Enhancing milk quality and modulating rectal microbiota of dairy goats in starch‑rich diet:the role of bile acid supplementation

Background Diets rich in starch have been shown to increase a risk of reducing milk fat content in dairy goats.While bile acids(BAs)have been used as a lipid emulsifier in monogastric and aquatic animals,their effect on ruminants is not well understood.This study aimed to investigate the impact of BAs supplementation on various aspects of dairy goat physiology,including milk composition,rumen fermentation,gut microbiota,and BA metabolism.Results We randomly divided eighteen healthy primiparity lactating dairy goats(days in milk=100±6 d)into two groups and supplemented them with 0 or 4 g/d of BAs undergoing 5 weeks of feeding on a starch-rich diet.The results showed that BAs supplementation positively influenced milk yield and improved the quality of fatty acids in goat milk.BAs supplementation led to a reduction in saturated fatty acids(C16:0)and an increase in monounsaturated fatty acids(cis-9 C18:1),resulting in a healthier milk fatty acid profile.We observed a significant increase in plasma total bile acid concentration while the proportion of rumen short-chain fatty acids was not affected.Furthermore,BAs supplementation induced significant changes in the composition of the gut microbiota,favoring the enrichment of specific bacterial groups and altering the balance of microbial populations.Correlation analysis revealed associations between specific bacterial groups(Bacillus and Christensenellaceae R-7 group)and BA types,suggesting a role for the gut microbiota in BA metabolism.Functional prediction analysis revealed notable changes in pathways associated with lipid metabolism,suggesting that BAs supplementation has the potential to modulate lipid-related processes.Conclusion These findings highlight the potential benefits of BAs supplementation in enhancing milk production,improving milk quality,and influencing metabolic pathways in dairy goats.Further research is warranted to elucidate the underlying mechanisms and explore the broader implications of these findings.

Effects of fumaric acid supplementation on methane production and rumen fermentation in goats fed diets varying in forage and concentrate particle size

Background: In rumen fermentation, fumaric acid(FA) could competitively utilize hydrogen with methanogenesis to enhance propionate production and suppress methane emission, but both effects were diet-dependent. This study aimed to explore the effects of FA supplementation on methanogenesis and rumen fermentation in goats fed diets varying in forage and concentrate particle size.Methods: Four rumen-cannulated goats were used in a 4 × 4 Latin square design with a 2 × 2 factorial arrangement of treatments: low or high ratio of forage particle size: concentrate particle size(Fps:Cps), without or with FA supplementation(24 g/d). Fps:Cps was higher in the diet with chopped alfalfa hay plus ground corn than in that with ground alfalfa hay plus crushed corn.Results: Both increasing dietary Fps:Cps and FA supplementation shifted ruminal volatile fatty acid(VFA) patterns toward more propionate and less acetate in goats. An interaction between dietary Fps:Cps and FA supplementation was observed for the ratio of acetate to propionate(A:P), which was more predominant when FA was supplemented in the low-Fps:Cps diet. Methane production was reduced by FA, and the reduction was larger in the low-Fps:Cps diet(31.72%) than in the high-Fps:Cps diet(17.91%). Fumaric acid decreased ruminal total VFA concentration and increased ruminal p H. No difference was found in ruminal DM degradation of concentrate or alfalfa hay by dietary Fps:Cps or FA. Goats presented a lower ruminal methanogen abundance with FA supplementation and a higher B. fibrisolvens abundance with high dietary Fps:Cps.Conclusions: Adjusting dietary Fps:Cps is an alternative dietary model for studying diet-dependent effects without changing dietary chemical composition. Fumaric acid supplementation in the low-Fps:Cps diet showed greater responses in methane mitigation and propionate increase.

Rumen microbiome structure and metabolites activity in dairy cows with clinical and subclinical mastitis

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<0.01),acetate,propionate,butyrate,valerate(P<0.001),and total volatile fatty acids(TVFAs)(P<0.01)concentrations were significantly decreased.In the rumen of CM cows,the significantly increased bacteria related to intestinal and oral inflammation,such as Lachnospiraceae(FDR-adjusted 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(FDRadjusted 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.

High rumen degradable starch decreased goat milk fat via trans-10,cis-12 conjugated linoleic acid-mediated downregulation of lipogenesis genes,particularly,INSIG1

Background:Starch is an important substance that supplies energy to ruminants.To provide sufficient energy for high-yielding dairy ruminants,they are typically fed starch-enriched diets.However,starch-enriched diets have been proven to increase the risk of milk fat depression(MFD)in dairy cows.The starch present in ruminant diets could be divided into rumen-degradable starch(RDS)and rumen escaped starch(RES)according to their different degradation sites(rumen or intestine).Goats and cows have different sensitivities to MFD.Data regarding the potential roles of RDS in milk fat synthesis in the mammary tissue of dairy goats and in regulating the occurrence of MFD are limited.Results:Eighteen Guanzhong dairy goats(day in milk=185±12 d)with similar parity,weight,and milk yield were selected and randomly assigned to one of three groups(n=6),which were fed an LRDS diet(Low RDS=20.52%),MRDS diet(Medium RDS=22.15%),or HRDS diet(High RDS=24.88%)for 5 weeks.Compared with that of the LRDS group,the milk fat contents in the MRDS and HRDS groups significantly decreased.The yields of short-,mediumand long-chain fatty acids decreased in the HRDS group.Furthermore,increased RDS significantly decreased ruminal B.fibrisolvens and Pseudobutyrivibrio abundances and increased the trans-10,cis-12 conjugated linoleic acid(CLA)and trans-10 C18:1 contents in the rumen fluid.A multiomics study revealed that the HRDS diet affected mammary lipid metabolism down-regulation of ACSS2,MVD,AGPS,SCD5,FADS2,CERCAM,SC5D,HSD17B7,HSD17B12,ATM,TP53RK,GDF1 and LOC102177400.Remarkably,the significant decrease of INSIG1,whose expression was depressed by trans-10,cis-12 CLA,could reduce the activity of SREBP and,consequently,downregulate the downstream gene expression of SREBF1.Conclusions:HRDS-induced goat MFD resulted from the downregulation of genes involved in lipogenesis,particularly,INSIG1.Specifically,even though the total starch content and the concentrate-to-fiber ratio were the same as those of the high-RDS diet,the low and medium RDS diets did not cause MFD in lactating goats.

Dynamics of methanogenesis,ruminal fermentation and fiber digestibility in ruminants following elimination of protozoa: a meta-analysis

Background: Ruminal microbes are vital to the conversion of lignocellulose-rich plant materials into nutrients for ruminants.Although protozoa play a key role in linking ruminal microbial networks,the contribution of protozoa to rumen fermentation remains controversial; therefore,this meta-analysis was conducted to quantitatively summarize the temporal dynamics of methanogenesis,ruminal volatile fatty acid(VFA) profiles and dietary fiber digestibility in ruminants following the elimination of protozoa(also termed defaunation).A total of 49 studies from 22 publications were evaluated.Results: The results revealed that defaunation reduced methane production and shifted ruminal VFA profiles to consist of more propionate and less acetate and butyrate,but with a reduced total VFA concentration and decreased dietary fiber digestibility.However,these effects were diminished linearly,at different rates,with time during the first few weeks after defaunation,and eventually reached relative stability.The acetate to propionate ratio and methane production were increased at 7 and 11 wk after defaunation,respectively.Conclusions: Elimination of protozoa initially shifted the rumen fermentation toward the production of more propionate and less methane,but eventually toward the production of less propionate and more methane over time.

Multi‑omics reveals that the host‑microbiome metabolism crosstalk of differential rumen bacterial enterotypes can regulate the milk protein synthesis of dairy cows

Background Dairy cows’lactation performance is the outcome of the crosstalk between ruminal microbial metabo-lism and host metabolism.However,it is still unclear to what extent the rumen microbiome and its metabolites,as well as the host metabolism,contribute to regulating the milk protein yield(MPY).Methods The rumen fluid,serum and milk of 12 Holstein cows with the same diet(45%coarseness ratio),parity(2–3 fetuses)and lactation days(120–150 d)were used for the microbiome and metabolome analysis.Rumen metabolism(rumen metabolome)and host metabolism(blood and milk metabolome)were connected using a weighted gene co-expression network(WGCNA)and the structural equation model(SEM)analyses.Results Two different ruminal enterotypes,with abundant Prevotella and Ruminococcus,were identified as type1 and type2.Of these,a higher MPY was found in cows with ruminal type2.Interestingly,[Ruminococcus]gauvreauii group and norank_f_Ruminococcaceae(the differential bacteria)were the hub genera of the network.In addition,differential ruminal,serum and milk metabolome between enterotypes were identified,where the cows with type2 had higher L-tyrosine of rumen,ornithine and L-tryptophan of serum,and tetrahydroneopterin,palmitoyl-L-carnitine,S-lactoylglutathione of milk,which could provide more energy and substrate for MPY.Further,based on the identi-fied modules of ruminal microbiome,as well as ruminal serum and milk metabolome using WGCNA,the SEM analysis indicated that the key ruminal microbial module1,which contains the hub genera of the network([Ruminococcus]gauvreauii group and norank_f_Ruminococcaceae)and high abundance of bacteria(Prevotella and Ruminococcus),could regulate the MPY by module7 of rumen,module2 of blood,and module7 of milk,which contained L-tyrosine and L-tryptophan.Therefore,in order to more clearly reveal the process of rumen bacterial regulation of MPY,we established the path of SEM based on the L-tyrosine,L-tryptophan and related components.The SEM based on the metabolites suggested that[Ruminococcus]gauvreauii group could inhibit the energy supply of serum tryptophan to MPY by milk S-lactoylglutathione,which could enhance pyruvate metabolism.Norank_f_Ruminococcaceae could increase the ruminal L-tyrosine,which could provide the substrate for MPY.Conclusion Our results indicated that the represented enterotype genera of Prevotella and Ruminococcus,and the hub genera of[Ruminococcus]gauvreauii group and norank_f_Ruminococcaceae could regulate milk protein synthesis by affecting the ruminal L-tyrosine and L-tryptophan.Moreover,the combined analysis of enterotype,WGCNA and SEM could be used to connect rumen microbial metabolism with host metabolism,which provides a fundamental understanding of the crosstalk between host and microorganisms in regulating the synthesis of milk composition.

