The present study was conducted to investigate the effects of glutamine (Gln) supplementation on intestinal inflammatory reaction and mucosa barrier of broilers administrated with lipopolysaccharide (LPS) stimuli. A total of 120 1-d-old male broilers were randomly divided into four treatments in a 2 × 2 experimental arrangement, containing immune challenge (injected with LPS in a dose of 0 or 500 μg/kg of body weight) and dietary treatments (supplemented with 1.22% alanine or 1% Gln). The results showed that growth performance of broilers intra-abdominally injected with LPS was impaired, and Gln administration alleviated the adverse effects on growth performance induced by LPS challenge. Furthermore, Gln supplementation reduced the increased concentration of circulating tumor necrosis factor-α, interleukin-6 and interleukin-1β induced by LPS challenge. Meanwhile, D-lactic acid and diamine oxidase concentration in plasma were also decreased by Gln supplementation. In addition, the shorter villus height, deeper crypt depth and the lower ratio of villus height to crypt depth of duodenum, jejunum and ileum induced by LPS stimulation were reversed by Gln supplementation. Gln administration beneficially increased LPS-induced reduction in the expression of intestine tight junction proteins such as zonula occludens protein 1 (ZO-1), claudin-1 and occludin except for the ZO-1 in duodenum and occludin in ileum. Moreover, Gln supplementation downregulated the mRNA expression of toll-like receptor 4, focal adhesion kinase, myeloid differentiation factor 88 and IL-1R-associated kinase 4 in TLR4/FAK/MyD88 signaling pathway. Therefore, it can be concluded that Gln administration could attenuate LPS-induced inflammatory responses and improve intestinal barrier damage of LPS-challenged broilers.

Introduction: The study evaluated the enzymatic hydrolysis processing on physicochemical properties and protein digestive dynamics of soybean meal (SBM), as well as the relationship between protein secondary structure and digestive parameters was established.Methods: Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR) were employed to analyze the microstructure and protein structure of the SBM and enzymatic hydrolysis processed soybean meal (ESBM). SBM and ESBM were incubated with pepsin at pH 3.5 and 39°C for 30 min, then with pancreatin at pH 6.8 for 0–240 min. The in vitro protein digestive dynamics were described as the release dynamics of amino acids and low molecular weight peptides (AA_LMW).Results: The results showed that enzymatic hydrolysis processing did not alter the chemical composition of SBM, but changed its microstructure and protein structure. After enzymatic hydrolysis processing, the size of blocky structures of SBM decreased, exhibiting a fibrous surface and a relatively loose internal structure. The β-sheet content of ESBM was lower than that of SBM (p < 0.05), while the α-helix, β-turn, and α-helix/β-sheet content was higher than that of SBM (p < 0.05). The release rates (k) of AA_LMW in SBM and ESBM were 0.0123 min⁻¹ and 0.0733 min⁻¹, respectively. Enzymatic hydrolysis processing increased the CP_fast content of SBM (p < 0.05) and decreased the CP_slow and CP_resistant contents (p < 0.05). α-helix, β-turn, and the ratio of α-helix to β-sheet were positively correlated with CP_fast and k (p < 0.05) and were negatively correlated with CP_slow and CP_resistant (p < 0.05). β-sheet was negatively correlated with CP_fast and k (p < 0.05) and was positively correlated with CP_slow and CP_resistant (p < 0.05).Discussion: Enzymatic hydrolysis processing altered the digestive dynamics of SBM, increased the CP_fast content and the release rate of AA_LMW, which might be attributed to the structure changes of SBM.

