Non-productive days/sow/year

The number of days that a nonproductive sow (i.e. a sow is not gestating or lactating) is kept in a herd. These days we do not include the waiting days until the first mating of the gilts.

In order to calculate de NPD in an easy way we can make the following operation:

365 days – [Farrowings/sow/year x (average pregnancy days + average lactation days)]

For instance, and taking into account the following data, the NPD would be:

Number of farrowings/sow/year = 2.35 Average pregnancy days = 114 Average lactation days: 21

[2.35 (114 + 21)] = 47.75 NPD