linked Traits

traits linked to genes on the X chromosome are often recessive. Males (XY) are more likely to express these traits because they have only one X chromosome. Examples include color blindness and hemophilia.

Inbreeding

The mating of closely related animals, which can lead to decreased fertility and survivability.

Linebreeding

A form of inbreeding that focuses on a specific ancestor to maintain desirable traits over generations.

Outcrossing

Mating individuals with no common ancestors within a breed to enhance genetic diversity and vigor.

Crossbreeding

Mating sires of one breed with dams of another breed to produce hybrids that exhibit hybrid vigor, leading to improved productivity and disease resistance.

What is included into the male reproductive anatomy?

Scrotum, Testes, Epididymus, Vas Deferens

Scrotum

A two-lobed skin sac that regulates the temperature of the testes, essential for sperm production.

Testes

Contain seminiferous tubules where sperm is produced. If stretched out, these tubules can cover a significant area, illustrating their extensive length.

Epididymis

A structure that transports, stores, and matures sperm. It also concentrates sperm by reabsorbing water.

Vas Deferens

Transports sperm through accessory sex glands, where seminal fluid is produced, consisting of fructose and sorbitol.

What is Cyrptochidism?

this is when the testes of a male fail to desend

Different types of castration methods

Surgical knife, elastrator (banding), emasculatome (crushing cord)

What is a elastrator?

A bloodless method that uses elastic bands to cut off blood supply, effective for young animals (1-3 weeks old).

What is a emasculatome?

A tool that crushes and ruptures the spermatic cord, leading to testicular atrophy. Used for older lambs and kids

What does the Hypothalamus do?

The hypothalamus releases Gonadotropin-Releasing Hormone (GnRH), which stimulates the pituitary gland

What do the pituitary hormones do?

Releases Follicle Stimulating Hormone (FSH) for spermatogenesis and Luteinizing Hormone (LH) for testosterone production.

What does testoterone do?

Essential for the development of male secondary sexual characteristics and reproductive function.

Are females born with all the eggs(ova) they will ever have?

Yes

When is puberty started?

it is marked by estrous cycle

What are the different phases of the estrous cycle?

Proestrus, Estrus, Meterstrus, Diestrus

Proestrus Phase

Lasts 3-4 days; FSH causes follicular growth and estrogen production, signaling the onset of heat.

Estrus Phase

The period of receptivity to males, lasting 12-18 hours, marked by the release of LH triggering ovulation.

Metestrus Phase

Occurs post-ovulation;3-4 days, fertilization may happen, and bleeding can occur from uterine capillaries.

Diestrus Phase

progesterone from CL, cycle restarts if no pregnancy. 10-14 days

Timing of Mating

Mating must occur towards the end of estrus for successful fertilization; sperm must be present when the ovum is released.

Sperm and Ovum Lifespan

The ovum survives 6-12 hours post-ovulation, while sperm can live up to 30 hours in the female reproductive tract.

nidation (implantation)

The process of embryo implantation into the uterine lining, which can take days to weeks after fertilization.

differentiation

The embryo develops germ layers and organs, floating in amniotic fluid for protection.

Gestation for Cattle

282 Days

Gestation for Sheep

145-150 Days

Gestation for Goat

145-150 Days

Gestation for Mare

337 Days

Gestation for Sow

114 Days

Gestation for Bitch

63-64 Days

Gestation for Woman

226 Days

Gestation for Queen

63 Days

Gestation for Rabbit doe

28-35 days

Gestation for Llama

340-345 Days

Gestation for Elephant

600-660 Days

Methods of Pregnacy Diagnosis

Rectal Palpation, Ultrasound, Hormone Assays

Rectal Palpation

A common method for early pregnancy detection, typically around 30-35 days.

Ultrasound

Used in ruminants from 28 days onwards to detect fetal heartbeat and development.

Hormone Assays

Measuring progesterone levels can indicate pregnancy status.

Stages of Labor Stage 1

Characterized by restlessness, vaginal discharge, and uterine contractions; lasts 2-6 hours.

Stages of Labor Stage 2

Delivery of the fetus, with the emergence of feet or legs; typically lasts 30 minutes to 4 hours.

Stages of Labor Stage 3

Expulsion of the placenta or fetal membranes, occurring within 8-12 hours post-delivery.

Poultry Reproduciton- Male Anatomy

Testes remain in the abdomen; sperm produced in seminiferous tubules and testosterone from interstitial cells.

Poultry Reproduction- Female Anatomy

Only the left ovary and oviduct are functional; yolk development is stimulated by light and FSH.

Egg Production Process - Oviduct Formation

The yolk enters the infundibulum, where it is fertilized by sperm stored in the oviduct.

Egg Produciton Process- Shell Formation

The egg undergoes several stages in the oviduct, including albumen and shell membrane formation, taking about 21 hours.

Rooster Courtship

Involves offering food and performing dances to attract hens; hens may respond in various ways indicating receptiveness.

Cloacal Kiss

The mating process in poultry where sperm is transferred during cloacal contact.