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

Abstract Diet, especially the intake of dietary fibre, 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 analysed for chromogranin A (CgA), cortisol, alpha-amylase, oxytocin, immunoglobulin A (IgA) and adenosine deaminase (ADA). CgA was higher at CW vs. LW in sows fed SBP-F (P=0.038). Alpha-amylase was higher in sows fed HAY-C at CW vs. LW (P=0.005) and in sows fed SBP-C at LW vs. CW (P=0.096). CgA and oxytocin were higher in sows fed SBP-F at CW vs. LW (P =0.038 and P =0.017, respectively). ADA was higher in sows fed SBP-C vs. HAY-C (P=0.035) at LW and at LW vs. CW in sows fed SBP-C (P=0.002). Piglet salivary CgA was higher at CW vs. LW in HAY-F (P=0.002) and SBP-F (P=0.031). Oxytocin was higher at CW vs. LW in piglets fed HAY-F (P=0.006). Piglet salivary IgA was higher in HAY-C vs. HAY-F at CW (P=0.010) and at LW vs. CW in piglets fed HAY-F (P=0.021). ADA was higher in piglets fed SBP-F vs. HAY-F (P=0.053) at CW and SBP-F vs. SBP-C (P=0.042) at LW. Dietary fibre 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.