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The objective of this study was to evaluate the effects of dietary addition of lactic acid and glutamine, and their interactions, on growth performance, nutrient digestibility, digestive enzyme activity, intestinal barrier functions, microflora, and expressions of intestinal development-related genes of weaning piglets. Ninety-six 24-day-old weaning piglets (Duroc × Landrace × Yorkshire, weaned at 21 ± 1 d and fed the basal diet for a 3 d adaptation period) with initial body weight of 7.24 ± 0.09 kg were randomly assigned to one of four dietary treatments with six replicates per treatment and four pigs per replicate in a 2 × 2 factorial treatment arrangements: (1) CON (a 2-period basal diet; control), (2) LS (supplemented with 2% lactic acid), (3) GS (supplemented with 1% glutamine), and (4) LGS (supplemented with 2% lactic acid and 1% glutamine). The study lasted for 28 d. On days 25-28, fresh fecal samples were collected to evaluate apparent total tract digestibility (ATTD) of nutrients. After 28 d, one weaning pig per pen was euthanized, and physiological samples obtained. Results showed that the supplementation of lactic acid improved the ADFI of the pigs ( p < 0.05), while the pigs fed the glutamine diet had a greater ADFI and higher G/F ( p < 0.05), and there were significant interactive effects between lactic acid and glutamine on the ADFI and G/F of the pigs ( p < 0.05). The ATTD of CP and ash for pigs fed with lactic acid was significantly enhanced, and pigs fed the glutamine diet had greater ATTD of CP and ash ( p < 0.05), while there were significant interactive effects between lactic acid and glutamine on the ATTD of CP and ash of the pigs ( p < 0.05). Pigs fed with lactic acid exhibited greater activity of α-amylase and lipase ( p < 0.05); moreover, the activity of lipase in the pigs showed a significant interactive effect between lactic acid and glutamine ( p < 0.05). There was a greater villus height and villus height to crypt depth ratio in pigs fed with lactic acid ( p < 0.05), and the villus height to crypt depth ratio of pigs fed with glutamine was greater ( p < 0.05). There were greater GLUT2 , IGF-1 , TGF-β2 , OCLN , and ZO-1 mRNA levels in pigs fed with lactic acid ( p < 0.05), and the supplementation of glutamine increased SGLT1 , GLUT2 , PepT1 , IGF-1 , IGF-1R , TGFβ-2 , GLP-2 , and OCLN mRNA levels ( p < 0.05), Additionally, expressions of SGLT1 , GLUT2 , PepT1 , IGF-1 , IGF-1R , TGFβ-2 , GLP-2 , CLDN-2 , OCLN , and ZO-1 mRNA levels of pigs showed a positive interactive effect between lactic acid and glutamine ( p < 0.05). Supplementation of lactic acid significantly increased the populations of Bifidobacterium in cecal digesta, Lactobacillus in colonic digesta, and the content of butyric acid in colonic digesta ( p < 0.05). In addition, there were significant interactive effects between lactic acid and glutamine on populations of Bifidobacterium in cecal digesta, Lactobacillus in colonic digesta, and the content of acetic acid, butyric acid, and total VFAs in cecal digesta of the pigs ( p < 0.05). Collectively, the current results indicate that dietary supplementation with lactic acid and glutamine had a positive synergistic effect on weaning pigs, which could improve growth performance through promoting the development of the small intestine, increasing digestive and barrier function, and regulating the balance of microflora in pigs, and which might be a potential feeding additive ensemble to enhance the health and growth of weaning piglets in the post-antibiotic era.

Post-weaning diarrhea significantly contributes to the high mortality in pig production, but the metabolic changes in weaned piglets with diarrhea remain unclear. This study aimed to identify the differential metabolites in the urine of diarrheal weaned piglets and those of healthy weaned piglets to reveal the metabolic changes associated with diarrhea in weaned piglets. Nine 25-day-old piglets with diarrhea scores above 16 and an average body weight of 5.41 ± 0.18 kg were selected for the diarrhea group. Corresponding to the body weight and sex of the diarrhea group, nine 25-month-old healthy piglets with similar sex and body weights of 5.49 ± 0.21 kg were selected as the control group. Results showed that the serum C-reactive protein and cortisol of piglets in the diarrhea group were higher than those in the control group ( p < 0.05). The mRNA expression of TNF-α , IFN-γ in the jejunum and colon, and IL-1β in the jejunum were increased in diarrhea piglets ( p < 0.05), accompanied by a reduction in the mRNA expression of ZO-1 , ZO-2 , and CLDN1 in the jejunum and colon ( p < 0.05); mRNA expression of OCLN in the colon also occurred ( p < 0.05). Metabolomic analysis of urine revealed increased levels of inosine, hypoxanthine, guanosine, deoxyinosin, glucosamine, glucosamine-1-p, N-Acetylmannosamine, chitobiose, and uric acid, identified as differential metabolites in diarrhea piglets compared to the controls. In summary, elevated weaning stress and inflammatory disease were associated with the abnormalities of purine metabolism and the hexosamine biosynthetic pathway of weaned piglets. This study additionally indicated the presence of energy metabolism-related diseases in diarrheal weaned piglets.

