Читать книгу Veterinary Treatment of Pigs - Graham R Duncanson - Страница 105

The farrowing index is literally the number of litters per sow per year. The target should be 2.25. This can be raised to 2.4 in really elite herds. The farrowing index is determined by four key factors:

• The length of pregnancy (this could be as short as 114 days but might creep up to 117 days).

• The length of lactation (this is problematic in the UK as the legal age for weaning of piglets is 28 days).

• The length of time it takes for normal sows to return to oestrus after weaning (this is normally 6 days but may be shorter particularly with the correct use of hormone injection; see Chapter 10).

• The so-called non-productive days.