23 Trainee Award: Vitamin and mineral supplementation in beef heifers and the impacts on intestinal vascularity and proliferation in neonatal calves at 30 hours of age

Abstract Abstract: Introduction Vitamins and minerals support nutrient metabolism, immunity, reproduction, and fetal development in beef cattle, with prenatal supplementation potentially impacting offspring growth, health, and tissue development. Objective Objectives were to assess intestinal vascularization and proliferation in neonatal calves in response to prenatal vitamin and mineral supplementation. Angus heifers (n = 14) were bred using female-sexed semen, stratified by body weight, and randomly assigned to receive either a basal diet (CON; n = 7) or the basal diet plus a vitamin and mineral supplement (VTM; n = 7) from day 60 before breeding to calving. Calves were hand reared and euthanized at 30 h of age for duodenum, jejunum, and ileum collection. Tissues were stained with CD31/CD34 and Ki-67 to assess intestinal vascularity and proliferation. Images were analyzed for capillary area density (CAD), capillary number density (CND), Ki-67 positivity ratio (KPR), and spatial cell density (SCD) within villi, crypts, and total capillary area. Results Maternal supplementation increased (P ≤ 0.05) CAD in duodenal crypts and in villi and total capillary area of the jejunum and duodenum, and tended (P ≤ 0.06) to increase CAD in jejunal crypts and villi of VTM calves. However, SCD was greater (P ≤ 0.03) in duodenal villi and total duodenal capillary area, and KPR tended (P = 0.08) to be greater in jejunal crypts of CON calves. Conclusion Maternal supplementation during pregnancy enhanced intestinal vascularity in neonates, while greater SCD and KPR in CON calves may reflect compensatory adaptations to nutrient restriction.