Intro to Animal Science Exam 2

Reproduction, Lactation, Meat Science, and Beef Industry

reproductive tracts

label the different parts of a female reproductive tract (uterus)

A. Ovary

B. Oviduct

C. Uterine Horns

D. Uterine Body

E. Cervix

F. Bladder

G. Vagina

What happens in the Ovary

• Production of oocytes (immature female eggs)

• Production of estrogen and progesterone

What happens in the Infundibulum & where is it located

• Transports ova from ovary to the oviduct

• Located in between ovary and oviduct

What happens in the Oviduct?

• the site of fertilization & early development

• transports ova and sperm

What happens in the Uterine Horns

• Assists in sperm transport

• Regulation of the Corpus Luteum

• Site of implantation and pregnancy

what happens in the cervix?

• Facilitates sperm transport (in sows and mares)

• prevents uterine contamination

what happens in the vagina?

• a copulatory organ

• the birth canal

label the different parts of the male reproductive tract

A. Penis

B. Testis

C. Scrotum

D. Epididymis

E. Vas Deferens

F. Prostate Gland

G. Cowper’s Gland

H. Urinary Bladder

I. Rectum

what happens in the tesis (testicles)?

• Testosterone production (leydig cells)

• Spermatoza production (seminiferous tubules)

what happens in the epididymis?

• a long and tightly coiled tube

• high concentration of sperm that is stored, matured, and transported

what happens in the vas deferens?

• transports mature sperm to the urethra

what are the important accessory glands to know?

1. seminal vessicles

2. prostate

3. cowper’s gland

what are seminal vessicles

• fluid contains fructose, prostaglandin, and proteins

  • this makes the repro tract contract to move sperm

what is prostate

the fluid produced to enhance the sperm motility

what is the cowper’s gland

• it produces a lubricating fluid that neutralizes the acidity of urine in males and females during copulation (sex)

what is the scrotum

provides support for the testicles

what is the penis

a copulatory organ

what are accessory glands

• they add fluid volume, nutrients, and buffers to semen

• they are secreted into the urethra

which animals have the heaviest pair of testes?

1. Swine (Boar)

2. Cattle (Bull) 

3. Sheep (Ram)

which animals have the highest sperm concentration?

1. Turkey: 8,000 - 30,000

2. Sheep & Goat: 2,000 - 3,000

3. Chicken: 3,000 - 7,000

4. Cattle: 800 - 2,000

Which animals have the highest amount os sperm per ejaculation?

1. Swine: 30-60 bil

2. Cattle/Horse: 5-15 bil

3. Turkey: 1-20 bil

4. Sheep: 2-4 bil

what are the hormones involved in ovarian function

• Gonadotropin releasing hormone (GnRH)

• Estrogen

• Progesterone

• FSH

• LH

what are the hormones involved in testicular function

• Gonadotropic Hormones

  • Luteinizing hormone (LH)

  • Follicle stimulating hormone (FSH)

• Testosterone

What does the gonadotropin-releasing hormone (GnRH) do

Produced in: Hypothalamus

Targets: Anterior Pituitary

Function: Stimulates the release of LH and FSH

what does the luteinizing hormone (LH) do

Produced in: Anterior Pituitary

Targets:

• Female: Ovary (luteal cells)

• Male: Testis (leydig cells)

Function:

• Female: Stimulates ovulation, CL formation, and progesterone production

• Male: stimulates testosterone production

what does the follicle stimulating hormone (FSH) do?

Produced in: Anterior Pituitary

Targets:

• Female: Ovary (grandulose cells)

• Male: Testis (seritoli cells)

Function:

• Female: stimulates development of follicle

• Male: stimulates sperm production

what does the prolactin hormone do?

Produced in: Anterior Pituitary

Targets: mammary tissue

Function: stimulates milk synthesis and maternal behavior

what does the oxytocin hormone do?

Produced in: Posterior Pituitary

Targets: 

• uterus

• mammary tissue

Function: 

• Uterus: stimulates gamete transport and uterine contraction

• Mammary tissue: stimulates milk let down

what does the estrogen hormone do?

Produced in: Follicle and Placenta

Targets:

• uterus

• hypothalamus

• mammary tissue

Function:

• stimulates mating behavior

• promotes GnRH release

• stimulates uterine growth

• stimulates secondary sex characteristics

what does the progesterone hormone do?