1,25-Dihydroxyvitamin D_3 modulates calcium transport in goat mammary epithelial cells in a dose- and energydependent manner

Background： Calcium is a vital mineral and an indispensable component of milk for ruminants. The regulation of transcellular calcium transport by 1,25-dihydroxyvitamin D3 （1,25-（OH）2D3, the active form of vitamin D） has been confirmed in humans and rodents, and regulators, including vitamin D receptor （VDR）, calcium binding protein Dgk （calbindin-Dgk）, plasma membrane Ca2＋-ATPase ] b （PMCAlb）, PMAC2b and Oral1, are involved in this process. However, it is still unclear whether 1,25-（OH）2D3 could stimulate calcium transport in the ruminant mammary gland. The present trials were conducted to study the effect of 1,25-（OH）2D3 supplementation and energy availability on the expression of genes and proteins related to calcium secretion in goat mammary epithelial cells. Methods： An in vitro culture method for goat secreting mammary epithelial cells was successfully established. The cells were treated with different doses of 1,25-（OH）2D3 （0, 0.1, 1.0, 10.0 and 100.0 nmol/L） for calcium transport research, followed by a 3-bromopyruvate （3-BrPA, an inhibitor of glucose metabolism） treatment to determine its dependence on glucose availability. Cell proliferation ratios, glucose consumption and enzyme activities were measured with commercial kits, and real-time quantitative polymerase chain reaction （RT-qPCR）, and western blots were used to determine the expression of genes and proteins associated with mammary calcium transport in dairy goats, respectively. Results： 1,25-（OH）2D3 promoted cell proliferation and the expression of genes involved in calcium transport in a dose-dependent manner when the concentration did not exceed 10.0 nmol/L. In addition, 100.0 nmol/L 1,25-（OH） 2D3 inhibited cell proliferation and the expression of associated genes compared with the 10.0 nmol/L treatment. The inhibition of hexokinase 2 （HK2）, a rate-limiting enzyme in glucose metabolism, decreased the expression of PMCA1 b and PMCA2b at the mRNA and protein levels as well as the transcription of Oral1, indicating that glucose avaitability was required for goat mammary calcium transport. The optimal concentration of 1,25-（OH）2D3 that facilitated calcium transport in this study was 10.0 nmol/L. Conclusions： Supplementation with 1,25-（OH）2D3 influenced cell proliferation and regulated the expression of calcium transport modulators in a dose- and energy-dependent manner, thereby highlighting the role of 1,25-（OH）2D3 as an efficacious regulatory agent that produces calcium-enriched milk in ruminants when a suitable energy status was guaranteed.

Long-term and combined effects of N-[2-(nitrooxy)ethyl]-3-pyridinecarboxamide and fumaric acid on methane production,rumen fermentation, and lactation performance in dairy goats

Background:In recent years,nitrooxy compounds have been identified as promising inhibitors of methanogenesis in ruminants.However,when animals receive a nitrooxy compound,a high portion of the spared hydrogen is eructated as gas,which partly offsets the energy savings of CH4mitigation.The objective of the present study was to evaluate the long-term and combined effects of supplementation with N-[2-(nitrooxy)ethyl]-3-pyridinecarboxamide(NPD),a methanogenesis inhibitor,and fumaric acid(FUM),a hydrogen sink,on enteric CH4production,rumen fermentation,bacterial populations,apparent nutrient digestibility,and lactation performance of dairy goats.Results:Twenty-four primiparous dairy goats were used in a randomized complete block design with a 2×2factorial arrangement of treatments:supplementation without or with FUM(32 g/d)or NPD(0.5 g/d).All samples were collected every 3 weeks during a 12-week feeding experiment.Both FUM and NPD supplementation persistently inhibited CH4yield(L/kg DMI,by 18.8%and 18.1%,respectively)without negative influence on DMI or apparent nutrient digestibility.When supplemented in combination,no additive CH4suppression was observed.FUM showed greater responses in increasing the molar proportion of propionate when supplemented with NPD than supplemented alone(by 10.2%vs.4.4%).The rumen microbiota structure in the animals receiving FUM was different from that of the other animals,particularly changed the structure of phylum Firmicutes.Daily milk production and serum total antioxidant capacity were improved by NPD,but the contents of milk fat and protein were decreased,probably due to the bioactivity of absorbed NPD on body metabolism.Conclusions:Supplementing NPD and FUM in combination is a promising way to persistently inhibit CH4emissions with a higher rumen propionate proportion.However,the side effects of this nitrooxy compound on animals and its residues in animal products need further evaluation before it can be used as an animal feed additive.

Effect of in ovo folic acid injection on hepatic IGF2 expression and embryo growth of broilers

Background： Insulin-like factor 2（IGF2） plays an important role in embryonic growth process by modulating intermediary metabolism and cell proliferation. Folic acid is involved in one carbon metabolism and contributes to DNA methylation which is related to gene expression. The purpose of this study was to explore whether folic acid could regulate IGF2 expression via epigenetic mechanism and further promote embryonic growth of new-hatched broilers.Methods： In the present study, 360 fertile eggs were selected and randomly assigned to four treatments. On11 embryonic day of incubation（E11）, 0, 50, 100 and 150 μg folic acid were injected into eggs respectively.After hatched, growth performance of broilers were calculated. Hepatic IGF2 expression, methylation level and chromatin structure of promoter region were analyzed.Results： Results have showed that IGF2 expression was up-regulated in 150 μg folic acid group（P 〈 0.05） and other two dose of folic acid did not affect gene expression（P 〉 0.05）. Meanwhile, methylation level of IGF2 promoter were lower in 100 and 150 μg groups, which was consistent with lower expression of DNA methyltransferase1（DNMT1）（P 〈 0.05）. What＇s more, chromatin looseness of IGF2 promoter was higher in 150 μg group than control group（P 〈 0.05）. Further, birth weight（BW）, liver and bursa index of new-hatched chickens in 150 μg folic acid group were higher than the other groups（P 〈 0.05）. There were positive correlations between hepatic IGF2 expression and BW and organs index（P 〈 0.05）.Conclusion： In conclusion, our data have demonstrated that 150 μg folic acid injection on E11 could up-regulate IGF2 expression by modulating DNA hypomethylation and improving chromatin accessibility in the gene promoter region,and ulteriorly facilitate embryonic growth and organ development of broilers.

Potential roles of the rectum keystone microbiota in modulating the microbial community and growth performance in goat model

Background Ruminal microbiota in early life plays critical roles in the life-time health and productivity of ruminant animals.However,understanding of the relationship between gut microbiota and ruminant phenotypes is very limited.Here,the relationship between the rectum microbiota,their primary metabolites,and growth rate of a total of 76 young dairy goats(6-month-old)were analyzed,and then 10 goats with the highest or lowest growth rates respectively were further compared for the differences in the rectum microbiota,metabolites,and animal’s immune parameters,to investigate the potential mechanisms by which the rectum microbiota contributes to the health and growth rate.Results The analysis of Spearman correlation and microbial co-occurrence network indicated that some keystone rectum microbiota,including unclassified Prevotellaceae,Faecalibacterium and Succinivibrio,were the key modulators to shape the rectum microbiota and closely correlated with the rectum SCFA production and serum IgG,which contribute to the health and growth rate of young goats.In addition,random forest machine learning analysis suggested that six bacterial taxa in feces could be used as potential biomarkers for differentiating high or low growth rate goats,with 98.3%accuracy of prediction.Moreover,the rectum microbiota played more important roles in gut fermentation in early life(6-month-old)than in adulthood stage(19-month-old)of goats.Conclusion We concluded that the rectum microbiota was associated with the health and growth rate of young goats,and can be a focus on the design of the early-life gut microbial intervention.

Effect of difference doses of Newcastle disease vaccine immunization on growth performance,plasma variables and immune response of broilers

Background： As a member of the Paromyxoviridoe group, Newcastle disease virus （NDV） is the key causative agent of Newcastle disease （ND） that attacks chickens, turkeys and other avian birds. Surviving birds showed lower feed utilization, growth performance or egg production, which results in severe economic losses. The purpose of this study was to determine the effect of different doses of NDV immunization on growth performance, plasma variables and immune response of broiler chickens. Methods： A total of 480 one-day-old Arbor Acres broilers were randomly administrated with 0, 4, 6 or 8 doses of NDV at 12 d and 28 d, respectively. Each group consisted of ten replicates with 12 birds each. Growth performance and organ weight were recorded. Plasma concentration of glucose, total protein, cholesterol, triglycerides and nonesterified fatty acid was determined using commercial kits. The concentration of plasma corticosterone and insulin was measured using commercially available radio immune assay kits. Serum antibody titer and peripheral blood lymphocyte proliferation were also recorded. Results： The results showed that NDV decreased body weight gain （BWG）, and increased Feed：Gain ratio at 1-2 ] d at all doses （P 〈 0.05）. Plasma insulin concentration was lower in all immunization groups after the first immunization at 12 d （P 〈 0.01）. The rest of the plasma indexes were not affected by NDV immunization, including glucose, total protein, cholesterol, triglycerides, nonesterified fatty acid, heterophil/lymphocyte ratio, as well as the proliferation of peripheral blood lymphocyte （P 〉 0.05）. Compared with the control group, NDVtreatment elevated NDV antibody titer at 10 d after the first inoculation （P 〈 0.05）, and at d 5, 9 and 13 after the second inoculation （P 〈 0.05）. Repeated NDV inoculation had no deleterious impacts on body composition at 42 d, and nutrient accretion rates at 8-42 d （P 〉 0.05）. Conclusions： In conclusion, NDV challenge decreased BWG and feed efficiency in earlier stage of growth. However NDV treatment at 6 doses down-regulated the Feed：Gain ratio by 6.36 % throughout the whole growing period. These data suggest that appropriate lower doses of NDV inoculation increase feed efficiency of broiler chickens.

Dietary saccharin sodium supplementation improves the production performance of dairy goats without residue in milk in summer

The purpose of this study was to investigate the effects of dietary saccharin sodium supplementation on production performance,serum biochemical indicators,and rumen fermentation of dairy goats in summer.Twelve Guanzhong dairy goats with similar body weight,days in milk,and milk yield were randomly divided into two dietary treatments:(1)CON:basal diet;(2)SS:basal diet+150 mg/kg saccharin sodium on the basis of dry matter.The experiment lasted 35 d,including 7 d for adaptation and 28 d for dietary treatments,sampling and data collection.Each dairy goat was housed individually in a clean separate pen with ad libitum access to diet and water.The goats fed SS diet had increased dry matter intake(DMI;P=0.037),4%fat corrected milk yield(P=0.049),energy corrected milk yield(P=0.037),milk protein yield(P=0.031),and total solids yield(P=0.036).Serum activity of aspartate aminotransferase(P=0.047)and concentrations of 70-kDa heat shock protein(P=0.090),malondialdehyde(P=0.092),and total protein(P=0.057)were lower in goats fed SS diet than those fed CON diet.Supplementation of saccharin sodium tended to increase activity of glutathione peroxidase in serum(P=0.079).The concentrations of rumen total volatile fatty acid(P=0.042)and butyrate(P=0.038)were increased by saccharin sodium supplementation.Dietary supplementation of saccharin sodium increased the relative abundance of Lachnobacterium(P=0.022),Pseudoramibacter(P=0.022),Shuttleworthia(P=0.025),and Syntrophococcus(P=0.037),but reduced the relative abundance of Prevotella_1(P=0.037)and Lachnospiraceae_UCG_008(P=0.037)in rumen.Saccharin sodium was observed in feces and urine of goats fed diet supplemented with saccharin sodium,but saccharin sodium was undetectable in the milk of goats receiving SS diet.In conclusion,administration of saccharin sodium was effective in increasing fat and energy corrected milk yield by increasing DMI and improving rumen fermentation and antioxidant capacity of dairy goats in summer.In addition,saccharin sodium residue was undetectable in the milk.