This experiment was conducted in weaned piglets to determine the effects of exogenous protease to low soybean meal (SBM) diets on growth performance, diarrhea rate, nutrient digestibility, and intestinal morphology. Seventy-two Duroc × Landrace × Yorkshire weaned barrows (21-day-old, 5.88 ± 0.95 kg) were randomly divided into four treatments with six replicates in each following a 2 × 2 factorial arrangement of SBM levels (0 to 14 d, 9%, 7.5%; 15 to 42 d, 20%, 18.5%) and protease (0 or 150 mg/kg) for a 42-day trial. Fecal samples were collected on days 11 to 14 and 38 to 42 of the experiment, and serum, intestinal tissue, and chyme samples were taken at the end of the experiments. Adding protease in low SBM diets had a significant increase in ADG ( p < 0.05) and a decrease in F/G ( p < 0.05). Protease significantly reduced the diarrhea rate ( p < 0.05). Low SBM level decreased the apparent total tract digestibility (ATTD) of crude protein (CP) and ash ( p < 0.05) but increased the ATTD of dry matter (DM), ash, organic matter (OM), and CP after the addition of protease ( p < 0.05). The apparent ileal digestibility (AID) of aspartic acid (Asp), threonine (Thr), serine (Ser), alanine (Ala), lysine (Lys), and total amino acids (AAs) were significantly increased by protease supplementation ( p < 0.05). Both the SBM-reduced and protease-added diets lead to lower albumin (ALB), albumin/globulin (A/G), and urea nitrogen (UREA) ( p < 0.05), but greater globulin (GLOB) with low SBM diets ( p < 0.05). The SBM-reduced and protease-added diets decreased the duodenum pH, respectively ( p < 0.05). The protease increased the villus:crypt (V:C) in the duodenum and ileum, and ileal villus length ( p < 0.05). In conclusion, the dietary supplementation of 150 mg/kg protease improved the intestinal health and performance of the weaned piglets and reversed the negative effect of a 1.5% SBM reduction in nutrient utilization, intestinal pH, and intestinal morphological parameters of weaned piglets.

To investigate the effects of lipid sources on growth performance and intestinal health, 72 weaned pigs were randomly allocated to three treatments. Pigs were fed with a corn-soybean meal diet containing 2% soybean oil (SO), or fish-palm-rice oil mixture (FPRO), or coconut-palm-rice oil mixture (CPRO). The trial lasted for 28 days; blood and intestinal tissue samples were collected. The results showed that the crude fat digestibility of the FPRO group was higher than that of the SO and CPRO groups ( p < 0.05). The FPRO group also had higher digestibility of dry matter, ash, and gross energy than the SO group ( p < 0.05); compared to the SO group, the serum interlukin-6 (IL-6) concentration was decreased. Interestingly, the FPRO and CPRO groups had higher villus height than the SO group in the jejunum and ileum, respectively ( p < 0.05). Moreover, the FPRO group had higher Lactobacillus abundance than the SO group in the colon and cecum ( p < 0.05). Importantly, the expression levels of tight junction protein ZO-1, Claudin-1, and Occludin in the duodenal and ileal mucosa were higher in the FPRO group than in the SO and CPRO groups ( p < 0.05). The expression levels of nutrient transporters such as the CAT-1, PepT1, FATP1, and SGLT1 were higher in the FPRO group than in the SO group ( p < 0.05). The improved digestibility and intestinal epithelium functions, as well as the reduced inflammatory cytokines, in the FPRO and CPRO group suggest that a mixed lipid source such as the FPRO deserves further attention.

