High Rumen-Degradable Starch Diet Promotes Hepatic Lipolysis and Disrupts Enterohepatic Circulation of Bile Acids in Dairy Goats

Effects of rumen-degradable starch on lactation performance, gastrointestinal fermentation, and plasma metabolomic in dairy cows

This study investigated the effects of rumen-degradable starch (RDS) on lactation performance, gastrointestinal fermentation, and plasma metabolomics in dairy cows. Six mid-lactation cows, fitted with rumen, duodenum, and ileum cannulas, were used in a duplicated 3 × 3 Latin square design with 28-day periods. The cows were fed a low RDS (LRDS; 62.18 %), medium-RDS (MRDS; 71.25 %), or high-RDS (HRDS; 80.32 %) diet. The results showed that cows fed HRDS had diet a lower milk fat content by 14.77 % (LRDS) and 11.73 % (MRDS), while increased somatic cell count compared to the LRDS and MRDS groups (34.42 and 29.38 %, respectively). Additionally, rumen fluid pH was decreased in the HRDS group than in the MRDS and LRDS groups (7.81 and 7.08 %, respectively), while microbial protein (MCP) concentration was higher in the MRDS group. The HRDS group had lower concentrations of total volatile fatty acids (TVFA) and acetate in the ileal digesta than the LRDS group. The HRDS diet decreased neutral detergent fibre (NDF) digestibility compared with LRDS and MRDS groups (7.68 and 8.50 %, respectively), and reduced plasma concentrations of superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX), while increasing plasma lipopolysaccharide (LPS) and serum amyloid-A (SAA) levels. Pathway analysis revealed that starch and sucrose metabolism, galactose metabolism, and carbohydrate digestion and absorption were upregulated in the MRDS and HRDS groups. The HRDS diet had a tendency to negatively affect linoleic acid metabolism, glycerophospholipid metabolism, and alpha-linolenic acid metabolism. These findings provide insights into optimising feed efficiency and milk quality by regulating RDS levels in dairy cow diets.

Pyrroloquinoline quinone supplementation attenuates inflammatory liver injury by STAT3/TGF-β1 pathway in weaned piglets challenged with lipopolysaccharide

This study is aimed to evaluate the effect and underling mechanism of dietary supplementation with pyrroloquinoline quinone (PQQ) disodium on improving inflammatory liver injury in piglets challenged with lipopolysaccharide (LPS). A total of seventy-two crossbred barrows were allotted into four groups as follows: the CTRL group (basal diet + saline injection); the PQQ group (3 mg/kg PQQ diet + saline injection); the CTRL + LPS group (basal diet + LPS injection) and the PQQ + LPS group (3 mg/kg PQQ diet + LPS injection). On days 7, 11 and 14, piglets were challenged with LPS or saline. Blood was sampled at 4 h after the last LPS injection (day 14), and then the piglets were slaughtered and liver tissue was harvested. The results showed that the hepatic morphology was improved in the PQQ + LPS group compared with the CTRL + LPS group. PQQ supplementation decreased the level of serum inflammatory factors, aspartate aminotransferase and alanine transaminase, and increased the HDL-cholesterol concentration in piglets challenged with LPS; piglets in the PQQ + LPS group had lower liver mRNA level of inflammatory factors and protein level of α-smooth muscle actin than in the CTRL + LPS group. Besides, mRNA expression of STAT3/TGF-β1 pathway and protein level of p-STAT3(Tyr 705) were decreased, and mRNA level of PPARα and protein expression of p-AMPK in liver were increased in the PQQ + LPS group compared with the CTRL + LPS group (P < 0·05). In conclusion, dietary supplementation with PQQ alleviated inflammatory liver injury might partly via inhibition of the STAT3/TGF-β1 pathway in piglets challenged with LPS.

