Decreased Ileal Permeability in Piglets at Weaning Following Exposure to Irradiated Topsoil

Weaning is a difficult transition for piglets that can result in significant loss of performance. Increased isolation of piglets early in life may prevent early exposure to pathogenic bacteria, but may also reduce exposure to beneficial bacteria which may prevent or delay intestinal development. In combination with the shift from a liquid based diet to a solid corn-soy based diet, these factors may be contributing to increased intestinal permeability following weaning. Therefore, we wanted to determine if exposure of piglets to topsoil or irradiated topsoil could decrease ileal permeability prior to weaning and potentially reduce the loss of performance experienced during weaning. Piglets were farrowed under normal commercial protocols, and allowed 2-4d prior to the topsoil exposure. At the commencement of the study, a pan containing nothing, topsoil, or irradiated topsoil was added to each pen. Pans were refreshed every 24 hours. Prior to weaning on d 17-20, a pig of average weight of each pen was selected to measure ileal permeability from the control (n=5), irradiated topsoil (n=6), and topsoil (n=5) treatments. Pigs were euthanized using captive bolt followed immediately by exsanguination. A 10cm section of the distal ileum was excised, flushed, transported under aeration, then mounted on an Ussing Chamber. Transepithelial electrical resistance (TEER) was collected for 10min prior to measuring the flux of fluorescein isothiocyanate labeled dextran from the mucosal to serosal side over the course of 1 hour (permeability). Data were analyzed using proc glimmix in SAS where treatment was fit as a fixed effect and pig as a random effect. Body weight, age, and TEER were similar across the control, topsoil, and irradiated topsoil treatments (P = 0.60, P = 0.88, P = 0.42; respectively). Ileal permeability was altered with exposure to the topsoil treatment (P = 0.01). Ileum collected from piglets exposed to irradiated topsoil were less permeable compared to ileum samples collected from control piglets (P = 0.01). Ileum collected from piglets exposed to topsoil were intermediate in permeability compared to ileum from control (P = 0.25) and irradiated topsoil (P = 0.07) piglets. While we did not see an improvement in the body weight prior to weaning, littermates exposed to topsoil and irradiated topsoil on average had 1kg heavier body weight at the end of the nursery phase, suggesting the decreased permeability may help mitigate performance loss during weaning.