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24 Cards in this Set
- Front
- Back
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What are the advantages of synch in beef herds?
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1. More efficient AI use
2. Groups time of parturition 3. Uniform crop of offspring for feedlot 4. More efficient labor usage 5. Can shorten breeding season |
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What are the advantages of synch in dairy herds?
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1. Decreased need for heat detection
2. Circumvents cystic ovarian disease 3. May increase fertile ovulation in anestrus cattle |
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What are the disadvantages of synch in cattle?
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1. Req. skilled labor and periods of intensive management
2. Req. adequate facilities 3. Higher input costs 4. Cannot be used in natural/organic herds |
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What drugs can you use for control of the estrus cycle?
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1. Prostaglandins (CL lysis)
2. Progestins (extends progesterone exposure, increases CL lifespan) 3. Gonadotropins (develops follicle, ovulation) |
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How do you control the length of the luteal phase
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Prolong it: progestins/progesterone, MGA (melengesterol acetate), Eazibreed CIDR
Shorten it/induce luteolysis: PGF2a, lutalyse, estrumate (in order of T1/2) |
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How do you initiate a new follicular wave?
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GnRH- will increase FSH
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How do you control the time of ovulation?
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1. Gonadotropins (increases LH)
2. hCG (LH like activity in cattle) |
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What does PGF2a do for estrus synch?
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Causes regression of the CL
By inducing luteolysis, removes PG block and allows follicles to grow and ovulate |
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What does GnRH do for estrus synch?
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Causes synth/release of LH and FSH
Stimulates follicular growth, maturation, and ovulation of large follicles |
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How do you synch with 1 PGF2a
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Inject PGF2a, heat check and AI 5 days later
Synch at the end of the luteal phase results in synch estrus |
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What are the pros/cons of 1 PGF2a synch?
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Pros: expect 75% of cycling females to exhibit estrus within 2-5 days
Cons: variable time to estrus, best results in days 2-7 of cycle |
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How do you synch with 2 PGF2a?
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1. Inject PGF2a
2. Heat check/AI at d5 3. Inject PGF2a 4. Heat check/AI at d16-19 |
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What are the pros/cons of 2 PGF2a synch?
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Pros: Less injections, more opportunities to AI if 1st injection not successful
Cons: Females must be cycling, need good animal handling facilities, timed breeding not recommended, need good heat detection |
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How do you synch with Ovsynch?
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1. GnRH (ovulate dominant follicle, synch emergents)
2. PGF2a 7 days later (regress CL) 3. GnRH 48 hours later (LH surge to ovulate follicle within 28 hours) 4. Timed AI 16 hours later |
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What are the pros/ cons of Ovsynch?
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Pros: Shortens time to AI (10d post tx), no heat check needed, decreases days to 1st service, "treats" cystic ovarian disease
Cons: Drug cost, multiple injections, less time spent observing animals (can miss detection), Variable response depending on day of cycle started, High semen costs |
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How do you improve Ovsynch results?
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Insure more cows are at mid-cycle when starting (d 5-10)
If too early: 1st GnRH doesn't alter follicular development If too late: follicles respond to first GnRH, endometrium PGF2a causes premature ovulation |
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How do you synch with the Pre-synch Ovsynch?
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1. PGF2a
2. PGF2a 14 d later 3. GnRH 12 d later 4. PGF2a 7 d later 5. GnRH 48 hours later 6. Timed AI 16 hours later |
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What are the advantages to Pre-Synch Ovsynch?
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Enhances repro tract health, places cows at 5-10 days into cycle, more presynch cows ovulate in response to 1st GnRH
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How do you Cosynch for beef?
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1. GnRH
2. PGF2a 7 days later 3. GnRH +timed AI 48 hours later (Can pre-synch with 2 PGF2a injections 14 and 12 days apart) |
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What are some characteristics of Cosynch?
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Can initiate estrus in a few anestrous cows
Pregnancy rate 5-8% less than ovsynch Separate calves from dam when PGF2a is given to increase pregnancy rates |
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How do you MGA synch?
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1. Start MGA
2. Stop MGA 14-18 days later 3. Give PGF2a 19 days later 4. Breed |
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What are some characteristics of MGA synch?
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Best used on heifers- 33d before breeding season
Inseminate all females at 72 h after PGF2a if not bred on observed estrus Estrus that occurs 5-7 days after MGA withdrawal is NOT fertile, DON'T BREED! |
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How do you CIDR-synch?
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1. Insert CIDR (1.38 g PG)
2. Give PGF2a 6 days later 3. Remove CIDR 1 day later 4. Observe heat and breed 2d later (Can remove CIDR and inject PGF2a at day 7 to min handling) |
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How do you do a G-6-G synch?
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1. Inject PGF2a
2. Inject GnRH on day 2 3. Inject GnRH on day 8 4. Inject PGF2a on day 15 5. Inject GnRH on day 17 6. Times AI 12-16 hours after 3rd GnRH |
