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Inflammatory bowel disease (IBD) is a global health problem in which metabolite alteration plays an important pathogenic role.

The internal environment of the cow's udder directly affects the udder health and milk quality. 16S rDNA sequencing and liquid chromatography-mass spectrometry (LC-MS) methods were used to investigate the significant differences in milk microbial diversity and metabolites among cows that are healthy (H) and those suffering from subclinical mastitis (SM) and clinical mastitis (CM). Results uncovered more than 16 and 192 differently abundant microbiota at the phylum and genus levels, respectively, and 673 different levels of metabolites enriched in 20 pathways in milk among the 3 groups. This study revealed the positive relevance between Staphylococcus and Streptococcus and ceramide in milk from CM cows. Similarly, Acinetobacter and Corynebacterium were positively associated with testosterone glucuronide and 5-methyl-tetrahydrofolate, in milk from SM cows. On the basis of the combined analysis of microbiome and metabolome, this study indicated that, apart from the exogenous pathogens, some beneficial symbiotic bacteria, such as Dietzia, Aeromicrobium, Alistipes, and Sphingobacterium, rarely reported in milk have been found to be significantly reduced during mastitis.

Evidence shows that effective nutritional intervention can prevent or mitigate the risk and morbidity of inflammatory bowel disease (IBD). Bovine milk extracellular vesicles (mEVs), a major bioactive constituent of milk, play an important role in maintaining intestinal health. The aims of this study were to assess the effects of mEV pre-supplementation on the colonic transcriptome and proteome in dextran sulphate sodium (DSS)-induced acute colitis, in order to understand the underlying molecular mechanisms of mEV protection against acute colitis. Our results revealed that dietary mEV supplementation alleviated the severity of acute colitis, as evidenced by the reduced disease activity index scores, histological damage, and infiltration of inflammatory cells. In addition, transcriptome profiling analysis found that oral mEVs significantly reduced the expression of pro-inflammatory cytokines (IL-1β, IL-6, IL-17A and IL-33), chemokine ligands (CXCL1, CXCL2, CXCL3, CXCL5, CCL3 and CCL11) and chemokine receptors (CXCR2 and CCR3). Moreover, oral mEVs up-regulated 109 proteins and down-regulated 150 proteins in the DSS-induced murine model, which were involved in modulating amino acid metabolism and lipid metabolism. Collectively, this study might provide new insights for identifying potential targets for the therapeutic effects of mEVs on colitis.

The compound 3-nitrooxypropanol (3-NOP) is a promising methane inhibitor, which performs well in inhibiting methane emission and does not affect animal feed intake and digestibility. However, it causes a significant increase in hydrogen production while suppressing methane emission, resulting in a waste of feed energy. Vitamin B

3-Nitrooxypropanol (3-NOP) is effective at reducing ruminal methane emissions in ruminants. But it also causes a drastic increase in hydrogen accumulation, resulting in feed energy waste. Fumarate is a key precursor for propionate formation and plays an important role in rumen hydrogen metabolism. Therefore, this study examined the effects of 3-NOP combined with fumarate on volatile fatty acids, methanogenesis, and microbial community structures in dairy cows in vitro. The in vitro culture experiment was performed using a 2-by-2 factorial design, two 3-NOP levels (0 or 2 mg/g dry matter [DM]) and two fumarate levels (0 or 100 mg/g DM), including 3 runs with 4 treatments, 4 replicates, and 4 blanks containing only the inoculum. Rumen fluid was collected from three lactating Holstein cows with permanent ruminal fistulas. The combination of 3-NOP and fumarate reduced methane emissions by 11.48% without affecting dry matter degradability. The propionate concentration increased and the acetate/propionate ratio decreased significantly. In terms of bacteria, the combination of 3-NOP and fumarate reduced the abundances of Ruminococcus and Lachnospiraceae_NK3A20_group and increased the abundances of Prevotella and Succiniclasticum. For archaea, the combination of 3-NOP and fumarate significantly increased the abundances of Methanobrevibacter_sp._AbM4, while the abundance of operational taxonomic unit 581 (OTU581) (belonging to an uncultured_rumen_methanogen_g__Methanobrevibacter strain) was significantly decreased. These results indicated that the combination of 3-NOP and fumarate could alleviate the accumulation of hydrogen and enhance the inhibition of methanogenesis compared with 3-NOP only in dairy cows. IMPORTANCE The global problem of climate change and the greenhouse effect has become increasingly severe, and the abatement of greenhouse gases has received great attention from the international community. Methane produced by ruminants during digestion not only aggravates the greenhouse effect but also causes a waste of feed energy. As a methane inhibitor, 3-nitrooxypropanol can effectively reduce methane emissions from ruminants. However, when it inhibits methane emissions, the emission of hydrogen increases sharply, resulting in the waste of feed resources. Fumarate is a propionic acid precursor that can promote the metabolism of hydrogen to propionic acid in animals. Therefore, we studied the effects of the combined addition of 3-nitrooxypropanol and fumarate on methanogenesis, rumen fermentation, and rumen flora. It is of great significance to inhibit methane emission from ruminants and slow down the greenhouse effect.