Dietary supplementation with inulin improves lactation performance and serum lipids by regulating the rumen microbiome and metabolome in 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.Sixteen Holstein dairy cows with similar body conditions were randomly divided into 2 groups(n=8 per group),with inulin addition at 0 and 200 g/d percow.The experiment lasted for 6 weeks,including a 1-week adaptation period and a 5-week treatment period.At the end of the experimental period,the milk,serum and rumen fluid were sampled and analyzed.The microbiome and metabolome in the rumen fluid were analyzed via 16 S rRNA sequencing and untargeted metabolomics,respectively.The results showed that supplementation with inulin(200 g/d per cow)increased the milk yield(P=0.001),milk protein(P=0.032),lacto se rate(P=0.004)and proportion of saturated fatty acids(SFA)in milk(P<0.001),but decreased the proportion of unsaturated fatty acids(USFA)(P=0.041).Rumen pH(P=0.040)and the concentration of NH3-N(P=0.024)were decreased;however,acetate(P<0.001),propionate(P=0.003),butyrate(P<0.001)and lactic acid(LA)(P=0.043)were increased.The total cholesterol(TC)(P=0.008)and triglycerides(TG)(P=0.01)in serum were also reduced.Additionally,inulin addition elevated the relative abundance of several beneficial symbiotic and short-chain fatty acid(SCFA)-producing bacteria,such as Muribaculaceae(false discovery rate[FDR]-adjusted P<0.01),Acetitomaculum(FDR-adjusted P=0.043),and Bu tyrivibrio(FDR-adjusted P=0.036),while elevating the levels of L-lysine(FDR-adjusted P=4.24×10^(-3)),L-proline(FDR-adjusted P=0.0158),and L-phenylalanine(FDRadj usted P=0.027).In contrast,several pathogens and ruminal bacteria abu ndant in high-fat diets,such as Escherichia-Sh igella(FD R-adj usted P=0.022),Erysipelo trichaceaeUCG-004(FD R-adjusted P<0.01)and RF39(FDR-adjusted P=0.042)were decreased along with the reduction of lysophosphatidylcholine(LysoPC)(18:1(9 Z))(FDR-adjusted P=1.03×10^(-3)),LysoPC(16:0)(FDR-adjusted P=0.0108),LysoPC(18:2(9 Z,12 Z))(FDRadjusted P=1.65×10^(-3))and 8-methylnonenoate.In conclusion,dietary inulin supplementation could increase the relative abundance of commensal microbiota and SCFA-producing bacteria,upregulate amino acidmetabolism and downregulate lipid metabolism in the rumen of dairy cows,which might further improve lactation performance and the level of serum lipids.

The mechanistic target of rapamycin complex 1 pathway involved in hepatic gluconeogenesis through peroxisome-proliferator-activated receptorγcoactivator-1a

Cattle can efficiently perform de novo generation of glucose through hepatic gluconeogenesis to meet post-weaning glucose demand.Substantial evidence points to cattle and non-ruminant animals being characterized by phylogenetic features in terms of their differing capacity for hepatic gluconeogenesis,a process that is highly efficient in cattle yet the underlying mechanism remains unclear.Here we used a variety of transcriptome data,as well as tissue and cell-based methods to uncover the mechanisms of high-efficiency hepatic gluconeogenesis in cattle.We showed that cattle can efficiently convert propionate into pyruvate,at least partly,via high expression of acyl-CoA synthetase short-chain family member 1(ACSS1),propionyl-CoA carboxylase alpha chain(PCCA),methylmalonyl-CoA epimerase(MCEE),methylmalonyl-CoA mutase(MMUT),and succinate-CoA ligase(SUCLG2)genes in the liver(P<0.01).Moreover,higher expression of the rate-limiting enzymes of gluconeogenesis,such as phosphoenolpyruvate carboxykinase(PCK)and fructose 1,6-bisphosphatase(FBP),ensures the efficient operation of hepatic gluconeogenesis in cattle(P<0.01).Mechanistically,we found that cattle liver exhibits highly active mechanistic target of rapamycin complex 1(mTORC1),and the expressions of PCCA,MMUT,SUCLG2,PCK,and FBP genes are regulated by the activation of mTORC1(P<0.001).Finally,our results showed that mTORC1 promotes hepatic gluconeogenesis in a peroxisome proliferator-activated receptor γ coactivator 1a(PGC-1a)dependent manner.Collectively,our results not only revealed an important mechanism responsible for the quantitative differences in the efficiency of hepatic gluconeogenesis in cattle versus non-ruminant animals,but also established that mTORC1 is indeed involved in the regulation of hepatic gluconeogenesis through PGC-1a.These results provide a novel potential insight into promoting hepatic gluconeogenesis through activated mTORC1 in both ruminants and mammals.

Tracing enterococci persistence along a pork production chain from feed to food in China

