Ruminal Degradation of Rumen-Protected Glucose Influences the Ruminal Microbiota and Metabolites in Early-Lactation Dairy Cows

Differential responses of rumen and fecal fermentation and microbiota of Liaoning cashmere goats after 2-hydroxy-4-(methylthio) butanoic acid isopropyl ester supplementation

The 2-hydroxy-4-(methylthio) butanoic acid isopropyl ester (HMBi), a rumen protective methionine, has been extensively studied in dairy cows and beef cattle and has been shown to regulate gastrointestinal microbiota and improve production performance. However, knowledge of the application of HMBi on cashmere goats and the simultaneous study of rumen and hindgut microbiota is still limited. In this study, HMBi supplementation increased the concentration of total serum protein, the production of microbial protein in the rumen and feces, as well as butyrate production in the feces. The results of PCoA and PERMANOVA showed no significant difference between the rumen microbiota, but there was a dramatic difference between the fecal microbiota of the two groups of Cashmere goats after the HMBi supplementation. Specifically, in the rumen, HMBi significantly increased the relative abundance of some fiber-degrading bacteria (such as Fibrobacter) compared with the CON group. In the feces, as well as a similar effect as in the rumen (increasing the relative abundance of some fiber-degrading bacteria, such as Lachnospiraceae FCS020 group and ASV32), HMBi diets also increased the proliferation of butyrate-producing bacteria (including Oscillospiraceae UCG-005 and Christensenellaceae R-7 group). Overall, these results demonstrated that HMBi could regulate the rumen and fecal microbial composition of Liaoning cashmere goats and benefit the host.

A Preliminary Study of the Potential Molecular Mechanisms of Individual Growth and Rumen Development in Calves with Different Feeding Patterns

At present, it is common to feed calves with "Concentrate", "Concentrate + hay" and TMR "Total Mixed Rations" feeding patterns in China, which achieved well feeding efficiency, but the three feeding patterns molecular regulation mechanism in actual production is still unclear. The study aimed to explore the most suitable feeding pattern for Chinese Holstein calves to improve the rumen fermentation function and growth performance of calves. In this regard, the interactions between rumen microorganisms and host metabolism were investigated. The rumen volume and weight of calves in the GF group were significantly higher than those in the GFF and TMR groups (p < 0.05), and the rumen pH of calves in the GF group was 6.47~6.79. Metagenomics analysis revealed that the rumen microbiome of GF and GFF calves had higher relative abundances of Methanobrevibacter, Methanosphaera, and Methanolacinia (p < 0.05). Prevotella multisaccharivorax was significantly more abundant in the rumen of GF calves (p < 0.05), indicating that GF group calves had a stronger ability to ferment sugars. Notably, in the pyruvate metabolic pathway, phosphoenolpyruvate carboxylase was significantly up-regulated in GF calves compared with the TMR group, and pyruvate-phosphate dikinase was significantly down-regulated. Metabolomic results showed that Ursodeoxycholic acid was significantly up-regulated in GF calves, and most of the differential metabolites were enriched in Bile secretion pathways. The association analysis study found that the microorganisms of Prevotella and Ruminococcaceae might cooperate with the host, which was helpful for the digestion and absorption of lipids and made the calves have better growth. The three feeding modes had similar effects, but the 'GF' feeding pattern was more beneficial to the individual growth and ruminal development regarding ruminal morphology, contents physiology and microorganisms. Furthermore, the synergistic effect of rumen microorganisms and the host could more effectively hydrolyze lipid substances and promote the absorption of lipids, which was of great significance to the growth of calves.

N-carbamylglutamate supplementation regulates hindgut microbiota composition and short-chain fatty acid contents in Charollais and Small Tail Han crossbred sheep

Introduction

The objective of this study was to investigate the effects of N-carbamylglutamate (NCG) supplementation on the growth performance, hindgut microbiota composition, and short-chain fatty acid (SCFA) contents in Charollais and Small Tail Han crossbred sheep.

