Dairy Cow Week 3 Study Questions

Question 1

What is the name of the device that is used to collect semen from a bull?

Answer 1

artificial vagina

Question 2

What five criteria are used in semen evaluation?

Answer 2

-ejaculate volume
-sperm concentration
-total sperm ejaculate
-progressive motility
-morphology

Question 3

What are the components of a sperm extender and what are their purpose?

Answer 3

-salt, buffer, egg or milk (protect during cooling)
-glycerol (protects from freezing)
-glucose (energy for sperm)
-antibiotic

Question 4

How is semen packaged and stored for long-term storage?

Answer 4

Frozen

Question 5

What is “sire conception rate”?

Answer 5

the probability that a bull’s semen would get a heifer pregnant

Question 6

What is “gender selected semen”?

Answer 6

sperm that has been sexed

Question 7

Advantages of gender selected semen

Answer 7

-90% of calves born will be female (replacement heifers)
-Cows you do not want to use to generate replacements can be inseminated with beef semen (dairy beef)

Question 8

Disadvantages of gender selected semen

Answer 8

-More expensive than conventional
($20-not sexed vs $40-sexed)
-Fertility to AI is lower

Question 9

What is the basis for separating X and Y semen using a flow cytometer?

Answer 9

X chromosomes are heavier
–> X chromosomes will make girls

Question 10

What is estrous synchronization?

Answer 10

Injecting cows or heifers with PGF 2a so that the group of heifers come into heat (estrus) on the same day

Question 11

What are three important things to know about PGF2α treatment for estrous synchronization?

Answer 11

-Will not regress the CL during first 5 days of the estrous cycle
-Heifers in heat 2 to 3 days after treatment
-Cows in heat 3 to 5 days after treatment

Question 12

Diagram/understand a program that uses two PGF2α treatments for estrous synchronization in heifers.

Answer 12

-Give PGF 2 a
–> 2-3 days check heat and AI
(Get about 70% of the heifers)
-After 14 days give the other 30% a PGF 2a dose
–> 2-3 days check heat and AI

Question 13

When (relative to estrus and ovulation) do we AI heifers and cows? Why?

Answer 13

Breed (AI) 12 hours before she ovulates
-So sperm can capacitate and get to oviduct

Question 14

Where is semen placed in the repro tract when a cow or heifer is AI?

Answer 14

body of the uterus

Question 15

Where does fertilization occur in the female repro tract?

Answer 15

the oviduct

Question 16

When does the fertilized embryo enter the uterus?

Answer 16

Embryo remains in the oviduct until day 5 when it enters the uterus

Question 17

Stages of early embryonic development from one cell to tubular embryo.

Answer 17

-Early cleavage stages: 1, 2,3,4 8, and 16 cell
-Morula (compact ball of cells)
-Blastocyst
-Hatched blastocyst

Question 18

blastocoel

Answer 18

the fluid-filled cavity of a blastula.

Question 19

inner cell mass

Answer 19

gives rise to the tissues of the embryo proper
–> The ICM is a cellular mass on one side of the hollow interior of the round embryo,

Question 20

trophoblast

Answer 20

a layer of tissue on the outside of a mammalian blastula, supplying the embryo with nourishment and later forming the major part of the placenta.

Question 21

What are the two cellular layers of the uterus?

Answer 21

-Outside layer: myometrium
-Inside layer: endometrium

Question 22

What do uterine glands do to help the embryo survive?

Answer 22

lands nourish the embryo → histotroph, nutrients

Question 23

What is interferon tau and how does it act to maintain the CL?

Answer 23

a hormone that blocks PGF2α release
from the uterus and rescues the CL
to maintain progesterone and
pregnancy.

Question 24

Parts of the placenta

Answer 24

-Cotyledons ( fetal placenta attachment points)
-fetus
-Amnion and amnionic fluid
-Placental arteries and veins
-Chorioallantois Allantoic fluid

Question 25

How are the bovine placenta and the human placenta different?

Answer 25

bovine placenta does not implant like human placenta

Question 26

Why doesn’t a pregnant cow come back into heat 21 days after breeding?

Answer 26

Progesterone keeps the cow from coming back into heat.

Question 27

What are three ways that you could diagnose pregnancy in a cow?

Answer 27

-Ultrasound
-Fluid : blood or milk
-Lateral flow test

Question 28

What are pregnancy-associated glycoproteins (PAG)?

Answer 28

show up 25 days into pregnancy

Question 29

When talking about pregnancy diagnosis, what is a “recheck”?

Answer 29

(approx 60 to 80 d after AI)
-Blood or milk PAG
-Palpitation
-Ultrasound – fetal sexting

Question 30

What is the difference between stroma and parenchyma in the mammary gland?

Answer 30

Stroma: supportive connective tissue
Parenchyma: glandular secretory (milk producing) tissue