Ji, W., Bi, Y., Cheng, Z. et al. 2021. Impact of early socialization environment on social behavior, physiology and growth performance of weaned piglets. Applied Animal Behaviour Science 238, 105314.
Weaning and mixing cause substantial social stress among piglets and frequently lead to stress, injury, inflammation, immunosuppression and growth retardation. This study aimed to investigate the effects of different early social environments on social behavior, physiology and growth performance of weaned piglets. In total, 133 YDM (Large White × DM [Duroc × Min pig]) piglets from 12 litters were studied from weaning (35 day-old) to the end of the nursery period (63 day-old). Three pre-weaning treatments were examined: intermittent contact (INT, 4 litters), piglets of two neighboring litters were socialized twice a week for 3 h from day (D) 14 to D35; continuous contact (CONTIN, 4 litters), piglets of two neighboring litters were socialized from D14 to D35; non contact (NC, 4 litters), the other 4 litters were kept separate. After weaning, NC piglets were randomly regrouped into 4 new litters as the control group (CON, 4 litters); 4 litters of INT were mixed with nonadjacent litters from same group as the intermittent mixing group (IM, 4 litters); similarly, CONTIN was regrouped into the continuous mixing group (CM, 4 litters). The results revealed that within 72 h after mixing, the number of fighting in CM < IM < CON (P = 0.001); the numbers of head knocks in IM and CM were lower than CON (P = 0.001); the oral-nasal contact of CM < IM < CON (P < 0.001). The feed conversion ratio was higher in CM than in CON and IM (P = 0.001); daily weight gain in IM was higher than CM (P = 0.005); CV in IM was lower than CON and CM (P = 0.043). The antibody blocking rate against CSFV in IM and CM were higher than that in CON (P < 0.001); IL1β of IM < CON < CM (P < 0.001); cortisol in IM was lower than that in CM and CON (P = 0.005); brain-derived neurotrophic factor (BDNF) in IM> CON (P = 0.024). This study revealed that intermittent socialization pattern had positive effects on social behaviors, growth performance and physiology of piglets after weaning. Intermittent socialization patterns may be helpful for improving the welfare of weaned piglets, but further confirmation is necessary.