Methods

A total of 16 female crossbred mutton sheep (Charollais × Small Tail Han), aged 4 months, with an initial body weight of 30.03 ± 0.08 kg, were utilized in a 60 days experiment. The sheep were divided into two groups based on their initial body weight. Each group consisted of 8 replicates, with each individual sheep considered as a replicate. The dietary treatments comprised a basal diet supplemented with either 0.00% or 0.12% NCG.

Results and discussion

Our findings indicate that NCG supplementation did not have a significant effect on the growth performance of mutton sheep. However, it did lead to changes in hindgut SCFA contents. Specifically, NCG supplementation increased the content of propanoic acid while decreasing acetic acid and hexanoic acid in the hindgut. Through microbiota analysis using the 16S rRNA technique, we identified Lachnospiraceae_NK3A20_group and Parasutterella as biomarkers for the hindgut microbiota in mutton sheep fed a diet containing NCG. Further analysis of the microbiota composition revealed that NCG supplementation significantly increased the abundance of Lachnospiraceae_NK3A20_group and Parasutterella, while decreasing unclassified_f_Lachnospiraceae and Lachnoclostridium. Correlation analysis between hindgut SCFA contents and microbiota composition revealed that the abundance of Lachnoclostridium was positively correlated with the contents of acetic acid and hexanoic acid, but negatively correlated with propanoic acid. Additionally, the abundance of Lachnospiraceae_NK3A20_group and Parasutterella was positively correlated with the content of propanoic acid, while being negatively correlated with acetic acid and hexanoic acid. Based on these findings, we conclude that dietary supplementation of 0.12% NCG can modulate hindgut SCFA contents in mutton sheep by regulating the composition of the hindgut microbiota.

Amylopectin Partially Substituted by Cellulose in the Hindgut Was Beneficial to Short-Chain Fatty Acid Production and Probiotic Colonization

Undigested amylopectin fermentation in the hindguts of humans and pigs with low digestive capacity has been proven to be a low-efficiency method of energy supply. In this study, we researched the effects and mechanisms of amylopectin fermentation on hindgut microbiota and metabolite production using an in vitro fermentation trial and ileal infusion pigs model. In addition, we also researched the effects of interaction between amylopectin and cellulose during hindgut fermentation in this study. Our results showed that amylopectin had higher short-chain fatty acid (SCFA) production and dry matter digestibility (DMD) than cellulose but was not significantly different from a mixture of amylopectin and cellulose (Amycel vitro) during in vitro fermentation. The Amycel vitro group even had the highest reducing sugar content and amylase activity among all groups. The ileal infusion trial produced similar results to vitro fermentation trial: the mixture of amylopectin and cellulose infusion (Amycel vivo) significantly increased the levels of reducing sugar, acetate, and butyrate in the hindgut compared with the amylopectin infusion (Amy vivo). The mixture of amylopectin and cellulose infusion also resulted in increased Shannon index and probiotic colonization in the hindgut. The relative abundance of Romboutsia in the Amycel vivo group, which was considered a noxious bacteria in the Amycel vivo group, was also significantly lower than that in the Amy vivo group. In summary, the high level of amylopectin fermentation in the hindgut was harmful to intestinal microbiota, but amylopectin partially substituted with cellulose was beneficial to SCFA production and probiotic colonization. IMPORTANCE A high-starch (mainly amylopectin) diet is usually accompanied by the fermentation of undigested amylopectin in the hindgut of humans and pigs with low digestive capacity and might be detrimental to the intestinal microbiota. In this research, we investigated the fermentation characteristics of amylopectin through an in vitro fermentation method and used an ileal infusion pig model to verify the fermentation trial results and explore the microbiota regulatory effect. The interaction effects between amylopectin and cellulose during hindgut fermentation were also researched in this study. Our research revealed that the large amount of amylopectin fermentation in the hindgut was detrimental to the intestinal microbiota. Amylopectin partially substituted by cellulose was not only beneficial to antioxidant ability and fermentation efficiency, but also promoted SCFA production and probiotic colonization in the hindgut. These findings provide new strategies to prevent intestinal microbiota dysbiosis caused by amylopectin fermentation.

