Exam 3 Flashcards
Scrotum
between the hind legs away from the body, pendulous, protects the testes
When do the testes descend
Between the last 30 days of gestation to the first 10 days postpartum
Cryptorchidism (ridgling)
One or both testes do not descend into the scrotum
Why is cryptorchidism undesirable
Most males are castrated and castrating one is very expensive ($2,000)
Bilateral C/R
No testes in the scrotum at all- not fertile
Unilateral C/R
Only one teste descends into the scrotum- still fertile
Testes
Sperm and testosterone production, oval shaped, horizontal orientation
Equine sperm
Tail is offset to one side of the head, swims in large arcs
Epididymis
Sperm maturation and storage, tail of the epididymis is towards the end of the stallion, head is towards head
Pampiniform plexus
Blood comes from an artery coming from the body to the testes and the veins around that artery cool the blood
Tunica dartos
One of the external muscles that goes around the whole scrotum- muscle is temperature dependent
Skin
has temperature sensitive sweat glands to help with evaporative cooling when temp is hot
Cremaster muscle
Not temperature dependent- a fight or flight muscle (sensitive to touch and the enviroment)
Accessory sex glands
ejaculate is a mix of seminal fluid and spermatozoa
Ampulla
two, secretions buffer and protect the sperm
Seminal vesicles
produce post ejaculate, gel fraction (very thick and viscous) gel fraction prevents sperm from getting through from other stallions
Prostate gland
produce post ejaculate, cleanse urethra after sperm has passed
Bulbourethral glands
responsible for producing the pre sperm fraction (cleanses the urethra prior to ejaculation)
Urethra
common passageway for both urine and semen, clean out any smegma one time a year (or bean) (geldings and stallions) if cleaned too often, the beneficial bacteria can be decreased
Smegma
Substance that protects the skin
Sheath
tissue that surrounds the non-erect penis, above prepuce
Prepuce and sheath
protect the penis itself, sheath cleaning
Penis
Musculo cavernosis, delivers ejaculate into cervix, bell shaped
Glands penis
bells out after breeding X4 size (stretches the cervix) causes an oxytocin release in mare to contract and take in ejaculate
Pre sperm fraction
Cleanses urethra (BG)
Sperm rich fraction
(75-95% of sperm) ampulla secretions in here as well
Post sperm fraction or gel fraction
seminal vesicle and prostate secretions
HPT-If given exogenous hormone
leads to less testosterone in testes, and less GnRH, sperm production
Leydig cells
in interstitium (between the tubules) , LH targets cells, cells produce testosterone
Sertoli cells
in seminiferous tubules, FSH targets cells, cells care for developing sperm
What is testosterone vital for
Spermatogenesis and libido
Stallion secondary sex characteristics
- Cresty neck, shiny coat, large jowls, and muscling
Seasonal effects- off season
Libido, sperm production, plasma hormone concentrations, and testicular weight and size is reduced
Spermatogenesis
Production of sperm cells, located in the seminiferous tubules
Blood testes barrier
separates basal and luminal layers, blocks blood from destroying sperm with small chromosome numbers
How long does spermatogenesis take
60 days- one sperm cell from the bottom to reach the top
What is included in spermatogenesis
Spermatocytogenesis, meiosis, spermiogenesis
Order of sperm travel
Seminiferous tubule lumen, rete testis, efferent duct, epididymis, efferent duct, urethra
Mitochondrial sheath in midpiece is important for what
Energy for sperm to move
When do we do a semen evaluation
Every time we collect a stallion
Semen handing
Ejaculate will be damaged in UV light and weather
Semen color
Anything from white to light tan is normal- red could indicate blood in sample
Semen Opacity
Affected by sperm count, the more concentrated, the more opaque
Semen Consistency
Should be watery, if thick there could be gel fraction in sample
Semen contamination
Blood, smegma, and urine
Volume of semen
Start with total- entire ejaculate with all components included
Gel free sample- most important sample