To explore the effect of dietary fiber on growth performance and intestinal health in different pig breeds, forty Taoyuan and Duroc pigs (pure breeds) of 60 days of age were randomly divided into a 2 (diet) × 2 (breed) factorial experiment (n = 10), and fed with a basal diet (BD) or high-fiber diet (HFD). The trial lasted for 28 d, and results showed that the Taoyuan pigs had a higher average daily feed intake (ADFI) than the Duroc pigs (p < 0.05). The average daily gain (ADG) and digestibilities of gross energy (GE) and crude protein (CP) were higher in Taoyuan pigs than in the Duroc pigs under HFD feeding (p < 0.05). The HFD increased the superoxide dismutase (SOD) and catalase (CAT) activity in Taoyuan pigs (p < 0.05). Interestingly, Taoyuan pigs had a higher jejunal villus height and ratio of villus height to crypt depth (V/C) than the Duroc pigs. The HFD significantly improved the villus height and V/C ratio in duodenum and jejunum (p < 0.05). The HFD also increased the jejunal maltase and ileal sucrase activities in Duroc and Taoyuan pigs, respectively (p < 0.05). Taoyuan pigs had a higher expression level of duodenal fatty acid transport protein-1 (FATP-1) than the Duroc pigs (p < 0.05). Furthermore, the HFD acutely improved the expression levels of ileal SGLT-1 and GLUT-2, and the expression levels of jejunal occludin and claudin-1 in Taoyuan pigs (p < 0.05). Importantly, Taoyuan pigs had a higher colonic Bifidobacterium abundance than the Duroc pigs (p < 0.05). The HFD not only elevated the colonic Lactobacillus abundance and butyrate acid content in Taoyuan pigs, but also increased the acetic and propionic acid contents in both the pig breeds (p < 0.05). These results indicated a difference in dietary fiber (DF) utilization by the two pig breeds, and results may also suggest a beneficial character of DF in regulating intestinal health.

This experiment was conducted to evaluate the effects of different protease levels on performance, diarrhea rate, nutrient digestibility, blood metabolites, digestive enzyme activities, and intestinal health of weaned piglets. A total of 96 weaned piglets (Duroc × Landrace × Yorkshire, 28 d of age, initial average BW = 6.55 ± 0.17 kg) were divided into four groups (4 pigs/pen and 6 replicates/group) according to a completely random block design. Piglets were fed different levels of protease (0, 150, 300 or 600 mg/kg of diet) for 28 d. The results showed that the addition of protease had no significant effect on the growth performance of weaned piglets (p > 0.05), and the addition of 300 mg/kg protease significantly increased the apparent total intestinal digestibility (ATTD) of nutrients and the apparent ileal digestibility (AID) of amino acids in weaned piglets (p < 0.05), while the addition of 150 mg/kg and 600 mg/kg protease had no significant effect on the digestibility (p > 0.05). The nutrient digestibility of dry matter (DM), organic matter (OM), crude protein (CP) and total energy (GE) showed a trend of increasing and then decreasing with increasing protease concentration (p < 0.05). Adding 300 and 600 mg/kg protease significantly decreased serum ALB/GLO levels (p < 0.05) and duodenal pH (p < 0.05) and increased duodenal villus height (p < 0.05). The addition of protease significantly increased jejunal trypsin and chymotrypsin activities (p < 0.01) and duodenal and jejunal mucosal tight junction proteins in piglets. The mRNA expression levels of ZO-1 and CLAUDIN-1 in the duodenum together with ZO-1 and OCCLUDIN in the jejunum of piglets in the 300 and 600 mg/kg protease supplementation groups were significantly higher than those in the control group (p < 0.05). The results showed that, compared with the control group, protease could promote nutrient absorption, improve small intestine morphology and enhance digestive enzyme activity in weaned piglets. The suitable addition amount was 150−300 mg/kg in the present study.

The purpose of this study was to investigate whether dietary lactose supplementation relieves rotavirus (RV)-induced diarrhea and gut dysfunction. Thirty-six crossbred weaned piglets were randomly allocated into three groups and fed diets containing 0, 4%, and 6% lactose for 20 days. On Day 15, half of the piglets in each group were orally infused with RV. RV infection impaired growth performance; induced severe diarrhea; decreased serum D-xylose concentration and morphology and sIgA level of jejunal mucosa; downregulated MUC1, MUC2, occludin, Bcl-2, IL-4, pBD3, pBD2, and pBD1 mRNA expression of jejunal mucosa and/or mesenteric lymph nodes; upregulated Bax, caspase-3, IL-2, IFN-γ, and IFN-β mRNA expression of jejunal mucosa and/or mesenteric lymph nodes; and damaged microbiota and metabolites of cecal digesta in weaned piglets (p < 0.05). Dietary lactose supplementation improved nutrient digestibility and growth performance and relieved the negative influence of RV challenge on intestinal barrier function, mRNA expression of cytokines, and host defense peptides of jejunal mucosa and/or mesenteric lymph nodes in weaned piglets (p < 0.05). Dietary administration of 6% lactose tended to relieve diarrhea (p = 0.07). These results suggest that lactose in feed increases growth performance and has a tendency to alleviate RV-induced diarrhea, derived from the improvement of nutrient utilization, gut barrier function, and immunity.