Effects of dietary wheat supplementation levels on growth performance, rumen bacterial community and fermentation parameters in Chinese Tibetan Sheep

The objective of this study was to evaluate various wheat supplementation levels on rumen microbiota and fermentation parameter in Tibetan sheep. A total of ninety ram with an average 12.37 ± 0.92 kg at the age of 2 months were randomly allocated to three treatments: 0% wheat diet (CW, N = 30), 10% wheat diet (LW, N = 30), and 15% wheat diet (HW, N = 30) on a dry matter basis. The experiment was conducted over a period of 127 days, including 7 days of adaption to the diets. Our results showed that sheep fed 10% wheat exhibited optimal average daily gain and feed gain ratio compared with HW group (p < 0.05). The serum alkaline phosphatase concentration was the lowest when fed the 10% wheat diet (p < 0.05), whereas serum aspartate aminotransferase concentration was the highest (p < 0.05). Both acetate and propionate increased with increase in dietary wheat ratio (p < 0.05), while a greater decrease in concentrations of NH3 -N was observed (p < 0.05). In rumen fluid, 3413 OTUs were obtained with 97% consistency. Phylum Firmicutes was the predominant bacteria and accounted for 49.04%. The CW groups supported significantly increased the abundance of Bacteroidetes (p < 0.05), as compared with the HW group. The abundance of Bacteroidales_UCG-001, Ruminococcus, and Mitsuokella possessed a higher relative abundance in HW group (p < 0.05). No differences in the bacterial community and fermentation parameters were observed between the sheep fed 0% and 10% wheat (p > 0.05). Ruminal bacterial community structure was significantly correlated with isobutyrite (r2  = 0.4878, p = 0.035) and valerate (r2  = 0.4878, p = 0.013). In conclusion, supplementation of 10% wheat in diet promoted the average daily gain and never altered microbial community structure and fermentation pattern, which can be effectively replace partial corn in Chinese Tibetan Sheep.

Multi-omics reveal mechanisms of high enteral starch diet mediated colonic dysbiosis via microbiome-host interactions in young ruminant

BACKGROUND

Although rumen development is crucial, hindgut undertakes a significant role in young ruminants' physiological development. High-starch diet is usually used to accelerate rumen development for young ruminants, but always leading to the enteral starch overload and hindgut dysbiosis. However, the mechanism behind remains unclear. The combination of colonic transcriptome, colonic luminal metabolome, and metagenome together with histological analysis was conducted using a goat model, with the aim to identify the potential molecular mechanisms behind the disrupted hindgut homeostasis by overload starch in young ruminants.

RESULT

Compared with low enteral starch diet (LES), high enteral starch diet (HES)-fed goats had significantly higher colonic pathology scores, and serum diamine oxidase activity, and meanwhile significantly decreased colonic mucosal Mucin-2 (MUC2) protein expression and fecal scores, evidencing the HES-triggered colonic systemic inflammation. The bacterial taxa Prevotella sp. P4-67, Prevotella sp. PINT, and Bacteroides sp. CAG:927, together with fungal taxa Fusarium vanettenii, Neocallimastix californiae, Fusarium sp. AF-8, Hypoxylon sp. EC38, and Fusarium pseudograminearum, and the involved microbial immune pathways including the "T cell receptor signaling pathway" were higher in the colon of HES goats. The integrated metagenome and host transcriptome analysis revealed that these taxa were associated with enhanced pathogenic ability, antigen processing and presentation, and stimulated T helper 2 cell (TH2)-mediated cytokine secretion functions in the colon of HES goats. Further luminal metabolomics analysis showed increased relative content of chenodeoxycholic acid (CDCA) and deoxycholic acid (DCA), and decreased the relative content of hypoxanthine in colonic digesta of HES goats. These altered metabolites contributed to enhancing the expression of TH2-mediated inflammatory-related cytokine secretion including GATA Binding Protein 3 (GATA3), IL-5, and IL-13. Using the linear mixed effect model, the variation of MUC2 biosynthesis explained by the colonic bacteria, bacterial functions, fungi, fungal functions, and metabolites were 21.92, 20.76, 19.43, 12.08, and 44.22%, respectively. The variation of pathology scores explained by the colonic bacterial functions, fungal functions, and metabolites were 15.35, 17.61, and 57.06%.

