There is a break of at least one week between sows being weaned and a new batch entering the farrowing house, allowing an all in-all out policy. This gives improved disease control. The success of batch farrowing relies on gilts being available and on heat when required. This involves stimulating gilts into first heat six weeks before they are needed to replace a cull sow. Stimulating gilts before they cycle naturally ensures that they fit in with the three-week system.
Hormone treatment can help with synchronisation.
Feeding Herd As a large number of pigs are weaned, sizing of pigs is much easier. In many cases this allows a batch of smaller pigs to be grouped together to receive additional care. Also these pigs can receive creep feed for a longer period. Again an all in-all out policy can operate in the feeding herd giving improved performance on units. A further benefit of the system is that labour can be used more efficiently.