Early weaning of piglets is often accompanied by a severe growth check and diarrhoea. It is well established that this process is multi-factorial and that post-weaning anorexia and undernutrition are major aetiological factors. Gastrointestinal disturbances include alterations in small intestine architecture and enzyme activities. Recent data indicate transiently-increased mucosal permeability, disturbed absorptive-secretory electrolyte balance and altered local inflammatory cytokine patterns after weaning. These responses appear to operate according to two distinct temporal patterns, an acute response followed by a long-lasting adaptation response. Pigs coexist with a diverse and dense commensal microbiota in their gastrointestinal tract. Most of these microbes are beneficial, providing necessary nutrients or protection against harmful pathogens for the host. The microbial colonisation of the porcine intestine begins at birth and follows a rapid succession during the neonatal and weaning period. Following the withdrawal of sow's milk the young piglets are highly susceptible to enteric diseases partly as a result of the altered balance between developing beneficial microbiota and the establishment of intestinal bacterial pathogens. The intestinal immune system of the newborn piglet is poorly developed at birth and undergoes a rapid period of expansion and specialisation that is not achieved before early (commercial) weaning. Here, new insights on the interactions between feed components, the commensal microbiota and the physiology and immunology of the host gastrointestinal tract are highlighted, and some novel dietary strategies are outlined that are focused on improving gut health. Prebiotics and probiotics are clear nutritional options, while convincing evidence is still lacking for other bioactive substances of vegetable origin.

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We investigated whether spray-dried plasma (SDP) improved growth and health of piglets challenged with enterotoxigenic Escherichia coli K88 (ETEC). Forty-eight pigs weaned at 21 d (BW = 4.88 +/- 0.43 kg) received one of four diets containing 6% SDP or fish proteins (as-fed basis) either nonmedicated (SDP-NM and FP-NM diets) or medicated with 0 or 250 mg/kg of colistine + 500 mg/kg of amoxycycline (SDP-M and FP-M diets), for 15 d. On d 4, pigs were orally challenged with ETEC. On d 15, eight pigs per dietary group were killed, blood and saliva were collected for analysis of K88 fimbriae-specific immunoglobulin (Ig)-A, and jejunum was removed for villi preparation, histological analysis, and cytokine expression. The presence or absence of K88 receptors (K88+ and K88- pigs respectively) was determined by villous adhesion assay. Effects of protein source on ADG (P = 0.04) and ADFI (P < 0.01), as well of medication on ADFI (P < 0.02), of all pigs were observed. In sacrified pigs, there was an effect of protein source on ADG (P = 0.03) and ADFI (P < 0.001), as well an interaction between medication and presence of K88 receptor (P = 0.02) for feed:gain ratio. Plasma K88 specific IgA were low in all K88 pigs and higher in K88+ pigs fed FP-NM compared with all the other groups (P < 0.05), except SDP-M. An interaction was found among protein source, medication, and presence of K88 receptors (P = 0.04). Saliva IgA concentrations were high in all pigs fed FP-NM and low in all other pigs. Jejunum of pigs fed FP-NM showed some ulcerations, edema, and mild inflammatory cell infiltration (ICI). In pigs fed FP-M, edema was reduced. Conversely, only a mild ICI was observed in pigs fed SDP-NM and SDP-M. Crypt depth was increased in K88+ pigs fed SDP-NM and an interaction between protein source and presence of K88 receptors was observed (P < 0.05). Expressions of tumor necrosis factor-alpha and interleukin (IL)-8 were lower in pigs fed SDP-NM and SDP-M than in those fed FP-NM and FP-M, either K88- or K88+ (P < 0.01). In pigs fed FP diets, expression of IL-8 tended to increase (P = 0.08) in K88+ compared with K88- subjects. Expression of interferon-gamma increased in K88 and K88+ pigs fed FP-M as compared with other pigs (P < 0.01). These results indicate that feeding with SDP improved growth performance and protected against E. coli-induced inflammatory status, and suggest that use of SDP-NM can be considered a valid antibiotic alternative.