Total minus gel, filtered sample that keeps gel back- in line gel filter keeps sperm cells from mixing with gel
pH testing
Normal 7.2-7.7, with ph meter, abnormally high with contamination or infection
Computer Assisted Sperm Analyzer
Shows motility, morphology, concentration, consistent- used by large stallion centers
I sperm
Mini CASA, Ipad app with kit- motility, morphology, concentration
Primary defects- worst to have
Primarily the result of spermiogenesis gone wrong- head and midpiece
Secondary defects
Tail, have to do with error during storage or handling
Hancock/eosin - nigrosine stain
add semen drop, mix, background will be purple, eosin will stain sperm head pink if damaged, generally heat fix can look at defects now – count 100 cells, then get percent of sperm that is normal
Morphology
used at the beginning of season, then spot check as season goes on (concerns)- see if sperm is being handled correctly
Concentration method 1- Hemocytometer (special slide)
Dilute 1:100 in formalin, can be run on the raw and extended samples, can be used to count doses from straws
Unipette
vial with amount of formalin in bottom, puncture hole in the top and insert the capillary tube with sample into the hole and release
Hemocytometer resupply kit
Vial has formalin in it, two capillary tubes, mix and shake formalin and sample together
Densimeter
measures just formalin, then passes light through the sperm cell sample (measures bounced back light waves to estimate concentration) – pretty accurate, very concentrated or very dilute, contamination can cause an overestimation- takes 4 minutes, only raw semen can be used with this method (extender bounces light back)
Motility
Look at 10 sperm cells and decide motility – use number to determine percentage (2/10= 20%)
Semen extender
extender is skim milk based, contains sugar and antibiotics, dilutes seminal plasma, gives sperm more room to move
Raw semen motility
First, take ejaculate and split it in two (one tube has just ejaculate and the other one has a little raw with extender)
Extended semen
we look for percentage of progressively motile sperm cells with this sample
Why do we look at raw and extended semen
We look at both to make sure if there is dead sperm its from the stallion himself or human error in the extender or handling
– knowing volume does not mean there are a certain number of sperm cells
What to use to determine if a horse should be bred
Valuable genetic qualities, purpose for foal and possibility of market, economic benefit vs sentimental reasons, ability to manage pregnant mare, ability to manage and train foal
Maiden mare
Has never been bred or had a foal
Foaling mare
Having a foal then cycling back and being bred again
Not bred
She’s had a foal but not been bred this year
Aborted/ slipped
Mare that has lost a foal but we do not know when she aborted it
Barren mare
Tried to get the mare pregnant and failed
Natural service or live cover methods
Pasture and hand breeding- stallion actually mounts the mare and deposits semen in repro tract
Artificial insemination methods
Fresh extended semen or on site AI, cooled transported or stored semen, frozen semen or frozen thawed semen-collect stallion, process semen, then deposit it in mare
Breeding shed requirements
Predictability, good footing, escape routes, free of distraction, strategy for height discrepancy
Stallion equipment
Halter or breeding bridle, lead/shank, breeding roll, cup or slide for dismount sample
Mare equipment
Halter, lead/shank, twitch, shroud, boots, leg restraint (hobbles/boots)
Stallion specific requirement of mares
Endometrial Culture
CEM Culture (imports)
Vaccination Against EVA
EHV Vaccinations
Mare processing- reduce the risk of pathogens and contamination
Identification, tail wrap, perineal cleaning, lubrication, stallion identifier, teasing box, set up and restrain, test mount
Stallion post breeding
Dismount sample, hygiene penis- with water
Other process to do for mare after breeding
Reinforcement breeding or impregnation, monitor PBE, confirm ovulation
Frequency of breeding method
Breed 12-48 hours before ovulation, breed every other day while in heat, ultrasound when to breed and induce ovulation
