The current study describes the development of the porcine microbiota and its metabolic activities during the neonatal and weaning period. Using 16S rRNA-based approaches, we first analysed the ileal and colonic microbiota of neonatal piglets at days 2, 5 and 12 after birth. To further investigate the effect of weaning at 3 weeks of age, 19-day-old piglets (n = 64) were randomly allocated into two groups. Half of the piglets remained with their sows throughout the study, while the remaining piglets were weaned. As revealed by sequence analysis of 16S rRNA gene amplicons, the samples of 2-day-old piglets harboured a consortium of bacteria related to Escherichia coli, Shigella flexneri, Lactobacillus sobrius, Lactobacillus reuteri and Lactobacillus acidophilus. Moreover, species-specific real-time polymerase chain reaction assays unveiled that L. sobrius and L. reuteri predominated in the ileal samples of the neonatal and unweaned piglets with population levels up to 7 x 10(8) cells per gram of lumen content. Following weaning, however, these two lactobacilli were detected at significantly lower levels (< 10(3)) in the ileal samples. Furthermore, a shift in composition and metabolic activities of the predominant microbiota, and emergence of clostridia and E. coli, were encountered in the intestinal samples of the piglets after the early post-weaning period.

-European-wide directives are in place to establish a sustainable production of pigs without using production enhancers and chemotherapeutics. Thus, an economically-viable pig production is now only possible when the physiological mechanisms of defense against pathogens and tolerance against nutrients and commensal bacteria in the intestinal immune system are taken into account. During the postnatal period the piglet is facing first the time large amounts of new antigens and at weaning a second wave of nutritional antigens is entering the intestinal tract. The appropriate development of humoral and cellular functions of the intestinal immune system is essential for optimum growth and performance of the piglets. The integrity of the intestinal surfaces is a prerequisite of intestinal immunity and tolerance. Secretory IgA serves to exclude harmful antigens from uptake. The induction of intestinal immune reactions starts with antigen presentation by professional antigen presenting cells of Peyer's patches and mesenteric lymph nodes. In addition, the intestinal lamina propria serves as a mucosal compartment for regulation of immune responses. Here especially T regulatory cells (CD4 + CD25 + ) have their function for maintaining intestinal homeostasis. The network of mucosal T and B cells develops after birth in a programmed sequence; it is almost completed at week 7 after birth. Weaning is associated with changes in the regulation of the lymphoid cells in the mucosa. In small and large intestine increases in pro-and anti-inflammatory cytokines were observed after weaning in lymphocytes. Epithelial cells were studied both in intestinal samples and in vitro. Here the cytokine patterns provide evidence that weaning is inducing a transient inflammation of the mucosa. Piglets weaned under conventional conditions have a thicker mucosa than pigs weaned from isolators. Cells of isolator-reared pigs show slightly higher levels of activation markers -probably * Corresponding author: hermann-josef.rothkoetter@medizin.uni-magdeburg.de 326 C.R. Stokes et al.reflecting the interaction of the foreign protein derived from bovine milk. The results presented in this overview demonstrate that further effort is necessary to elucidate the function of the porcine intestinal immune system in the postnatal period and at the time of weaning to provide criteria for porcine intestinal health.inflammation / intestinal immunity / mucosa / nutrition / pig / postnatal / weaning Résumé -Développement postnatal de l'immunité intestinale chez le porcelet : implications pour le processus de sevrage. Des directives européennes ont été adoptées, en vue de mettre en place une production durable de porcs sans facteurs de croissance ni antibiotiques. Dans ce contexte, un élevage porcin ne sera économiquement viable que si sont pris en compte les mécanismes physiologiques de défense contre les agents pathogènes, et de tolérance vis-à-vis des aliments et des bactéries commensales, mécanismes engageant le système immunitaire intestinal des animaux. ...

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In recent years, it has become evident that limitations exist in our ability to meaningfully assess palaeodiet using stable isotope compositions. These limitations in part arise because many of the fundamental assumptions about tissue-diet relationships are poorly understood. In order to redress this deficiency, a controlled feeding experiment was undertaken to define the impact of terrestrial-vs. marine-derived dietary protein consumption on consumer tissue carbon isotopic compositions (δ 13 C). Two generations of pigs were raised on one of five feeds with varying proportions of terrestrial (soy) and marine (fish meal) protein. A comprehensive range of tissues and fluids from 49 pigs was submitted for δ 13 C analysis.The observed tissue-whole diet and tissue-dietary protein carbon isotopic offsets were found to be highly dependent on the percentage of marine protein in diet. We suggest that the trend in δ 13 C offsets most likely derives from the increased routing of non-essential amino acids, especially glycine, with the increasing proportion of marine protein in the diet. These findings demonstrate that solely using bulk δ 13 C compositions not only masks considerable information about diet, but may also lead to erroneous representations of marine and terrestrial resource consumption in the past.

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