Evaluating Semen: Sperm Motility and Morphology Flashcards
Obtaining Semen Sample
Artificial Vagina
Stallion and Trained Bull
Interior compartment is filled with warm water
Provides temperature stimulation and pressure stimulation
Obtaining semen sample
Manual Stimulation
Dog and Boar
Obtaining Semen Sample
Electroejaculation
Bull, Billy / Ram, Wildlife
Semen Motility
Chart
To evaluate semen supplies should be?
All slides, stains, cover slips, and semen should be kept WARM at all times
Sperm Morphology
Sperm Viability
While it is obvious taht a sperm must be viable to fertilize on oocyte, the criteria that define a viable sperm are not clear
Viability stains (eosin or propidium iodine) rely on a permeable plasma membrane to define a non-viable sperm
This measures only a single aspect of viability
Only modest correlations have been reported between this type of a viability measurement and fertility
Abnormal Sperm Morphology
Rather than different insults causing different morphologic abnormalities - it appears that, a number of different insults cause “stress” which result in specific abnormalities to germ cells in specific phases of development/maturation
Inherited Sperm Abnormalities
Knobbed defect
Dag defect
Tail stump defect
Azoospermia / oligospermia
Decapitated defect
Rolled head / nuclear crest / giant head syndrome
Sperm morphology classification systems
Primary abnormalities
believed to arise during spermiogenesis in the seminiferous tubules due to pathological processes in the seminiferous epithelium
Abnormal heads, abnormal midpieces, proximal cytoplasmic droplets
Sperm Morphology Classification Systems
Secondary Abnormalities
Believed to arise after the sperm cells had left the testis such as abnormal epididymal function
Bent tails, coiled tails
Sperm Morphology Classification Systems
Major abnormalities
Those that have been correlated to impaired fertility
Sperm Morphology Classification Systems
Minor Abnormalities
Those that seem to be of minor importance
Sperm Morphology Classification systems
Compensable abnormalities
Those defects taht cause an affected sperm cell to fail to reach and therefore fail to fertilize the ovum - increasing the dose of sperm for A.I. will result in more total normal sperm and improved fertility
Tail problems that preclude forward motility
Sperm Morphology Classification Systems
Uncompensable Abnormalities
These defects taht don’t prevent a sperm cell from reaching and fertilizing the ovum but that prevent noral development of the embryo - increasing the dose of sperm for A.I. will result in the same % of abnormal sperm and hence the same fertility
Fertility Dose-Response Curve
Fertility plateaus at about 5-10 million sperm cells
Bull C has compensable sperm abnormalities
Bull D has non-compensable traits
Distal Midpiece Reflex
Minor - secondary abnormality
Coiled tail
Minor - Secondary abnormality
Detached Head
Minor - Secondary Abnormality
Distal Droplet
Minor - Secondary Abnormalilty
*NOT ABNORMAL
Elongated Head
Major - Primary Abnormalilty
Misshapen head
Major - Primary Abnormality
Proximal Droplet
Major - Primary Abnormality
Pyriform Head and Bent Midpiece
Major - Primary Abnormality
Reversed Tail
Minor - Secondary Abnormality
Breeding Soundness Examiniation
Limitations
Only reflects the breeding soundness on the day tested
The sperm cells seen today where begun weeks ago
Does not predict ability to cause conception in the future
Better at identifying subfertile males than highly fertile males
Many factors affecting fertility are not measured
Breeding soundness Examination
Strengths
Guarantees that known sub-fertile males are not used for breeding
Removes subfertile males from the genetics of herd and breed
Over time - herd and breed fertility is increased
Breeding soundness Examination
Interpretation
We are pretty good at identifying males that perform poorly
We are not successful predicting how males that pass a BSE will perform
Additional Tests
Thermography
Thermoregulation of testes of major domestic species is essential
If scrotal surface temperature is high and/or displays littel decrease as one moves from top to bottom of scrotum
More abnormal sperm
Fewer pregnancies
Additional tests
Ultrasound
Can be used to evaluate / detect fibrosis, soft areas, spermatoceles
Additional Tests
Computer Aided Sperm Analysis
Software programs that utilize video capture form a microscope video recorder
Usually phase-contrast or darkfield scope
More repeatable than subjective methods
Motility characteristics can be altered by: dilution of semen, image setting, semen viscosity and ionic composition, temperature extremes
Percentage live sperm not highly correlated to fertility
Evaluating Frozen Semen
Much slower motility - want >50% linear motility
Evaluate at thaw and 2 hours post thaw
If AI uses fewer sperm cells and many are damaged - how do we get any cows/mares/bitches pregnant
Evaluation of sperm quality has arisen because of our desire to predict fertility
Goal has not been achieved because of the complex nature of fertilization / fertility
