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Sheep reproduction - Coggle Diagram

- - - - foetus
      - foetal stomach contents
      - piece of placenta
      - maternal serum sample
  - - - pregnant women at risk (zoonotic)
      - vaccine available
      - exposure of susceptible sheep to high levels of infected uterine discharge and aborted material
      - does not result in abortion unless ewe is more than 6 weeks from her due lambing date
        
        infection typically results in abortion/birth of fresh dead +/- weak lambs during the last 3w of gestation
        
        live lambs rarely survive more than a few hours, despite supportive care
      - ewe clinical signs
        
        not sick and may only be identified by a red/brown vulval discharge staining the wool around the tail/perineum and a drawn-up abdomen
      - Treatment
        
        whole flock long acting oxytetracycline injection (20mg/kg)
        
        emergency measure that may reduce the abortions from C.abortus infection
        
        will not reverse placental damage with the result that lambs are carried closer to term, but remain weak at birth with consequent high mortality
      - prevention
        
        maintain a closed clean flock with strict biosecurity measures
        
        vaccination
        
        if sheep already infected will not prevent all abortions but can reduce the incidence
    - - protozoan parasite toxoplasma gondii
      - sexual cycle in cats, asexual cycle in sheep + other species
      - infection during early pregnancy --> embryo/early foetal loss with an increased number of returns to service after an irregular extended interval or an increased barren rate
        
        often the highest no of barren sheep is in the younger age group
      - infection mid pregnancy --> abortion/production of weakly live lambs near term often with a small and leathery mummified foetus
      - diagnosis
        
        placental changes
        
        high levels of antibodies in ewe blood
        
        Abs may also be present in foetal fluids and can be detected in newborn lambs before they have had colostrum intake
        
        blood sampling alone not sufficient as may just be indicative of a previous infection
      - prevention
        
        sheep feed stored in vermin-proof facility (prevention cat + other vermin contamination)
        
        vaccination 3w before the breeding season
    - - Campylobacter fetus subspecies fetus and Campylobacter jejuni
      - The common presentation is abortion during late gestation although some lambs are carried to full-term and are born weak and succumb soon after birth.
      - main source of infection is purchased carrier sheep
    - - Salmonella Montevideo, Salmonella Dublin and Salmonella Typhimurium
      - may lead to abortion/death in pregnant ewes
      - sources of infection
        
        contaminated feedstuffs and water courses, sewage effluent overflow, carrier cattle, and carrion, sea birds
      - zoonotic risk
- - - - Typical protocol (from the data sheet)
        
        Treatment regime:Day 1 (30 weeks before intended start of lambing).
        
        As the presence of any ram (and also male goats) will interfere with the ovulatory process, isolate ewes from all males. The ewes should be out of sight, sound and smell. Separating males into the next field from females is not adequate.
        
        Day 7:Implant ewes at the base of the ear. Do not administer if sheep are wet or dirty. Ewes must remain isolated from male sheep and goats.
        
        Day 42 (35 days after implantation):The period between implanting and introduction of the males must be not less than 30 days and no more than 40 days. Introduce rams, but expect a delay of 14-21 days before mating activity commences. Vasectomised rams may be used for the first 14 days to ensure a more compact lambing period. The peak of mating activity will occur 25-35 days after introduction of the rams.
    - - induce oestrus
      - increase ovulation rate
      - increase embryo viability
    - - suffolk and dorset horn cross respond best
    - - older and early weaned
  - - - Unlicensed in the UK
      - 2 injections 7 – 11 days apart
      - Response not amazing – low preg rates
  - - - Progestagen impregnated vaginal implants
      - Chrongest, CIDR Ovis
      - Combined with PMSG
      - Insert and leave in place for 14 days.(12 days CIDR)
      - Hygiene important
      - PMSG injected at the day of removal
      - AI – 55 hours later if required. (1-2 days for CIDR)
- - - - fine wool breeds e.g. merino have shorter anoetrus than others e.g. suffolk