Early nutrition of fattening lambs modifies bacterial community and lymphocytes of the ileum

Abstract

Feed efficiency and immunity parameters can be deeply impacted by colonization of gastrointestinal (GIT) mucosa during early life. Thus, the aim of the present study was to determine if the composition of the bacterial populations firmly attached to the ileal mucosa (epimural) is modified by the level of milk intake during the suckling phase of lambs, thus promoting long-term effects during the fattening period. Twenty four merino lambs (average LBW 4.77±0.213 kg) were used, twelve of them (ad libitum, ADL) being kept permanently with the dams whereas the other group (restricted, RES) was separated periodically from the dams and milk restricted. After weaning all the animals were penned individually, offered the same complete pelleted diet at a restricted level (40 g/kg LBW to ensure no differences of DMI) and slaughtered with 27 kg. Ileal tissue samples were collected for immunohistochemistry, morphometric analysis and T-RFLP analysis (microbial diversity). All the data were analysed using one-way analysis of variance with the milk intake level as the only source of variation, excepting those corresponding to T-RFLP, which were analysed by discriminant analysis. During the fattening period, the RES group showed higher feed:gain ratios (3.05 vs 3.69, P<0.001). In addition, the ileal epimural bacterial community of the RES group showed lower relative height of two peaks compatible with probiotics and Proteobacteria. These changes could be associated with the higher infiltration of lymphocytes (T and B) in the ileal lamina propria, a higher presence of M cells and a greater thickness of submucosa layer when compared to the ADL group. In conclusion, the level of nutrition during the suckling period of merino lambs promoted changes in ileal epimural bacterial community and local immune response that could be related to differences in feed efficiency traits during the fattening period.