Repeated inoculation with rumen fluid accelerates the rumen bacterial transition with no benefit on production performance in postpartum Holstein dairy cows

Background The dairy cow’s postpartum period is characterized by dramatic physiological changes,therefore imposing severe challenges on the animal for maintaining health and milk output.The dynamics of the ruminal microbiota are also tremendous and may play a crucial role in lactation launch.We aim to investigate the potential benefits of early microbial intervention by fresh rumen microbiota transplantation(RMT)and sterile RMT in postpartum dairy cows.Twelve fistulated peak-lactation dairy cows were selected to be the donors for rumen fluid collection.Thirty postpartum cows were divided into 3 groups as the transplantation receptors respectively receiving 10 L fresh rumen fluid(FR),10 L sterile rumen fluid(SR),or 10 L saline(CON)during 3 d after calving.Results Production performance,plasma indices,plasma lipidome,ruminal microbiome,and liver transcriptome were recorded.After fresh and sterile RMT,we found that the molar proportion of propionic acid was increased on d 7 in the FR and SR groups and the bacterial composition was also significantly changed when compared with the CON group.A similarity analysis showed that the similarities between the CON group and FR or SR group on d 7 were 48.40%or 47.85%,whereas the similarities between microbiota on d 7 and 21 in the FR and SR groups were 68.34%or 66.85%.Dry matter intake and feed efficiency were not affected by treatments.Plasmaβ-hydroxybutyrate concentration in the FR group was decreased and significantly different lipids mainly included phosphatidylcholine and lysophosphatidylcholine containing polyunsaturated fatty acids.Hepatic transcriptomics analysis indicated acutephase response pathways were upregulated in the SR group.Conclusions Our study suggests that RMT can shorten the transition process of the ruminal microbiota of postpartum dairy cows with no benefit on dry matter intake or feed efficiency.Inoculation with rumen fluid may not be a useful approach to promote the recovery of postpartum dairy cows.

Maternal supplementation with n-3 fatty acids affects placental lipid metabolism, inflammation, oxidative stress, the endocannabinoid system, and the neonate cytokine concentrations in dairy cows

Background The placenta plays a crucial role in supporting and influencing fetal development.We compared the effects of prepartum supplementation with omega-3(n-3)fatty acid(FA)sources,flaxseed oil(FLX)and fish oil(FO),on the expression of genes and proteins related to lipid metabolism,inflammation,oxidative stress,and the endocannabinoid system(ECS)in the expelled placenta,as well as on FA profile and inflammatory response of neonates.Late-pregnant Holstein dairy cows were supplemented with saturated fat(CTL),FLX,or FO.Placental cotyledons(n=5)were collected immediately after expulsion,and extracted RNA and proteins were analyzed by RTPCR and proteomic analysis.Neonatal blood was assessed for FA composition and concentrations of inflammatory markers.Results FO increased the gene expression of fatty acid binding protein 4(FABP4),interleukin 10(IL-10),catalase(CAT),cannabinoid receptor 1(CNR1),and cannabinoid receptor 2(CNR2)compared with CTL placenta.Gene expression of ECS-enzyme FA-amide hydrolase(FAAH)was lower in FLX and FO than in CTL.Proteomic analysis identified 3,974 proteins;of these,51–59 were differentially abundant between treatments(P≤0.05,|fold change|≥1.5).Top canonical pathways enriched in FLX vs.CTL and in FO vs.CTL were triglyceride metabolism and inflammatory processes.Both n-3 FA increased the placental abundance of FA binding proteins(FABPs)3 and 7.The abundance of CNR1 cannabinoid-receptor-interacting-protein-1(CNRIP1)was reduced in FO vs.FLX.In silico modeling affirmed that bovine FABPs bind to endocannabinoids.The FLX increased the abundance of inflammatory CD44-antigen and secreted-phosphoprotein-1,whereas prostaglandin-endoperoxide synthase 2 was decreased in FO vs.CTL placenta.Maternal FO enriched neonatal plasma with n-3 FAs,and both FLX and FO reduced interleukin-6 concentrations compared with CTL.Conclusion Maternal n-3 FA from FLX and FO differentially affected the bovine placenta;both enhanced lipid metabolism and modulated oxidative stress,however,FO increased some transcriptional ECS components,possibly related to the increased FABPs.Maternal FO induced a unique balance of pro-and anti-inflammatory components in the placenta.Taken together,different sources of n-3 FA during late pregnancy enhanced placental immune and metabolic processes,which may affect the neonatal immune system.

