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Control of Repro= COW (Whats Normal (3 categories of Cows (A. 0-5d=…

- - - - Used to combined with oestrogen (similar to induction regimes)
      - What= Crestar implants, Intravaginal devices
      - Regime
        
        Prog for 7-14d (fits into normal timing)
        
        Give for 14d (if cow @ A- progresses into late B/C, If B- held at C, If C- also held at C)
        REMOVE= most in season in 2-3d
        
        Give for 7d (A- progresses to B and has active CL at device removal time, B- late B or C and held at C, C- held at C)
        Need luteolysis to cause active CL to regress
        
        Prog for 7-10d, PG at beginning/day before end of prog (causing luteolysis of own active CL)
        
        GnRH at removal= enhance surge= ovulation
        
        Inseminate at fixed time post removal/ to detected oestrus
        
        Fixed time AI= once at 56hrs/ 2x-48 and 72 hrs post removsl
        
        If >14d= ova aged too much
        
        < 14d= need to use luteolytic agent as CL not regressed
    - - Cl responsive from 5-17d (B)
      - Luteolysis occurs over 24hrs, oestrus occurs in 2-5d
      - Inseminate at fixed time (3-4d) or to detected oestrus
      - Regimes
        
        i) PG injection twice to all cows 11 days apart (waiting ensures all cows have a responsive CL at time of second injection)
        
        ii) PG to all, inseminate, second PG to non-mated onces 6d later and inseminate
        
        iii) Inseminate all in oestrus for 6d, then PG to rest and inseminate others
        
        Important to understand the 3 categories
    - - Induces Gn surge= alters follicular growth pattern= induce ovulation of DF (stage dependent)
      - Ovsynch
        
        PG 7d= luteolysis/regression of CL, luteinised follicle induced by the GnRH, CL present following an earlier spontaneous ovulation
        
        End up with a DF on ovary all at same time= respond to second GnRH @ 2d after PG and ovulate 26-32hrs later
        
        Fixed time insemination @ 18hrs later
        
        Inject 5d after last ovulation, DF ovulates and new wave of follicles recruited
      - Presynch
        
        pre-synch with PG (2 injections 14d apart), 11d before first GnRH
        
        Why- removes variation
      - Prosynch: add Prog releasing device at beginning to help synch
      - Double Oversynch
- - - - Causes luteolysis
      - 6-90d, abortion in 10d
    - - e.g. 25mg dex. +/- PG= mid/late preg
      - long acting= 6 mnths onwards
    - - 24-48hr after service
- - - - Mechanism= feedback on potuitary and hypothalamus to mimic normal events in cycle, initiate hormonal events
      - Oestradiol= luteolysis of any CL, after feedback: LH surge
      - Prog= mimics luteal function until cessation, priming to assist in display of behavioural oestrus
      - Fixed time AI/ observe oestrus and mate
      - NO LONG USED FOR FOOD PRODUCING ANIMALS THOUGH
      - Types
        
        i) Crestar (implant and injection)
        
        ii) PRID (prog releasing intravaginal device)
        
        iii) CIDR (controlled internal drug releasing)
        
        iv) Cue-mate (similar to CIDR)
      - Use
        
        Prog releasing device inserted for 8-10d
        
        Oestrogen given at device insertion- luteolytic
        
        Oestrogen (Oestradiol benzoate) given after device removed= induce LH
        
        Inseminate to detected oestrus
- - - - Short acting= 25mg Dex in last 2wks, calve in 24-72hr, high likelihood of RFM.
      - Long-acting= 3mnths before due, calve in 7-23d, high calf mortality, some cow mortality, less RFM
    - - Give 253d+, calve in 24-72 hr, 50-60% RFM.
      - Can give 24 hrs after short acting cortico. for improved timing of induction