REPRODUCTION - Stallion Fertility Flashcards
What is the only accurate indicator of fertility?
Pregnancy rate per cycle (PRPC)
What are the three influences on pregnancy rate per cycle (PRPC)?
Mare fertility
Stallion fertility
Management
When do stallions reach sexual maturity?
Stallions reach sexual maturity at approximately 2 years old, however their testicle size and sperm production will be maximal at around 4 - 5 years old
When are stallions classfied as reaching sexual maturity based on their ejaculate?
5 x 10^6 sperm with more than or equal to 10% motility
How do you approach a stallion breeding soundness examination?
- Breeding history
- Thorough clinical examination
- Semen analysis
- Estimate daily sperm output (DSO)
- Assess the external genitalia (penis and testicles)
- Test for veneareal disease
Which history questions are beneficial to ask during a stallion breeding soundness examination?
- Has the stallion been involved in any previous breeding?
- Has the stallion has any previous breeding soundness exams?
- What were the foaling rates from this stallion during the previous season?
- Management?
- Any previous disease?
- Medications?
Which factors should you assess during clinical examination of a stallion for a breeding soundness exam?
Thorough clinical exam
Assess for lameness
Assess joints
Assess conformation
Assess vision
Assess for any heritable conditions which could be propagated to their offsprings
How can you collect semen samples from the stallion?
Artificial vagina
Dismount samples from natural cover
Chemical ejaculations
Which drug can be used for chemical ejaculation?
Xylazine
How do you use an artificial vagina for semen collection in the stallion?
The stallion will be exposed to a teaser mare who may be behind a teaser barrier or hobbles may be used. When the stallion gets an erection, he will either be directed to the mare and the penis will be redirected into the artificial vagina when necessary, or the stallion will be directed to the ‘phantom mare’ and into the artificial vagina
What should normal semen look like?
Normal semen will have a watery grey to creamy white appearance depending on the semen concentration and the volume will vary depending on sexual stimulation
What can cause discolouration of the semen?
Dirt/debris from the penis
Pyospermia
Urospermia
Haemospermia
How can you diagnose the cause of pyospermia?
Urinalysis
Semen sampling
Ultrasound of the accessory glands and testicles
What can cause haemospermia?
Urogenital trauma
Urethral rent
Neoplasia
Seminal vesiculitis
Habronemiasis
What is seminal vesiculitis?
Seminal vesiculitis is inflammation of the seminal vesicles
How can you diagnose the cause of haemospermia?
Careful assessment of the urogenital tract
Endoscopy
How can you treat haemospermia?
Sexual rest and/or surgical repair of trauma or urethral rents
Which factors do you assess during semen evaluation?
Sperm concentration
Sperm motility
Sperm longevity
Sperm morphology
What is the recommended method to determine sperm concentration within a semen sample?
Haemocytometer
What is the minimum sperm concentration requirement for a breeding stallion?
1x10^9 sperm in the second ejaculate
What is the minimum sperm motility requirement for a breeding stallion?
30-35% progressively motile sperm
What is the minimum sperm morphology requirement for a breeding stallion?
Over 60% of the sperm have to be of normal morphology
What is daily sperm output (DSO)?
Daily sperm output (DSO) estimates the number of spermatozoa a stallion can produce per day
How can you estimate daily sperm output (DSO)?
You can estimate daily sperm output based on testicular measurements, however be aware that daily sperm output varies with age, season and testicular health