Busy stallions
Goal is to breed once per estrus- doubling is breeding mare twice within 48 hours- strongly discouraged
Natural services advantages
Optimizes semen quality, high sperm count, no semen processing errors, cervical dilation, uterine contractions, often less expensive than AI
Natural service disadvantages
Need to transport mare (may have foal), stallion scheduling, potential for disease transmission, less ideal for PBE, risk of injury
Semen collection methods
Artificial vagina (jump mare, ground collection, phantom) condom
Missouri AV
Lightest out of all and manipulable, but harder to hold and not as well insulated
Nishikawa AV
A firm metal casing that holds latex liners, goes to a point that stallions have gotten stuck in
Colorado AV
Takes a lot of time to build, can be cleaned easily, super insulated, heavy when full- easy to hold but hard to manipulate
Processing for on site AI or fresh extended semen
Collect semen, evaluate semen, add extender for breeding doses
On site breeding doses
500 million PMS, 10-80 mL total volume, 1:1 dilution- extender-semen
Mare process for on site AI
Inseminate mare within 3 hours- load breeding dose into syringe, wrap up and tie tail, hygiene, inseminate, monitor PBE, confirm ovulation
Advantages of AI
Decreased risk of injury to mare or stallion, can breed multiple mares with one ejaculate, decreased risk of disease transmission
Disadvantages of AI
Requires advanced knowledge and skills, semen processing, mare management
Processing for cooled transported semen or cooled semen
Collect semen, evaluate semen, add extended for breeding dose- do not warm up semen
Cooled semen breeding doses
1 billion PMS, 40-60 mL total volume, minimum 3:1 dilution, 25-50 million sperm/mL fluid
Packaging of cooled semen
Each shipment has two doses, placed into shipping unit to cool (equitainer)
Mare process for cool shipped AI
Breed mare within 24-36 hours of collection, load breeding dose into syringe, inseminate, monitor PBE, confirm ovulation
How to know when to breed for cool shipped
Edema maximal 24 hours before ovulation, follicles grow 2.5-3 mm per day
Cool shipped semen timing strategies
tease or ultrasound to determine start of estrus, track with ultrasound to determine when to order, order semen 24 hours prior to desired breeding, induce ovulation and breed, ultrasound to confirm ovulation
Benefits of cool transported semen
Increase available genetics, no transportation of mare or stallion
Disadvantages of cool transported semen
Semen availability constraints, problems with shipments
Processing for frozen semen
Collect semen, evaluate semen, add extender and centrifuge, re suspend in freezing extender, package in straws, freeze in liquid nitrogen
Frozen semen breeding doses
No industry standard (250 million PMS after thawing, 800 million total sperm) varies from single 0.5 mL straw to 4-8 straws, increase number of PMS if acceptable pregnancy rate is not achieved
Sperm and oocyte survival time
Sperm- 6-8 hours, oocyte- 12 hours
Highest pregnancy rates with insemination
12 hours before to 6 hours after ovulation
Frozen semen timing strategies- timed protocol using two semen doses
Induce ovulation(35 mm follicle+edema) AI with thawed semen 24 hours later, AI with thawed semen 16 hours after that, monitor PBE, confirm ovulation
Frozen semen strategies- labor intensive using one dose only
Induce ovulation then ultrasound every 6 hours- once ovulation is confirmed, AI with thawed semen
Types of AI with frozen semen
Deep horse insemination at UTG, deposit semen with AI gun, deposit semen with traditional pipette, hysteroscopic insemination (spray uterine horn)
Advantages to frozen semen
International shipping, breeding to deceased stallions, semen can arrive before breeding
Disadvantages to frozen semen
Semen is expensive, no live foal guarantee, not ideal for older/ problemed mares
Success in breeding: breeding management
experience of breeder, estrus detection, selection of breeding method, identifying and treating problems
Success in breeding: Mare factors
Health and breed, age, parity, interval since last foaling, previous problems
