Repro Flashcards
High preg rate if
95% cycling during <20d of breeding season
70% conceive on first service
> 90%cycling if
Cows calve in 60d period, heifers in 45d period
Cows in at least BCS 5+ at calving
Heifers separated from cows pre and post calving
70% conceive on first service if
Cows gain wt at breeding
Highly fertile bulls used
Breeding season
Cows 60-70 d
Heifers 42d
Calves born in first 21d
> 65%
65d breeding season
Uniform calves
Labor intensive for short period
Better manage health issues
Must match nutritional resources
PGF2a
2injections 2wks apart
Be e aware of high % of noncyclic animals
Heat 24-120h After injection (peak heat at 72h)
GnRH
Extra trips through chute
Early heats
Expense
Progestagens (MGA) - melengestrol acetate
Low cost
Don’t breed the first heat after MGA withdrawal (subfertile)
Estrus synchronization
Detection, facilities, BCS at calving, number cycling, experience, choosing appropriate program
AI
Am pm rule or timed AI
Semen handling thaw 95f for 30sec
Ultrasound
Early preg diagnosis 24d
Embryo viability >30d
Fetal sexing 57-80d
Fetal age
ET
High value semen
Control dz transmission
Rapid generation of EPD
But requires additional costs, labor, and experience
ET steps
- Select donor. 2. Selection or recipients 3. Superovulation
- Flushing. 5. Embryo evaluation. 6. Cryopreservation
- ET. 8. Marketing
Before super ovulation, check…
Cervical permeability
Optimal time superovulation
8-12d of estrus cycle (high P4)
20-30% of cows fail superovulation
Collect 6-8d after estus
Embryos graded for
Viability and morphology
Cryopreservation
Begin at -6C, hold for 6min
Seeded at 1 min
Cooled at .5C/min to -30 or -32C
Plunges into LN2 (-196C)
Follicular aspiration
US guided aspiration
New wave in 2days
Attached to vacuum line and collection filter
Produces…
AI 1calf/yr
ET 1calf/m
IVF 1calf/wk
Sexing
X 7% more DNA than Y
