Artificial insemination Flashcards
What types of AI semen can be used?
fresh
fresh-extended
extended-chilled
extended-frozen-thawed
What are the advantages of AI?
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.
When might you undertake a breeding soundness exam?
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)
What function tests can you carry out on sperm?
PH, temperature, ATP concentration and penetration of cervical mucus in order to discriminate between moderate and high fertility
How is total sperm count calculated?
multiplying semen volume and semen concentration
How is semen concentration determined?
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)
The sperm are very sensitive to cooling so what should be done during evaluation?
microscope slides + diluents must be warmed.
What are the two methods of evaluating sperm motility?
Subjective assessment - This is a standard method
Objective assessment - Computer aided
What can a Computer Assisted Sperm Evaluation measure?
Mean sperm velocity, Mean sperm linearity, Lateral head deviation, Mean curvilinear velocity
How do you carry out a sperm motility evaluation?
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
What two ways can sperm be observed?
1) Staining of sperm with dyes and observation under phase microscope
2) Observation of fixed sperm by differential interference contrast (DIC)
What do we stain sperm with
Nigrosin (background stain) and eosin (vital stain).
How does dying the sperm evaluate the membrane integrity?
Sperm with damaged membranes allow eosin to penetrate so sperm appear pink, sperm with intact membranes exclude eosin so sperm remain unstained (white).
Which method is better for assessing the morphology of sperm?
Observation of fixed sperm by differential interference contrast (DIC) at 100X microscope objective is considered more accurate in allowing you to evaluate morphology
What are the three types of sperm defect?
Primary (defect of spermatogenesis)
Secondary (epididymis)
Tertiary (post-ejaculation)
Name some common abnormalities
pyriform head, knobbed acrosome, detached or swollen acrosome, nuclear vacuoles, detached heads, distal Midpiece reflex, looped tail, coiled tail, cytoplasmic droplets
How long will the following types of preserved semen last?
Fresh-extended (room temperature)
Diluted / cooled (5oC)
Diluted / frozen (-196oC)
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.
What is the function of extender solution?
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.
If freezing rate is sufficiently slow and cell permeable to water what happens to the semen?
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
If freezing rate is too rapid or the cell is impermeable what happens to the semen?
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
If freezing rate is too slow what happens to the semen?
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
What is the general method for freezing sperm?
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
How is sperm sexed?
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
Semen from bulls is usually collected by ………………… and inseminated by ……………..
It has a sucess rate similar to calving.
Artificial vagina
Uterine insemination
