The null weaning is generated automatically by the system when a sow has not been weaned and has run out of piglets due to death or transfer entries. Even if there is a partial weaning, the system will take read the last event posted in which the sow was left empty.
How to undo a Null Wean?
To undo a Null Weaning you need to delete the last event that left the sow empty. Therefore you need to delete the death entry or transfer that left the sow empty.
To delete, you can access:
Management > farrowing > Data entry > Piglet Death or Fostering Piglet> Filter by Female > Delete the data that caused the null weaning.
Null weaning generated by a foster piglet event:
In cases where the null weaning was added by a "Piglet transfer", in order to be able to delete, all subsequent Receiving Matrix events must be deleted until the piglet receipt event.
As a reminder the Null Weaning only appears when adding a piglet death or foster as the option "Do the open sow" is selected. If the option "Keep Lactating" is selected, the system will not generate a null weaning due to the reproductive status that the sow will be.
Also, to check what actually caused the null weaning, take a look at the sow card: