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.

Rumen microbiota succession throughout the perinatal period and its association with postpartum production traits in dairy cows:A review

The transition period for dairy cows usually refers to the 3 weeks pre-calving to the 3 weeks post-calving.During this period,dairy cows undergo metabolic and physiological adaptations because of their susceptibility to metabolic and infectious diseases.Poor feeding management under these circumstances may adversely affect the health and subsequent production performance of the cows.Owing to long-term adaptation and evolution,the rumen has become a unique ecosystem inhabited by a complex microbial community closely associated with its natural host.Dietary components are metabolized by the rumen microbiota,and volatile fatty acids and microbial protein products can be used as precursor substances for synthesizing meat and milk components.The successful transition of perinatal dairy cows includes changes in diet,physiology,and the rumen microbiota.Rumen microbial profiles have been confirmed to be heritable and repairable;however,adverse circumstances affect rumen microbial composition,host digestion and metabolism,as well as postpartum production traits of dairy cows for a certain period.Preliminary evidence indicates a close relationship between the rumen microbiota and animal performance.Therefore,changes in rumen microbes during the transition period and the intrinsic links between the microbiota and host postpartum phenotypic traits need to be better understood to optimize production performance in ruminants.

Effects of biochanin A on lactational performance,nitrogen metabolism,and blood metabolites in dairy cows

Optimizing nitrogen utilization efficiency and mitigating nitrogen losses in cows plays a pivotal role in fostering economic sustainability within contemporary agricultural systems.Biochanin A(BCA),a natural component in red clover,has the potential to improve nitrogen metabolism in dairy cows.The primary objective of this study was to probe the impact of biochanin A supplementation on lactational performance,nitrogen metabolism,and blood metabolites in dairy cows.A complete randomized block design experiment was conducted over 28 d,involving 36 multiparous Holstein cows(comparable milk yield=37.1±2.90 kg,BW=642±70.0 kg,days in milk=92±8.0 d,and parity=2.4±0.50),which were allocated to three treatment groups:the Control group(with 0 g/d BCA),the Low group(with 10 g/d per cow BCA),and the High group(with 40 g/d per cow BCA).Biochanin A supplementation improved the lactational performance of cows by increasing milk yield by 6.3%(P=0.007)and feed efficiency by 12.7%(P=0.009).Total intestinal apparent digestibility was unaffected by BCA supplementation(P>0.05),but microbial nitrogen was increased by 30.0%(P=0.002)for promoting nitrogen utilization efficiency by 20.7%(P=0.004).Milk competent yields(protein,lactose,and non-fat milk solid)were increased with increasing BCA supplementation(P 0.05).BCA did not affect body health of dairy cows.Additionally,none of the plasma endocrine hormones were affected(P>0.05).A total of 95 significantly different metabolites were screened from the plasma metabolites of cows in the BCA-added and non-added groups.After performing an enrichment analysis of the metabolic pathways associated with the different metabolites,six specific pathways were identified:bile acid biosynthesis,aspartate metabolism,pyrimidine metabolism,arginine and proline metabolism,the urea cycle,and ammonia recycling.The inclusion of BCA is suggested to enhance milk yield and modulate nitrogen metabolism by influencing relevant metabolites within the metabolic pathways.

Effect of red clover isoflavones on hormone,immune,inflammatory,and plasma biochemistry in lactating dairy cows