A total of 16 crossbred (Duroc × Landrace × Yorkshire) barrows, with an average initial body weight of 8.61 ± 0.24 kg (28 days of age), were randomly allotted into the control group (CON group) and high ambient temperature group (HT group) with 8 replicates per group, 1 pig per replicate. The ambient temperature of the CON group was controlled at 26 ± 1 °C, and the HT group was controlled at 35 ± 1 °C. The study lasted for 21 days. Our results showed that high ambient temperature significantly decreased the average daily feed intake (ADFI) and average daily gain (ADG) of piglets (p < 0.05), and the feed-to-gain ratio was significantly increased (p < 0.05). The liver index, spleen index, and thymus index of piglets in the HT group were significantly decreased (p < 0.05). The villous height (VH) of the duodenum, jejunum, and ileum of piglets in the HT group was significantly decreased (p < 0.05), whereas the crypt depth (CD) of the duodenum was significantly increased (p < 0.05), and the VH-to-CD ratio of the duodenum and ileum was significantly decreased (p < 0.05). The piglets in the HT group showed a higher (p < 0.05) observed-species index, PD whole tree index, and Shannon index, indicating that there was a significant difference in species richness and diversity between the two groups. At the genus level, the piglets in the HT group showed a greater (p < 0.05) percent of Desulfovibrio, Occillibater, and Catenisphaera. HT reduced glycan biosynthesis and metabolism, transport and catabolism, lipid metabolism, amino acids metabolism, secondary metabolites biosynthesis, aging, endocrine system, signaling molecules, and interaction of colon microbiota (p < 0.05), and increased signal transduction, cell motility, transcription, and genetic information processing (p < 0.05).

Low birth-weight (LBW) neonates exhibit a lower growth rate and impaired intestinal development. However, the reasons for abnormal development of small intestine in LBW piglets have not been widely studied. The present study focused on the redox status and mitochondrial morphology and functions of the small intestine in LBW newborn piglets. Ten newborn normal birth-weight (NBW) piglets and LBW piglets from 10 primiparous sows with the same parturition day were selected and sampled immediately without sucking colostrum. The small intestine tissues were collected and measured. Compared with NBW newborn piglets, LBW newborn piglets had a significantly decreased length and weight of the small intestine ( p < 0.05) as well as the villus height/crypt depth (V/C) index in the jejunum ( p < 0.05). Furthermore, LBW piglets had a lower gene expression of tight junction protein zonula occluden-1 ( ZO1 ), claudin 1 , antioxidant enzyme catalase ( CAT ), glutathione peroxidase ( GPX ) and heme oxygenase-1 ( HO-1 ) in jejunum ( p < 0.05). Meanwhile, LBW induced mitochondrial vacuolation and significantly decreased the mRNA expression of PPARγ coactivator-1α ( PGC-1α ) ( p < 0.05) and tended to decrease the expression of cytochrome coxidase IV ( Ccox IV ) ( p = 0.07) and cytochrome C ( Cytc ) ( p = 0.08). In conclusion, LBW newborn piglets showed an abnormal development of the small intestine and disturbed redox status, and this may be caused by impaired morphology and the functions of mitochondria in the jejunum.

Low-temperature is one of the most significant risks for the animal industry. In light of this, the present study aimed to explore the effects of low-temperature on growth performance, nutrient digestibility, myofiber types and mitochondrial function in weaned piglets. A total of sixteen 21-day-old male Duroc × Landrace × Yorkshire (DLY) piglets were randomly divided into a control group (CON, 26 ± 1 °C) and a low-temperature group (LT, 15 ± 1 °C), with eight duplicate piglets in each group. The trial period lasted for 21 days. We showed that LT not only increased the ADFI ( p < 0.05), as well as increasing the diarrhea incidence and diarrhea index of weaned piglets in the early stage of the experiment ( p < 0.01), but it also decreased the apparent digestibility of crude protein (CP), organic matter (OM) and dry matter (DM) ( p < 0.05). Meanwhile, in the LT group, the mRNA expression of MyHC IIa ( p < 0.05) in longissimus dorsi muscle (LM) and MyHC I ( p < 0.01) in psoas muscle (PM) were increased, while the mRNA expression of MyHC IIx in PM was decreased ( p < 0.05). In addition, LT increased the mRNA expression of mitochondrial function-related genes citrate synthase (CS) and succinate dehydrogenase-b (SDHB) in LM, as well as increased the mRNA expression of CS ( p < 0.05) and carnitine palmitoyl transferase-1b (CPT-1b) ( p < 0.01) in PM. Furthermore, LT increased the T-AOC activity in serum and LM ( p < 0.01), as well as increased the T-SOD activity in PM ( p < 0.05). Taken together, these findings showed that low-temperature could negatively affect the growth performance and nutrient digestibility, but resulted in a shift toward oxidative muscle fibers, which may occur through mitochondrial function regulation.

