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The timing of inseminslion is the single most important factor affecting fertilisation rate and the overall success of At. If the sow/gilt is inseminated too early (24 hours before ovulation) or too late (after ovulation), the result will be poorer litter sizes and reduced farrowing rates. An Al strategy has to be developed to optimise insemination timing.

    1. Time of weaning must be consistent so all sows can be sorted and bunched according to size and condition
    2. Weaning-to-oestrus interval varies between sows
    3. Sows showing early oestrus, say four days after weaning, tend to be in oestrus longer (3 days) than sows which come on heat on day 6-7 (2 days)
    4. The weaning to oestrus interval varies with season arid length of lactation
    5. Body condition of sows at weaning has a major influence on the weaning-to-oestrus interval. Lean sows tend to exhibit later oestrus Q The best farrowing rates and numbers born alive are associated with longer duration of oestrus
    6. High feed intake during lactation improves weaning-to-oestrus interval, and consequently improves farrowing rate and numbers of piglets born alive
    7. Ovulation occurs during the last ⅓ of the standing oestrous period
    8. Never inseminate a sow/gilt that is not in standing oestrus
    9. 90% of sows weaned on the same day will ovulate in a 12-hour window
    10. Average standing to oestrus time can change 12 hours between good/poor breeding times. Typically, oestrus January to May will tend tooccur earlier than oestrus September to January
    11. Unfertilised ova degenerate after approximately 8 hours of waiting following ovulation
    12. Sperm can live within the uterine tract for approximately 24 hours
    13. Long-life extenders help prolong sperm life up to the point of insemination
    14. Treat each sow as an individual.
    1. Accurate twice-per-day standing oestrous detection is essential (7am/4pm)
    2. Twice/day oestrous identification allows more accurate heat detection and thus timing of insemination. If twice/day oestrous detection is operated, an example insemination programme is shown in Table 1. Therefore from Table 1:
    3. Sows found in oestrus on day 4 am are left until day 5 am to be served
    4. Sows found in oestrus on day 4 pm are served day 5 pm
    5. Sows found in oestrus on day 5 pm are served day 6 am
    6. Sows found in oestrus on day 6 are inseminated immediately.
Table 1 is a guide and will need to be modified according to when standing oestrus is first identified.

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