The review discusses the topics presented below, with experimental data and more evidence for some aspects which are problematic for the pig producer. To obtain high quality processed pig products, heavy pig production in Italy is subjected to rules fixed by several Consortia, on the basis of the experience of producers and the results from scientific research. Slaughter animals of at least 9 months of age and 160 kg live weight are required to provide heavy cuts with excellent meat. Breeds are limited to Italian Large White and Landrace, selected for specific parameters such as loss at 1 st salting of the ham, and their crosses. Crosses with Duroc and hybrids can be used if obtained from selection and crossing schemes that fit the objectives of Italian selection. Backfat thickness must be "sufficient" to obtain retailed fresh hams with fat cover ranging from 20 to 30 mm, depending on ham weight, and the content of linoleic acid in ham fat cover cannot exceed 15%. Fat quantity and quality in feeds should be carefully controlled to satisfy the quality of fat in the ham. The feeding level is also relevant, due to the imposed minimum age at slaughter. Feed restriction is a necessary practice to respect the rules for ham production. For castrate males of medium genetic value, the restriction should reduce fat deposition, but the diet composition can be adapted to maintain the maximum growth of protein. For strains with high lean deposition potential and particularly for gilts, protein deposition should also be limited to maintain a sufficient fat cover of ham.

Metabolic diseases and obesity are developing worldwide in a context of plethoric intake of high energy diets. The intestine may play a pivotal role due to diet-induced alterations in microbiota composition and increased permeability to bacterial lipopolysaccharide inducing metabolic inflammation. Early programming of metabolic disorders appearing in later life is also suspected, but data on the intestine are lacking. Therefore, we hypothesized that early disturbances in microbial colonization have short- and long-lasting consequences on selected intestinal components including key digestive enzymes and protective inducible heat shock proteins (HSP). The hypothesis was tested in swine offspring born to control mothers (n = 12) or mothers treated with the antibiotic amoxicillin around parturition (n = 11), and slaughtered serially at 14, 28 and 42 days of age to assess short-term effects. To evaluate long-term consequences, young adult offspring from the same litters were offered a normal or a fat-enriched diet for 4 weeks between 140 and 169 days of age and were then slaughtered. Amoxicillin treatment transiently modified both mother and offspring microbiota. This was associated with early but transient reduction in ileal alkaline phosphatase, HSP70 (but not HSP27) and crypt depth, suggesting a milder or delayed intestinal response to bacteria in offspring born to antibiotic-treated mothers. More importantly, we disclosed long-term consequences of this treatment on jejunal alkaline phosphatase (reduced) and jejunal and ileal dipeptidylpeptidase IV (increased and decreased, respectively) of offspring born to antibiotic-treated dams. Significant interactions between early antibiotic treatment and later diet were observed for jejunal alkaline phosphatase and sucrase. By contrast, inducible HSPs were not affected. In conclusion, our data suggest that early changes in bacterial colonization not only modulate intestinal architecture and function transiently, but also exert site- and sometimes diet-specific long-term effects on key components of intestinal homeostasis.

-Weaned pigs are susceptible to frequent infectious diseases. Antibiotics have been used over decades to reduce pathogen infections, but many microorganisms are becoming resistant to antibiotics. Thus, there is an urgent need to find alternatives to in-feed antibiotics. Up to now, various compounds have been used as alternatives, giving promising but sometimes contrasting results. In recent years, the in vitro models of cell culture have been proposed for the screening of various compounds and understanding their mechanisms of action. The intestine is a complex system with a continuous cross-talk among epithelial cells, the local immune system and microflora. Alternatives to in-feed antibiotics may interact with any of these constituents. This review presents data on the protective effects of probiotics, zinc salts and organic acids, used as alternatives to in-feed antibiotics, against pathogen induced damage and inflammatory processes in the intestinal cells and the underlying mechanisms, with an attempt to compare in vitro and in vivo results. All the alternatives tested resulted in effective protection against pathogens by a series of interactions with intestinal cells and pathogens, including the inhibition of adhesion and invasion of pathogens, interference in signalling pathways induced by pathogenic bacteria, maintenance of the epithelial cell cytoskeleton and junctional structure and modulation of the host immune response. microorganismes sont devenus résistants à ces substances. Aussi, est-il urgent de trouver des alternatives aux antibiotiques additifs alimentaires. Jusqu'à présent, diverses alternatives ont été envisagées, certaines donnant des résultats prometteurs, d'autres des résultats variables. Au cours des dernières années, les modèles in vitro de cultures cellulaires ont été proposés pour cribler ces substances et élucider leurs mécanismes d'action. L'intestin est un système complexe faisant intervenir des communications permanentes entre les cellules épithéliales, le système immunitaire local et la microflore. Les alternatives aux antibiotiques peuvent interagir avec n'importe lequel de ces composants. Le présent article fait la synthèse des effets protecteurs et des mécanismes d'action des probiotiques, des sels de zinc et des acides organiques, utilisés comme alternatives aux antibiotiques dans les processus inflammatoires et les altérations cellulaires épithéliales in vitro, induites par des agents pathogènes. Elle tente de comparer ces résultats avec les observations in vivo. Toutes les alternatives évaluées ont été efficaces contre les agents pathogènes, via des mécanismes d'interaction cellules épithéliales-agents pathogènes. Ces mécanismes incluaient l'inhibition de l'adhésion et de l'invasion cellulaire par ces pathogènes, la modulation des mécanismes de signalisation intracellulaire induits par les bactéries pathogènes, le maintien de la structure du cytosquelette et des jonctions serrées des cellules épithéliales, et enfin la modulation des réponses immunitaires de la cellu...