Success in breeding: stallion factors
Health and age, breed, breeding routine, semen processing, booking
Reinforcement breeding
Increases per cycle pregnancy rate by 12%
General rule for frozen semen
Per cycle expect 50% of pregnancy rate achieved using fresh extended or cooled transported semen from stallion
General goals of ART
Produce offspring from diseased horses and increase number of foals from genetically valuable animals
Embryo transfer: Donor mares
Performance mares, young mares, need healthy uterine environment
Embryo transfer: recipient mares
Age: 3-10 years, previous foals, size match to donor
Donor mare ET procedure
Routine breeding management, super ovulate, 50% embryos recovered during ovulation
Recipient mare ET procedure
Ideally ovulate 1-2 days after donor- can use a large recipient herd or synchronize privately
ET cryopreservation
morula, 6 days after ovulation- transcervical
ET immediate transfer
Blastocyst, 7-8 days post ovulation- transcervical
Preserving ET embryos
shipping cooled embryos (transfer within 24 hours) or freezing by vitrification (store in liquid nitrogen)
ET procedure outcomes
3 attempts yields 1 live foal, multiple ovulations increase chances of success, pregnancy rate loss is 10% more than typical AI
Oocyte retrieval
Harvested from dead mares, transvaginal follicular fluid aspiration, used for oocyte transfer or ICSI
Interplastic sperm injection (ICSI)
Take harvested oocyte and inject the sperm into the oocyte, * Transcervical transfer of ~7-day embryo (blastocyst) More successful than IVF in horses
Cloning
Around $85,000 to clone
First Cloned Equids born in 2003
Genetic Banking- have a certain animal forever, preserve genetics
Performance Areas w/o Breed Registrations
Viagen >1,000 Horses
Sex sorted semen
X and Y chromosome sperm physically separated by flow cytometry
Low dose insemination method (fresh or frozen)
~93% Gender Accuracy;
Sorting Process $5,000-$10,000
not very popular
Epidydimal sperm
Harvesting non-ejaculated sperm from vas deferens and tail of the epididymis
Testes removed at death or castration
Low dose insemination method (fresh or frozen)
Pregnancy rates 30-45%
Costs $1,400
Three components of a breeding exam
Physical health, free form hereditary defects, reproductive health
BSE with a maiden mare
usually abbreviated BSE unless aged or concerns with abbreviated exam – her uterus should be in great condition
Mare BSE process
Physical exam and history, external repro tract exam, rectal palpation, ultrasonography, cervix exam, endometrial culture, cytology, and biopsy
What is targeted in the mare BSE external repro tract exam
Pneumovagina, vulva alignment, abnormal size of tract
Ovarian abnormalities
Granulosa cell tumor
Uterine abnormalities
Air in uterus, uterine fluid, uterine cysts- along the endometrial folds, map cysts because they can be misdiagnosed as embryos
Cystic nests
are problematic- a grouping of cysts at the base of a horn – blocks the embryo from touching all aspects of the uterus, effects placentation
Mare BSE cervical exam
palpation or speculum- palpation does not allow as much contamination into the cervix
Endometrial fibrosis
scarring of the endometrial lining, look at a sample under microscope – no glands would = scarring
Standards of a stallion BSE
Should be able to breed 40 mares by natural cover or 120 mares bred by artificial insemination, want them to have a 75% seasonal pregnancy rate
Overview of stallion BSE process
General exam and history, eval of teasing behavior, external genitalia exam, microbial cultures, eval of breeding behavior, 1st collection and semen eval, examine scrotal contents and internal contents, 2nd collection and eval
Stallion BSE: Evaluation of Teasing Behavior
Time to Erection – in less than two minutes
“Handleability”- is the stallion safe to handle
Juvenile Behavior – really slow to get erect or do not pay attention to the handler
Libido – young stallion from show career to breeding career have a hard time expressing breeding behavior and breeding
Goal of 1st stallion collection in BSE
One billion PMMN in first ejaculate
