in the model run with 330 weaned sows the return to estrus rate was not affected (p ) by the number of weaned piglets but sows with a lactation length (LL) of 15-16 days had 3.5 times higher odds ( P-0.005) of a return to estrus than sows with of 20-21 days return to estrus in weaned sows was also affected by the interaction between PO and body condition score (BCS) loss during lactation