Sows need to farrow within a week of each other to keep their piglets within a compatible age range. Penning sows ready to cycle next to boars helps to synchronize estrus naturally. This decreases stress and increases breeding success. A quiet environment is critical for a sow to communicate with her litter. Researchers found that sow milk let-down lasts only 20 seconds, on average.
Sows grunt to signal a nursing opportunity is imminent.
Piglets that miss the call because there is too much mechanical noise or they don't recognize their mother don't get their share of milk and colostrum, and get off to a slow start. Closed, insulated barns with deep straw packs maximize piglet survival but require high-volume air movement. The straw-manure mixture gives off heat and gases as it composts. Simply installing bigger fans caused too much noise for piglet-sow nursing communication. Farmers isolated fans and built quieter ventilation systems.