This study was to conducted to investigate the effect of red clover isoflavones on the health indicated by immune status and blood biochemistry in dairy cows.Sixty-eight healthy Holstein lactating cows were randomly divided into four treatments(n=17 per treatment)from 5 blocks according to milk yield using a randomized complete block design.No initial differences in parity(2.13±1.21),days in milk(165±21 d),and milk yield(33.93±3.81 kg/d)between groups.Cows were fed the basal diet supplemented with 0,2,4,or 8 g/kg red clover extract(RCE)in diet(dry matter based).Feeding,refusal feed weights,and milk yield were recorded three consecutive days in weeks 0,4,8,and 12.Blood was collected from the tail vein of the cows on the last day of weeks 4,8 and 12,1 h after the morning feeding,and analyzed for hormones,immunoglobulins,inflammatory markers,and markers of liver and kidney activities.The dry matter intake was significantly decreased by 3.7%in the 8 g/kg group(P<0.05).The fat-corrected milk yield was significantly higher in both of the 2 and 4 g/kg groups(P<0.01).Plasma estradiol and prolactin showed a quadratic effect with increasing RCE levels,with the highest in the 4 g/kg group(P<0.05).Plasma tumor necrosis factor(TNF)-a,interleukin(IL)-6,and IL-1βlevels decreased linearly with increasing dietary RCE levels.Plasma IL-18 levels showed a quadratic effect with increasing dietary RCE levels,with significantly lower levels in both of the 2 and 4 g/kg groups(P<0.05).Plasma immunoglobulin A and D-lactic acid levels showed a quadratic effect with increasing dietary RCE levels,with significantly higher level in the 4 g/kg group(P<0.05).The liver function and kidney activity makers were similar(P>0.05).These results recommend the supplementation of RCE at a level from 2 to4 g/kg DM.

细菌脲酶蛋白复合物及其活化机制

脲酶能够催化尿素分解生成氨,在农业和医学领域中具有重要的意义。细菌脲酶蛋白包括结构蛋白(UreA、UreB和UreC)和辅助蛋白(UreD/UreH、UreE、UreF和UreG),它们在脲酶活化过程中各自具有独特的作用,结构蛋白形成脲酶活性中心,而辅助蛋白主要负责镍离子的传递。文中综述了细菌脲酶蛋白复合物的结构和功能,以及各蛋白之间如何相互作用完成其活化过程,以期为脲酶活性调控研究及脲酶抑制剂开发等提供理论指导。

Sodium butyrate promotes gastrointestinal development of preweaning bull calves via inhibiting inflammation,balancing nutrient metabolism,and optimizing microbial community functions

Butyrate promotes the growth and gastrointestinal development of calves.But,the mechanisms behind its effects on signaling pathways of the gastrointestinal tract and rumen microbiome is unclear.This study aimed to reveal transcriptomic pathways of gastrointestinal epithelium and microbial community in response to butyrate supplementation in calves fed a high fiber starter.Fourteen Holstein bull calves(39.9±3.7 kg,14 d of age)were assigned to 2 groups(sodium butyrate group,SB;control group,Ctrl).The SB group received 0.5%SB supplementation.At d 51,the calves were slaughtered to obtain samples for analysis of the transcriptome of the rumen and jejunum epithelium as well as ruminal microbial metagenome.Sodium butyrate supplementation resulted in a higher performance in average daily gain and development of jejunum and rumen papillae.In both the rumen and jejunum epithelium,SB downregulated pathways related to inflammation including NF-κB(PPKCB,CXCL8,CXCL12),interleukin-17(IL17A,IL17B,MMP9),and chemokine(CXCL12,CCL4,CCL8)and up-regulated immune pathways including the intestinal immune network for immunoglobulin A(IgA)production(CD28).Meanwhile,in the jejunum epithelium,SB regulated pathways related to nutritional metabolism including nitrogen metabolism(CA1,CA2,CA3),synthesis and degradation of ketone bodies(HMGCS2,BDH1,LOC100295719),fat digestion and absorption(PLA2G2F,APOA1,APOA4),and the PPAR signaling pathway(FABP4,FABP6,CYP4A11).The metagenome showed that SB greatly increased the relative abundance of Bacillus subtilis and Eubacterium limosum,activated ruminal microbial carbohydrate metabolism pathways and increased the abundance of carbohydrate hydrolysis enzymes.In conclusion,butyrate exhibited promoting effects on growth and gastrointestinal development by inhibiting inflammation,enhancing immunity and energy harvesting,and activating microbial carbohydrate metabolism.These findings provide new insights into the potential mechanisms behind the beneficial effects of butyrate in calf nutrition.