Accumulating evidences demonstrate that fermented feed and liquid feeding exerted a great beneficial influence on growth performance and health in the pig industry. This experiment was conducted to evaluate the effects of fermented liquid feeding on the growth performance and intestinal function of pigs. Two hundred and eighty-eight 27-day-old weaned piglets (8.21 ± 0.27 kg) were randomly allocated to a control group (basal diet (CON)), an antibiotic group (basal diet supplemented with antibiotics (AB)) and a fermented liquid feeding group (basal diet with fermented liquid feeding (FLF)), with 6 replicates per treatment and 16 weaned piglets per replicate. The experiment lasted for 160 days. Fresh fecal samples were collected to evaluate the apparent total tract digestibility (ATTD) of nutrients from the last 4 days of each stage. The results are shown as follows: (1) Compared with the CON group, in the whole stage, the FLF diet significantly increased the final body weight (BW) and ADG of pigs ( P < 0.05), and had a tendency to increase ADFI ( P = 0.086), but had no effect on F/G. (2) The ATTD of dry matter (DM), crude protein (CP), ether extract (EE), crude ash (CA), crude fiber (CF), gross energy (GE), calcium (Ca) and total phosphorus (TP) in the FLF group was significantly elevated compared with those of the CON group at 8-20 kg stage ( P < 0.05). Meanwhile, the ATTD of EE in the FLF group was significantly increased compared with that of the CON group at the 50-75 kg and 100-125 kg stages ( P < 0.05), and the ATTD of Ca was higher than that of CON group at the 100-125 kg stage ( P < 0.05). (3) Compared with that of the CON group, the level of serum leptin in the FLF group had a tendency to decrease ( P = 0.054), the level of serum ghrelin in the FLF group was significantly elevated ( P < 0.05) and the level of serum peptide YY in the FLF group was significantly decreased ( P < 0.05). (4) The abundance of Lactobacillus in cecal and colonic digesta was observably enhanced in FLF group. Meanwhile, the abundance of Escherichia coli in cecal and colonic digesta were dramatically reduced in the FLF group compared with that in the CON and AB groups ( P < 0.05). (5) The levels of acetic acid in colonic digesta were significantly increased in the FLF group ( P < 0.05), and an increasing trend was observed in total VFA in colonic digesta compared with CON ( P < 0.1). The levels of acetic acid in colonic digesta were significantly promoted in the FLF group compared with that of the AB group ( P < 0.05). In conclusion, these results indicate that fermented liquid feeding improved the growth performance of pigs, which might be associated with gastrointestinal hormone and intestinal functions.

This study aimed to investigate the effects of chronic exposure to low levels of dietary aflatoxin B 1 (AFB 1 ) on growth performance, apparent total tract digestibility and intestinal health in pigs. In a 102-day experiment, fourteen barrows (Duroc×Landrace×Yorkshire, initial BW = 38.21 ± 0.45 kg) were randomly divided into control (CON, basal diet) and AFB 1 groups (the basal diet supplemented with 280 μg/kg AFB 1 ). Results revealed that the AFB 1 exposure decreased the final BW, ADFI and ADG in pigs ( p < 0.10). AFB 1 exposure also decreased the apparent total tract digestibility of dry mater and gross energy at 50 to 75 kg and 105 to 135 kg stages, and decreased the apparent total tract digestibility of ether extract at 75 to 105 kg stage ( p < 0.05). Meanwhile, AFB 1 exposure increased serum diamine oxidase activity and reduced the mRNA abundance of sodium-glucose cotransporter 1, solute carrier family 7 member 1 and zonula occluden-1 in the jejunal mucosa ( p < 0.05). Furthermore, AFB 1 exposure decreased superoxide dismutase activity ( p < 0.05) and increased 8-hydroxy-2'-deoxyguanosine content ( p < 0.10) in jejunal mucosa. AFB 1 exposure also increased tumor necrosis factor-α, interleukin-1β and transforming growth factor-β mRNA abundance in jejunal mucosa and upregulated Escherichia coli population in colon ( p < 0.05). The data indicated that chronic exposure to low levels of dietary AFB 1 suppressed growth performance, reduced the apparent total tract digestibility and damaged intestinal barrier integrity in pigs, which could be associated with the decreased intestinal antioxidant capacity and the increased pro-inflammatory cytokine production.