Background: Promoting the synchronization of glucose and amino acid release in the digestive tract of pigs could effectively improve dietary nitrogen utilization. The rational allocation of dietary starch sources and the exploration of appropriate dietary glucose release kinetics may promote the dynamic balance of dietary glucose and amino acid supplies. However, research on the effects of diets with different glucose release kinetic profiles on amino acid absorption and portal amino acid appearance in piglets is limited. This study aimed to investigate the effects of the kinetic pattern of dietary glucose release on nitrogen utilization, the portal amino acid profile, and nutrient transporter expression in intestinal enterocytes in piglets. Methods: Sixty-four barrows (15.00 ± 1.12 kg) were randomly allotted to 4 groups and fed diets formulated with starch from corn, corn/barley, corn/sorghum, or corn/cassava combinations (diets were coded A, B, C, or D respectively). Protein retention, the concentrations of portal amino acid and glucose, and the relative expression of amino acid and glucose transporter mRNAs were investigated. In vitro digestion was used to compare the dietary glucose release profiles. Results: Four piglet diets with different glucose release kinetics were constructed by adjusting starch sources. The in vivo appearance dynamics of portal glucose were consistent with those of in vitro dietary glucose release kinetics. Total nitrogen excretion was reduced in the piglets in group B, while apparent nitrogen digestibility and nitrogen retention increased (P < 0.05). Regardless of the time (2 h or 4 h after morning feeding), the portal total free amino acids content and contents of some individual amino acids (Thr, Glu, Gly, Ala, and Ile) of the piglets in group B were significantly higher than those in groups A, C, and D (P < 0.05). Cluster analysis showed that different glucose release kinetic patterns resulted in different portal amino acid patterns in piglets, which decreased gradually with the extension of feeding time. The portal His/Phe, Pro/Glu, Leu/Val, Lys/Met, Tyr/Ile and Ala/Gly appeared higher similarity among the diet treatments. In the anterior jejunum, the glucose transporter SGLT1 was significantly positively correlated with the amino acid transporters B⁰AT1, EAAC1, and CAT1. Conclusions: Rational allocation of starch resources could regulate dietary glucose release kinetics. In the present study, group B (corn/barley) diet exhibited a better glucose release kinetic pattern than the other groups, which could affect the portal amino acid contents and patterns by regulating the expression of amino acid transporters in the small intestine, thereby promoting nitrogen deposition in the body, and improving the utilization efficiency of dietary nitrogen.

In this study, three samples were randomly selected from corn, wheat, and broken rice before and after extrusion for electron microscope scanning, Fourier transform infrared spectral analysis, and in vitro digestion to investigate the impact of extrusion on physicochemical characteristics and starch digestion kinetics of cereals. The cereals used for extrusion were sourced identically before and after the process, with each analysis conducted in triplicate. The results showed that the extrusion compromised the physical structure of cereal, resulting in loose structure arrangement, and the ratio of Fourier transform infrared spectral absorbance at wavelength 1047 cm⁻¹ and 1022 cm⁻¹, which characterized the short-range order of starch, was significantly reduced (p < 0.05). In addition, the proportion of rapidly digestible starch (RDS), the velocity parameter k of digestive kinetics and the predicted glycemic index of cereals were significantly increased by extrusion (p < 0.05). Digestibility kinetics showed a total increase of 10.7%, 7.3%, and 5.4% for cereals, along with a sharp rise in digestion rate within the first 15 minutes. The findings revealed that the compromising of starch’s structural integrity and the increase in proportion of RDS not only enhanced overall starch digestibility, but also significantly accelerated its digestion, particularly during the initial 15 min of intestinal digestion.

The present study aimed to investigate the effect of glutamine (Gln) addition on the damage of porcine intestinal epithelial cells (IPEC-J2) induced by heat stress (HS). IPEC-J2 cultured in logarithmic growth period in vitro were firstly exposed to 42°C for 0.5, 1, 2, 4, 6, 8, 10, 12 and 24 h for cell viability and cultured with 1, 2, 4, 6, 8 or 10 mmol Gln per L of culture media for heat-shock protein 70 (HSP70) expression to determine the optimal disposal strategy (HS, 42℃ for 12 h and HSP70 expression, 6 mmol/L Gln treatment for 24 h). Then IPEC-J2 cells were divided into three groups: control group (Con, cultured at 37 ℃), HS group (HS, cultured at 42 ℃ for 12 h) and glutamine group (Gln + HS, cultured at 42 ℃ for 12 h combined with 6 mmol/L Gln treatment for 24 h). The results showed that HS treatment for 12 h significantly decreased the cell viability of IPEC-J2 (P<0.05) and 6 mmol/L Gln treatment for 12 h increased HSP70 expression (P<0.05). HS treatment increased the permeability of IPEC-J2, evidenced by the increased the fluorescent yellow flux rates (P<0.05) and the decreased transepithelial electrical resistance (P<0.05). Moreover, the down-regulated protein expression of occluding, claudin-1 and ZO-1 were observed in HS group (P<0.05), but Gln addition alleviated the negative effects on permeability and the integrity of intestinal mucosal barrier induced by HS (P<0.05). In addition, HS resulted in the elevations in HSP70 expression, cell apoptosis, cytoplasmic Cytc potential expression and the protein expressions of apoptosis related factors (Apaf1, Caspase-3 and Caspase-9) (P<0.05), however, the reductions in mitochondrial membrane potential expression and Bcl-2 expression were induced by HS (P<0.05). But Gln treatment attenuated HS-induced adverse effects above mentioned (P<0.05). Taken together, Gln treatment exhibited protective effects in protecting IPEC-J2 from cell apoptosis and the damaged integrity of epithelial mucosal barrier induced by HS, which maybe associated with the mitochondrial apoptosis pathway mediated by HSP70.