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ASC 410 > Introduction to Equine Reproduction > Flashcards

Introduction to Equine Reproduction Flashcards

(61 cards)

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1
Q

Mares are seasonally polyestrous and have multiple estrous cycles when?

A

in the spring and summer

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2
Q

Seasonality is triggered by

A

increasing day length

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3
Q

Each estrous cycle is about how long?

A

18-23 days long (average = about 21 days)

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4
Q

What are the two phases of an estrous cycle?

A

estrus and diestrus

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5
Q

Estrus

A

when the mare is receptive to the stallion
-aka heat

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6
Q

What is estrus under the influence of?

A

estradiol

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7
Q

Diestrus

A

when the mare is not receptive to the stallion

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8
Q

What is diestrus under the influence of?

A

progesterone

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9
Q

Anestrous

A

when the mare is not cycling

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10
Q

Each estrus period is usually about..

A

3-7 days long

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11
Q

Each diestrus period is usually about..

A

12-18 days long

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12
Q

Ovulation occurs when?

A

24-48 hours before estrus ends

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13
Q

Fertilization of the oocyte occurs in the…

A

oviduct

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14
Q

The oocyte remains fertile for about

A

12-18 hours after ovulation (window of opportunity once ovulation occurs is small)

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15
Q

Once in the mare, normal sperm should remain fertile for about…

A

48-72 hours if fresh

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16
Q

The best time to breed a mare is…

A

24-48 hours before ovulation

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17
Q

The best time to breed a mare in the estrus cycle is..

A

the second day of estrus and every other day until estrus ends

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18
Q

From day of conception to delivery of a normal foal, gestation length in mares…

A

can range from 10.75-12 months

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19
Q

If a mare conceived on May 15 of 2023, when would you expect her foal?

A

mid/late April 2024

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20
Q

When mares conceive twins, it is considered…

A

normal but not desirable

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21
Q

About how many foals (all breeds) are born each year in the US and Canada?

A

100,000-150,000

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22
Q

If the annual foal crop in 2024 is 150,000 about how many mares were bred in 2023?

A

200,000-225,000 (55-60% live foal rate)

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23
Q

Why is live foal rate important?

A

-the more mares you have to breed to get more foals, the more expensive
-a live foal is needed in order for the stallion owner to get paid
-helps us understand and do better with reproductive efficiency

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24
Q

Broodmare

A

any mare intended for breeding

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25
Barren mare
mare was bred and didn't get pregnant
26
Maiden mare
a mare being bred or producing a foal for the first time
27
Rested mare
mare has had foals but is not bred or pregnant one year
28
Wet mare
mare that is lactating
29
A "breeding system"
the management process intended to result in a foal
30
What is the breeding system regulated by?
breed associations -some systems/procedures may be completely prohibited -some systems/procedures may be allowed under some circumstances -
31
Two main types of breeding systems:
-assisted reproduction (AI, embryo transfer, etc.) -natural service
32
Assisted reproduction systems have...
-large human intervention -breed/registry may include restrictions, require fees and permits
33
Artificial insemination
semen is collected from a stallion and later inseminated in a mare
34
Types of semen:
-fresh -cooled -frozen
35
Fresh semen
used in a few hours, usually on farm or local
36
Cooled semen
5 degrees C -shipped overnight -most common in the US
37
Frozen semen
frozen in liquid N -stored frozen -shipped frozen -can have it for years -some stallions' semen does not tolerate being frozen
38
Typical stallion management for AI:
-train stallion to use phantom/dummy -train stallion to use artificial vagina -collect semen as needed
39
What is a common collection schedule for AI for stallions?
-3-4 times/week: M, W, F, maybe Sat -if freezing, when the stallion is available
40
What do people typically do with the first stallion collection?
test collect to determine best conditions, temp, extenders, freezability, etc.
41
When collecting semen to breed mares:
-evaluate semen: volume, concentration, motility, morphology -extend and divide doses -cool and ship or freeze and store/ship
42
Typical mare management for AI
-heat detection program (teasing, vet exams, etc.) to forecast ovulation time -order semen -schedule for vet insemination -check mare for ovulation (vet) in 24 hours
43
When do we want to inseminate AI for a mare?
close to ovulation
44
Embryo transfer
A donor mare is bred (usually AI) and ovulation is tracked. The embryo is collected and inserted into a recipient mare that will carry the foal to term
45
When is the donor mare flushed for the embryo?
about day 7
46
Who is the official dam of the foal from embryo transfer?
the donor mare
47
Recipient mare in embryo transfer:
-synchronized with donor, ideally ovulate at the same time -embryo is transferred after collection
48
Success with fertile mares in embryo transfer is as high as
85%
49
How to choose a recipient mare for ET:
-reproductively healthy -raised a previous foal (good maternal behavior) -same size as donor
50
Natural service is allowed by...
all breed registries -it is the only one allowed in the Thoroughbred industry
51
Natural service is also known as:
live cover
52
Hand-mating live cover
-mares travel to where the stallion is -mares wear a neck cover/tail wraps/boots to protect the stallion and her during breeding -mare is teased and an ultrasound is done to check estus cycle -mare and stallion are being held and possibly assisted while mating occurs
53
Pasture mating
stallion breeds mare(s) in an enclosure -a mare may be taken to a stallion and turned out with him for a certain period of time -more commonly a stallion is put in with a herd of mares at the beginning of the breeding season and left there until the breeding season is over
54
Advantages of pasture mating
-less stressful -less work for people -no risk of injury to people -effective (allowed by registries) -allows "extensive" management system -lower cost (labor/equiptment)
55
Disadvantages of pasture mating
-more risk of infection transmittal -more risk of injury to all horses involved (including foals) -no info on conception rate until end of season -less info on breeding dates (then won't know foaling date) -fewer mares per stallion -reduce genetic choices
56
Advantages of hand mating
-known breeding date -genetic choices -better hygiene -less risk of injury to the horses (especially foals) -ability to follow pregnancy rates -allowed by all registries -collect semen for evaluation -more mares per stallion (with high management)
57
Disadvantages of hand mating
-more labor before and during breeding -more stressful for mare (may need to travel, or leave foal) -more risk for people -higher cost (more labor and facilities)
58
Advantages of AI
-use of competition horses -more mares/season -more mares/ejaculate (less stressful for stallion) -more genetic choice -mare and stallion in different places (better biosecurity) -less risk of injury for people and horses -more opportunities to evaluate semen
59
Disadvantages of AI
-cost (shipping, vet procedures, equipment, access to more expensive stallions) -genetics (could decrease genetic diversity if too many mares are bred to one or two stallions) -scheduling and logistics are challenging -more expertise needed -registry requirements (fees or not allowed at all)
60
Advantages of embryo transfer
-preserve genetics of mares that are not capable of having a foal -obtain foals from mares that are currently competing -may be able to obtain several foals from 1 mare/year
61
Disadvantages of embryo transfer
-expertise and equipment needed -expense (at least two mares) -registration and reporting requirements

ASC 410 (22 decks)

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