Harboring various proteins, lipids, and RNAs, the extracellular vesicles (EVs) in milk exert vital tissue-specific immune-protective functions in neonates via these bioactive cargos. This study aims to explore the anti-inflammatory effects of bovine milk-derived EVs on a dextran sulfate sodium (DSS)-induced colitis model and to determine the underlying molecular mechanisms. Sixty C57BL/6 mice were divided into the NC group (normal control), DSS group (DSS + PBS), DSS + LOW group (DSS + 1.5 × 108 p/g EVs), DSS + MID group (DSS + 1.5 × 109 p/g EVs), and DSS + HIG group (DSS + 1.0 × 1010 p/g EVs). Histopathological sections, the gut microbiota, and intestinal tissue RNA-Seq were used to comprehensively evaluate the beneficial functions in mitigating colitis. The morphology exhibited that the milk-derived EVs contributed to the integrity of the superficial epithelial structure in the intestine. Additionally, the concentrations of IL-6 and TNF-α in the colon tissues were significantly decreased in the EVs-treated mice. The abundances of the Dubosiella, Bifidobacterium, UCG-007, Lachnoclostridium, and Lachnospiraceae genera were increased in the gut after treatment with the milk-derived EVs. Additionally, the butyrate and acetate production were enriched in feces. In addition, 1659 genes were significantly down-regulated and 1981 genes were significantly up-regulated in the EVs-treated group. Meanwhile, 82 lncRNAs and 6 circRNAs were also differentially expressed. Overall, the milk-derived EVs could attenuate colitis through optimizing gut microbiota abundance and by manipulating intestinal gene expression, implying their application potential for colitis prevention.

The milk microbiota and mediated metabolites directly affect the health of the udder in dairy cows. Inulin, a dietary prebiotic, can modulate the profile of gastrointestinal microbiota. However, whether the inulin intake affects the milk microbial population and metabolites remains unknown. In this study, 40 subclinical mastitis (SCM) cows were randomly divided into 5 groups. Five inulin addition doses, 0, 100, 200, 300, and 400 g/day per cow, based on the same basal diet, were supplemented. The experiments lasted for 8 weeks. The results showed lower relative abundance of mastitis-causing and proinflammation microbes in milk (i.e., Escherichia-Shigella, Pseudomonas, Rhodococcus, Burkholderia-Caballeronia-Paraburkholderia, etc.) and higher abundances of probiotics and commensal bacteria, such as Lactobacillus, Bifidobacterium, etc., in the cows fed 300 g/day inulin compared to that in the control group. Meanwhile, the levels of arachidonic acid proinflammatory mediators (leukotriene E3, 20-carboxy-leukotriene B4, and 12-Oxo-c-LTB3) and phospholipid metabolites were reduced, and the levels of compounds with antibacterial and anti-inflammatory potential (prostaglandin A1, 8-iso-15-keto-prostaglandin E(2) [PGE(2)], etc.) and participating energy metabolism (citric acid, l-carnitine, etc.) were elevated. These data suggested that inulin intake might modulate the microflora and metabolite level in extraintestinal tissue, such as mammary gland, which provided an alternative for the regulation and mitigation of SCM. IMPORTANCE The profile of the microbial community and metabolic activity in milk are the main determinants of udder health status and milk quality. Recent studies have demonstrated that diet could directly modulate the mammary gland microbiome. Inulin is a probiotic dietary fiber which can improve the microbiota population in the gastrointestinal tract. However, whether inulin intake can further regulate the profile of the microbiota and metabolic activities in milk remains unclear. In subclinical mastitic cows, we found that inulin supplementation could reduce the abundance of Escherichia-Shigella, Pseudomonas, Rhodococcus, and Burkholderia-Caballeronia-Paraburkholderia and the levels of (±)12, 13-DiHOME, leukotriene E3 and 20-carboxy-leukotriene B4 etc., while it elevated the abundance of Lactobacillus, Bifidobacterium, and Muribaculaceae, as well as the levels of prostaglandin A1 (PGA1), 8-iso-15-keto-PGE2, benzoic acid, etc. in milk. These data suggest that inulin intake affects the profile of microorganisms and metabolites in milk, which provides an alternative for the regulation of mastitis.

