Dietary fiber and weaning age affect stress and immune markers in saliva of sows and their offspring.

Diet, especially the intake of dietary fiber, and weaning practices may influence pig wellbeing. This study assessed changes in salivary stress and immune markers in sows and their offspring fed either hay (HAY) or sugar beet pulp (SBP), either fine (F) or coarse (C), during gestation and lactation. The effect of weaning age (conventional-CW, late-LW) on these markers was also evaluated. Saliva was analyzed for chromogranin A (CgA), cortisol, alpha-amylase, oxytocin, immunoglobulin A (IgA), and adenosine deaminase (ADA). CgA was higher at CW versus LW in sows fed SBP-F (P = 0.038). Alpha-amylase was higher in sows fed HAY-C at CW versus LW (P = 0.005) and in sows fed SBP-C at LW versus CW (P = 0.096). CgA and oxytocin were higher in sows fed SBP-F at CW versus LW (P = 0.038 and P = 0.017, respectively). ADA was higher in sows fed SBP-C versus HAY-C (P = 0.035) at LW and at LW versus CW in sows fed SBP-C (P = 0.002). Piglet salivary CgA was higher at CW versus LW in HAY-F (P = 0.002) and SBP-F (P = 0.031). Oxytocin was higher at CW versus LW in piglets fed HAY-F (P = 0.006). Piglet salivary IgA was higher in HAY-C versus HAY-F at CW (P = 0.010) and at LW versus CW in piglets fed HAY-F (P = 0.021). ADA was higher in piglets fed SBP-F versus HAY-F (P = 0.053) at CW and SBP-F versus SBP-C (P = 0.042) at LW. Dietary fiber type, weaning age, and to a lesser extent grinding degree affect stress and immune markers in pigs. These findings highlight the impact of diet and weaning practice on pig welfare.