Forages and pastures symposium: forage biodegradation: advances in ruminal microbial ecology

The rumen microbial ecosystem provides ruminants a selective advantage, the ability to utilize forages, allowing them to flourish worldwide in various environments. For many years, our understanding of the ruminal microbial ecosystem was limited to understanding the microbes (usually only laboratory-amenable bacteria) grown in pure culture, meaning that much of our understanding of ruminal function remained a "black box." However, the ruminal degradation of plant cell walls is performed by a consortium of bacteria, archaea, protozoa, and fungi that produces a wide variety of carbohydrate-active enzymes (CAZymes) that are responsible for the catabolism of cellulose, hemicellulose, and pectin. The past 15 years have seen the development and implementation of numerous next-generation sequencing (NGS) approaches (e.g., pyrosequencing, Illumina, and shotgun sequencing), which have contributed significantly to a greater level of insight regarding the microbial ecology of ruminants fed a variety of forages. There has also been an increase in the utilization of liquid chromatography and mass spectrometry that revolutionized transcriptomic approaches, and further improvements in the measurement of fermentation intermediates and end products have advanced with metabolomics. These advanced NGS techniques along with other analytic approaches, such as metaproteomics, have been utilized to elucidate the specific role of microbial CAZymes in forage degradation. Other methods have provided new insights into dynamic changes in the ruminal microbial population fed different diets and how these changes impact the assortment of products presented to the host animal. As more omics-based data has accumulated on forage-fed ruminants, the sequence of events that occur during fiber colonization by the microbial consortium has become more apparent, with fungal populations and fibrolytic bacterial populations working in conjunction, as well as expanding understanding of the individual microbial contributions to degradation of plant cell walls and polysaccharide components. In the future, the ability to predict microbial population and enzymatic activity and end products will be able to support the development of dynamic predictive models of rumen forage degradation and fermentation. Consequently, it is imperative to understand the rumen's microbial population better to improve fiber degradation in ruminants and, thus, stimulate more sustainable production systems.

Effect of methionine hydroxy analog feed supplements: Significant alteration and enrichment of rumen microbiota and metabolome in Hu sheep

Methionine hydroxy analogs (MHA) are widely used as the main sources of methionine in ruminant feed production. The purpose of this study was to explore the effect of using MHA supplements such as MHA as a salt of calcium (MHA-Ca) and 2-hydroxy-4-(methylthio)-butanoic acid isopropyl ester (HMBi) as sources of methionine on the rumen microbiota and metabolome in Hu sheep. Seventy-two healthy Hu sheep were randomly assigned to three dietary treatment groups: control, MHA-Ca, and HMBi groups. The results showed that the concentrations of total volatile fatty acids, acetate, and propionate were higher in the HMBi group than in the control group. The HMBi and MHA-Ca groups had higher alpha diversity values than those in control group. We compared the rumen microbiota by using 16S rRNA gene sequencing. At the phylum level, the HMBi group had a higher relative abundance of Firmicutes and a lower relative abundance of Synergistetes than did the control group. At the genus level, the control group had a higher relative abundance of Treponema_2 than did the HBMi group and a higher relative abundance of Prevotellaceae_UCG_004 than did the MHA-Ca group. Metabolomic analyses revealed that fatty acids, amino acids, lipids, organic acids, sugars, amines, and nucleosides were significantly altered in both MHA-Ca and HMBi groups. Metabolites with significant differences were enriched in amino acid and carbohydrate metabolisms, such as phenylalanine metabolism, biosynthesis of amino acids, tryptophan metabolism, galactose metabolism, and tyrosine metabolism. Above all, the findings presented in this study indicate that MHA alter the rumen microbiota and metabolites and that different forms of MHA have different impacts. The results of our study contribute to a better understanding of the effects of MHA.