CONCLUSIONS

Our findings revealed that enteral starch overload can trigger interrupted hindgut host-microbiome homeostasis that led to impaired mucosal, destroyed colonic water absorption, and TH2-mediated inflammatory process. Except for the colonic metabolites mostly contribute to the impaired mucosa, the nonnegligible contribution from fungi deserves more future studies focused on the fungal functions in hindgut dysbiosis of young ruminants. Video Abstract.

The impact of different levels of wheat diets on hepatic oxidative stress, immune response, and lipid metabolism in Tibetan sheep (Ovis aries)

BACKGROUND

Compared with corn, wheat contains higher crude protein, amino acids concentration. However, wheat contains a mass of anti-nutritional factors, resulting in increased of the digesta viscosity and impaired the intestinal function in ruminant.

OBJECTIVE

This study aimed to investigate the effects of substitution of different amounts of wheat for corn on hepatic metabolism in the Tibetan lamb.

METHODS

Ninety Tibetan lambs (Body weight = 12.37 ± 0.92 kg) were randomly assigned to three groups: 0% wheat diet (Control), 10% wheat diet (Low group), and 15% wheat diet (High group). The feeding trial lasted for 130 d, including a 10 d adaption period. Hepatic gene expression profiling was performed via RNA sequencing after the conclusion of the feeding trials.

RESULTS

Results showed that greater level of glutathione peroxidase levels in L group compared with those of the C and H groups (P < 0.05). The immune indexes, including interleukin-1β (IL-1β), immunoglobulin A (IgA), and IgM were also elevated in L group compared with the other groups (P < 0.05). Compared with H group, the hepatocytes were arranged radially, and hepatic plates anastomosed with each other to form a labyrinth-like structure in L group. Transcriptomic analysis showed 872 differentially expressed genes (DEG) between H and L group, of which 755 were down-regulated and 117 were up-regulated. Through Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis, 32 pathways were significantly enriched (Q-value < 0.05), such as the cAMP signaling pathway, Th1 and Th2 cell differentiation, leukocyte transendothelial migration, platelet activation and adipocytokine signaling pathway. Additionally, the expression of comment DEGs were verified via quantitative reverse-transcription polymerase chain reaction.

CONCLUSION

In summary, our findings suggest that wheat can be supplemented up to 10% in Tibetan sheep, contributing to improve the hepatic oxidative stress, immune response and lipid metabolism through regulating the expression of related genes.

Low rumen degradable starch promotes the growth performance of goats by increasing protein synthesis in skeletal muscle via the AMPK-mTOR pathway