The occurrence and development of mastitis is linked to dysbiostic gastrointestinal microbiota. Inulin is a dietary prebiotic that improves the profile of intestinal flora. Our previous study showed that inulin supplementation could improve the ruminal microbes of subclinical mastitis (SCM) cows. The current study attempted to further investigate the response of hindgut (fecal) microbiome and metabolites, serum metabolism, and protein expression to inulin in the in SCM cows. Different levels of inulin (0, 100, 200, 300, and 400 g/day per cow) were supplemented in SCM cows. Compared with control group

Objective: An experiment was conducted to evaluate the effects of Lonicera japonica extract (LJE) on milk production, rumen fermentation and blood biomarkers of energy metabolism, inflammation and oxidative stress during the perinatal period of Holstein dairy cows.Methods: Eighteen Holstein dairy cows were used in a complete randomized design experiment with 3 dietary treatments and 6 cows per treatment. All cows received the same basal total mixed ration (TMR) including a prepartal diet (1.35 Mcal of net energy for lactation [NEL]/kg of dry matter [DM], 13.23% crude protein [CP]) from –60 d to calving and a postpartal diet (1.61 Mcal of NEL/kg of DM, 17.39% CP) from calving to 30 days in milk (DIM). The 3 dietary treatments were TMR supplemented with LJE at 0 (control), 1 and 2 g/kg DM, respectively. LJE was offered from 21 d before calving to 30 DIM. Dry matter intake (DMI) and milk production were measured daily after calving. Milk and rumen fluid samples were collected on 29 and 30 d after calving. On –10, 4, 14, and 30 d relative to calving, blood samples were collected to analyze the biomarkers of energy metabolism, inflammation and oxidative stress.Results: Compared with control diet, LJE supplementation at 1 and 2 g/kg DM increased DMI, milk yield and reduced milk somatic cell count. LJE supplementation also decreased the concentrations of blood biomarkers of pro-inflammation (interleukin-1β [IL-1β], IL-6, and haptoglobin), energy metabolism (nonesterified fatty acid and β-hydroxybutyric acid) and oxidative stress (reactive oxygen metabolites), meanwhile increased the total antioxidant capacity and superoxide dismutase concentrations in blood. No differences were observed in rumen pH, volatile fatty acid, and ammonia-N (NH3-N) concentrations between LJE supplemented diets and the control diet.Conclusion: Supplementation with 1 and 2 g LJE/kg DM could increase DMI, improve lactation performance, and enhance anti-inflammatory and antioxidant capacities of dairy cows during perinatal period.

Background: Most of the dairy cows in early lactation suffer from a period of negative energy balance (NEB) and hypocalcemia metabolic disorders. Calcium propionate is a source of energy and calcium for alleviating NEB and hypocalcemia. The objective of the study was to investigate the changes of milk compositions and blood metabolites of postpartum dairy cows fed with calcium propionate for 5 weeks.Methods:Thirty-two multiparous Holstein cows after calving were randomly allocated to control (CON), low calcium propionate (LCaP), medium calcium propionate (MCaP) and high calcium propionate (HCaP) groups with 8 cows per group balanced with parity, milk yield and body weight. The dairy cows in the four groups were oral drenching with 0, 200, 350, 500 g/d calcium propionate per cow from calving to d 35 in early lactation, respectively.Results:The results showed that the milk yield in MCaP group was significantly higher than those in the other groups. At d 35, the somatic cell count (SCC) in MCaP group tended to be lower than those in other groups. Compared with the CON group, serum non-esterified fatty acid (NEFA) in MCaP and HCaP groups tended to decrease. The serum alanine aminotransferase (ALT) concentration in MCaP group was lowest among the four groups. The concentration of aspartate aminotransferase (AST) in HCaP group was significantly higher than the other groups. Feeding calcium propionate had no significant effect on serum calcium, phosphorus and magnesium concentrations. The serum parathyroid hormone (PTH) in HCaP group tended to decrease. The calcium propionate treatments significantly decreased the serum alkaline phosphatase (ALP) level. The MCaP treatment significantly decreased serum total antioxidant capacity (T-AOC), glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) and catalase (CAT) activity, while increased the concentration of malondialdehyde (MDA) when compared with the other groups. The metabolomic results showed that calcium propionate significantly affected the bile acid compositions. Conclusions: It was concluded that the 350 g/d calcium propionate feeding level could significantly improve milk performance, alleviate body fat mobilization and bone calcium utilization, however decrease antioxidant capacity of dairy cows as well. The effect of calcium propionate on milk performance and serum metabolites in early lactation cows may be regulated through the serum bile acids metabolism.

