Artificial insemination

Question 1

What types of AI semen can be used?

Answer 1

fresh
fresh-extended
extended-chilled
extended-frozen-thawed

Question 2

What are the advantages of AI?

Answer 2

AI is used to allow greater access to superior genetics and maximise genetic improvement, it reduces mating costs and risks as well as controlling reproductive diseases. Frozen AI allows the use of dead/injured sires.

Question 3

When might you undertake a breeding soundness exam?

Answer 3

When lowered fertility is suspected
When abnormal sexual behaviour is seen
Before sale
Before the breeding season
If a pathogenic infection is suspected (to enable culture/isolation of pathogens)

Question 4

What function tests can you carry out on sperm?

Answer 4

PH, temperature, ATP concentration and penetration of cervical mucus in order to discriminate between moderate and high fertility

Question 5

How is total sperm count calculated?

Answer 5

multiplying semen volume and semen concentration

Question 6

How is semen concentration determined?

Answer 6

The concentration of sperm is determined by placing sperm onto a haemocytometer diluted with distilled water containing detergent to kill the sperm (and prevent clumping)

Question 7

The sperm are very sensitive to cooling so what should be done during evaluation?

Answer 7

microscope slides + diluents must be warmed.

Question 8

What are the two methods of evaluating sperm motility?

Answer 8

Subjective assessment - This is a standard method

Objective assessment - Computer aided

Question 9

What can a Computer Assisted Sperm Evaluation measure?

Answer 9

Mean sperm velocity, Mean sperm linearity, Lateral head deviation, Mean curvilinear velocity

Question 10

How do you carry out a sperm motility evaluation?

Answer 10

Place standard volume onto a warmed slide (on a heated stage) and evaluate immediately after
0 = dead
1 = very few appear alive
2 = No waves but some sperm movement approx 20-40% active
3 = small slow moving waves 45-65% active
4 = vigorous moving waves 70-80% active
5 = Dense, rapidly moving waves and individual sperm cannot be seen 90% active

Question 11

What two ways can sperm be observed?

Answer 11

1) Staining of sperm with dyes and observation under phase microscope
2) Observation of fixed sperm by differential interference contrast (DIC)

Question 12

What do we stain sperm with

Answer 12

Nigrosin (background stain) and eosin (vital stain).

Question 13

How does dying the sperm evaluate the membrane integrity?

Answer 13

Sperm with damaged membranes allow eosin to penetrate so sperm appear pink, sperm with intact membranes exclude eosin so sperm remain unstained (white).

Question 14

Which method is better for assessing the morphology of sperm?

Answer 14

Observation of fixed sperm by differential interference contrast (DIC) at 100X microscope objective is considered more accurate in allowing you to evaluate morphology

Question 15

What are the three types of sperm defect?

Answer 15

Primary (defect of spermatogenesis)
Secondary (epididymis)
Tertiary (post-ejaculation)

Question 16

Name some common abnormalities

Answer 16

pyriform head, knobbed acrosome, detached or swollen acrosome, nuclear vacuoles, detached heads, distal Midpiece reflex, looped tail, coiled tail, cytoplasmic droplets

Question 17

How long will the following types of preserved semen last?
Fresh-extended (room temperature)
Diluted / cooled (5oC)
Diluted / frozen (-196oC)

Answer 17

Fresh-extended (room temperature) up to 8 hours
Diluted / cooled (5oC) up to 4 days and up to 10 days in the boar
Diluted / frozen (-196oC) then thawed will last indefinitely until thawing.

Question 18

What is the function of extender solution?

Answer 18

The dilution of semen with extender solution aims to protect sperm during the freezing/warming process (protective agents include mik/egg protein and glycerol), supply an energy source to the sperm, maintain pH, osmolality and ionic strength as well as preving bacterial growth.

Question 19

If freezing rate is sufficiently slow and cell permeable to water what happens to the semen?

Answer 19

During freezing water leaves cell which progressively dehydrates and Small ice crystals form inside cell
On thawing the Ice crystals melt and cell rehydrates and is functional

Question 20

If freezing rate is too rapid or the cell is impermeable what happens to the semen?

Answer 20

During freezing the cell does not dehydrate so Large ice crystals form inside the cell = cell is damaged
On thawing the Cell is non-functional

Question 21

If freezing rate is too slow what happens to the semen?

Answer 21

During freezing the cells dehydrate and solute concentration increases. Solutes tend to precipitate (solution effect) so cells shrink beyond a minimum compatible with survival = cell is damaged
On thawing the cell is non-functional

Question 22

What is the general method for freezing sperm?

Answer 22

The general practice to prevent this is to dilute in a freezing buffer, slowly cool to 5’C, allow for equilibration (2-4 hours), then load into 0.5/1/4ml straws and freeze at the standard freezing rate in liquid nitrogen vapour before plunching into liquid nitrogen.
The straws are best if thawed rapidly, so plunged into a water bath at 37’c

Question 23

How is sperm sexed?

Answer 23

X chromosomes have more DNA than Y chromosomes (3-4% more DNA) so separation is obtained by labelling the sperm with a DNA florescent dye and sorting by flow cytometry

Question 24

Semen from bulls is usually collected by ………………… and inseminated by ……………..
It has a sucess rate similar to calving.

Answer 24

Artificial vagina

Uterine insemination

Question 25

In rams AI is usually done….

Answer 25

Trans-vaginal uterine insemination difficult so either cervical or laparoscopic uterine insemination used
Success rates depend upon site of insemination:
♣ 40% lambing rate for cervical insemination of non-frozen semen
♣ 70% lambing rate for uterine insemination of non-frozen semen

Question 26

In the boar semen freezes …………… and sows are inseminated via ………………. it has a similar success rate to natural mating.

Answer 26

Poorly

Uterine insemination

Question 27

In the stallion semen freezes ………….. and insemination is done via …………………. it has less success rate than natural mating

Answer 27

Poorly

Uterine