Since starch digestion in the small intestine provides more energy than digestion in the rumen of ruminants, reducing dietary rumen degradable starch (RDS) content is beneficial for improving energy utilization of starch in ruminants. The present study tested whether the reduction of rumen degradable starch by restricting dietary corn processing for growing goats could improve growth performance, and further investigated the possible underlying mechanism. In this study, twenty-four 12-wk-old goats were selected and randomly allocated to receive either a high RDS diet (HRDS, crushed corn-based concentrate, the mean of particle sizes of corn grain = 1.64 mm, n = 12) or a low RDS diet (LRDS, non-processed corn-based concentrate, the mean of particle sizes of corn grain >8 mm, n = 12). Growth performance, carcass traits, plasma biochemical indices, gene expression of glucose and amino acid transporters, and protein expression of the AMPK-mTOR pathway were measured. Compared to the HRDS, LRDS tended to increase the average daily gain (ADG, P = 0.054) and decreased the feed-to-gain ratio (F/G, P < 0.05). Furthermore, LRDS increased the net lean tissue rate (P < 0.01), protein content (P < 0.05) and total free amino acids (P < 0.05) in the biceps femoris (BF) muscle of goats. LRDS increased the glucose concentration (P < 0.01), but reduced total amino acid concentration (P < 0.05) and tended to reduce blood urea nitrogen (BUN) concentration (P = 0.062) in plasma of goats. The mRNA expression of insulin receptors (INSR), glucose transporter 4 (GLUT4), L-type amino acid transporter 1 (LAT1) and 4F2 heavy chain (4F2hc) in BF muscle, and sodium-glucose cotransporters 1 (SGLT1) and glucose transporter 2 (GLUT2) in the small intestine were significantly increased (P < 0.05) in LRDS goats. LRDS also led to marked activation of p70-S6 kinase (S6K) (P < 0.05), but lower activation of AMP-activated protein kinase (AMPK) (P < 0.05) and eukaryotic initiation factor 2α (P < 0.01). Our findings suggested that reducing the content of dietary RDS enhanced postruminal starch digestion and increased plasma glucose, thereby improving amino acid utilization and promoting protein synthesis in the skeletal muscle of goats via the AMPK-mTOR pathway. These changes may contribute to improvement in growth performance and carcass traits in LRDS goats.

High-Grain Diet Feeding Altered Blood Metabolites, Rumen Microbiome, and Metabolomics of Yaks

Currently, information available on the comprehensive changes in the rumen bacteria and metabolites of yaks fed high-grain diets is limited. This study aimed to investigate the effects of high-grain diet feeding on the blood metabolites, rumen microbiome, and metabolomics of yaks by using 16S rDNA gene sequencing and liquid chromatography–mass spectrometry (LC/MS). Here, fourteen healthy male yaks (body weight, 249.61 ± 8.13 kg) were randomly assigned to two different diets: a hay diet (0% grain, CON, n = 7), or a high-grain diet (70% grain, HG, n = 7). At the 74th day of treatment, blood and ruminal fluid samples were collected for the blood metabolites, rumen microbiome, and metabolomics analyses. The HG diet increased lipopolysaccharides (LPS), aspartate aminotransferase (AST), gamma-glutamyltransferase (GGT), haptoglobin (HPT), serum amyloid-A (SAA), interleukin-1β (IL1-β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) serum concentrations (p < 0.05). Compared with the CON diet, the HG diet decreased rumen pH (p < 0.05), and increased total volatile fatty acids concentration, and proportion of butyrate (p < 0.05). The relative abundance of Firmicutes and Saccharibacteria were higher (p < 0.05), while Bacteroidetes was lower (p < 0.05) in the HG group than those in the CON group. At the genus level, the relative abundance of Christensenelaceae_R-7_group, Ruminococcaceae_NK4A214_group, Lachnospiraceae_NK3A20_group, and Acetitomaculum were higher than in those in the HG diet (p < 0.05). Compared with the CON group, the HG diet increased the concentrations of biogenic amines (histamine, tyramine, and putrescine), common amino acids (phenylalanine, threonine, serine, etc.), and arachidonic acid (prostaglandin H2, prostaglandin E2, 12(S)-HPETE, etc.). Collectively, these findings demonstrate that the HG diet altered the microbiota and metabolites, as well as potentially damaged their rumen health and induced inflammation in yaks.

High-grain diet feeding alters ileal microbiota and disrupts bile acid metabolism in lactating dairy cows