The present study aimed to investigate the effects of dietary fiber on the gut health of growing pigs. In total, 30 growing pigs with an initial average body weight of 45.8 ± 2.78 kg were divided into three groups with 10 replicates per treatment, and one pig per replicate. The treatments included a corn-soybean meal-based diet (control group, 1.5% crude fiber (CF)), corn-soybean meal + beet pulp-based diet (beet pulp group, 5.74% CF) and corn-soybean meal-based diet (feed intake-pairing group (pairing group); the feed intake was equal to the beet pulp group, 1.5% CF). The whole trial lasted 28 days. The beet pulp group had a longer length of the large intestine, higher weight of the small intestine and whole intestine, greater density of the large intestine and whole intestine, and higher villus height in the jejunum and ileum than the control group ( p < 0.05). The messenger RNA (mRNA) expression levels of epidermal growth factor (EGF), glucagon-like peptide 2 (GLP-2), and glucagon-like peptide 2 receptor (GLP-2R) in the duodenum, EGF and GLP-2 in the jejunum, EGF in the ileum, and GLP-2 in the colon were higher in the beet pulp group than in the control group ( p < 0.05). Moreover, the apparent total tract digestibility of crude ash, energy, dry matter (DM), and crude protein (CP) was lower in the beet pulp group than in the control group ( p < 0.05), while the apparent total tract digestibility of CF, the activity of jejunal lactase, and the mRNA abundance of duodenal GLP-2 were higher in the beet pulp group than in the control and pairing groups ( p < 0.05). In addition, the beet pulp group had more goblet cells in the colon, more Bifidobacterium spp. in the cecal digesta, higher concentrations of acetic acid and butyric acid in the cecal digesta, and higher mRNA abundance of duodenal regeneration protein Ⅲγ (REG-Ⅲγ), jejunal mucin 2 (MUC-2), and ileal G protein-coupled receptor 43 (GPR-43) than the control group ( p < 0.05). However, these parameters did not differ between the control and pairing groups ( p > 0.05). These findings indicate feeding a high-fiber diet (5.74% CF, obtained from beet pulp) to pigs could modulate the gut microbiota composition, increase the short-chain fatty-acid (SCFA) content in the hindgut, and improve gut health, which is independent of the feed intake.

The present experiment was conducted to dissect the effects of different carbohydrate combinations on the growth performance, nutrient digestibility, and microbial communities in weaned pigs. The combination was optimized by constructing L 9 (3 4 ) orthogonal design. Three factors include starch (amylose to amylopectin (AM/AP) ratio 2:1, 1:1, 1:2), non-starch polysaccharides (NSP) (1%, 2%, 3%, a mixture of inulin with cellulose by 1:1), and mannan-oligosaccharide (MOS) (400, 800, 1200 mg/kg) were investigated and nine combinations were implemented under different levels of these factors. One hundred and sixty-two weaned pigs were randomly assigned to nine dietary treatments with six replicates per treatment and three pigs per replicate. Results exhibited that different combinations of starch, NSP, and MOS affected the gain to feed (G:F) ( p < 0.05), diarrhea incidence ( p < 0.10), nutrient digestibility ( p < 0.05), microbial communities, and short-chain fatty acid (SCFA) concentrations ( p < 0.05). In the present study, taking into account three-way ANOVA, range, and direct analysis, we found that the optimal carbohydrate combination was starch AM/AP 1:1, NSP 3%, MOS 400 mg/kg for weaned pigs. Moreover, feeding this combination diet could promote the growth performance and nutrient digestibility, increase the butyrate-producing bacteria, and to some extent improve lipid metabolism. This study provided a novel way to evaluate the carbohydrate quality in swine production.

