Bap Quiz 3

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

Artificial Vagina

What five criteria are used in semen evaluation?

-Ejaculate volume- 5 ml (range 1-15 lm)
Sperm concentration- 1200 M/ml range 300-2500 M/ml
Total sperm per ejaculate Typically 4-5 M
Progressive motility- greater than 30%
Morphology - greater than 70% normal
Progressive motility: should go linear, not circles

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

- Salts (isotonic)
- Buffer
- Egg yolk or milk (protect during cooling)
- Glycerol (protect sperm during freezing)
- Glucose or fructose (energy for sperm)
- Antibiotic (prevent bacterial growth)

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

liquid nitrogen

What is “sire conception rate”?

the semen fertility of a bull

What is “gender selected semen”?

Semen that has been sorted and either has mostly X's or mostly Y's

What are the advantages and disadvantages of gender-selected semen?

Advantage: Can select for herd replacement heifers Disadvantage -More expensive than conventional semen
- Fertility to AI is lower

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

- Sperm are pumped through the system after having been stained with a DNA-binding dye
- Piezoelectric crystal vibrator causes 90L droplets to form each second as stream exits system
- UV laser illuminates sperm as they flow by beam
- X sperm fluorescence with 4% more intensity than Y sperm
- The signal detected with a photomultiplier tube is sent to a computer that processes the fluorescence detected and categorize sperm as X, Y, or uncertain

What is estrous synchronization?

Injecting Cows or heifers with PGF2a so that the group of cows or heifers comes into heat (estrus) on the same day

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

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

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

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

It's important to breed the heifers after they've been in heat, but before they ovulate. The sperm needs time to capacitate before ovulation and to get to the oviduct.

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

just beyond the cervix

Where does fertilization occur in the female repro tract?

In the oviduct

When does the fertilized embryo enter the uterus?

Day 5

Know the stages of early embryonic development from one cell to tubular embryo.

Morula (compact balls of cell)
Blastocyst (has fluid filled cavity blastocoel)
Hatched blastocyst
Zona pellucid (thick coating around the egg)
Trophoblast will become placenta
Inner cell mass will become the fetus
Myometrium is outside layer, important for calving
Endometrium is inside layer
Endometrium cross section has glands that nourish early embryo: histatroph
When embryo gets too big it hatches out of the embryo and becomes a spherical embryo
Then becomes tubular

Define blastocoel, inner cell mass and trophoblast.

Blastocyst (has fluid filled cavity blastocoel)
Inner cell mass will become the fetus
Trophoblast will become placenta

What are the two cellular layers of the uterus?

Myometrium is outside layer, important for calving
Endometrium is inside layer

What do uterine glands do to help the embryo survive?

nourish it

What is meant by the term “maternal recognition of pregnancy”?

cow realizes she's pregnant

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

Molecule produced by embryo that blocks PGF2a release from the uterus and rescues the CL to maintain pregnancy and progesterone

Know the parts of the 80-day placenta.

How are the bovine placenta and the human placenta different?

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

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

ultrasound
palpation
PAG test

What are pregnancy-associated glycoproteins (PAG)?

are produced by the binucleate cells of the ruminant placenta and can be used to diagnose pregnancy.

When (day of pregnancy) can you test for PAG and where (what biological fluids) do you look for them?

Day 28 after AI
blood, milk, serum

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

checking to make sure fetus is still alive

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

- Stroma (supportive connective tissue)
- Parenchyma (glandular secretory, milk producing, tissue)