Nutrition consistently affects microbe-host interactions in the gastrointestinal tract. This study aimed to unravel how undernutrition reshapes the microbial composition and the homeostasis of epithelium in the jejunum and ileum. Sixteen late-gestation Hu-sheep were randomly assigned to the control group (n = 8, 100% ad libitum feeding levels) or the undernutrition group (n = 8, which received 30% ad libitum feeding levels). After 15-d treatment, all ewes were slaughtered, and jejunal and ileal digesta and epithelium samples were collected for 16S rRNA gene sequencing and transcriptome sequencing, respectively. Results indicated that undernutrition decreased the jejunal and ileal tissue weights (P = 0.005 and P = 0.022) and the levels of volatile fatty acids (P = 0.019 and P = 0.007) and microbial protein levels (P = 0.019 and P = 0.031) in jejunal and ileal digesta. The relative abundance of acetate producing microbiota, including Clostridia UCG-014 norank, Ruminococcus, [Ruminococcus] gauvreauii, and Lachnospiraceae_Blautia, were significantly reduced (P < 0.05) in the jejunum and ileum. Undernutrition up-regulated (P < 0.05) the expression of genes involved in amino acid synthesis and fatty acid oxidation, but down-regulated (P < 0.05) the expression of genes associated with amino acid degradation, fatty acid synthesis, and extracellular structures in jejunal and ileal epithelium. In the jejunal epithelium, genes associated with extracellular matrix–receptor interactions, cell growth, and immune response were down-regulated (P < 0.05) upon undernutrition. Taken together, undernutrition changed the microbial community in the jejunum and ileum, which altered the fermentation mode and the production of volatile fatty acids and microbial protein. These affected the energy and protein system in the epithelium and reprogrammed substance metabolism and extracellular structures, which probably further influenced cell growth and immune response. These insights provide a foundation for completely clarifying the crosstalk between small intestinal microbiota and the host.

An 8-week feeding trial was conducted to investigate the effects of replacing dietary fish oil (FO) with black soldier fly larval oil (BSFO) on growth performance, antioxidant and immune response, lipid metabolism and mitochondrial function of the juvenile mud crab. A total of 160 mud crabs (18.58 ± 0.02 g) were randomly distributed into five treatments spread across 160 aquaria. There were 4 replicates per treatment and 8 crabs per replicate. The basal diet (Control) contained 3% fish oil and fish oil was replaced with BSFO at 25%, 50%, 75%, and 100% in the remaining four treatments. The results showed that when the proportion of BSFO replacing FO was less than 50%, there were no significant differences in percent weight gain (PWG), specific growth rate (SGR) and feed efficiency (FE) between the experimental and the control groups (P > 0.05); however, PWG and SGR decreased as the percentage of substitution increased from 50% to 100% (P < 0.01). When the percentage of substitution was less than 50%, the expression levels of genes related to lipid synthesis and catabolism were significantly up-regulated and down-regulated, respectively (P < 0.05). When 25% and 50% FO were replaced with BSFO, the antioxidant and immune responses enhanced (P < 0.05), and antioxidant and immune-related enzyme activities and metabolite concentrations in the hemolymph and hepatopancreas significantly increased (P < 0.05), and the concentrations of malondialdehyde (MDA) and protein carbonyl (PC), and the apoptosis index in the hepatopancreas significantly decreased (P < 0.05). Moreover, mitochondrial function indexes in the hepatopancreas, such as mitochondrial DNA copy number and expression levels of energy metabolism-related genes were significantly up-regulated (P < 0.05). Hepatopancreas mitochondria were more abundant in crabs fed diets with 25% and 50% replacement of FO with BSFO, while adenosine triphosphate content was the highest in 25% FO replacement group (P = 0.003). In summary, the results of the present study demonstrated that the replacement of FO with BSFO at less than 50% (i.e. in-feed BSFO level of 1.5%) did not negatively affect the growth performance of mud crabs, and could improve the antioxidant capacity, immune response, and enhance mitochondrial function.

The current study aims to investigate the potential interaction between glycosylation profiles of the Ningxiang breed (NX) and Western Duroc × Landrace × Yorkshire breed (DLY) weaned piglets, and their characteristic microbes, employing integrated analyses of transcriptomics and metagenomics. Twenty-four (12 NX and 12 DLY) at 28 days of age were transported into an experimental house and fed the same weaned piglet diet. The trail period was 7 days. Results revealed that the NX piglets had a higher growth-to-feed ratio, body weight gain scale, and lower pathological score of intestinal injury compared with the DLY piglets (P < 0.01). DLY piglets displayed elevated mRNA expression levels of MUC2 and MUC5AC in colonic mucosal tissue than NX piglets (P < 0.05). Within the O-linked glycosylated differentially expressed genes (DEGs), FNTA, GALNT18, POMGNT1, POMGNT2, and POMT1 were significantly upregulated in DLY piglets relative to NX piglets (P < 0.05). Conversely, C1GALT2, GALNT1, KMT2C, and OGT were significantly downregulated in DLY piglets compared to NX piglets (P < 0.05). The KMT2C gene was hardly expressed in the transcriptome of DLY piglets. At the phylum taxonomic level, NX piglets had a higher abundance of Firmicutes, while DLY piglets had a higher abundance of Proteobacteria. At the genus taxonomic level, NX piglets had a higher abundance of Lactobacillus, whereas DLY piglets had a higher abundance of Collinsella, Enterococcus and Escherichia. The results of the correlation between intestinal differential bacteria and O-chain glycosylated DEG showed that C1GALT2, GALNT1 and KMT2 were associated with Lactobacillus_pontis showed a positive correlation (R = 0.67). Through comparative analysis of differentially glycosylated genes and their associated functions, this study highlights the potential role of reduced expression of GALNT1 and KMT2C genes, involved in O-linked protein and glycan reactions, in impairing the intestinal barrier function of DLY piglets. Furthermore, members of the Lactobacillus and Prevotella genera may actively contribute to the regulation of piglet colon glycosylation profiles.

The synchronized absorption of amino acids and glucose in the gut is essential for amino acid utilization and protein synthesis in the body. The study aimed to investigate how the starch digestion rate and amino acid levels impact the growth and intestinal starch and amino acid digestion, transport, and metabolism in juvenile broilers. The experiment was conducted with 702 Arbor Acres Plus broilers at 1 d old, which were randomly divided into 9 treatments with 6 replicates of 13 chickens each. The treatments included 3 different starch sources (corn, waxy corn, and tapioca) with 3 different apparent ileal digestible lysine (AID Lys) levels (1.08%, 1.20%, and 1.32%). A notable interaction was noted for dietary starch sources and AID Lys levels in the feed-to-gain ratio (F/G) and distal ileal starch digestibility (P < 0.01). The tapioca starch and waxy corn starch diets with 1.32% of AID Lys significantly decreased F/G compared with corn starch (P < 0.01). There was no significant difference in F/G of broilers among waxy corn starch diet with 1.08% AID Lys level, tapioca starch diet with 1.20% AID Lys level, and corn starch diet with 1.32% AID Lys level (P > 0.05). The 1.32% AID Lys level and the waxy corn starch both improved the body weight (BW) of broilers from 0 to 3 weeks of age, intestinal starch digestibility, and intestinal villi height or the ratio of villi height to crypt depth (P < 0.05). Compared with the corn starch diet, waxy corn starch and tapioca starch diets significantly elevated the AID of Met, Glu, Lys, Arg, Asp, His, Ile, Tyr, Gly, and Val levels (P < 0.05). The carbon metabolomics results revealed that the waxy corn starch diet significantly reduced malic acid and cis-aconitic acid levels (P < 0.05) in the tricarboxylic acid cycle compared to the corn starch diet. It was concluded that a waxy corn starch diet improves the growth performance of broilers by improving intestinal morphology, increasing the absorption and transport of amino acids, reducing the amino acid oxidation for energy supply in the intestinal mucosa, and promoting protein synthesis in muscles, which not only reduces the need for dietary AID Lys but also saves on production costs.