The prevalence and transmission of vancomycin-resistant Enterococcus(VRE)in enterococci being as probiotics has been neglected in the scientific literature.The application of enterococci in feed,food and health products may cause VRE transmission through the food chain.This study evaluated phenotypic resistance of Enterococcus species to 20 antibiotics along a pork production chain from feed to food.It also assessed the genetic diversity of Enterococcus faecium isolates.A total of 510 samples(feed,n=70;swine manure,n=400;swine carcasses,n=20,and retail pork,n=20)were collected in Beijing,China.A total of 328 enterococci isolates with 275 E.faecium and 53 Enterococcus faecalis were identified using 16 S rRNA.Antimicrobial susceptibility to all enterococci isolates was conducted using the KeB method for 20 antibiotics from 9 categories.Multilocus sequence typing(MLST)was conducted on the E.faecium isolates to survey the dissemination of enterococci in the pig industry.The results showed that only 26 enterococci isolates were sensitive to the 20 antibiotics,while half of the isolates(164/328)had acquired multi-drug resistance.The resistant rate to furazolidone was 68.60%,followed by 42.99%to tetracycline.One vancomycin-resistant E.faecium isolates were isolated from feed origin and 2 from manure origin,with minimum inhibitory concentrations to vancomycin of 1,024,64,and 64 mg/mL,respectively.The MLST outcomes showed that the 275 E.faecium isolates belonged to 11 sequence types(ST)including ST40,ST60,ST94,ST160,ST178,ST296,ST361,ST695,ST726,ST812 and ST1014.The ST of the feedsourced VRE was ST1014,while the 2 manure-sourced VRE was ST69.ST1014 evolved from ST78,which was the dominant clonal complex in most cities of China,leading to the spreading of VRE.These findings revealed the potential safety hazards of commercial probiotic enterococci in China and showed that there is a risk of the VRE horizontally transferring from feed to food.

Yak rumen microbiome elevates fiber degradation ability and alters rumen fermentation pattern to increase feed efficiency

Rumen microbes play an important role in ruminant energy supply and animal performance.Previous studies showed that yak(Bos grunniens)rumen microbiome and fermentation differ from other ruminants.However,little is understood about the features of the rumen microbiome that make yak adapted to their unique environmental and dietary conditions.This study was to investigate the rumen microbiome and metabolome to understand how yak adapt to the coarse forage and harsh environment in the Qinghai-Tibetan plateau.Nine female Qaidam yellow cattle(Bos taurus),9 dzomo(hybrids of cattle and yak)and 9 female plateau yak(B.grunniens),about 5 to 6 years old,were used in this study.Rumen fermentation parameters,fibrolytic enzyme activities,and rumen metataxonomic were determined.Then 18(6 samples per group)were selected for rumen metagenomic and metabolome analysis.Metataxonomic analysis revealed that the rumen microbiota was significantly different among plateau yak,Qaidam yellow cattle,and dzomo(P<0.05).Metagenomic analysis displayed a larger gene pool encoding a richer repertoire of carbohydrate-active enzymes in the rumen microbiome of plateau yak and dzomo than Qaidam yellow cattle(P<0.05).Some of the genes encoding glycoside hydrolases that mediate the digestion of cellulose and hemicellulose were significantly enriched in the rumen of plateau yak than Qaidam yellow cattle,but glycoside hydrolase 57 that primarily includes amylases was abundant in Qaidam yellow cattle(P<0.05).The rumen fermentation profile differed also,Qaidam yellow cattle having a higher molar proportion of acetate but a lower molar proportion of propionate than dzomo and plateau yak(P<0.05).Based on metabolomic analysis,rumen microbial metabolic pathways and metabolites were different.Differential metabolites are mainly amino acids,carboxylic acids,sugars,and bile acids.Changes in rumen microbial composition could explain the above results.The present study showed that the rumen microbiome of plateau yak helps its host to adapt to the Qinghai-Tibetan plateau.In particular,the plateau yak rumen microbiome has more enzymes genes involved in cellulase and hemicellulase than that of cattle,resulting higher fibrolytic enzyme activities inyak,further providing stronger fiber degradation function.

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 ru-minants,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 concen-trate,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 concen-tration(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 2a(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.

Active dry yeast supplementation benefits ruminal fermentation,bacterial community,blood immunoglobulins,and growth performance in young dairy goats,but not for intermittent supplementation