The microbial community in the guts of mammals is often seen as an important potential target in therapeutic and preventive interventions. The aim of the present study was to determine whether enterotoxigenic Escherichia coli (ETEC) F4 infection in young animals might be counteracted by a probiotic treatment with Lactobacillus sobrius DSM 16698. The experiment was conducted in three randomized consecutive replications, each consisting of 16 piglets, and including a control group and an L. sobrius fed group, both experimentally challenged with ETEC. During the entire trial, the animals' health status, body weight, and microbial parameters were monitored periodically. Probiotic supplementation containing L. sobrius significantly reduced the levels of ETEC in the ileum when fed directly to piglets after weaning. In contrast, the number of days when the piglets had an increased faecal water content was significantly higher in the probiotic group. Nevertheless, an improved daily weight gain was also observed in the animals that received probiotic L. sobrius relative to the control fed group. The data indicate that L. sobrius may be effective in the reduction of the E. coli F4 colonization and may improve the weight gain of infected piglets.

The EU ban on in-feed antibiotics has stimulated research on weaning diets as a way of reducing post-weaning gut disorders and growth check in pigs. Many bioactive components have been investigated but only few have shown to be effective. Amongst these, organic acids (OA) have been shown to exert a bactericidal action mediated by non-dissociated OA, by lowering gastric pH, increasing gut and pancreas enzyme secretion and improving gut wall morphology. It has been postulated that they may also enhance non-specific immune responses and improve disease resistance. In contrast, relatively little attention has been paid to the impact of OA on the stomach but recent data show they can differently affect gastric histology, acid secretion and gastric emptying. Butyrate and precursors of butyric acid have received special attention and although promising results have been obtained, their effects are dependent upon the dose, treatment duration, initial age of piglets, gastrointestinal site and other factors. The amino acids (AA) like glutamine, tryptophan and arginine are supportive in improving digestion, absorption and retention of nutrients by affecting tissue anabolism, stress and (or) immunity. Glutamine, cysteine and threonine are important for maintaining mucin and permeability of intestinal barrier function. Spray-dried plasma (SDP) positively affects gut morphology, inflammation and reduces acquired specific immune responses via specific and a-specific influences of immunoglobulins and other bioactive components. Effects are more pronounced in early-weaned piglets and under poorer health conditions. Little interaction between plasma protein and antibiotics has been found, suggesting distinct modes of action and additive effects. Bovine colostrum may act more or less similarly to SDP. The composition of essential oils is highly variable, depending on environmental and climatic conditions and distillation methods. These oils differ widely in their antimicrobial activity in vitro and some components of weaning diets may decrease their activity. Results in young pigs are highly variable depending upon the product and doses used. These studies suggest that relatively high concentrations of essential oils are needed for beneficial effects to be observed and it has been assumed that these plant extracts mimic most of the effects of antibiotics active on gut physiology, microbiology and immunology. Often, bioactive substances protective to the gut also stimulate feed intake and growth performance. New insights on the effects of selected OA and AA, protein sources (especially SDP, bovine colostrum) and plant extracts with anti-bacterial activities on the gut are reported in this review.