Assessing seromuscular layer and serosa removal on intestinal permeability measurements in weaned piglet everted sac segments.

The integrity of the intestinal barrier is crucial for regulating the passage of pathogens and toxins, while facilitating nutrient absorption. The everted gut sac technique, an ex-vivo technique, can be used to study interventions on barrier function. This cost-effective approach utilizes relatively large gut segments to study specific intestinal regions. Typically, intact (non-stripped) intestinal segments are used, but their use may underestimate permeability due to the medial positioning of blood vessels relative to the seromuscular layer and serosa. However, removing these layers risks physical damage, resulting in an overestimation of intestinal permeability. Therefore, we investigated the impact of stripping jejunal segments on permeability to fluorescein isothiocyanate-dextran (FITC, 4 kDa) and tetramethylrhodamine isothiocyanate-dextran (TRITC, 40 kDa), and on the absorption of glucose, lysine, and methionine in jejunal segments from 80 piglets at 8 d postweaning. Piglets were subjected to either high or low sanitary housing conditions and diets provoking intestinal protein fermentation or not, expected to influence intestinal permeability. Stripping of the seromuscular layer and serosa increased the passage of 4 kDa FITC-dextran (stripped vs. non-stripped; 1.1 vs. 0.9 pmol/cm2/min, P < 0.001), glucose (40.0 vs. 19.1 pmol/cm2/min, P < 0.001), lysine (2.5 vs. 2.0 nmol/cm2/min, P < 0.001), and methionine (4.1 vs. 2.7 pmol/cm2/min, P < 0.001). As permeability increased, the differences in methionine passage between stripped and non-stripped intestinal segments also increased (slope = 1.30, P = 0.009). The coefficients of variation were comparable between stripped and non-stripped intestines (over all treatments, stripped vs. non-stripped 38% vs. 40%). Stripping, by isolating mucosal processes without introducing additional variation, is thus recommended for studies on intestinal permeability or absorption.

The intestinal barrier is vital for nutrient passage, while impeding pathogen and toxin translocation. The everted gut sac technique is used to study intestinal permeability, incubating an isolated, everted, intestinal segment filled with buffer solution in a medium containing the substances of interest. After incubation, the translocation of the substances into the created intestinal sac can be measured. Typically, intact intestinal segments are used, but under physiological conditions, nutrients do not need to pass the seromuscular layer and serosa to enter the blood flow. Therefore, removing these layers may be preferable, but, on the other hand, also risks physical damage. This study compared the use of non-stripped vs. stripped intestinal segments. Permeability to two markers (FITC-dextran, 4kDa and TRITC-dextran, 40 kDa), and absorption of glucose, lysine, and methionine were measured in non-stripped and stripped jejunal segments obtained from 80 piglets at 8 d postweaning. The piglets were housed under different hygiene and dietary conditions, which were anticipated to alter intestinal permeability. Stripping the seromuscular layer and serosa increased the passage of FITC-dextran, glucose, lysine, and methionine, without reducing assay precision due to physical damage. Thus, removal of the seromuscular layer and serosa is preferred for studying intestinal permeability or absorption.

Effect of adding soluble viscous fibers to diets containing coarse and finely ground insoluble fibers on digesta transit behavior and nutrient digestibility in broiler chickens.

This paper aimed to study the interactive effects of the addition of soluble arabinoxylans (AX) and the particle size (PS) of soybean hulls (SBH) on digesta mean retention time (MRT) and nutrient digestibility in broiler chickens. A total of 288 one-day old Ross 308 female chicks were assigned to 32 pens (9 birds/pen) and fed a commercial starter diet for 10 d. At 10 d of age, pens were assigned to 1 of 4 dietary treatments (8 pens/diet) containing 120 g/Kg coarse or fine SBH, with or without addition of 50 g/Kg of soluble wheat AX, substituting maize starch. Titanium dioxide (4 g/Kg) and cobalt-EDTA (1 g/Kg) were added as inert markers. Excreta were quantitatively collected from d 22 to 25. Gastrointestinal tract and digesta were collected on d 28, 29, or 30. Arabinoxylans reduced the weight of the gizzard relative to body weight (RW) by 0.07% units (P = 0.005), and increased ceca RW (0.28 vs. 0.34%, P < 0.001) and length (10.45 vs. 11.21 cm/Kg BW, P < 0.001). Arabinoxylans increased digesta MRT in the crop (solids/liquids: +12 min, P < 0.05), small intestine (solids/liquids: +17 min, P < 0.01), and hindgut (liquids: +77.5 min, P < 0.05); and reduced apparent ileal digestibility (AID) and apparent total tract retention (ATTR) of DM (-5.4 and -3.9%, P < 0.001, respectively) and starch (-1.35 and -0.7%, P < 0.001, respectively). Particle size of SBH only affected the ATTR of non-starch polysaccharides, presenting higher retention values with fine SBH (-4.3%-units, P = 0.034). The addition of AX reduced AID of N by 4.3%-units, only in presence of fine SBH (interaction, P < 0.05). In conclusion, arabinoxylans greatly influenced digestion in the chicken GIT, while PS of SBH had marginal effects. Arabinoxylans reduced AID of N only with fine SBH, suggesting coarse SBH counteracted AX effects on N digestion, speculatively by modifying digesta viscosity.