Dairy cows in early lactation are prone to a negative energy balance because their dry matter intake cannot meet the energy requirements of lactation. Rumen-protected glucose is used as an effective feed additive to alleviate the negative energy balance of dairy cows in early lactation. However, one thing that is overlooked is that people often think that rumen-protected glucose is not degraded in the rumen, thus ignoring its impact on the microorganisms in the rumen environment. Our investigation and previous experiments have found that rumen-protected glucose is partially degraded in the rumen. However, there are few reports on this subject. Therefore, we conducted research on this problem and found that rumen-protected glucose supplementation at 350 g/day can promote the development and metabolism of rumen flora. This provides a theoretical basis for the extensive application of rumen bypass glucose at a later stage., Rumen-protected glucose (RPG) plays an important role in alleviating the negative energy balance of dairy cows. This study used a combination of rumen microbes 16S and metabolomics to elucidate the changes of rumen microbial composition and rumen metabolites of different doses of RPG’s rumen degradation part in early-lactation dairy cows. Twenty-four multiparous Holstein cows in early lactation were randomly allocated to control (CON), low-RPG (LRPG), medium-RPG (MRPG), or high-RPG (HRPG) groups in a randomized block design. The cows were fed a basal total mixed ration diet with 0, 200, 350, and 500 g of RPG per cow per day, respectively. Rumen fluid samples were analyzed using Illumina MiSeq sequencing and ultrahigh-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry. MRPG supplementation increased bacterial richness and diversity, including increasing the relative abundance of cellulolytic bacteria, such as Ruminococcus, Lachnospiraceae_NK3A20_group, Ruminiclostridium, and Lachnospiraceae_UCG-008. MRPG significantly increased the concentrations of acetate, propionate, butyrate, and total volatile fatty acid in the rumen. Ruminal fluid metabolomics analysis showed that RPG supplementation could significantly regulate the synthesis of amino acids digested by protozoa in the rumen. Correlation analysis of the ruminal microbiome and metabolome revealed some potential relationships between major bacterial abundance and metabolite concentrations. Our analysis found that RPG supplementation of different doses can change the diversity of microorganisms in the rumen and affect the rumen fermentation pattern and microbial metabolism and that a daily supplement of 350 g of RPG might be the ideal dose. IMPORTANCE Dairy cows in early lactation are prone to a negative energy balance because their dry matter intake cannot meet the energy requirements of lactation. Rumen-protected glucose is used as an effective feed additive to alleviate the negative energy balance of dairy cows in early lactation. However, one thing that is overlooked is that people often think that rumen-protected glucose is not degraded in the rumen, thus ignoring its impact on the microorganisms in the rumen environment. Our investigation and previous experiments have found that rumen-protected glucose is partially degraded in the rumen. However, there are few reports on this subject. Therefore, we conducted research on this problem and found that rumen-protected glucose supplementation at 350 g/day can promote the development and metabolism of rumen flora. This provides a theoretical basis for the extensive application of rumen bypass glucose at a later stage.

Additional file 1 Table S1 TMR Ingredient and nutrient component (% of DM). Table S2 Criteria to judge California mastitis test (CMT) results. Table S3 Basic information and grouping of experimental cows. Table S4 Rumen microbial composition and relative abundances of cows with different udder health states (phylum level). Table S5 Rumen microbial composition and relative abundances of cows with different udder health states (genus level). Table S6 Differentially abundant KEGG function abundance among health, subclinical and clinical mastitis groups at level 2. Table S7 Differentially abundant KEGG function abundance among health, subclinical and clinical mastitis groups at level 3. Table S8 Correlation analysis between the differentially abundant bacteria and parameters of rumen fermentation as well as lactation performance. Table S9 Significantly different metabolites between rumen fluid samples from healthy and clinical mastitis cows, udder positive ion mode. Table S10 Significantly different metabolites between rumen fluid samples from healthy and clinical mastitis cows, udder negative ion mode. Table S11 Significantly different metabolites between rumen fluid samples from healthy and subclinical mastitis cows, udder positive ion mode. Table S12 Significantly different metabolites between rumen fluid samples from healthy and subclinical mastitis cows, udder negative ion mode. Table S13 Significantly different metabolites between rumen fluid samples from subclinical and clinical mastitis, udder positive ion mode. Table S14 Significantly different metabolites between rumen fluid samples from subclinical and clinical mastitis cows, udder negative ion mode. Table S15 Correlation analysis of differential metabolites and index of lactation and rumen fermentation. Table S16 Correlation analysis of differential bacteria genus and differential metabolites in rumen samples.