Grape seed proanthocyanidin (GSP) is a type of plant polyphenol with a wide variety of biological activities, such as antioxidant properties. This study investigated the effects of GSP supplementation on growth performance and meat quality in growing-finishing pigs. A total of 180 pigs (with an initial average body weight of 30.37 ± 0.66 kg) were randomly assigned to five treatments: a control diet or a control diet supplemented with GSP at 15, 30, 60, and 120 mg/kg. Each treatment group comprised six replicate pens (6 pigs per pen). Results showed that GSP supplementation linearly increased the average daily gain (P = 0.048) and quadratically decreased the feed intake to gain ratio (P = 0.049) with the lowest values at 30 and 60 mg/kg GSP. Serum concentrations of immunoglobulins (Ig) (IgA, IgG, IgM), total antioxidative capacity, catalase, and total superoxide dismutase were elevated with the peak levels at 30 mg/kg GSP (P < 0.05). Serum glutathione peroxidase increased and malondialdehyde decreased quadratically (P < 0.05), with peak and trough levels at 120 and 60 mg/kg GSP, respectively. The GSP also improved dressing percentage and muscle redness (a^*_{45 min}) with optimal levels at 30 and 60 mg/kg (P < 0.05). Additionally, GSP supplementation quadratically reduced the muscle yellowness (b^*_{24 h}) and shear force (P < 0.05), with the lowest values at 120 mg/kg. The expression level of myosin heavy chain I in muscle was quadratically increased with maximum expression at 30 and 60 mg/kg (P = 0.015). Furthermore, the expression levels of fatty acid synthase, phosphoenolpyruvate carboxykinase (PEPCK), and glucokinase in the muscle were decreased quadratically (P < 0.05) with the lowest values at 120 mg/kg. Additionally, GSP supplementation at 60 mg/kg upregulated the expression of hepatic hormone-sensitive triglyceride lipase and PEPCK (P < 0.05). These results suggest that GSP enhances carcass characteristics and meat quality in growing-finishing pigs, potentially through improved antioxidative capacity, modified muscle fiber type distribution, and altered glucose-lipid metabolism in muscle and liver.

During the growing period, the gastrointestinal tract of layer pullets is not yet well developed and may be susceptible to dietary energy level. The energy level and composition might impact the intestinal energy metabolism of layer pullets. To test this hypothesis, a total of 480 “Jing Tint 6” layer pullets were used in an 8-week study and allocated to 4 groups, each consisting of 8 replicates, with 15 birds per replicate. Pullets were treated with low or high starch:fat ratios (LS, 10:1; HS, 20:1) in a 2 × 2 factorial arrangement with regular energy (RE, 11.85 and 11.68 MJ/kg for birds from 6 to 10 weeks of age and 11-14 weeks of age, respectively) or low energy (LE, 0.55 MJ/kg lower than RE) levels. A significant interaction (P < 0.05) showed that HS increased glandular stomach weight and the jejunal villus length to crypt depth ratio (VCR) in LE diets, but decreased these parameters in RE diets. Dietary energy reduction impaired energy metabolism in the ileum (P < 0.05) mainly via decreasing the gene expression of enzymes involved in the tricarboxylic acid (TCA) cycle (α-ketoglutarate dehydrogenase complex [α-KGDH]; isocitrate dehydrogenase (NAD (+) [IDH] catalytic; citrate synthase [CS]) and adenosine triphosphate (ATP) synthesis, reducing contents of phosphoenolpyruvate (PEP) and adenylate energy charges (AEC) and down-regulating the adenosine monophosphate-activated protein kinase (AMPK) pathway. HS stimulated AMPKα phosphorylation, increased protein abundance of peroxisome proliferator activated-receptor gamma coactivator 1α (PGC1α) and improved contents of amino acids (aspartate, glutamate, glutamine, alanine and threonine) and malate in the ileum regardless of energy levels (P < 0.05). By an interaction (P < 0.05), the transition from LS to HS diets up-regulated ileal gene expression of AMPKα1 and decreased content of adenosine monophosphate (AMP), accompanied by higher AEC but only in birds fed with LE diets. Collectively, these results suggest that low energy feeding may not be enough for maintaining intestinal energy homeostasis in layer pullets and emphasizes the importance of a relatively high starch:fat ratio in restoring energy metabolism in the ileum.