Produced in: Corpus luteum (CL) and Placenta

Targets:

• uterus

• mammary tissue

• hypothalamus

Function:

• Maintains pregnancy

• mammary development

• inhibits GnRH release

what does the testosterone hormone do

Produced in: leydig cells of testes

Targets: skeletal muscle, seminiferous tubules, repro tract

Function:

• stimulates anabolic grown

• sperm production

• secondary sex characteristics

what does the prostaglandin F_^2a hormone do

Produced in: endometrium of the uterus

Targets: uterus (myometrium) and graafian follicles

Function: 

• released if pregnancy doesn’t occur

• stimulates the regression of CL and ovulation

• uterine contraction

what does the placental lactogen hormone do

Produced in: placenta

Targets: mammary gland

Function: promotes lactation

what does the relaxin hormone do

Produced in: ovary and placenta

Targets: cervix and pelvis

Function: stimulates cervical dilation and pelvic expansion

what does the cortisol (fetal) hormone do

Produced in: adrenal glands of the fetus

Targets: dam’s uterus

Function: stimulates the initiation of parturition (birth)

what does the melatonin hormone do?

Produced in: pineal gland

Targets: hypothalamus

Function: partially controls seasonal reproductive pattern

outilne testicular function through hormones

1. LH & FSH are produced in the anterior pituitary gland

2. LH stimulates the production of testosterone in leydig cells

3. FSH stimulates the development of sperm in seminiferous tubules

outline ovarian function through hormones

1. the hypothalamus releases GnRH in the presence of estrogen and when progesterone is low

2. GnRH activates LH and FSH which increase the cyclic activity

3. these hormones control the estrous cycle (a period)

what is estrous vs. estrus

estrous: referring to the cycle

estrus: referring to the heat displayed by animals

what are the 3 types of cycles

1. polyestrous

2. seasonally polyestrous

3. monoestrous

what are polyestrous animals

• multiple cycles throughout the year

  • ex) cattle and swine

what are seasonally polyestrous animals

• multiple cycles during a certain time of the year

  • ex) sheep, goats, horses

what are monoestrous animals

• one cycle per year

  • ex) dogs

what animals have the longest estrous cycles

1. Horse (22)

2. Cattle (21)

3. Sheep (17)

what animals have the longest duration of estrus?

1. Horse (7 days)

2. Swine (60 hrs)

3. Goat (39 hrs)

4. Sheep (30 hrs)

which animals begin puberty at the youngest age

1. Goat (4-8)

2. Swine (5-10)

3. Sheep (6-12)

4. Cattle (6-18)

explain the estrous cycle

explain the process of fertilization

explain the pre-attachment embryo development

• embryonic cells duplicate their genes and divide every 20 hours

• the embryo migrates through to oviduct to the uterus in 3-4 days

• maternal recognition of pregnancy signals the presence of the embryo and allows the attachment to the uterus

explain the process of pregnancy

• the placenta produces hormones that maintain pregnancy, stimulate the mammary glands, and enhance fetal growth

• Attachment of placentation/chorion takes many days

  • this is critical for embryonic survival

what does the placenta do

its a temporary organ that facilitates metabolic connections between the dam and the fetus

How many days does it take for attachment of placentation in cows, mares, and ewes?

• cows: 20-30 days

• mares: 36-38 days

• ewes: 13-14 days

what are the 4 different types of attachment of chorion (the fetal component of the placenta)

1. diffuse: uniformly cover the chorion in mares and sows

2. cotyledonary: series of structures called placentomes in ewes, cows and does

3. zonary: congregates to a specific band or zone in dogs and cats

4. discoid: 1 or 2 distinct disc-like structures in primates and rats

what animals have the longest gestation lengths

what are the 5 positions of parturition

1. normal presentation: “diving” position with front legs in front of head

2. breech; the butt of the sheep is the first part of the body facing exterior

3. upside down and backwards: the lamb is in a breech position but flipped upside down

4. head back: head is tilted backwards with front legs in front of head

5. backwards: lamb is facing legs first and head to the back to the uterus

lactation

what are the important structures of the mammary gland

alveoli: where milk collects and gains constituents

exocrine gland: produces external secretion of milk through a series of ducts

what are 2 functions of milk

1. provides nutrients

2. a source of passive immunity from mother to offspring

what are the alveoli

• the secretory tissue of the mammary gland

• milk travels through the ducts to a gland cistern during milk letdown

what is the structure of a cow’s mammary glands

• 4 separate mammary glands terminating into 4 teats

• 1 canal/cistern per teat

what is the structure of a horse’s mammary glands

• 4 mammary glands terminate into 2 teats

• 2 canals/cisterns per teat

what is the structure of a goat/ewe’s mammary glands

• 2 mammary glands terminate into 1 teat

• 1 canal/cistern per teat

what is the structure of a sow’s mammary glands

• 6-20 mammary glands terminate into 1 teat

• 2 canals/cisterns per teat

• typically only 10-14 mammary glands are functional

what hormones are responsible for lactation and how

1. growth hormones, addrenal corticoids, and prolactin

2. estrogen and progesterone levels decrease

3. oxytocin is released by suckling which initiates milk let down

what influences the maintenance of lactation

• hormones like prolactin, thyroid hormones, adrenal hormones, and growth hormones

