Semen Collection and Evaluation Flashcards
what are the 4 common breeding schemes for horses?
- AI
- hand mating
- pasture mating
- corral mating
describe hand mating
prep the mare and hobble her by attaching cushioned straps so she can’t kick the stallion and then introduce the two to breed
describe pasture mating
more simulates the natural environment; one stallion in a pasture with multiple mares, but must watch them to see which mares were covered
describe corral mating
one mare, one stallion, in an enclosed area and left to their business
what has caused the popularity of AI in horses to increase recently?
- increased breeding/ejaculate thanks to semen extension methods
- safety for the stallion and handlers
- acceptance by more and more breed associations
why is cooled semen more popular than frozen semen in horses?
frozen semen only has a 30-40% success rate and some stallions freeze better than others (some stallions just don’t freeze well)
when is semen evaluation peformed?
collected twice early in the breeding season
what are the 6 REQUIREMENTS of a semen collection area?
- spacious
- clean
- free of distractions
- safe for both horses and handlers
- flooring surface with good traction
- minimize distance from collection area to lab
what qualifies as bad flooring surfaces for semen collection areas and why?
wet floor (no traction), shavings, gravel (stallions can paw and strike and sling dirt and gravel onto their nice washed penis/the poor mare’s vulva)
can you use an outdoor area to breed? what must you be careful of?
yes but limit distraction
what is another place that can be used for semen collection?
breeding sheds
why do you want to minimize the distance from the semen collection area to the lab?
want to process and chill/freeze sperm ASAP
what are the 3 methods of semen collection?
- condom
- pharmacological
- artifical vagina
what logistical issues are posed by using condoms for semen collection?
put on - dangerous
take off = can lose semen
describe pharmacological method of semen collection and why it is used
give drugs to cause ejaculation; this is used if a horse has great genetics and performance but has been injured and cannot stand on his hind legs for collection
what is the most popular method of semen collection?
artificial vagina
what are the 2 types of artificial vaginas used? describe
- missouri: most popular
- colorado: sturdy, but heavier at 25lbs
describe an artificial vagina (2)
- fitted with a water jacket that can modify the internal diameter to modulate pressure to simulate entering the mare repro tract and allows for control of internal temp (44-48C)
- lubricant (NON SPERMICIDAL) added to innermost liner that the stallion is in contact with
what kind of lubricant is commonly used with artificial vagina
HR lubricating jelly
how do you know if a stallion ejaculated?
flagging of the tail, which bobs up and down during ejaculation
immediately follows semen collection (2)
- lab analysis
- addition of extenders
what is done to the mare before breeding?
she is washed with mild soap
what is done to the stallion at the start of each breeding season?
washed with mild soap
what is done to the stallion before each breeding?
washed with warm water
how is semen collected (horsey wise)
- stallion is presented to a mare or phantom at the side to make sure mare knows what is about to happen
- after achieving full erection (MUST BE DONE BEFORE FULL MOUNT TO ACHIEVE SUCCESS)
- collector guides penis to AV and keeps it in position
what 4 parameters are evaluated of semen?
- volume
- concentration
- motility
- morphology
is a stallion is fertile, what volume of semen will he ejaculate?
25-100mL
what is the concentration of sperm in a fertile stallion?
30-800million sperm/mL
what percentage of progessively motile sperm must a stallion ejaculate to be considered fertile? also define progressively motile
moves in a straight line; 60-100%
what percent of a fertile stallion’s ejaculated sperm must be morpholigically normal?
70-80%
in what two ways are semen concentration measured? describe
- densimeter: is a photometer that tells concentration based on how much light passes through a sample (higher concentration yields less light)
- chemometric nucleocounter: looks at fluorescent DNA strain but really expensive
what is the benchmark minimum insemination dose? also give range
usually 500million progressively motile sperm, but range from 400-800million
in a chilled program, how is semen delivered?
in 2 50mL doses, depending on the stallion and the number of mares booked (if a lot of mares may only get one dose)
what was the old protocol for chilled semen? what is the new protocol?
old: inseminate with first dose immediately, then the second dose 12-24 hours later
new: inseminate with btoh doses when received because sperm lose viability in refrigeration
how is frozen semen delivered? (3)
- in 0.5mL straws
- 50-100million sperm/straw
- dose is 6-8 straws per mare
give an example of an assissted reproductive technology (ART) and describe
ICSI: intracytaplasmic sperm injection
collect one ovum and one sperm, fertilize in vitro, then allow embryo to mature 6-8 days before implanting in horn of recipient mare
what are the drawbacks of ICSI?
expensive, lots of room to go wrong
when would ICSI be used?
only when there is a lot of money on the line for BOTH mare and stallion
how is dose volume according to the number of progressively motile sperm in raw semen from stallions determined?
divide motile sperm in raw ejaculate by total number of parts in dilution ratio, to get nunber of sperm in final dose; then divide 500 (for 500million benchmark) by number of sperm in final dose to get dose volume
what are 4 teasing methods used if you have a stallion?
- tease rail
- stall teasing
- paddock teasing
- chute
how can you tease if don’t have a stallion?
get a studly gelding and hope for the best
describe a tease rail, give drawback
a solid wall between amre and stallion, but time consume because must bring each mare up one at a time
describe stall teasing and give drawback
mares in stalls and lead stallion through the barn, but cannot always see all ehat behavior (winking)
describe paddock teasing and give a drawback
stallion in a small enclosure inside the paddoc and let mares approach him; is good for mares with foals but more submissive mares might not approach if there are dominant mares present
describe chute teasing; give drawback
long chute with one side for mares, head to tail, lead stallion down other side; you can see all of the mares’ behavior but mares can hurt each other if kick
what are 5 signs of heat in mares?
- winking vulva
- squatting
- urinating
- raising tail
- talking to/receptive of stallion
what will a mare do when teased if not in heat?
will squeal and kick at the stallion
what is foal heat and when does it occur?
estrogen spike 7-10 days after parturition
is foal heat a good time to breed? why or why not? (4)
no!
1. conception rates are low
2. uterus not completely involuted
3. repro tract environment not optimal for conception
4. if mare just had a rougher parturition she will be less likely to conceive
