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50 Cards in this Set
- Front
- Back
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Synchronization of estrous
-purpose |
-allow group mating usually via A.I.
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Timing the onset of estrus and the events leading up to ovulation of fertile oocytes is determined by _______
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-human interaction
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Synchronization of estrus
-main goal |
-get a group of females to display estrus and ovulate fertile oocytes within a few hrs of eachother
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Main hormones that humans can use to control the estrous cycle
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-GnRH
-Progesterone -PGF2a |
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GnRH
-produced where |
-hypothalamus
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GnrH
-effect |
-pituitary release of LH*** and FSH
-affects ovulation timing |
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GnRH
-action |
-release of LH
-ovulation or luteinization (depending on age of follicle) -initiation of new follicular wave -CL formation |
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Progesterone
-produced where |
-CL
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Progesterone
-function |
-prepare the uterus for the egg
-overrides estrogen to prevent estrous behavior -jump starts anestrus females |
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Progesterone
-R |
-MGA
-Regu-Mate -CIDR insert |
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Why are high levels of progesterone needed?
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-higher levels are needed to prevent ovulation
-don't want to only be preventing estrus (lower levels) |
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We control the estrous cycle by controlling _____
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-progesterone
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PGF2a
-produced where |
-non-pregnant endometrium
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PGF2a
-function |
-lyse CL
-initiate process leading to ovulation |
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PGF2a
-Rx |
-Lutalyse
-Estrumate |
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PGF2a
-why isn't it useful in swine? |
-very short time fram for PG to lyse CLs
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Why don't we try to synchronize dogs?
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-not polyestrous
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Reason to synchronize bovine estrous cycle
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-enhance utilization of AI
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Effect of progesterone on diestrus
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-lengthen diestrus
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Effect of PGF2a on diestrus
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-shorten diestrus
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If treatment with progesterone is 14 days or less, what must be done?
-why |
-combine with luteolytic agent (PGF2a) to successfully control time of estrus
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Why does long term exposure to progesterone want to be avoided?
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-decreased fertility
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PGF2a
-effect when given during the luteal phase -when is the luteal phase |
-luteolysis and return to estrus
-more successful when given late in luteal phase (d10-17) -d5-17 |
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When is synchrony of estrus tighter in cattle?
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-when the cattle are at a similar stage of the estrous cycle when treated with PGF2a
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Estrogen synchronization protocols involve
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1) shortening diestrus with PGF2a
2) lengthening diestrus with progesterone 3) combination |
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Gonadotropins are used when?
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-sheep and goats to transition from seasonal anestrus to seasonal polyestrus times of the year
-swine to induce later puberty |
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PGF2a
-resistance |
-CLs are resistant to PGF2a for a few days following ovulation
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PGF2a resistance
-sheep |
-5 days
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PGF2a resistance
-cow |
-5-7 days
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PGF2a resistance
-mare |
-5 days
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PGF2a resistance
-swine |
-17 days
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Estrus synchronization in sheep
-use of PGF2a alone |
-2 injections 9 days apart
-only works in cycling ewes |
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Estrus synchronization in sheep
-use of progesterone alone |
-administer 12-14 days via CIDR or sponge
-estrus 36-40 hrs after progesterone removed |
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Estrus synchronization in pig
-use of hormone treatment in gilts |
-can use hormones to reduce the age of puberty of gilts
-can reduce age of puberty to within 1 month of natural puberty -50-70% will exhibit estrus within 7 days, but can't breed -give PGF2a 2x 2 wks apart (abortifactient) -feed gilts (not sows) progestogen for 14-18 days and they return to estrus in 4-5 days |
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Estrus synchronization in pigs
-hormone used to reduce age of puberty in pigs |
-combination of eCG and hCG
-inject PGF2a 18 days later to tighten synchrony |
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Pigs
-why does PGF2a not work in cycling pigs |
-pig CL does not have PGF2a receptors until late in diestrus
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Effect of PGF2a in pregnant gilt
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-lyse CL ---> dec. progesterone ---> resorb embryo ---> return to estrus in 4-5 days
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Way to sync sows
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-wean at the same time
*delayed return to estrus in some genetic lines |
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Strategy for syncing sows via weaning
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-PGF2a w/n 24 hrs of farrowing
-PG 600 at time of weaning |
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Equine
-why is manipulating estrus easier than synchronizing ovulation |
-longer estrus periods than bovine/ovine (4-7 days)
-variable timing of ovulation relative to estrus |
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Equine
-benefits of estrus manipulation/synchronization |
-efficient use of stallion
-ability to schedule breeding -synchronization of recipients for ET |
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Equine estrus synchronization
-hormone drugs approved for use in the mare |
-PGF2a
-Progesterone |
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Equine synchronization
-PGF2a use in mare facts |
-need lower dose than cattle
-CL can be lysed in late estrus and during diestrus -pronounced side-effects |
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Equine
-how long after ovulation can a CL be lysed by PGF2a |
- >5days
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Equine
-side effects of PGF2a injection |
-sweating
-colic (increased GIT motility) -inc. HR -weakness/ataxia |
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Equine estrus synchronization
-use of PGF2a |
2 injections 14 days apart
-90% in estrus @ 6 days -ovulation 2-12 days after last injection (importance of palpation/US) |
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Equine
-progestogen effects in mare |
-prolong luteal phase of the cycle (replaces the CL)
-suppresses LH but not FSH -synchronizes estrus but not ovulation -prevent estrus in competition horses |
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Equine estrus synchronization
-progestogen use |
-give PO for 10 days
-PGF2a on last day --estrus 4-7 days after Progestogen removal --ovulation 7-12 days after Progestogen Combine w/ deslorelin acetate (GnRH) -induce ovulation in 48 hrs if > 30 mm follicle |
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Canine estrus manipulation
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-usually don't manipulate because polyestrus
-dogs are usually either bred or spayed |
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Canine estrus manipulation
-drugs (use) |
Milolerone
-prevents estrus by blocking LH -give daily orally -needs to be given at least 30 days prior to proestrus -discontinue after 24 months |