Additional file 2 Fig. S1 Pan-Species curve of OTU number in the cows with different udder health status. Pan species was the sum of all the species in a sample, which was used to observe the increase in the total number of species as the number of samples increases. H, healthy; SM, subclinical mastitis; CM, clinical mastitis. Fig. S2 Rarefaction curve of OUT number in the cows with different udder health status. H, healthy; SM, subclinical mastiti; CM, clinical mastitis. Fig. S3 Rumen microbial community composition analysis. a At phylum level. b At genus level. H, healthy; SM, subclinical mastitis; CM, clinical mastitis. Fig.S4 Hierarchical cluster analysis (HCA) of rumen bacteria at genus level. Each row in the figure represents a sample, each column represents a genus, and the color indicates the relative abundance of bacteria measured in the group. Red indicates the high relative abundance, and the green indicates low relative abundance. H, healthy; SM, subclinical mastitis; CM, clinical mastitis. Fig. S5 Linear discriminant analysis effect size (LEfse) analysis of multilevel species differences in ruminal microbiota. a Cladogram; b LEfSe Bar graph. H, healthy; SM, subclinical mastitis; CM, clinical mastitis; LDA, linear discriminant analysis. Fig. S6 The total ion chromatograms (TIC) plot of quality control (QC) samples in a positive ion mode and b negative ion mode. Fig. S7 Orthogonal partial least squares discriminant analysis (OPLS-DA) (a, c, e) and response permutation testing (RPT) (b, d, f) of rumen metabolites between H, SM and CM groups in positive ion mode. H, healthy; SM, subclinical mastitis; CM, clinical mastitis. R2X and R2Y represent the interpretation rate of the built model to the X and Y matrix, R2X (cum) and R2Y (cum) represent the cumulative interpretation rate; Q2 indicates the predictive power of the model. Fig. S8 Orthogonal partial least squares discriminant analysis (OPLS-DA) (a, c, e) and response permutation testing (RPT) (b, d, f) plots of rumen metabolites between H, SM and CM groups in negative ion mode. H, healthy; SM, subclinical mastitis; CM, clinical mastitis. R2X and R2Y represent the interpretation rate of the built model to the X and Y matrix, R2X (cum) and R2Y (cum) represent the cumulative interpretation rate; Q2 indicates the predictive power of the model. Fig. S9 HMDB compound classification (Superclass level) of significantly differential metabolites between a CM and H groups, b SM and H groups and c CM and SM groups. HMDB, Human Metabolome Database; H, healthy; SM, subclinical mastitis; CM, clinical mastitis.

Background Inulin is a kind of fructo-oligosaccharide (FOS) derived mainly from Jerusalem artichoke and chicory tubers, which is also a soluble dietary fiber. Inulin has become a scientifically proven prebiotic product with satisfactory effects in improving the structure of intestinal flora, regulating blood lipid and glycemia, etc., in humans and monogastric. However, unlike monogastric animals, ruminal microbes are the largest microbiota in ruminants. The microflora profile and metabolism activity in the rumen are closely related to the health of dairy cows. This study investigated the effects of inulin on rumen fermentation parameters, ruminal microbiome and metabolites, as well as lactation performance and serum indexes in dairy cows. A total of 16 Holstein dairy cows with similar body condition were randomly divided into two groups (n = 8 per group), with inulin addition at 0 and 200 g/d per cow, respectively. Experiment was lasted for 6 weeks including 1 week of adaptation period and 5 weeks of treatment period. At the end of the experimental period, the milk, serum and rumen fluid were sampled and analyzed. The rumen microbiota and metabolites were analyzed via 16S rRNA sequencing and untargeted metabolomics, respectively. Results The supplementation of inulin (200 g/d per cow) increased the milk yield (P = 0.001), milk protein (P = 0.032), lactose rate (P = 0.004) and the proportion of saturated fatty acids (SFA) in milk (P P = 0.041). Rumen pH (P = 0.040) and concentration of NH3-N (P = 0.024) were decreased, however, acetate (P P = 0.003), butyrate (P P = 0.043) were increased. The total cholesterol (TC) (P = 0.008) and triglycerides (TG) (P = 0.01) in serum were also reduced. Additionally, the inulin addition elevated the relative abundance of several beneficial symbiotic and short-chain fatty acids (SCFA)-producing bacteria, such as Muribaculaceae (FDR-adjusted P Acetitomaculum (FDR-adjusted P = 0.043), and Butyrivibrio (FDR-adjusted P = 0.036) etc., meanwhile elevated the levels of L-Lysine (FDR-adjusted P = 4.24 × 10− 3), L-Proline (FDR-adjusted P = 0.0158), L-Phenylalanine (FDR-adjusted P = 0.027), etc. By contrast, several pathogens and ruminal bacteria abundant in high-fat diets, such as Escherichia-Shigella (FDR-adjusted P = 0.022), Erysipelotrichaceae__UCG-004 (FDR-adjusted P RF39 (FDR-adjusted P = 0.042) etc., were decreased along with the reduction of LysoPC (18:1(9Z)) (FDR-adjusted P = 1.03 × 10− 3), LysoPC (16:0) (FDR-adjusted P = 0.0108), LysoPC (18:2(9Z, 12Z)) (FDR-adjusted P = 1.65 × 10− 3) and 8-Methylnonenoate etc. Conclusion The results indicated the supplementation of inulin in dietary can increase the relative abundance of commensal microbiota and SCFAs-producing bacteria, meanwhile, upregulate amino acids (AAs) metabolism and downregulate lipid metabolism in rumen of dairy cows, which might further improve lactation performance and the level of serum lipids.

