Fichas
Reproduction synchronisation in cattle
Fichas del conjunto (19)
- 1Aim of prostaglandin-type protocolsSynchronise P4 decline
Cause luteolysis of any present CL
Initiate follicular phase
May be repeated if cows in early dioestrous or in follicular phase already - 2Advantages of PG-type protocolsEasy IM admin
Variety of protocols
Fertility normal
Economical - 3Disadvantages of PG protocolsOnly works if CL present
May cause abortion if pregnant
May cause abortion/respiratory difficulties in humans
Doesn't synchronise follicular development - 4Why should cows be treated in days 5-19 (heifers) or days 7-18 (cows) with PG protocols?Ensure enough PG receptors available to bind
- 5Aims of progestin-based protocolsGet anoestrous cows cycling
Provide artificial CL to prevent ovulation
Combined with GnRH and PGs to synchronise new wave + luteolyse any present CLs
Can be combined with ovulation synchronisation (GnRH, oestrogen, eCG - 6How do Progestin protocols work in anoestrous cows?Anoestrous = high negative feedback sensitivity of oestrogen on hypothalamus
Progesterone reduces hypothalamic sensitivity --> allows production of LH and FSH in response to oestrogen (positive feedback)
Deep anoestrous cows take longer to return. - 7How to disinfect intravaginal P4 devicesAutoclave
Soak + rinse in pressured water + soak in Virkon/bleach + rinse, dry, and store away from light
Can be reused once effectively - 8Variations of progestin protocolsOestrogen or GnRH admin
Place intravaginal P4 device for 5-7 days
Admin PG 1-2 times (8 hours apart) when removing P4 devise
Admin oestrogen 1-2 days or GnRH 54-72 hours after PG admin
AI immediately with ovulation protocol (Co-synch - GnRH) or 12-16 hours after - 9Describe what the admin of the below doesEB/GnRH - synch new wave emergence
IVD - prevents ovulation
PG - removes endogenous P4
EB - stimulates ovulation - 10Advantages of GnRH based protocolsSimple
Some efficacy in anoestrous cows
Useful if poor heat detection - 11Disadvantages of GnRH protocolsReduces pregnancy rates in heifers
Reduced conception rates (but increases if IVD and PG also used)
Reduces oestrous behaviour
Cost
Requires pre-synchronisation treatments - 12What are examples of pre-synchronisation treatments and why are they used?Increases % of follicles that respond to GnRH
May increase fertility
BUT increased cost + handling
2 PG injections 14 days apart, 14 days prior to starting OvSynch
PG injection + heat detection and AI for 3 days, then starting GnRH
Double OvSynch - 13Indications of OvSynchPoor heat detection
Reluctance to practice continuous heat detection
Simplicity
May help anoestrous cows
Combined with progestin protocols - 14Aim of resynchronisation protocolsProduce synchronised return to oestrous after 1st/2nd AI in cows that aren't pregnant
+/- pregnancy testing - 15Describe a resynch protocol without pregnancy testingLeave 11 days between programs
Day 0 --> oestradiol + IVD implant for 8 days
Day 8-12 - PG injection, oestradiol injection day 9, and AI
Day 23 --> oestradiol + IVD for 8 days
Day 31-35 - remove IVD, oestradiol day 32, AI
Day 46 --> oestradiol + IVD for 8 days
Day 54-58 - remove IVD, oestradiol D55, AI - 16—Re-synch protocol
- 17In dairy cows, should you use Oestradiol, GnRH or can you use both?GnRH.
Oestradiol is banned in dairy cows - 18In a resynch protocol that uses pregnancy testing, describe the protocolPregnancy test on day 30 after 1st round
If non-pregnant:
PG + GnRH and fixed time AI
Second oestrous doesn't require GnRH before inserting the CIDR
Only admin PG after P4 removal if non-pregnant - 19—Pregnancy testing + resynch protocol
