Any day that a breeding female is not lactating or gestating is
defined as a non-productive day (NPD, Stalder, 2002). Nonproductive
sow days typically occur between weaning and the
next successful mating. These days are costly to commercial
pork operations, because there is no opportunity for the sow to
generate income and be profitable. Non-productive days can
cost pork producers up to $2.60 per sow per day (Rix and
Ketchem, 2009). Reducing this cost in a commercial swine operation
could greatly impact its profitability. Swine operations