To investigate the effects of dietary starch structure (amylose/amylopectin ratio, AR) on serum glucose absorption metabolism and intestinal health, a total of ninety weaned piglets (Duroc × (Yorkshire × Landrace)) were randomly assigned to 5 dietary treatments and fed with a diet containing different AR (2.90, 1.46, 0.68, 0.31, and 0.14). The trial lasted for 21 d. In this study, the growth performance was not affected by the dietary starch structure ( p > 0.05). Diets with higher amylose ratios (i.e., AR 2.90 and 1.46) led to a significant reduction of the serum glucose concentration at 3 h post-prandium ( p < 0.01), while high amylopectin diets (AR 0.31 and 0.14) significantly elevated The expression of gene s at this time point ( p < 0.01). High amylopectin diets also increased the apparent digestibility of crude protein (CP), ether extract (EE), dry matter (DM), gross energy (GE), and crude ash ( p < 0.001). Interestingly, diet rich in amylose (AR 2.90) significantly elevated the butyric acid content ( p < 0.05) and decreased the pH value ( p < 0.05) in the cecal digesta. In contrast, diet rich in amylopectin (i.e., AR 0.14) significantly elevated the total bacteria populations in the cecal digesta ( p < 0.001). Moreover, a high amylopectin diet (AR 0.14) tended to elevate the mRNA level of fatty acid synthase ( FAS , p = 0.083), but significantly decreased the mRNA level of sodium-dependent glucose transporter 1 ( SGLT1, p < 0.05) in the duodenal and jejunal mucosa, respectively. These results suggested that blood glucose and insulin concentrations were improved in high AR diets, and the diet also helped to maintain the intestinal health.

Excessive fat deposition in the liver could lead to fatty liver and an increased risk of many metabolic diseases. Apple polyphenols (APPs), the major antioxidants in apples, possess wide-ranging beneficial biological functions. The present study aimed to investigate the effects of APPs on hepatic fat deposition and antioxidant capacity in finishing pigs, and their mechanisms. Results showed that APPs improved lipid profiles, increased antioxidant enzyme activities and reduced the fat deposition in the liver. In the liver, SOD1, CAT, GPX1, GST , NF-E2-related nuclear factor 2 ( Nrf2 ), hormone sensitive lipase ( HSL ), carnitine palmitoyl transferase-1b ( CPT1b ), peroxisome proliferator-activated receptor α ( PPARα ), cholesterol 7α-hydroxylase ( CYP7A1 ) and low-density lipoprotein receptor ( LDL-R ) mRNA levels were increased by APPs, while Kelch-like ECH-associated protein 1 ( Keap1 ) mRNA level, C16:0 and C20:4n-6 proportions and Δ9-18 dehydrogenase activity were decreased. In conclusion, this study indicated that APPs might be an effective dietary supplementation for improving lipid profiles, increasing antioxidant capacities and decreasing fat deposition in the liver., Competing Interests: The authors declare no conflict of interest.

Inulin is one of the commercially feasible dietary fibers that has been implicated in regulating the gut health and metabolism of animals. This experiment was conducted to investigate the effect of dietary inulin supplementation on growth performance and meat quality in growing-finishing pigs. Thirty-six Duroc × Landrace × Yorkshire White growing barrows (22.0 ± 1.0 kg) were randomly allocated to two dietary treatments consisting of a basal control diet (CON) or basal diet supplemented with 0.5% inulin (INU). Results showed that inulin supplementation tended to increase the average daily gain (ADG) at the fattening stage (0.05 < p < 0.10). Inulin significantly increased the dressing percentage ( p < 0.05) and tended to increase the loin-eye area. The serum concentrations of insulin and IGF-I were significantly higher ( p < 0.05) in the INU group than in the CON group. Moreover, inulin supplementation significantly elevated the expression level of myosin heavy chain II b ( MyHC IIb ) in the longissimus dorsi ( p < 0.05). Inulin significantly upregulated the expression of mammalian rapamycin target protein ( mTOR ) but decreased ( p < 0.05) the expression level of muscle-specific ubiquitin ligase MuRF-1 . These results show the beneficial effect of inulin supplementation on the growth performance and carcass traits in growing-finishing pigs, and will also facilitate the application of inulin in swine production.

We conducted this experiment to determine if feeding 25-hydroxyvitamin D 3 (25(OH)D 3 ) to weaned pigs would alleviate porcine epidemic diarrhea virus (PEDV) infection and immune response. Forty-two weaned pigs were allotted to 1 of 6 dietary 25(OH)D 3 treatments (5.5, 5.5, 43.0, 80.5, 118.0, 155.5 μg 25(OH)D 3 /kg diet) for 26 days. On day 22 of the trial, all the treatments were orally administrated with PEDV except for one of the 5.5 μg 25(OH)D 3 /kg treatments, which was challenged with the same volume of sterile saline and served as control. Another 5.5 μg 25(OH)D 3 /kg group for PEDV challenge was named CON-PEDV. Average daily gain ( p < 0.05) was reduced by PEDV infection. PEDV administration also induced severe diarrhea ( p < 0.05), reduction of villous height and the ratio of villous height to crypt depth, and increase of crypt depth and serum diamine oxidase activity ( p < 0.05). Serum IgM and complement component 4 levels were increased by PEDV challenge. However, 155.5 μg 25(OH)D 3 /kg supplementation alleviated intestinal damage ( p < 0.05) compared with CON-PEDV. Furthermore, 155.5 μg 25(OH)D 3 /kg supplementation downregulated the mRNA abundance of inflammatory cytokines and interferon signal pathway-related genes ( p < 0.05) compared with CON-PEDV. These results suggested that dietary supplementation of 155.5 μg 25(OH)D 3 /kg could alleviate intestinal damage and protect against PEDV-induced inflammatory status.

