Flashcards in Breeding Management Deck (60):
What are 3 goals of breeding management concerning mares?
- Maximum number of pregnant mares in a breeding season
- Achieve maximum number of pregnant mares as soon as possible at the lowest cost
- Deliver maximum number of live, healthy foals the following year
What are 2 areas of motivation and constraint that needs to be considered with the breeder?
Which type of factors are easier to change, management or biologic?
What are 4 factors for maximizing the chances of getting a mare pregnant?
- Good management
- Clean mare
- Good timing
- Good semen
Are breeding management factors multiplicative or additive?
What are 6 key factors to obtaining good fertility in the horse?
- Normality of the estrous cycle
- Pre and post-breeding therapies
- Timing of insemination
- Place of insemination
- Number of sperm in the inseminate
- Volume of the inseminate
T/F: When it comes to breeding mares, if you cannot do it right, it is ok to cut corners.
False - If you cannot do it right, then do not do it!
The pregnancy rate equals what?
Number of mares pregnant divided by number of mares bred.
What is the pregnancy rate target for mares per cycle?
- Greater than 60% per cycle
- Over 90% per season
TB's can be bred how often per day?
What is the limiting factor?
- 2-4x per day
Stallions collected for AI will get the maximum number of sperm when collected how often?
Every other day throughout the season.
When does uterine edema appear during the estrous cycle in a mare?
What happens after it appears?
- Early in estrus
- Progressive increase
What happens to uterine edema as the mare approaches ovulation?
Approximately when does this start?
- Starts to decrease
- About 24 hours prior to ovulation
Most normal mares will ovulate with a low degree of what?
When the cervix is relaxed and edematous, it gives what sort of appearance?
What grade of endometrial edema does this coincide with?
- Fish bone
- Grade 2
What size follicle is usually associated with and endometrial edema grade of 2?
30-35 mm or 40+mm
Some folds are easily observed with hyperechoic centers with what endometrial edema grade?
Folds are thicker with a hypo echoic center and hyper echoic wall with what grade of endometrial edema?
What grade of endometrial edema has a "cart wheel" appearance?
What grade of endometrial edema is considered an abnormal finding and is a state of "hyper-edema?"
If the endometrial folds are very thick to the point they lose their "normal" US structure and have an increased surface area with very little to no free fluid observed, this is considered what grade of endometrial edema?
With grade 5 endometrial edema, how to the follicles appear?
Variable but often pre-ovulatory or recently ovulated.
How does increasing amounts of uterine fluid affect the first cycle pregnancy rate in a mare?
The season pregnancy rate?
Increasing uterine fluid decreases the rate for both.
How long can sperm survive in the oviduct of the mare after natural breeding?
With fresh semen?
Days for both
How long can sperm survive in the oviduct of the mare in relation to ovulation with cooled semen?
With frozen semen?
- 0-48 hours prior to ovulation with cooled
- 4 hours prior to 12 hours post with frozen.
There is no question that breeding a mare when results in higher pregnancy rates?
Prior to ovulation
A mare should be bred how many hours prior to ovulation when using natural breeding or fresh semen?
A mare should be bred how many hours prior to ovulation when using fresh cooled semen?
A mare should be bred how many hours prior to ovulation when using frozen semen?
Less than 12 hours
Whether or not a mare should be inseminated both before and after ovulation depends on what 3 factors?
- Type of semen used
- Susceptibility of the mare to infections
- Proximity of AI to ovulation
What is the recommendation for breeding a good mare using good semen?
Any time, once or twice
What is the recommendation for breeding a good mare using poor semen?
Once or twice, the closer to ovulation the better
What is the recommendation for breeding a poor mare using good semen?
Only once, the closer to ovulation the better
what is the recommendation for breeding a poor mare using poor semen?
Only once, very close to ovulation
What are 4 components of preparing the mare for breeding?
- Bandage tail
- Wash and rise vulva and perineum
- Dry washed area
- Proper mare restraint
What, if done properly, in most cases will enhance the fertility of the mare and/or stallion?
Proper AI technique in the horse includes what 3 features?
- Good quality semen
- Mare's uterus is clean
- Semen placed at right time
The standard place for semen deposition in the mare is where?
With natural mating, how many sperm are deposited in the uterus of the mare?
How long does it take the sperm to get from the uterine body to the oviduct in a mare?
How long does it remain there?
- 0.5-4 hours
- Hours or days
What are responsible for eliminating excess fluid from the uterus of a mare?
What else do they do?
- Myometrial contractions
- Move sperm up the oviduct
Maximal colonization of the oviduct in the mare appears to be achieved by when?
How are sperm normally distributed in the oviducts of a mare?
50% in left and 50% in right
T/F: If properly done, natural breeding is a cheap alternative to artificial insemination.
False - It is NOT a cheap alternative.
What is the fertility rate in horses when using sperm of adequate quality with natural cover or fresh AI?
With cooled semen AI?
With frozen semen AI?
- Greater than 60%
- Greater than 50%
- Greater than 40%
Does evidence suggest that it is slightly better to perform AI once or twice when using frozen semen?
What is always a concern when it comes to semen?
To reduce semen usage, what are often performed?
AI can result in acceptable pregnancy rates with post-ovulation breeding provided the semen are deposited when?
"Very soon" after ovulation (Less than 4 hours)
What technique can reduce inseminate volume, sperm numbers and uterine-sperm time contact?
What can this help reduce?
- Deep horn insemination
- Uterine inflammation
What are 6 advantages of deep horn semen deposition?
- Increase number of mares bred per ejaculate
- Maximize frozen semen usage
- Increase efficiency of sexed sperm AI
- Utilize stallions with sub-optimal semen quality
- Reduce incidence of post-breeding endometritis
- Increase fertility in some mares
What are 5 advantages of AI?
- Maximize efficiency of stallion usage
- Increase genetic pool due to increased availability of stallions
- More regular evaluation of stallion semen
- Reduce risk of sexually transmittable diseases
- Increases safety of animals and handlers
If still having trouble breeding a mare after trying AI, what are 3 assisted reproductive techniques that can be used?
- Embryo transfer
- Oocyte transfer
- Intra-cytoplasmic sperm injection
When using embryo transfer, at what age is the embryo transferred to the synchronized recipient?
7 or 8 day old embryo
What are 4 indications for use of embryo transfer?
- Young mares in competition
- Mares with severe uterine problems
- More than one foal a year
- Biopsy for a desired outcome
Embryo transfers can be used with fertility problems not related to what?
Ovulation or the oviduct
What are 4 indications for intra-cytoplasmic sperm injection use?
- Old mares where it is not possible to retrieve an embryo
- Oviductal disease
- Mares that have died
- Use of stallions with very limited amount of semen available
What is the procedure for intra-cytoplasmic sperm injection?
- TVA of several immature oocytes
- In-vitro oocyte maturation
- Inject a single sperm into oocyte
- Culture in-vitro to sec for cleavage
- At morula stage, freeze or transfer to recipient
What are 3 indications for oocyte transfer?
- Old mares where it is not possible to retrieve an embryo
- Oviductal disease
- Mares with unexplained infertility