This study evaluated the effects of active dry yeast(ADY)supplementation and supplementation stra-tegies on ruminal fermentation,bacterial community,blood metabolites,and growth performance in young dairy goats.Sixty young female Guanzhong dairy goats of similar age(4.00±0.50 months)and BW(19.65±0.41 kg)were randomly divided into 3 groups(n=20):(1)basal diet group(CON);(2)basal diet continuously supplemented with 3.0 g/goat per day commercial ADY(a proprietary strain of Saccharomyces cerevisiae with 5.0×10^(9)cfu/g)group(CSY);(3)basal diet with intermittently supple-mented ADY group(ISY;5 d supplementation with ADY at 4.5 g/goat per day following 5 d of no sup-plementation).The experiment lasted 67 d with the first 7 d as an adaptive period.Rumen fluid and blood samples were collected bi-weekly.Data were analyzed using the MIXED procedure combined with the SLICE option in SAS.Specific orthogonal contrasts of ADY vs.CON and CSY vs.ISY were also analyzed.During the experimental period,ADY supplementation resulted in greater DMI(P=0.03),ruminal ac-etate proportion(P<0.01)and acetylesterase activity(P=0.01),and blood contents of glucose(P=0.01)and IgM(P=0.02)and tended to have greater ADG(P=0.05)and paunch girth(P=0.06)than the CON,despite the propionate proportion(P=0.03)and contents of total protein(P=0.04)and IgA(P=0.03)being lower.The lower ruminal NH_(3)-N(P<0.01)and blood urea nitrogen(P=0.07)contents indicated greater nitrogen utilization with ADY supplementation.ADY supplementation showed persistent effects after it was stopped because the BW at 12 months of age(P=0.03)and birth weight of lambs(P=0.02)were greater than the CON.However,the ISY did not show those benefits and had significantly lower relative abundances of fiber-degrading related bacteria than the CSY.In conclusion,ADY supplementa-tion,especially continuously supplemented,may enhance ADG and ADG:DMI ratio by improving DMI,ruminal cellulolytic bacteria abundance and enzyme activity,nitrogen utilization,and immune status.These findings provide a theoretical basis for the rational application of ADY and have important practical implications for the design of nutritional strategies in growing dairy goats.

Regulation of pancreatic exocrine in ruminants and the related mechanism: The signal transduction and more

The unique structure of the stomach,including the rumen,reticulum,omasum,and abomasum,indicates the differences between the ruminant and monogastric animals in the digestion of nutrients.This difference is reflected in the majority of dietary nutrients that may be fermented in the rumen.Significant proteins and a certain amount of starch can flow to the small intestine apart from rumen.The initial phase of small intestinal digestion requires pancreatic digestive enzymes.In theory,the enzymatic digestion and utilization efficiency of starch in the small intestine are considerably higher than that in the rumen,but the starch digestibility in the small intestine is quite low in ruminants.Therefore,improving the digestion of nutrients,especially starch in the small intestine is more urgent for high-yield ruminants.Although the pancreas plays a central role in nutrient digestion,the progress of research investigating pancreatic exocrine regulation in the ruminant is slow due to some factors,such as the complex structure of the pancreas,the selection of experimental model and duration,and internal(hormones or ages) and external(diet) influences.The present review is based on the research findings of pancreatic exocrine regulation of dairy animals and expounded from the physiological structure of the ruminant pancreas,the factors affecting the digestion and exocrine processing of carbohydrates,and the regulatory mechanism governing this process.The review aims to better understand the characteristics of enzymatic digestion,thereby advancing pancreatic exocrine research and improving the digestion and utilization of nutrients in ruminants.Additionally,this review provides the theoretical basis for improving nutrient utilization efficiency,reducing wastage of feed resources,and promoting the efficient development of the dairy industry.

Rumen bacterial cluster identification and its influence on rumen metabolites and growth performance of young goats

Enterotypes,which are defined as bacterial clusters in the gut microbiome,have been found to have a close relationship to host metabolism and health.However,this concept has never been used in the rumen,and little is known about the complex biological relationships between ruminants and their rumen bacterial clusters.In this study,we used young goats(n=99)as a model,fed them the same diet,and analyzed their rumen microbiome and corresponding bacterial clusters.The relationships between the bacterial clusters and rumen fermentation and growth performance in the goats were further investigated.Two bacterial clusters were identified in all goats:the P-cluster(dominated by genus Prevotella,n=38)and R-cluster(dominated by Ruminococcus,n=61).Compared with P-cluster goats,Rcluster goats had greater growth rates,concentrations of propionate,butyrate,and 18 free amino acids)and proportion of unsaturated fatty acids,but lower acetate molar percentage,acetate to propionate ratio,and several odd and branched chain and saturated fatty acids in rumen fluid(P<0.05).Several members of Firmicutes,including Ruminococcus,Oscillospiraceae NK4A214 group,and Christensenellaceae R-7 group were significantly higher in the R-cluster,whereas Prevotellaceae members,such as Prevotella and Prevotellaceae UCG-003,were significantly higher in P-cluster(P<0.01).Co-occurrence networks showed that R-cluster enriched bacteria had significant negative correlations with P-cluster enriched bacteria(P<0.05).Moreover,we found the concentrations of propionate,butyrate and free amino acids,and the proportions of unsaturated fatty acids were positively correlated with R-cluster enriched bacteria(P<0.05).The concentrations of acetate,acetate to propionate ratio,and the proportion of odd and branched chain and saturated fatty acids were positively correlated with P-cluster enriched bacteria(P<0.05).Overall,our results indicated that rumen bacterial clusters can influence rumen fermentation and growth performance of young goats,which may shed light on modulating the rumen microbiome in early life to improve the growth performance of ruminant animals.