This study aimed to determine the effects of dietary aged maize with supplementation of different levels of oxidized fish oil on growth performance, nutrient digestibility, serum antioxidant activity and gut health in piglets. Forty-two piglets were arranged in 2 × 3 factorial treatments in a complete randomized block design with seven replicates per treatment and one pig per replicate for 28 d. Diets included twp types of maize (normal maize or aged maize) and three levels of oxidized fish oil (OFO) (3% non-oxidized fish oil (0% OFO), 1.5% OFO and 1.5% non-oxidized fish oil (1.5% OFO), and 3% OFO (3% OFO). Results showed that dietary aged maize did not affect growth performance, diarrhea, and the apparent total tract digestibility (ATTD) of nutrients in piglets ( p > 0.05). However, aged maize increased malonaldehyde (MDA) content and decreased total antioxidant capacity (T-AOC) in serum on both 14th and 28th days ( p < 0.05) compared to the normal maize groups. Meanwhile, compared with normal maize, dietary aged maize showed a slight, but not significant ( p > 0.10) decrease in total superoxide dismutase (T-SOD) activity and VE content in serum on the 14th day. In addition, aged maize significantly decreased GLUT2 mRNA expression ( p < 0.05) and tended to increase ( p < 0.10) TNF-α and IL-6 mRNA expression in jejunal mucosa. Compared with non-oxidized fish oil, oxidized fish oil resulted in the decrease of the 14-28 d and 0-28 d ADG, as well as the ATTD of dry matter (DM), ether extract (EE), organic matter (OM) ( p < 0.05), whereas the increase in diarrhea index ( p < 0.05) and F/G of the whole period ( p < 0.05). Oxidized fish oil decreased serum T-AOC on both the 14th and the 28th days ( p < 0.05), and decreased serum T-SOD activity and VE content on the 28th day ( p < 0.05), whereas increased serum MDA content on the 28th day ( p < 0.05) and 14th day ( p < 0.10) compared with fresh fish oil. Meanwhile, MUC2 ( p < 0.05) and SGLT1 ( p < 0.10) mRNA expression in jejunal mucosa were decreased compared with non-oxidized fish oil. In addition, dietary oxidized fish oil tended to decrease 14-28 d ADFI and the ATTD of CP ( p < 0.10), and piglets fed oxidized fish oil significantly decreased 14-28 d ADFI, the ATTD of CP, GLUT2 and SGLT1 mRNA expressions in jejunal mucosa when piglet also fed with aged maize ( p < 0.05). Collectively, these results indicated that dietary oxidized fish oil decreased growth performance and nutrients digestibility of piglets fed with aged maize. This nutrient interaction may be mediated by inhibiting intestinal nutrient transporter, inducing intestinal inflammation, and reducing antioxidant capacity.

This study investigated β-glucan derived from Agrobacterium sp. ZX09 with high (2000 kDa) and low (300 kDa) molecular weight (MW) to compare their effects on growth performance and gut function in LPS-induced weaned piglets. Changes in jejunal morphology, mucosal barrier function, microbial populations, and fermentation in the piglets were determined. Data showed that β-glucan prevented body weight loss in LPS challenged piglets. Supplementation with both β-glucan fractions improved jejunal morphology. Compared to low MW, β-glucan of high MW generally up-regulated transcripts of ZO-1 , MUC1 , and MUC2 in jejunal mucosa to a lesser extent. Mucosal D-lactate, diamine oxidase, and anti-oxidation index were effectively resumed in β-glucan treatment. Both β-glucan diets provoked the emergence of a balanced microbiota and a richer concentration of volatile fatty acids in the colon. The richest community of bifidobacterium and concentration of butyrate emerged after feeding β-glucan with high MW. Results suggested that the effect of Agrobacterium sp. ZX09 β-glucans on the gut-modulatory function is largely linked to their MW. Low MW β-glucan mainly improved the mucosal barrier function in the jejunum, while high MW β-glucan had profound effects on the microbial community and fermentation in the hindgut of piglets.