Bile acids (BAs) play an important role in the regulation of lipid metabolic homeostasis, but little is known about their metabolism in dairy cows fed a high-grain (HG) diet. In the present study, we examined the bacterial community, BA profile, and the FXR/FGF19 signaling pathway in the ileum and liver to investigate the gut microbe-BA metabolism interactions response to HG diet and the changes in the subsequent enterohepatic circulation of dairy cows. The results showed that the ileal bacterial community was altered, with an increase of Paraclostridium, Anaerobutyricum, Shuttleworthia, and Stomatobaculum in the relative abundance in the HG group. Moreover, real-time polymerase chain reaction (PCR) showed that the abundance of total bacteria and bacterial bile-salt hydrolase (BSH) genes was increased in the ileal digesta in the HG group. Meanwhile, HG feeding also decreased the total BA content in the digesta of jejunum and ileum and in feces. HG feeding altered the BA profile in the ileal digesta by increasing unconjugated BAs and decreasing conjugated BAs. In addition, the intestinal FXR/FGF19 signaling pathway was activated. The expression of CYP7A1 (cholesterol 7α-hydroxylase) was depressed, which inhibited BAs synthesis in the liver of cows fed HG. Overall, HG feeding altered the ileal bacterial community and BA profile, and activated FXR/FGF19 signaling pathway, resulting in a decrease of BA level in the ileal digesta via the inhibition of hepatic BA synthesis. The findings provided novel insights into understanding the relationship between gut microbiota and the homeostasis of BAs in dairy cows fed a HG diet.

Supplementing a Clay Mineral-Based Feed Additive Modulated Fecal Microbiota Composition, Liver Health, and Lipid Serum Metabolome in Dairy Cows Fed Starch-Rich Diets

Starch-rich diets are a commonly adopted strategy in order to sustain high milk yields in dairy cows. However, these diets are known to increase the risk of gut dysbiosis and related systemic health disorders. This study aimed to evaluate the effects of supplementing a clay mineral-based feed additive (CM; Mycofix® Plus, BIOMIN) on fecal microbiota structure, fecal short-chain fatty acid (SCFA) fermentation, serum metabolome, and liver health in primiparous (PP, n = 8) and multiparous (MP, n = 16) early-lactation Simmental cows (737 ± 90 kg of live body weight). Cows were randomly assigned to either a control or CM group (55 g per cow and day) and transitioned from a diet moderate in starch (26.3 ± 1.0%) to a high starch diet (32.0 ± 0.8%). Supplementation of CM reversed the decrease in bacterial diversity, richness, and evenness (p < 0.05) during high-starch diet, demonstrating that CM supplementation efficiently eased hindgut dysbiosis. The CM treatment reduced levels of Lactobacillus in PP cows during starch-rich feeding and elevated fecal pH, indicating a healthier hindgut milieu compared with that in control. Butyrate and propionate levels were modulated by CM supplementation, with butyrate being lower in CM-treated MP cows, whereas propionate was lower in MP but higher in PP cows. Supplementing CM during high-starch feeding increased the concentrations of the main primary bile salts and secondary bile acids in the serum and improved liver function in cows as indicated by reduced levels of glutamate dehydrogenase and γ-glutamyl-transferase, as well as higher serum albumin and triglyceride concentrations. These changes and those related to lipid serum metabolome were more pronounced in PP cows as also corroborated by relevance network analysis.

Mucosal Microbiota and Metabolome in the Ileum of Hu Sheep Offered a Low-Grain, Pelleted or Non-pelleted High-Grain Diet