what hormones are involved in the development/growth of mammary glands

• estrogen: for duct and cistern growth

• progesterone: for the growth of the alveoli

• placental lactogen: for general cell growth of mammary gland

what factors affect milk production

1. genetics

2. feed and management (routine feeding/milking schedules)

3. health (mastitis = inflammation of the udder)

4. gender of the offspring (males need more milk)

5. number of offspring (twins/triplets produce more milk than those with singles)

6. age of female

which animals have the highest solids and fats in their milk

1. reindeer

2. water buffalo

3. sow

4. ewe 

which animals have the most protein in their milk

1. reindeer

2. ewe & sow

3. water buffalo

which animals have the most lactose in their milk

1. humans

2. mares

3. sow

what is the milk composition for a hooded seal

• 60% fat

• feeds pups only 4 days

• pups are born on ice

what is the milk composition for black rhinos

• 0.2% fat

• nurse for 2 years

what is the milk composition for tammar wallabies

• 14% sugar

• can produce 2 different milks for joeys of different ages

what is the milk composition for eastern cottontails

• 15% protein

• leave young for long periods

what are immunoglobins (ig)

they are involved in the passive immunity transfer from mother to offspring and are gained through colostrum in large/domestic livestock

what is colostrum

the first milk

how does consuming colostrum help passive immunity transfer

• the igs in colostrum give the newborn protection from microorganisms

• the intestinal wall of newborns has pores so colostrum antibodies are absorbed

• the wall becomes less porous afte 24 hours which allows less absorption of antibodies

  • this is why the immunity of the newborn is dependent on consuming colostrum within the first few hours of birth

meat science

what red meats and poultry meats do we mainly look at

Red meats:

• beef

• pork

• lamb

Poultry:

• chicken

• turkey

what is the etymology for the meat of a calf

veal

what is meat mostly classified as

skeletal muscle

what is meat science

the study of the unique characteristics of muscle and other animal tissues as they are transformed into meat

what does finish mean in meat head terms

the fat on in animal that is deposited in the final months before harvest

what does carcass mean in meat head terms

the primary product of animal slaughter

what does wholesale cut mean in meat head terms

cuts into which the carcasses are cut according to industry defined standards

• ex: rib, round, chuck, loin

what does primal cut mean in meat head terms

a wholesale cut trimmed to specific dimensions

what does finish retail cut in meat head terms

cuts prepared for sale in a retail market

• ex) ribeye steak, round roast, arm roast

what are the types of proteins in meat

• sarcoplasmic proteins: water soluble proteins

• myofibrilar proteins: salt soluble proteins

• stromal proteins: connective tissue

what is myoglobin

the primary pigment responsible for meat color

• contains a heme group (Fe)

explain how myoglobin plays a role in meat color

what are some things that meat tenderness are affected by

1. animal age

2. post mortem age

3. quality grade

4. genetics

5. muscle

6. animal nutrition

what are the reasons for meat processing

• allow us to use the whole animal

• preserve meat for longer

• more convenient products

• good source of inexpensive protein

• prevent food borne illnesses

what is added to meats to cure them

Nitrite

why is nitrite added to processed meats

1. color development

2. flavor development

3. prevents spoilage

4. controls growth of botulism

food safety

what are the top 5 food borne illnesses

1. norovirus

2. campylobacter

3. salmonella

4. clostridium perfringens

5. e. coli

which pathogens contribute to the most deaths

1. salmonela

2. campylobacter

3. norovirus

4. listeria monocytogens

5. e. coli

explain the norovirus

what: stomach flu or food poisoning

contamination from: food workers in food service

symptoms: nausea, vomiting, diarrhea, cramps, fever, etc

onset after exposure: 12-48 hours

duration: 12-60 hours

explain hepatitis A

contamination from: food service

symptoms: jaundice, anorexia, diarrhea, vomiting, flu-like symptoms

• patients shed viral bacteria for weeks before and after illness

onset after exposure: 15-50 days

duration: 12-60 hours