Background Due to the high prevalence and complex etiology, bovine mastitis (BM) is one of the most important diseases to compromise dairy cow health and milk quality. The shift in milk compositions has been widely investigated during mastitis, but recent studies suggested that gastrointestinal microorganism also has a crucial effect on the inflammation of other peripheral tissues and organs, including the mammary gland. However, research focused on the variation of rumen inner-environment during mastitis is still limited. Therefore, the ruminal microbial profiles, metabolites, and milk compositions in cows with different udder health conditions were compared in the present study. Furthermore, the correlations between udder health status and ruminal conditions were investigated. Based on the somatic cell counts (SCC), California mastitis test (CMT) parameters and clinical symptoms of mastitis, 60 lactating Holstein dairy cows with similar body conditions (excepted for the udder health condition) were randomly divided into 3 groups (n = 20 per group) including the healthy (H) group, the subclinical mastitis (SM) group and the clinical mastitis (CM) group. Lactation performance and rumen fermentation parameters were recorded. And rumen microbiota and metabolites were also analyzed via 16S rRNA amplicon sequencing and untargeted metabolomics, respectively. Results As the degree of mastitis increased, rumen lactic acid (LA) (P P P P = 0.039), Moraxella (FDR-adjusted P = 0.011) and Neisseriaceae (FDR-adjusted P = 0.036), etc., were accompanied by a significant increase in 12-oxo-20-dihydroxy-leukotriene B4 (FDR-adjusted P = 5.97 × 10− 9) and 10beta-hydroxy-6beta-isobutyrylfuranoeremophilane (FDR-adjusted P = 3.88 × 10− 10). Meanwhile, in the rumen of SM cows, the Ruminiclostridium_9 (FDR-adjusted P = 0.042) and Enterorhabdus (FDR-adjusted P = 0.043) were increased along with increasing methenamine (FDR-adjusted P = 6.95 × 10− 6), 5-hydroxymethyl-2-furancarboxaldehyde (5-HMF) (FDR-adjusted P = 2.02 × 10− 6) and 6-methoxymellein (FDR-adjusted P = 2.57 × 10− 5). The short-chain fatty acids (SCFAs)-producing bacteria and probiotics in rumen, including Prevoterotoella_1 (FDR-adjusted P = 0.045) and Bifidobacterium (FDR-adjusted P = 0.035), etc., were significantly reduced, with decreasing 2-phenylbutyric acid (2-PBA) (FDR-adjusted P = 4.37 × 10− 6). Conclusion The results indicated that there was a significant shift in the ruminal microflora and metabolites associated with inflammation and immune responses during CM. Moreover, in the rumen of cows affected by SM, the relative abundance of several opportunistic pathogens and the level of metabolites which could produce antibacterial compounds or had a competitive inhibitory effect were all increased.

Simple Summary Enteric methane emissions from ruminants are a major contributor to atmospheric greenhouse gas accumulation in agricultural production systems, which may consequently contribute to climate change. Accurate measurement of methane production in ruminants is vital to develop robust national greenhouse gas emission inventories and to evaluate mitigation strategies of methane emissions. This review summarizes several common methane measurement techniques suitable for ruminant production and discusses the advantages and disadvantages of each method. There is not a perfect technique for all situations. The appropriate technique depends on the objectives and resources available. Sophisticated techniques such as respiration chambers, sulphur hexafluoride tracer and ventilated hood are usually highly accurate but labor and time intensive. Simplified techniques such as GreenFeed, sniffer method, facemask, laser methane detector and portable accumulation chamber may be less accurate but are rapid with a high throughput. In general, an understanding of measurement mechanisms and the advantages and disadvantages with an appreciation of animal behavior and welfare is necessary for all techniques. Abstract To identify relationships between animal, dietary and management factors and the resulting methane (CH4) emissions, and to identify potential mitigation strategies for CH4 production, it is vital to develop reliable and accurate CH4 measurement techniques. This review outlines various methods for measuring enteric CH4 emissions from ruminants such as respiration chambers (RC), sulphur hexafluoride (SF6) tracer, GreenFeed, sniffer method, ventilated hood, facemask, laser CH4 detector and portable accumulation chamber. The advantages and disadvantages of these techniques are discussed. In general, RC, SF6 and ventilated hood are capable of 24 h continuous measurements for each individual animal, providing accurate reference methods used for research and inventory purposes. However, they require high labor input, animal training and are time consuming. In contrast, short-term measurement techniques (i.e., GreenFeed, sniffer method, facemask, laser CH4 detector and portable accumulation chamber) contain additional variations in timing and frequency of measurements obtained relative to the 24 h feeding cycle. However, they are suitable for large-scale measurements under commercial conditions due to their simplicity and high throughput. Successful use of these techniques relies on optimal matching between the objectives of the studies and the mechanism of each method with consideration of animal behavior and welfare. This review can provide useful information in selecting suitable techniques for CH4 emission measurement in ruminants.

