Equine Breeding Management Flashcards
where is the breeding capital of thoroughbreds
Kentucky
stud fees range from_____ to ______________; foal values range from _______ to _______________
$100; $500,000; a few hundred; several million
T/F the equine industry varies greatly across breeds in breeding methods and costs/values
T
what is a stallions book
list of mares bred to stallion in a given year
cover vs mount
cover is natural breeding; mount is using a dummy
what are 4 methods of mare breeding
1) natural cover
2) on-farm AI
3) shipped fresh chilled AI
4) frozen AI
natural cover is the only method approved in what breed to obtain a registered foal
thoroughbreds
what are 4 advantages of natural cover
1) minimal equipment costs
2) it is obvious when the mare is in heat
3) no knowledge of semen handling needed
4) no semen shipments lost
what are 4 disadvantages of natural cover
1) risk of injury - need trained personnel
2) one mare bred per ejaculation
3) costly to bring mare to stallion
4) some mares will not accept stallion
what is one way to tell that the stallion ejaculated during natural cover
they may fall asleep afterwards
what is a unique concern with natural cover
need to be diligent with swabs and testing ahead of time to prevent spread of veneral diseases
what are some advantages of using AI
1) safety
2) more efficient as many mares can be bred with a single ejaculation
3) mare can stay at home
4) semen lasts 48+ hours when an extender is added
5) with frozen semen the stallion’s performance career is not interrupted
what are 2 disadvantages associated with AI
1) expenses of lab, shipping, mare management
2) requires a lot of knowledge in semen handling
frozen semen is stored at what temperature
-196 degrees C
one breeding dose of frozen semen is packed into how many straws and what size
1-8 1/2 mL straws
what are 2 disadvantages of using frozen semen
lower fertility rate; higher costs
what are 4 reasons for estrous cycle manipulation in mares
1) high costs associated with some foals
2) high costs associated with transporting the mare/semen
3) pressure for early foaling
4) for the purpose of embryo transfer, IVF, ICSI
what percentage of mares will cycle year round
10%
describe the uterus of a mare in anestrus
flaccid, no edema
when does spring transition occur in mares
march - april
what is spring transition characterized by
irregular or prolonged estrus periods with NO ovulation
why is there no ovulation during spring transition
there are no LH receptors on the theca cells and low bioactive LH
horses cycle every ____ days
21
what are some signs of estrus in the mare
winking, receptive to stallion, increased urination, posturing
what are physical signs that the mare is in diestrus
aggressively refusing the stallion (kicking, biting, pinning ears)
what is characteristic of fall transition in horses
anovulatory follicles present on the ovary
what gene turns off during fall transition
LH gene
T/F the fall transition is characterized by less progesterone and luteal failure
T
what is the standard amount of light needed to bring a horse out of anestrus
14.5-16h total
T/F you should add light to the start of the day to bring a horse out of anestrus
F; add to end of day
horses resume cycling ______ days after you start the light program
60-70
you should continue a lighting program for horses until days are naturally how long
14h (mid-March)
you should start a lighting program in what period for February breeding
Nov 15 - Dec 5
what is the most economical way to manipulate daylength in mares to bring them out of anestrus and how does it work
1.5-2h of high intensity light between 2am-4am; works because the photosensitive period in horses is 8-10 hours after onset of darkness
does high or low wavelength light most effectively inhibit melatonin secretion
low
T/F you should slowly increase the duration of light
F; just start right away with 14.5-16 h
do the effects of season or the effects of foaling predominate
effects of season; meaning you need to put pregnant, early foaling mares in your program to ensure they continue cycling after foaling
T/F PGF2α can be used to pull mares out of anestrus
F; no CL
T/F GnRH and hCG can be used to pull mares out of anestrus
T but very low success due to lack of circulating LH and lack of LH receptors on the theca cells during this time
what hormone CAN be used to pull mares out of anestrus
dopamine antagonists (increase prolactin to stimulate follicular activity)
sulpiride and domperidone are what
dopamine antagonists
T/F dopamine antagonists are most effective at pulling mares out of anestrus when combined with lighting programs and estrogen
T
what hormones can be used to pull horses out of spring transition
1) progesterone
2) domperidone and estrogen
3) GnRH or hCG
what is Regumate
synthetic progesterone
how often should you give regumate to induce the first ovulation and bring mares out of spring transition
10-14 days
what is a consideration for using regumate to bring a mare out of spring transition
she must be mid-transition or later
Τ/F you should give PGF2α to mares receiving progesterone therapy on the last day just in case she ovulated during treatment
T
what is the estradiol and domperidone combination therapy
give initial injection of estradiol on the first day of therapy; give domperidone orally daily for 7-14 days
estradiol/domperidone therapy hastens ovulation in what percentage of mares
40%
why does the GnRH method of bringing a mare out of anestrus work poorly usually
lack of functional LH receptors
when is PGF2α used most often in mare breeding
to control when she comes into estrus for planned breeding
if you give a mare PGF2α on a friday, when should you expect her to come into ovulation and when should you be ready to breed
come into ovulation in 2-5 days (Mon/Tues) and breed by end of week
T/F CIDRs are available for use in horses in NA
F
what form of progesterone is most commonly used to prolong the luteal phase in horses
oral regumate
T/F long-acting injectible progesterone can be compounded
T
what are 2 other reasons to use progesterone in mares
1) keep her out of heat
2) help her maintain pregnancy
when can hCG be used in mares
strong uterine edema and large follicles
most horses ovulate how many hours after being given hCG
36h
what is a problem with giving hCG
produces antibodies and therefore get reduced efficacy when used more than twice in a year
if a mare is no longer responding to hCG, what should we switch to instead
GnRH
what is deslorelin
GnRH analogue
T/F GnRH is more expensive but more effective than hCG in inducing ovulation in mares in estrus
T
follicles grow how much per day
3-6mm
as ovulation approaches, follicles become
softer, more irregular, larger
size of follicle on ovulation depends on (2) history
breed and mare
describe the P and E combination program
daily progesterone and estradiol injections for 10 days; PGF2α on last day; in estrus 7-9 days later and ovulate day 20-21 of program