Co-fermented yellow wine lees by Bacillus subtilis and Enterococcus faecium regulates growth performance and gut microbiota in finishing pigs

Fermented yellow wine lees (FYWL) are widely used to increase feed utilization and improve pig performance. Based on the preparation of co-FYWL using Bacillus subtilis and Enterococcus faecalis, the purpose of this study was to investigate the effects of co-FYWL on growth performance, gut microbiota, meat quality, and immune status of finishing pigs. 75 pigs were randomized to 3 treatments (5 replicates/treatment), basal diet (Control), a basal diet supplemented with 4%FYWL, and a basal diet supplemented with 8%FYWL, for 50 days each. Results showed that the 8% FYWL group significantly reduced the F/G and increased the average daily weight gain of pigs compared to the control group. In addition, 8% FYWL improved the richness of Lactobacillus and B. subtilis in the gut, which correlated with growth performance, serum immune parameters, and meat quality. Furthermore, acetate and butyrate in the feces were improved in the FYWL group. Simultaneously, FYWL improved the volatile flavor substances of meat, increased the content of flavor amino acids, and played a positive role in the palatability of meat. In addition, FYWL increased serum IgA, IgM, IL-4 and IL-10 levels. Overall, the growth performance, the gut microbiota associated with fiber degradation, meat quality, and immune status were improved in the 8% FYWL group.

Rumen Fermentation and Microbiome Responses to Enzymatic Hydrolysate of Cottonseed Protein Supplementation in Continuous In Vitro Culture

This study aimed to evaluate the effect of enzymatic hydrolysate of cottonseed protein (ECP) on the kinetic of gas production, rumen fermentation characteristics, and microbial diversity in continuous in vitro culture with a single factorial design of supplementation with various concentrations of ECP or yeast culture. Treatments were control (without supplementation, CON), supplementation with 10 g/kg Diamond-V XP yeast culture of substrate (XP), and supplementation with 6, 12 and 18 g/kg ECP of substrate (ECP1, ECP2, ECP3), each incubated with 30 mL of buffered incubation fluids and 200 mg of fermentation substrate in graduated glass syringes fitted with plungers for 48 h. Compared with the CON treatment, supplementation of XP yeast culture increased the cumulative gas production at 12 and 24 h, the concentration of ammonia nitrogen (NH3-N) concentration at 24 and 36 h, the concentration of microbial protein (MCP) concentration at 24 and 48 h, the molar butyrate proportion at 12, 24, and 48 h, the molar valerate proportion at 48 h, and the ratio of non-glucogenic to glucogenic acids (p < 0.05). Compared with the CON treatment, the concentration of MCP and the molar propionate proportion at 12 h were higher in the ECP1 treatment (p < 0.05); the cumulative gas production at 2, 4, and 12 h, the concentration of NH3-N at 36 h and the molar valerate proportion at 48 h were higher in the ECP2 treatment (p < 0.05); the cumulative gas production at 2, 12, and 48 h, the concentration of NH3-N at 12 and 36 h, the concentration of MCP at 12, 36, and 48 h, the molar butyrate proportion at 12 and 48 h, and the molar valerate proportion at 48 h were higher in the ECP3 treatment (p < 0.05). Compared with the CON treatment, supplementation with XP yeast culture significantly altered the relative abundance of the phyla Firmicutes, Kiritimatiellaeota, and Proteobacteria, while supplementation with ECP had minimal effect on bacterial diversity. The prediction of bacterial functions showed that the main gene functions of rumen bacteria are associated with carbohydrate metabolism, amino acid metabolism, and membrane transport. The findings of this study suggest that ECP can be used as a superior feed ingredient for ruminants, the suitable level of ECP was 18 g/kg in vitro experiment.

In vitro and in vivo Studies of Soybean Peptides on Milk Production, Rumen Fermentation, Ruminal Bacterial Community, and Blood Parameters in Lactating Dairy Cows

