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23 Cards in this Set
- Front
- Back
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why synchronize estrus?
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control time of AI, targeted breeding (cooler seasons), targeted milk production (highest prices), no heat detection (timed AI protocols), concentrate labor (breeding and calving), more uniform calf crop, control time of embryo collection and transfer
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what must you plan for in synchronizing estrus in cattle?
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minimum of 40 days between calving and synchronization, cows must be in good body condition, cows should have had minimal calving difficulties, heifers must weight at least 65% of their projected mature body weight, people and facilities (experience w/heat detection, experience w/semen thawing and AI, facilities good for cattle movement, facilities and equipment good for an AI program?
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what concepts affect synchronizing estrus?
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control life-span of corpus luteum, control follicular development, control time of estrus, control time of ovulation, maintain normal fertility
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how do we manipulate the estrus cycle?
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synchronization of follicular growth (GnRH, estradiol, progesterone, follicle aspiration), regulation of CL regression (PGF2a, progestogens-progesterone), induction of ovulation (GnRH, estradiol, hCG)
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what drugs/hormones are used for synchronization of estrus?
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progestogens (progesterone), luteolytic prostaglandins, GnRH (not estrogens)
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what progesterones are used for estrus synchronization?
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progesterone (CIDR: controlled internal drug release), synthetic progestogen (MGA: melengesterol acetate)
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what luteolytic prostaglandins (PGF2a) are used for estrus synchronization?
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lutalyse, estrumate, prostamate, in sync
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what GnRH is used for estrus synchronization?
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cystorelin, factrel, fertagyl, ovacyte
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how are prostaglandins used for estrus synchronization?
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animals must be cyclic, effective from d6-17 of cycle, 1 injection controls 60-70%, 2 injections control 70-90%
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when are prostaglandin injections used for estrus in heifers and cows?
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heifers 11d, cows 14d
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how are progestogens used for estrus synchronization?
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effective only in combination with PGF or estrogen, lowers fertility when used alone due to persistent or aged follicle
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how are progesterone + PGF used for estrus synchronization?
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progesterone prevents estrus, PGF induces luteolysis
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what is a generic protocol for MGA progesterone + PGF?
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feed MGA 1-14d, inject PGF on d31, heat detect and breed d32-35
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what is a generic protocol for CIDR progesterone + PGF?
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insert CIDR 0-7d, PGF d6/7, heat detect and breed d8-11
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what are the effects of MGA/CIDR on estrous cycle and fertility?
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may induce cyclicity in anestrous postpartum cows and peri-pubertal heifers, increase estrous response during the synchronized period, enhances fertility in the second synchronized estrus
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how are anestrous heifers/cows treated?
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progestogens (withdrawal increases LH & FSH, primes animal to show estrus), estrogen (controls follicle wave), gonadotropins (control follicle development)
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what are common protocols?
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Ov-sync (problems detecting heat, timed protocol), selectsynch (alternative, used in beef), CIDR + GnRH + PGF (CIDR + Select Synch, initiates more animals in heat and better breeding)
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what is the Ov-synch protocol
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GnRH + PGF + GnRH: 1st GnRH (d0) initiates new follicle wave/ovulation, PGF (d7) induces luteolysis, 2nd GnRH (d9) induces ovulation, AI (d10) - all cows
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what is the select synch protochol?
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GnRH (d0), PGF (d7), Heat detect/AI (d10+)
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what is CIDR + Select synch?
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GnRH and insert CIDR (d0), PGF and remove CIDR (d7), heat detect & breed (d8-10)
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how is synchronization of estrus in sheep and goats?
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hormones: Progesterone-prevents estrus, PGF-induces luteolysis
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what must you remember in sheep estrus synchronization?
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reducing daylight triggers cycle…don’t try in spring!
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what protocol is used in does and ewes?
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double injection of PGF2a: does d0 & d11, ewes D0 & d10, breed d13-16, CIDR + PGF: insert CIDR d0, remove and PGF2a d5, breed (generally natural service)
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