Ruminal microbiota-host interaction and its effect on nutrient metabolism

Rumen microbiota has a close and intensive interaction with the ruminants.Microbiota residing in the rumen digests and ferments plant organic matters into nutrients that are subsequently utilized by the host,making ruminants a unique group of animals that can convert plant materials indigestible by humans into high-quality animal protein as meat and milk.Many studies using meta-omics technologies have demonstrated the relationships between rumen microbiome and animal phenotypes associated with nutrient metabolism.Recently,the causality and physiological mechanisms underpinning the host-microbiota interactions have attracted tremendous research interest among researchers.This review discusses the host-microbiota interactions and the factors affecting these interactions in ruminants and provides a summary of the advances in research on animal husbandry.Understanding the microbiota composition,the functions of key bacteria,and the host-microbiota interaction is crucial for the development of knowledge-based strategies to enhance animal productivity and host health.

Urea transport and hydrolysis in the rumen: A review

Inefficient dietary nitrogen(N)conversion to microbial proteins,and the subsequent use by ruminants,is a major research focus across different fields.Excess bacterial ammonia(NH3)produced due to degradation or hydrolyses of N containing compounds,such as urea,leads to an inefficiency in a host’s ability to utilize nitrogen.Urea is a non-protein N containing compound used by ruminants as an ammonia source,obtained from feed and endogenous sources.It is hydrolyzed by ureases from rumen bacteria to produce NH_(3) which is used for microbial protein synthesis.However,lack of information exists regarding urea hydrolysis in ruminal bacteria,and how urea gets to hydrolysis sites.Therefore,this review describes research on sites of urea hydrolysis,urea transport routes towards these sites,the role and structure of urea transporters in rumen epithelium and bacteria,the composition of ruminal ureolytic bacteria,mechanisms behind urea hydrolysis by bacterial ureases,and factors influencing urea hydrolysis.This review explores the current knowledge on the structure and physiological role of urea transport and ureolytic bacteria,for the regulation of urea hydrolysis and recycling in ruminants.Lastly,underlying mechanisms of urea transportation in rumen bacteria and their physiological importance are currently unknown,and therefore future research should be directed to this subject.

Ruminal bacterial community is associated with the variations of total milk solid content in Holstein lactating cows

Total milk solid(TMS)content directly reflects the quality of milk.Rumen bacteria ferment dietary components,the process of which generates the precursors for the synthesis of milk solid,therefore,the variation in rumen bacterial community could be associated with milk solid in dairy cows.In this study,45 healthy mid-lactation Holstein dairy cows with the similar body weight,lactation stage,and milk yield were initially used for the selection of 10 cows with high TMS(HS)and 10 cows with low TMS(LS).All those animals were under the same feeding management,and the individual milk yield was recorded for 14 consecutive days before milk and rumen fluid were sampled.Rumen fluid was used to determine bacterial community by 16S rRNA gene sequencing technique.The HS cows had significantly greater feed intake and milk TMS,fat,protein content than LS cows(P<0.05).Among the volatile fatty acids(VFA),propionic acid and valeric acid concentrations were significantly greater in HS cows than those in LS cows(P<0.05).There was no significant difference in the concentrations of acetate,butyrate,isobutyrate,valerate,and the total VFA(P>0.05),nor was the acetate-to-propionate ratio,pH value,ammonia nitrogen and microbial crude protein concentrations(P>0.05).Significant differences in the relative abundances of some bacterial genera were found between HS and LS cows.Spearman’s rank correlation analysis revealed that TMS content was correlated positively with the abundances of Ruminococcaceae UCG-014,Ruminococcaceae NK4A214 group,Prevotellaceae UCG-001,Butyrivibrio 2,Prevotellaceae UCG-003,Candidatus Saccharimonas,Ruminococcus 2,Lachnospiraceae XPB1014 group,probable genus 10,Eubacterium ventriosum group,but negatively correlated with Pyramidobacte.In addition,Ruminococcaceae UCG-014,Ruminococcus 2,Ruminococcaceae UCG001,probable genus 10 and Eubacterium ventriosum group might boost the total VFA production in the rumen.In conclusion,the dry matter intake of dairy cows and some special bacteria in rumen were significantly associated with TMS content,which suggests the potential function of rumen bacteria contributing to TMS content in dairy cows.