Soybean peptides (SPs), a feed additive derived from soybean, exhibit nutritional function and biological activity in monogastric animals, but limited studies have been conducted in dairy cows. Our experiments were conducted to evaluate the effects of SPs on the nutrient degradability of dry matter (DM), crude protein (CP), neutral detergent fiber (NDF), and acid detergent fiber (ADF) in vitro and milk production, rumen fermentation and bacterial community, and blood parameters of dairy cows. For in vitro experiment, ruminal fluids were collected from three ruminal cannulated Holstein dairy cows. A total of three levels of SPs (0, 0.38, and 1.92 g/kg DM of SPs) were added to the total mixed ration (TMR). Nutrient degradability and fermentation fluid pH were determined at 24 and 48 h using 3.0 g samples of the substrate. Gas production after 48 h was recorded by an automated trace gas recording system using 0.5 g samples of the substrate. The results showed that DM, NDF, ADF (p < 0.01), and CP (p < 0.05) degradabilities were significantly increased at 1.92 g/kg DM of SPs at 24 h, and asymptotic gas production (p = 0.05) was increased at 48 h. For in vivo experiment, 110 lactating Holstein cows (209.7 ± 65.2 DIM; 37.2 ± 6.4 kg/d milk yield) were randomly assigned to 0 (control group, CON) or 50 g/head/day SPs (SP-supplemented group). Yields of milk (p < 0.05), milk protein (p < 0.05), and milk lactose (0.05 < p < 0.10) increased on SPs supplementation; however, the milk fat percentage decreased (p < 0.05). The concentrations of individual volatile fatty acids (VFAs) (p < 0.05) and superoxide dismutase (SOD) (p < 0.01) were also increased. Rumen bacterial diversity in SP-supplemented cows was higher (p < 0.05). The relative abundances of Rikenellaceae_RC9_gut_group, Butyrivibrio, Selenomonas, and Shuttleworthia were significantly increased and that of Coprococcus was decreased (p < 0.05). Our results showed that supplementing 1.92 g/kg DM of SPs could improve the nutrient degradability in vitro and 50 g/head/day of SPs could improve milk production and antioxidant ability of dairy cows. The rumen bacterial diversity was also enhanced by SP supplementation.

Effect of Methionine Supplementation on Serum Metabolism and the Rumen Bacterial Community of Sika Deer (Cervus nippon)

Methionine is the first or second limiting amino acid for ruminants, such as sika deer, and has a variety of biological functions such as antioxidant activity, immune response, and protein synthesis. This study aimed to investigate the effects of methionine supplementation on antler growth, serum biochemistry, rumen fermentation, and the bacterial community of sika deer during the antler-growing period. Twelve 4-year-old male sika deer were randomly assigned to three dietary groups supplemented with 0 g/day (n = 4, CON), 4.0 g/day (n = 4, LMet), and 6.0 g/day (n = 4, HMet) methionine. No significant difference (p > 0.05) was found in the production performance between the three groups, but antler weight was higher in both the LMet and HMet groups than in the CON group. Methionine supplementation significantly increased the serum glutathione peroxidase activity (p < 0.05). The serum immunoglobulin G level was significantly higher in the HMet group than in the other two groups (p < 0.05). No significant effect was found on the apparent amino acid digestibility of the three groups, but cysteine and methionine digestibility were higher in the LMet group. The serum hydroxylysine level was significantly lower in the LMet and HMet groups, whereas the serum lysine level was significantly lower in the HMet group compared with the CON group (p < 0.05). The LMet group had the highest but a nonsignificant total volatile fatty acid content and significantly higher microbial protein content in the rumen than the CON group (p < 0.05). The phyla Bacteroidetes, Firmicutes, and Proteobacteria were dominant in the rumen of the sika deer. The principal coordinate analysis (PCoA) and analysis of similarities (ANOSIM) results showed a significant change in the bacterial composition of the three groups (p < 0.05). The relative abundance of Prevotella and Rikenellaceae-RC9 was significantly higher in the LMet group compared with the CON group and CON and HMet groups, respectively. These results revealed that methionine supplementation improved the antioxidant activity and immune status, affecting amino acid metabolism and rumen microbial composition of the sika deer.

Calcium Propionate Supplementation Has Minor Effects on Major Ruminal Bacterial Community Composition of Early Lactation Dairy Cows

