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The effects of socializing piglets prior to weaning on lactating sows
Socializing piglets from different litters before weaning has shown to have positive effects on piglet performance with minimal consideration of the lactating sows. This study was conducted to determine if piglet socialization before weaning had any effect on the behavior, stress, or re-breeding of lactating sows. An environmentally controlled farrowing room with 6 pens was used and data were obtained from 23 sows. The solid barriers between 3 farrowing pens were removed on d 14 after farrowing to permit co-mingling of piglets and the barriers remained separating the other 3 farrowing pens until weaning of all piglets on d 21 after birth. Saliva was collected from each sow twice daily using medical absorbent cotton from d 12 through d 21 after farrowing. Cortisol levels were determined after extraction from the salivary samples using an enzyme immunoassay. Sow activity was continually recorded using surveillance video from d 12 to d 21 after farrowing. The behavior of each sow (standing, sitting, nursing, lying, restlessness) was recorded by 10 observers using digital video playback. The duration of a behavior was timed and recorded when the sow was engaging a specific behavior during the elapsed time period. Sows experiencing piglet socializing had significantly higher levels of cortisol (P < 0.05) on d 1 (797.3 ± 89.1 pg/mL) and d 2 (448.0 ± 33.1 pg/mL) of barrier removal compared to all other times. Sows not experiencing piglet socializing also had significantly higher levels of cortisol (P < 0.05) on d 1 (850.2 ± 50.1 pg/mL) of barrier removal compared to all other times. Sows had a significantly longer (P < 0.05) amount of restlessness during the first 2 d following barrier removal compared to all other times. There was a significant decrease (P < 0.05) in restlessness between d 1 (1.93 ± 0.04 h) and d 2 (0.80 ± 0.04 h) following barrier removal. Sows spent significantly less time (P < 0.05) lying down (15.22 ± 0.66 h) during d 1 following barrier removal compared to all other times. Socializing litters 7 d prior to weaning did not significantly affect the sows’ return to estrus, conception rates, and number of piglets born alive. The results of this study suggest that socializing piglets 14 d after birth leads to an increase in temporary restlessness and stress in lactating sows, but does not affect their subsequent reproductive performance after weaning.
Keywords: lactating sow, stress, socializing