Background: Thiamine supplementation in high-concentrate diets (HC) was confirmed to attenuate ruminal subacute acidosis through promoting carbohydrate metabolism, however, whether thiamine supplementation in HC impacts methane metabolism is still unclear. Therefore, in the present study, thiamine was supplemented in the high-concentrate diets to investigate its effects on ruminal methanogens and methanogenesis process. Methods: an in vitro fermentation experiment which included three treatments: control diet (CON, concentrate/forage = 4:6, DM basis), high-concentrate diet (HC, concentrate/forage = 6:4, DM basis) and high-concentrate diet supplemented with thiamine (HCT, concentrate/forage = 6:4, DM basis, thiamine supplementation content = 180 mg/kg DM) was conducted. Each treatment concluded with four repeats, with three bottles in each repeat. The in vitro fermentation was sustained for 48h each time and repeated three times. At the end of fermentation, fermentable parameters, ruminal bacteria and methanogens community were measured. Results: HC significantly decreased ruminal pH, thiamine and acetate content, while significantly increasing propionate content compared with CON (p &lt, 0.05). Conversely, thiamine supplementation significantly increased ruminal pH, acetate while significantly decreasing propionate content compared with HC treatment (p &lt, 0.05). No significant difference of ruminal methanogens abundances among three treatments was observed. Thiamine supplementation significantly decreased methane production compared with CON, while no significant change was found in HCT compared with HC. Conclusion: thiamine supplementation in the high-concentrate diet (HC) could efficiently reduce CH4 emissions compared with high-forage diets while without causing ruminal metabolic disorders compared with HC treatment. This study demonstrated that supplementation of proper thiamine in concentrate diets could be an effective nutritional strategy to decrease CH4 production in dairy cows.

Milk is a dynamic source of nutrients and bioactive factors, varying with the nutrition status of the cattle. We partly replaced alfalfa hay with whole cotton seed and soybean hull (non-forage fiber source, NFFS) in the feed formula of treated cows and evaluated the effects on milk extracellular vesicles (EVs). The NFFS supplement did not affect the shape of milk EVs observed using a transmission electron microscope. Nanoparticle tracking analysis revealed that the EV concentration increased significantly in treated cows (P = 0.019), with the peak diameter unaffected by the treatment. The EV-RNA concentration and small RNA content, particularly rRNAs and tRNAs, significantly increased in the treated cows (P < 0.05). The other small RNAs, i.e. miRNAs, cis-regulatory elements, snRNAs, and other Rfam RNAs showed no significant difference between the two groups. Totally 276 milk EV-miRNAs were identified. Thirteen miRNAs, accounting for 76%, in the highly expressed top 20, were immune-related. In addition, 9 differently expressed miRNAs (4 up-regulated and 5 down-regulated) were identified (P < 0.05). Kyoto Encyclopedia of Genes and Genomes pathway analysis showed that the differently expressed miRNAs were related to the citrate cycle, fat digestion and absorption process, taurine and hypo-taurine metabolism, and glycosphingolipid biosynthesis. This study documents the milk nutrition assessment from macromolecules, especially EVs.

Wheat straw is considered an abundant lignocellulosic biomass source in China. However, its recalcitrance hinders the degradation of wheat straw by enzymes and microbes. In this study, we investigated the optimum steam explosion conditions of pretreated wheat straw by response surface methodology to improve its nutrition level as a feedstuff for the ruminant industry or as a feedstock for biofuel production. The highest volatile fatty acid (VFA) yield (30.50 mmol L−1) was obtained at 2.3 MPa, 90 s and a moisture content of 36.46%. Under optimal conditions, steam explosion significantly altered the fermentation parameters in vitro. Ionic chromatography showed that pretreating wheat straw could improve the production of fermentable sugar, which was ascribed to the degradation of cellulose and hemicellulose. In addition, high throughput 16S rRNA amplicon sequencing analysis revealed that steam explosion changed the microbial community and enhanced the colonization of cellulolytic bacteria. Our findings demonstrated that steam explosion pretreatment could greatly improve the digestibility of wheat straw by facilitating sugar production and microbial colonization.

Simple Summary Kelp powder has been widely used as feed ingredient or additives in monogastric animal production and presented positive effects on production performance and intestinal microbiota because of its abundance in biomass output, novel oligosaccharides, and iodine. However, little information is available for the nutritional effects of kelp on ruminants. Therefore, the objective of the present study was to investigate the effects of kelp partial replacing dietary forage on rumen fermentation and production performance of dairy cows. Results indicated that, a substitution of 5% kelp powder for forage in the diet reduced the fiber content in the feeding diet and then regulated the proliferation of ruminal microbiota, which lead to a significant reduction of NH3-N while increasing acetate, propionate, and total volatile fatty acids (TVFA) concentrations in rumen, and finally partly increasing milk production and milk fat content. The present study may provide more comprehensive cognition of the nutritional value of kelp powder as a dietary raw material. It may further promote the utilization of kelp powder and provide a useful dietary raw material to the husbandry of dairy cows. Abstract Background: Kelp powder, which was rich in novel oligosaccharides and iodine might be utilized by the rumen microbiome, promoted the ruminal fermentation and finally enhanced the lactation performance of dairy cows. Therefore, the purpose of this study was to investigate the effects of kelp powder partially replacing dietary forage on rumen fermentation and lactation performance of dairy cows. (2) Methods: In the present study, 20 Chinese Holstein dairy cows were randomly divided into two treatments, a control diet (CON) and a kelp powder replacing diet (Kelp) for a 35-d long trial. Dry matter intake (DMI), milk production, milk quality, ruminal fermentable parameters, and rumen microbiota were measured to investigate the effects of kelp powder feeding on dairy cows. (3) Results: On the lactation performance, kelp significantly increased milk iodine content and effectively enhanced milk production and milk fat content. On the fermentable aspects, kelp significantly raised TVFA while reducing the ammonia-N content. On the rumen microbial aspect, kelp feeding significantly promoted the proliferation of Firmicutes and Proteobacteria while suppressing Bacteroidetes. (4) Conclusion: kelp powder as an ingredient of feedstuff might promote the rumen fermentation ability and effectively increase milk fat and iodine content, and consequently improve the milk nutritional value.