Calcium propionate is one kind of good source for preventing and treating hypocalcemia and ketosis for dairy cows in early lactation. However, little is known about the effects of different feeding levels of calcium propionate on the ruminal bacterial community of early lactation dairy cows. This study aimed to explore the effects of different calcium propionate feeding levels on the ruminal fermentation and bacterial community composition of early lactation dairy cows. Twenty-four multiparous cows were randomly allocated into control (CON), low calcium propionate (LCaP), medium calcium propionate (MCaP), and high calcium propionate (HCaP) groups with six cows per group after calving. The CON group cows were fed the normal total mixed ration (TMR), and the cows of the LCaP, MCaP, and HCaP groups were fed TMR supplemented with 200, 350, and 500 g/day calcium propionate for 35 days after calving, respectively. The rumen fermentation parameters were measured every week, and the ruminal bacterial community composition of the last week was analyzed by 16S rRNA gene sequencing. Under the same diet, the rumen pH showed no difference among the four groups, but the content of microbial crude protein (MCP) and ammonia nitrogen quadratically decreased and linearly increased with calcium propionate supplementation, respectively. The feeding of calcium propionate linearly increased the concentrations of total volatile fatty acid (VFA), acetate, propionate, butyrate, iso-valerate, and valerate in the rumen. In all the treatment groups, Bacteroidetes, Firmicutes, and Proteobacteria were the dominant phyla, and Prevotella_1 and Succiniclasticum were the dominant genera in the rumen. Compared with the CON group, the addition of calcium propionate to the early lactation dairy cows quadratically improved the alpha diversity index of Chao1 estimator and observed species, but had little effect on the relative abundance of the major bacterial at phyla and genera level. These results suggested different levels of calcium propionate supplementation improved the rumen fermentation and the ruminal bacterial diversity but had little impact on the major ruminal bacterial community composition of dairy cows in early lactation.

Integration of Multiplied Omics, a Step Forward in Systematic Dairy Research

Due to their unique multi-gastric digestion system highly adapted for rumination, dairy livestock has complicated physiology different from monogastric animals. However, the microbiome-based mechanism of the digestion system is congenial for biology approaches. Different omics and their integration have been widely applied in the dairy sciences since the previous decade for investigating their physiology, pathology, and the development of feed and management protocols. The rumen microbiome can digest dietary components into utilizable sugars, proteins, and volatile fatty acids, contributing to the energy intake and feed efficiency of dairy animals, which has become one target of the basis for omics applications in dairy science. Rumen, liver, and mammary gland are also frequently targeted in omics because of their crucial impact on dairy animals’ energy metabolism, production performance, and health status. The application of omics has made outstanding contributions to a more profound understanding of the physiology, etiology, and optimizing the management strategy of dairy animals, while the multi-omics method could draw information of different levels and organs together, providing an unprecedented broad scope on traits of dairy animals. This article reviewed recent omics and multi-omics researches on physiology, feeding, and pathology on dairy animals and also performed the potential of multi-omics on systematic dairy research.

Active Rumen Bacterial and Protozoal Communities Revealed by RNA-Based Amplicon Sequencing on Dairy Cows Fed Different Diets at Three Physiological Stages

Seven Italian Simmental cows were monitored during three different physiological stages, namely late lactation (LL), dry period (DP), and postpartum (PP), to evaluate modifications in their metabolically-active rumen bacterial and protozoal communities using the RNA-based amplicon sequencing method. The bacterial community was dominated by seven phyla: Proteobacteria, Bacteroidetes, Firmicutes, Spirochaetes, Fibrobacteres, Verrucomicrobia, and Tenericutes. The relative abundance of the phylum Proteobacteria decreased from 47.60 to 28.15% from LL to DP and then increased to 33.24% in PP. An opposite pattern in LL, DP, and PP stages was observed for phyla Verrucomicrobia (from 0.96 to 4.30 to 1.69%), Elusimicrobia (from 0.32 to 2.84 to 0.25%), and SR1 (from 0.50 to 2.08 to 0.79%). The relative abundance of families Succinivibrionaceae and Prevotellaceae decreased in the DP, while Ruminococcaceae increased. Bacterial genera Prevotella and Treponema were least abundant in the DP as compared to LL and PP, while Ruminobacter and Succinimonas were most abundant in the DP. The rumen eukaryotic community was dominated by protozoal phylum Ciliophora, which showed a significant decrease in relative abundance from 97.6 to 93.9 to 92.6 in LL, DP, and PP, respectively. In conclusion, the physiological stage-dependent dietary changes resulted in a clear shift in metabolically-active rumen microbial communities.