The Gastrointestinal Tract of Piglets From First Parity Sows Develops More Slowly And Is More Permeable Than Piglets From Later Parity Sows

Progeny from primiparous sows (gilt) have lower birth weights, higher mortality and poorer performance than the progeny from multiparous sows. The reasons for this are complex but may involve poorer quality colostrum and impaired gastrointestinal tract (GIT) barrier function. With evidence that events early in life impact whole‐of‐life mortality and productivity the aim of this experiment was to investigate the influence of sow parity on piglet and GIT development at birth and weaning. The experiment comprised of 72 mixed gender Large White x Landrace piglets from parity 2–3 sows (SP) vs gilts (GP). Piglets were euthanased at birth (pre‐suckle), 24 h, pre‐weaning (PW,~28 d.) and 24 h after weaning (W). After euthanasia piglets were dissected and gross anatomy quantified relative to body weight (BW) unless otherwise stated. The transepithelial resistance (TER, Ω) of the stomach, jejunum, ileum and colon and jejunum and ileum permeability to 4 kDa FITC and 150 kDa TRITC labelled dextran (FD4 and TD150) was immediately quantified with Ussing chambers. All data was analysed using a REML (Genstat v18) for the effects of sow parity (SP v GP) and time (0 vs 24h and pre‐ v post‐ weaning). All procedures were approved by the institutional animal ethics committee.Weights of GP were ~25 and 15% less at birth (P<0.001) and weaning (P=0.003) than SP. GP had increased brain weights at birth (P<0.001), which was consistent with lower birth weights and reduced intra‐uterine growth. The body composition of GP was differed to SP, with less skeletal muscle (quadriceps:femur g/cm) at birth and weaning (P<0.05). Relative weights of the liver, heart and spleen did not differ at birth, however enlargement of these organs was observed at weaning (P=0.012, 0.003 and 0.076). There was substantial remodelling of the gastrointestinal tract (GIT) in the first 24h, with increases >20% in SI length, >30% in stomach and SI weights (P<0.01). Concurrently stomach and colon TER reduced (P<0.001) and jenunum FD4 permeability increased (P=0.008). This likely reflects disruption of the mucosa and tight junctions accompanying introduction of enteral feeding and microbiota and was not influenced by sow parity. By weaning GP had lower small intestine (SI, g/cm) and stomach weights, indicating reduced growth of the GIT (P=0.025 and 0.056 respectively). Weaning reduced SI weight but not TER or FD4 and was not further influenced by sow parity. However GP had increased FD4 permeability (P=0.022) overall at the weaning time point, which together with lower GIT organ weights is consistent with reduced development and barrier function. Passive uptake of maternal immunoglobulin (IgG) was assessed with TD150. Consistent with FD4 no differences in permeability between SP and GP at birth and 24 h were observed, indicating passive uptake of maternal IgG is not likely to differ between SP and GP, but does not exclude differences in active transport mechanisms.In summary GP are born underdeveloped compared to SP and differ in body composition by weaning. This includes enlargement of vital organs, which is linked to disease states and reduced muscle growth which will reduce productivity. Furthermore increased GIT permeability is associated with inflammation and increased susceptibility to enteric pathogens. Collectively these differences likely underpin whole‐of‐life morbidity and production losses and highlight the need to develop targeted management strategies for gilts and their progeny.Support or Funding InformationPartial funding by Australian Pork Limited is gratefully acknowledged.