-The post-weaning period in pigs is characterized by an immediate but transient drop in feed intake resulting in severe undernutrition and growth check. This in turn affects various aspects of small intestinal architecture and function leading to gut-associated disorders and often diarrhea. Among these, villus atrophy and digestive enzyme activity depression have been documented. More recent investigations clearly demonstrate early signs of local inflammation including immune cell infiltration and increased pro-inflammatory cytokine gene expression, signs of cytoprotection through up-regulation of so-called heat shock proteins, indications of tissue alterations by proteases (stromelysin) and finally epithelial functional disorders in mineral absorption/secretion and permeability. This is followed by a regenerative phase, probably stimulated by feed intake resumption, resulting in down-regulation of many intestinal indicators. However, some of them then display new spatio-temporal adult-type adaptive patterns of maturation. A limited number of substances, particularly nitrogenous compounds and complex preparations of animal origin (colostrum, plasma) have proven to be successful, at least partly, in minimizing post-weaning intestinal disturbances. Thus further research in intestinal physiology, in association with microbiology and immunology, is warranted to strengthen our understanding of the mechanisms of gut disorders in order to provide a better rational basis for designing suitable alternatives to in-feed antibiotics for pigs. clairement montré des signes précoces d'inflammation incluant une infiltration cellulaire et l'expression accrue des gènes de plusieurs cytokines inflammatoires, une cytoprotection renforcée par la sur-expression des protéines du choc thermique, des indications d'altérations tissulaires par des protéases (stromélysines), et finalement des désordres fonctionnels épithéliaux d'absorption et de sécrétion minérales et de la perméabilité intestinale. Ceci est suivi par une phase de régénération intestinale, probablement stimulée par la reprise de consommation alimentaire, et conduisant à un retour à la normale de plusieurs indicateurs. Cependant, certains d'entre eux ont évolué vers des profils spatio-temporels adaptatifs de type adulte. Un nombre limité de substances, particulièrement des composés azotés et des produits animaux (colostrum, plasma) ont démontré leur capacité, au moins partielle, à minimiser les perturbations digestives post-sevrage. De nouvelles recherches en physiologie digestive, en association avec la microbiologie et l'immunologie, sont nécessaires pour renforcer notre compréhension des mécanismes des troubles digestifs. Ceci permettra de fournir des bases plus rationnelles pour développer des solutions alternatives satisfaisantes aux antibiotiques dans les aliments pour porcelets.intestin / nutrition / physiopathologie / porcelet / sevrage

The mucus gel covering the gut epithelium is in dynamic balance between synthesis and secretion of mucin from goblet cells and proteolytic and physical erosion that releases mucin into the lumen. In the lumen, mucin is partially protected from proteolysis by carbohydrate chains, and it contributes to endogenous protein reaching the ileum. Dietary components modulate the contribution of mucin to endogenous protein components and their qualitative composition. In addition, mucin plays a key role in gastrointestinal protection in association with the microflora. In this review, we will attempt to evaluate the consequences of dietary manipulation of mucin on gut health.

Intestinal mucin, a family of glycoproteins secreted by goblet cells, is the main constituent of the mucus protecting the gastrointestinal tract. For optimal mucosal protection, both the quantitative and qualitative characteristics of mucin are essential. To evaluate how viscosity influences ileal apparent digestibility and mucin biology, a highly viscous nonfermentable soluble polysaccharide, carboxymethylcellulose (CMC), was fed to weaned piglets for 15 d. The ileal crude mucin concentration was determined by ethanol precipitation, and changes in goblet cell subtypes were analyzed by the histochemistry of ileal and colonic tissues. As expected, CMC increased the viscosity of ileal digesta and the moisture of feces (P < 0.001). The crude mucin concentration and output at the ileum were higher (P < 0.05) in pigs fed CMC than those fed the control diet. Increasing intestinal content viscosity in pigs fed CMC had no significant effects on the ileal apparent digestibility of dry matter, organic matter, nitrogen, and minerals. The number of total ileal goblet cells per villus also was higher (+30%, P < 0.05) in pigs fed the CMC diet compared with controls. This increase was essentially accounted for by increased numbers of acidic and acidic sulfated mucin-containing cells (+30%, P < 0.05). Trends (P = 0.06) toward decreased numbers of neutral and acidic mucin-containing cells in ileal crypts were also noted. In conclusion, increasing intestinal content viscosity in weaned piglets fed CMC increased the ileal mucin output and numbers and maturation of goblet cells in ileal villi without effects on the apparent digestibility of the diet.

-Mucin is the main constituent of gastrointestinal mucus and is responsible for its physicochemical and physiological properties. Previous studies have suggested that this glycoprotein represents a major component of undigested endogenous protein at the ileum. The aim of the study was to estimate the ileal output of this glycoprotein using three methods: direct ELISA, hexosaminebased method and ethanol precipitation. For setting up the ELISA assay, the glycoprotein was isolated from intestinal mucus scraping by cesium chloride density gradient ultracentrifugation and a rabbit hyperimmune plasma was raised against the purified glycoprotein. Ileal outputs of hexosamine and glycoprotein were measured in weaned piglets fed a control diet (C) based on casein or diets which contained 50% crude protein supplied by white (WCP) or black (BCP) chickpea. The hexosamine output was higher (P < 0.05) with the WCP diet (2.3 and 1.5 g·kg -1 of dry matter intake for glucosamine and galactosamine, respectively) than with diet C (1.1 and 0.7 g·kg -1 of DMI). The hexosamine-based and ethanol precipitation methods, but not the ELISA, showed significant differences between the diet treatments (P < 0.05). Although hexosamine-based and ethanol precipitation methods for the estimation of ileal glycoprotein appeared to be more satisfactory than the developed ELISA to display diet effects in this study, it remains to be determined whether the higher glycoprotein data variability observed with ELISA reflects the actual biological variability of the phenomenon or not.small intestine / methods / glycoprotein / piglet