Scutellariae radix flavonoid extract (SFE) has been acknowledged for its antioxidant, anti-inflammatory and antimicrobial properties in enhancing gastrointestinal microbial communities and improving the host’s immunity. Nevertheless, the impacts of dietary supplementation with SFE on the gastrointestinal microbes and host metabolism in dairy cows remain uncertain. Therefore, the aim of this study was to assess the effects of dietary supplementation with SFE on the lactation performance, gastrointestinal microbes, and plasma biochemical parameters of dairy cows. Six ruminally and duodenally cannulated multiparous dairy cows were used in a crossover design over 28-d periods that included a 21-d adaptation and a 7-d sample collection period. Cows were fed a basal diet (CON group) or a basal diet supplemented with SFE at 25 g/d (SFE group). SFE supplementation tended to increase milk yield (P = 0.067) and milk urea N concentration (P = 0.079), and decreased the milk somatic cell counts (SCC, P = 0.036). Cows in the SFE group had lower plasma aspartate aminotransferase (AST), malondialdehyde (MDA), tumor necrosis factor (TNF-α), and interleukin-1β concentrations compared with the CON (P < 0.05). Meanwhile, SFE supplementation increased butyrate concentration in the rumen (P = 0.044). The microbial structure of rumen and duodenum were affected by SFE supplementation (P = 0.009 and P = 0.031; respectively), resulting in enrichment of Butyrivibrio in both parts of the SFE cows (P = 0.034 and P = 0.029; respectively). However, microbial structure and composition of feces were not affected by SFE supplementation. Overall, our study indicated that dietary supplementation with SFE could enhance lactation performance and milk quality in dairy cows by improving the gastrointestinal inner environment and health status.

The intensifying global warming may increase the impact of heat stress on the dairy industry. Our previous study showed that chromium yeast (CY) alleviated the negative effects of heat stress and improved the lactation performance by increasing milk protein content and yield in mid-lactation dairy cows. This study further investigated whether the increased milk protein after CY supplementation results from the promotion of microbial crude protein (MCP) synthesis by regulating rumen microorganisms and amino acid metabolites. Twelve heat-stressed dairy cows were divided into two treatment groups: one with CY supplementation (0.36 mg Cr/kg DM) and the other without CY supplementation. Samples were collected after eight weeks of formal experiment in a hot summer with the mean temperature-humidity index of 79.0 ± 3.13. Dietary CY supplementation did not affect rumen pH, total volatile fatty acid, acetate, propionate, isobutyrate, butyrate, isovalerate, and valerate, but increased ruminal MCP concentration (P < 0.05). Simultaneously, the alpha or beta diversity of rumen microbial bacteria were not influenced by CY supplementation. At genus level, supplementation with CY increased the relative abundances of Olsenella, Lachnospiraceae_UCG-002, and Shuttleworthia (P < 0.05) and decreased those of Enterobacter, Escherichia-Shigella, Oribacterium, and Bacteroidetes_BD2-2 (P < 0.05). There were 17 up-regulated and 57 down-regulated differential metabolites in the CON and CY groups. The partial least-squares discriminant analysis (PLS-DA) and orthogonal partial least-squares discriminant analysis (OPLS-DA) scores clearly distinguished the two groups. Chromium yeast supplementation reduced the concentrations of D-(+)-proline, DL-glutamic acid, DL-lysine, Gly-l-pro, L-(−)-serine, L-(+)-alanine, and L-(+)-aspartic acid (P < 0.05) in the ruminal fluid, which were involved in arginine biosynthesis (P = 0.029), glutathione metabolism (P = 0.047), lysine degradation (P = 0.069), and D-amino acid metabolism (P = 0.084). Spearman correlation analysis showed that milk protein content was positively correlated with MCP and negatively correlated with amino acid concentrations in the ruminal fluid (P < 0.05). Collectively, CY supplementation promoted the utilization of amino acids by rumen microorganisms to synthesize MCP, thereby increasing milk protein content and yield in heat-stressed dairy cows.