Calcium is one of the most abundant and indispensable elements in biology, as it is a vital component of nerves, bones, and muscles and maintains the excitability of normal neuromuscular muscles. However, it may be harmful to the human body and even damage the organs if the calcium content exceeds the standard value by several times. To evaluate the level of calcium ions (Ca2+), an electrochemical biosensor (FET/SWNTs/Cazyme) was developed using a nonspecific DNAzyme with high stability, which combined the unique advantage of field-effect transistors and single-walled carbon nanotubes, while being easy-to-use and having excellent sensitivity. The incubation time and voltage after optimization were 15 min and +0.02 V. The nonspecific DNAzyme-based biosensor was sensitive to Ca2+, but it was also interfered with by Pb2+, which affected the detection accuracy. To solve this shortcoming, an electrochemical device was proposed, in which FET/SWNTs/Cazyme combined with other specific biosensors for Pb2+, and then established some data processing models were established through support vector machine regression (SVMR) and artificial neural network fitting (ANNF). For the optimal SVMR, the electrochemical device can determine the Ca2+ concentration in the range of 7.5–1000 μM with a detection limit of 5.48 μM. Finally, the prepared electrochemical device was employed to detect the Ca2+ in different milk and water samples.

Only parts of heavy metal ions have sensitive and selective deoxyribozymes(DNAzymes), but most of heavy metal ions do not have the specific DNAzyme that limits the development of high-precise biosensors. As for cadmium ion (Cd2+), it lacks a specific DNAzyme that can be interfered by the multiple heavy metal ions (Hg2+ and Pb2+), causing poor accuracy if only non-specific DNAzyme-based biosensor measures the Cd2+ concentration. Here, one approach to solve this problem is proposed that uses in conjunction with other biosensors and the analysis data model to explore the interference law and improve the detection accuracy. The non-specific DNAzyme-based biosensor is fabricated using a field-effect transistor(FET), single-walled carbon nanotube(SWNTs) and non-specific DNAzyme. The performances are characterized by different spectral and electronic methods, indicating excellent sensitivity, stability and repeatability. Under the optimized conditions, the non-specific DNAzyme-based biosensor can determine Cd2+ down to 3.4 × 10-2 nM, and the linear range is varying from 5.0 × 10-2 to 1.0 × 103 nM with the correlation coefficient 0.98. To qualitatively and quantitatively analyze Cd2+ in a real sample, other biosensors with high sensitivity for Hg2+ and Pb2+ are selected and optimized to form a biosensor array, and then the detecting signals are processed by a mathematical model. At last, the prepared biosensor array is applied to measure the Cd2+ in feed to evaluate the detection accuracy.

The objective of this study was to evaluate if high-quality grass could sustain a similar feeding efficiency to concentrate meals for two breeds of lowland ewe lambs. Sixteen lowland ewe lambs of approximately 13 mo age and 61.5 ± 5.28 kg live weight were used in a 2 × 2 factorial study, with 2 diets (fresh perennial ryegrass [Lolium perenne] vs. fresh perennial ryegrass plus 0.5 kg/d fresh concentrate) × 2 breeds (Highlander vs. Texel). Grass was cut daily in the morning from a single zero-grazing sward and offered ad libitum. The animals were individually housed in pens and fed experimental diets for an adaptation phase of 19 d, and then transferred to respiration calorimeter chambers, remaining there for 5 d, with feed intake, feces and urine outputs, and methane (CH4) emissions measured during the final 4 d. There were no significant interaction effects between diets and breeds on any variables. Ewe lambs offered 0.5 kg/d concentrate supplementation had slightly greater DM intake and energy (GE, DE, and ME) intake, but had significantly higher N intake and N excretion in feces and urine than those fed the grass-only diet. However, diets had no significant effects on nutrient digestibility, energy or N utilization, or CH4 emission. Texel breed had a significantly lower DM intake and CH4 emissions per kg live weight, whereas the breed had no significant effect on nutrient digestibility or energy or N utilization. These results implicate that good quality grass could sustain high nutrient utilization efficiency as effectively as diets supplemented with concentrates for ewe lamb production. The two breeds of lowland ewe lambs can utilize good quality grass at a similar level of efficiency.