Lecture 7: Equine Breeding Management (Macpherson) Flashcards
What is breeding (management)?
- the mating and production of offspring by animals
- the activity of controlling the mating and production of offspring of animals
types of breeding programs
- natural service
- AI (not allowed
How must horses be mted in registered Jockey clubs?
natural mating only
factors that affect pregnancy rates
- breeding management**
- stallion fertility
- mare fertility
- early pregnancy detection
1 cause for infertility in horses
breeding management, NOT breeding the proper time
what things to assess in stallion fertility
- athletic and breeding history
- Breeding soundness: annual exam, physical health, semen quality, venereal disease
components of mare repro health
- feritlity/foaling history
- type of breeding program
- breeding soundness exam
steps of breeding management
1) heat dection
2) monitoring the repro tract
3) induction of ovulation
4) breeding
5) post-breeding management
6) pregnancy detection
LH peak occurs before or after ovulation in mare?**
after
when does mare ovulate?
approx. 24hrs before end of estrus. Just before LH peak, just after estrogen peak
which hormone maintains pregnancy?
progesterone. Keeps other hormones at low lvls, prevents ovulation
what structure produces progesterone?
CL
see slide 10
:)
how long does estrus last in mare?
4-7 days (longer during short days of year and vice versa)
behavioral signs of estrus
(under influence of ESTROGEN):
tail up
urinate
wink (clitoral eversion)
role of oxytocin post-mating
stimulates uterine contractions to clear infection from mating, and to help sperm travel up oviduct
how long does diestrus last in mares?
14 days
behavioral signs of diestrus
(under influence of PROGESTERONE):
ears back
strike
kick
uterine edema present in presence of:
estrogen
tone of cervix when mare in het
soft, billowy
tone of cervix when under influence of progesterone/pregnant
tubular
methods of monitoring the repro tract
transrectal palpation and ultrasonography:
- ovaries (for follicular development)
- uterus (tone and edema)
- cervix (tone/relaxation)
describe “inside-out” anatomy of mare ovary
- medullary region is on the OUTSIDE of the ovary and is where the majority of the follicles form
- everything ovulates through the ovulation fossa
- follicles develop on outside of ovary, but ovulate through fossa
Who has larger pre-ovulatory follicle: horse or cow?
horse
when is corpus hemorrhagicum present? is it palpable?
about 24 hrs post-ovulation. Yes.
why is CL NOT palpable in mare?**
forms internally. Therefore, NOT a structure we can use to stage diestrus in the mare!!
When is cervix longest, tightest and most tubular?
during pregnancy
see green star slides
:)
when is cervix shortest, softest, most edematous?
under maximl influence of estrogen during estrus
can see cross-section of ____ on transrectal ultrasonography
uterine horns
what do uterine horns look like in mare in heat?
“orange slice configuration”
what is another way to detect presence of CL if can’t see on ultrasound?**
measure progesterone
can mares double ovulate?
Y
can follicles be present in diestrus?
yes, but they are small, with no wagon wheel appearance.
methods of predicting ovulation
-follicular: size (at least 35mm) texture (softer = closer to ovulation) shape (point forming = very close to ovulation -uterine edema
an ideal follicle to breed should be at least how big?
35mm
HPO interaction
hypothalamus releases GnRH, which stims. anterior pituitary to release LH, FSH. LH and FSH act on ovaries.
deslorelin acetate
ovulatory agent
- GnRH analog
- acts upstream
- only administer if: follicle at least 30mm, there is estrus edema, and relaxed cervix
- causes ovulation 40-48 post-administration
- expensive
human chorionic gandotropin (hCG)
ovulatory agent
- mimics LH
- acts downstream
- only use if: follicle at least 35mm, there is estrus edema, relaxed cervix.
- ovulation occurs 24-48 hrs later (larger window than with deslorelin acetate)
- less expensive
methods of bringing mare back into heat quicker if she ovulates too early
Give prostaglandin when mare has mture CL (5 days post-ovulation) to cause her to come back into heat
Where is prostaglandin naturally produced?
endometrium
-causes luteolysis 5 days post-ovultion and onset of estrus
when is the best time to breed?***
as close to ovulation as possible
oocyte longevity
24 (12) hrs
sperm longevity
fresh: 48+ hrs
chilled: 24-48 hrs
frozen: 12 hrs post-thaw
hand mating
breeding naturally under controlled conditions
types of natural service breeding
pasture mating
hand mating
*should breed every 48 hrs, while monitoring mare’s trct to determine if follicle present and if she is ovulating
how many “progressively motile” sperm in fresh semen?
500 million
how many sperm/dose in fresh cooled semen?
at least 1 billion (but assume 50% die in transport)
-2 doses usually included
when re ovulatory agents often used?
when using fresh cooled or frozen seme
how many sperm/dose in frozen-thawed semen?
800 million to 1 billion, but with limited viability
goals for breeding with frozen-thawed semen**
at least 12 hrs PRIOR to ovulation, or less than 8 hours AFTER ovulation
if you see big billowy edema in uterus after breeding, what should you do?
post-breeding therapy to calm uterus down before embryo comes in at 5-6 days
when to first examine for pregnancy and what to look for
14 days post-ovulation
-look for twins/early embryonic death