Antarctic krill meal (KM) (Euphausia superba) as a substitute for fishmeal in aquatic animal diets is gaining popularity worldwide. A quantitative approach investigating the efficacy of using this protein on the production performance of aquatic animals remains widely limited. Here, we employed a meta-analysis to quantify the overall effects (Hedges’g [g] value effect size) of KM on the specific growth rate (SGR), feed conversion ratio (FCR), protein efficiency ratio (PER), and survival rate (SR) of several aquaculture species. A total of 22 records published during 2006 to 2022 from different countries, targeting 14 aquatic species, were employed in the present study. Overall, KM has a high nutritional value relative to fishmeal, particularly from the high protein and amino acid composition. Dietary KM significantly increased the overall effect size of SGR (g = 1.92) (P = 0.001); the positive effect was illustrated in marine species (g = 1.32 to 9.10) (P < 0.05) and sturgeon (Acipenser gueldenstaedtii) (g = 6.59) (P < 0.001). The overall g value for FCR (–2.42) was significantly improved compared to the control group (P < 0.001). The inclusion of KM in aquatic animal diets did not affect g value of PER (1.52, 95% confidence interval: –1.04 to 4.07) and survival rate (0.08, 95% confidence interval: –0.63 to 0.79) (P = 0.252 and 0.208, respectively). The meta-regression models indicated that SGR of rainbow trout (Oncorhynchus mykiss) was significantly correlated with dietary KM by a positive linear model (P = 0.022). The cod and sturgeon (A. gueldenstaedtii) appeared to efficiently utilize krill-containing diets as illustrated by a negative linear model (P = 0.011 and P = 0.024, respectively) between dietary KM and FCR. Dietary KM positively correlated with PER for Atlantic cod (P = 0.021). Our meta-analysis highlighted the significant outcome of KM in diets for aquaculture species by reducing pressure on forage fish from marine resources and sparing edible foods. Specifically, including KM significantly reduced economic fish-in fish-out (eFIFO) in four taxa—the top forage fish consumers (P < 0.05): marine fish, salmon, shrimp, and trout. The meta-analysis revealed the decreased food-competition feedstuff in diets for important aquaculture species (P < 0.05) fed dietary KM. The outlook for efficient use of KM from marine resources in aquafeeds was elucidated in the present work.

This study evaluated the effect of maternal glycerol monolaurate (GML) supplementation during late gestation and lactation on sow reproductive performance, transfer of immunity and redox status, milk fat and fatty acid profile, and fecal microbiota. Eighty multiparous sows (Landrace × Large white) were randomly allocated to two treatment groups (with or without 1000 mg/kg GML) with 40 replicates per treatment. The feeding experiment lasted from d 85 of gestation (G85) to d 23 of lactation (L23). The samples were collected on d 1 (L1) and 21 (L21) of lactation. Our results showed that maternal GML supplementation significantly increased litter weight (P = 0.002), average daily gain of piglets (P = 0.048), and sow average daily feed intake (P = 0.032). Compared with CON group, the concentrations of lauric acid (C12:0; P = 0.022), C16:0 (P = 0.001), and total saturated fatty acids (P = 0.006) in colostrum as well as C12:0 in L21 milk (P = 0.001) were higher in GML group. Besides, the concentrations of immunoglobulin A (IgA) and IgG in colostrum as well as sow and piglet plasma, the total antioxidant capacity and superoxide dismutase activity in sow colostrum were also significantly higher in the GML group (P < 0.05). Microbiome results showed that GML addition increased fecal microbial alpha diversity as well as the relative abundances of short chain fatty acids producing bacteria Ruminococcaceae and Parabacteroides; and decreased the harmful Proteobacteria of sows (P < 0.05). The Spearman analysis showed that the microbial biomarkers Prevotellaceae, Ruminococcaceae, and Parabacteroides were positively correlated with IgA and IgG of sow plasma and milk (P < 0.05). Besides, maternal GML addition up-regulated the relative protein expressions of proliferating cell nuclear antigen, cyclin D1, G protein-coupled receptor 84 (GPR84) and phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) pathway in the duodenum and jejunum of piglets. Collectively, current findings suggested that maternal GML supplementation enhanced piglet growth during lactation, which might be associated with improving milk fat and lauric acid contents, microbiota derived immunoglobulins transfer, and gut health through potential involvement of GPR84 and PI3K/Akt signaling pathway.