Alterations in mucosal microbiota and metabolites are critical to intestinal homeostasis and host health. This study used a combination of 16S rRNA gene sequencing and liquid chromatography-mass spectrometry (LC/MS) to investigate mucosal microbiota and their metabolic profiles in the ileum of Hu sheep fed different diets. Here, we randomly allocated 15 Hu sheep to three diets, a non-pelleted low-grain diet (control diet; CON), a non-pelleted high-grain diet (HG), and a pelleted high-grain diet (HP). After 60 days of treatment, ileal mucosal samples were collected for microbiome and metabolome analysis. The results of principal coordinate analysis and permutation multivariate analysis showed that there was a tendency for microbial differentiation between the CON and HG groups (P < 0.1), although no significant difference between the HG and HP groups was observed (P > 0.05). Compared with the CON diet, the HG diet decreased (P < 0.05) the abundance of some probiotic species (e.g., Sphingomonas and Candidatus Arthromitus) and increased (P < 0.05) the abundance of acid-producing microbiota (e.g., Succiniclasticum, Nesterenkonia, and Alloprevotella) in the ileal mucosa. Compared with the HG diet, the HP diet decreased (P < 0.05) the abundance of Alloprevotella and increased (P < 0.05) the abundance of Mycoplasma in the ileal mucosa. Furthermore, partial least squares discriminant analysis and orthogonal partial least-squared discriminant analysis indicated that different dietary treatments resulted in different metabolic patterns in the ileal mucosa of the CON, HG, and HP groups. The HG diet altered (VIP > 1 and P < 0.05) the metabolic patterns of amino acids, fatty acids, and nucleotides/nucleosides (such as increased amounts of ornithine, tyrosine, cis-9-palmitoleic acid, and adenosine) compared with the CON diet. However, 10 differential metabolites (VIP > 1 and P < 0.05; including tyrosine, ornithine, and cis-9-palmitoleic acid) identified in the HG group exhibited a diametrically opposite trend in the HP group, suggesting that the HP diet could partially eliminate the changes brought upon by the HG diet. Collectively, our findings demonstrate that different diets altered the ileal mucosal microbiota and metabolites and provide new insight into the effects of high-grain diets on the intestinal health of ruminant animals.

A Metagenomic Insight Into the Hindgut Microbiota and Their Metabolites for Dairy Goats Fed Different Rumen Degradable Starch

High starch diets have been proven to increase the risk of hindgut acidosis in high-yielding dairy animals. As an effective measurement of dietary carbohydrate for ruminants, studies on rumen degradable starch (RDS) and the effects on the gut microbiota diversity of carbohydrate-active enzymes (CAZymes), and Kyoto Encyclopedia of Genes and Genomes (KEGG) Orthology functional categories are helpful to understand the mechanisms between gut microbiota and carbohydrate metabolism in dairy goats. A total of 18 lactating goats (45.8 ± 1.54 kg) were randomly divided equally into three dietary treatments with low dietary RDS concentrations of 20.52% (LRDS), medium RDS of 22.15% (MRDS), and high RDS of 24.88% (HRDS) on a DM basis for 5 weeks. Compared with the LRDS and MRDS groups, HRDS increased acetate molar proportion in the cecum. For the HRDS group, the abundance of family Ruminococcaceae and genus Ruminococcaceae UCG-010 were significantly increased in the cecum. For the LRDS group, the butyrate molar proportion and the abundance of butyrate producer family Bacteroidale_S24-7, family Lachnospiraceae, and genus Bacteroidale_S24-7_group were significantly increased in the cecum. Based on the BugBase phenotypic prediction, the microbial oxidative stress tolerant and decreased potentially pathogenic in the LRDS group were increased in the cecum compared with the HRDS group. A metagenomic study on cecal bacteria revealed that dietary RDS level could affect carbohydrate metabolism by increasing the glycoside hydrolase 95 (GH95) family and cellulase enzyme (EC 3.2.1.4) in the HRDS group; increasing the GH13_20 family and isoamylase enzyme (EC 3.2.1.68) in the LRDS group. PROBIO probiotics database showed the relative gene abundance of cecal probiotics significantly decreased in the HRDS group. Furthermore, goats fed the HRDS diet had a lower protein expression of Muc2, and greater expression RNA of interleukin-1β and secretory immunoglobulin A in cecal mucosa than did goats fed the LRDS diet. Combined with the information from previous results from rumen, dietary RDS level altered the degradation position of carbohydrates in the gastrointestinal (GI) tract and increased the relative abundance of gene encoded enzymes degrading cellulose in the HRDS group in the cecum of dairy goats. This study revealed that the HRDS diet could bring disturbances to the microbial communities network containing taxa of the Lachnospiraceae and Ruminococcaceae and damage the mucus layer and inflammation in the cecum of dairy goats.