Effect of Extending Voluntary Waiting Period on Health of Holstein Friesian Dairy Cows

The aim of this of this experimental study to investigate the effect of 3 voluntary waiting periods (VWP) on health of dairy cows. A total of 100 lactations of 100 Holstein Friesian cows with high milk production (average 9.442 ± 620 kg) were randomly (based on the ear tags digits of cows) distributed to 1 to 3 experimental groups with VWP of 50 (VWPG50;n = 32), 100 (VWPG100;n = 34) or 150 days (VWPG150;n = 34). Observations relating to diseases of the cows were made by the farm veterinarian and research personnel. Were defined eight disease: puerperal fever, retained fetal membranes, displaced abomasum, metritis, clinical ketosis, clinical mastitis, ovarian cysts, and claw diseases. The experimental days (ED) were from 4 days in milk (DIM) to 100 days after the next calving. The experiment was managed at Dairy Research Farm ?imnic-Craiova January 2018 to December 2022. A clear set of clinical signs were used to define a case at the diseases without the need for laboratory confirmation. Values of Lactational incidence risk (LIR) median postpartum days at diagnosis and pairwise comparison of proportion between VWPs were calculated. LIR for puerperal fiver, retained fetal membranes, displaced abomasum, clinical ketosis, clinical mastitis, ovarian cysts and claw disease were 4;5;2;8;8;and 4% respectively. Numerically, cows with VWP of 100 and150 days had more disease cases compared with VWP of 50 days. The differences between experimental groups of cows regarding proportions of cows with disease cases were not statistically significant. Any of the eight disorders reported in this study was analyzed independently to other health problems. For all enrolled cows (n = 100) VWP was extended until 100 or 150 days postpartum with no effect on the lactational incidence risk for the eight disorders analyzed.

Feeding Calcium Salts of Linseed Oil on Metabolic Status and Reproductive Traits in Grazing Dairy Cows

This experiment aimed to evaluate the effect of calcium salts of linseed oil (rich in alpha-linolenic acid (ALA, C18:3n-3) on metabolic and reproductive traits in high-producing dairy cows under grazing. Thirty-six Holstein dairy cows were randomly assigned, in a complete block design, to receive ALA supplementation (0.85 kg∙day−1 of calcium salts of linseed oil) or to remain as untreated control (CON). The concentrate was formulated to offer the same amount of energy across treatments (CON cows received an extra kg of corn to compensate for the higher energy density of ALA treatment). A PMR + Alfalfa pasture was offered to all cows at the same time. A fixed time artificial insemination (FTAI) at 80 DIM, preceded by a Presynch plus Ovsynch protocol was implemented for the first service and later, on return to estrus, heat detection and artificial insemination (AI) were performed. Pregnancy diagnosis was checked at 30, 42, 60, and 90 d after AI. Blood and milk samples were taken biweekly. Treatment affected plasma cholesterol concentration (160.36 vs. 186.70 mg∙dl−1, p = 0.03, for ALA and CON, respectively) and on size of corpus luteum (CL, 17.6 vs. 13.7 mm, p = 0.02, for ALA and CON, respectively). Supplementation tended (p = 0.136) to increase conception rate by 200 DIM (81.69% vs. 55.43% in ALA and CON cows, respectively). However, treatment had no effect (p > 0.05) on body weight (BW), body condition score (BCS), and circulating levels of beta-hydroxybutyrate (BHBA), glucose, insulin, growth hormone (GH) and insulin-like growth factor (IGF-I). Our results suggest that supplementation with calcium salts of linseed oil could enhance ovarian function without affecting energy metabolism in early lactation dairy cows.

Spatially resolved transcriptomic profiling of placental development in dairy cow

The placenta plays a crucial role in successful mammalian reproduction.Ruminant animals possess a semi-invasive placenta characterized by a highly vascularized structure formed by maternal endometrial caruncles and fetal placental cotyledons,essential for full-term fetal development.The cow placenta harbors at least two trophoblast cell populations:uninucleate(UNC)and binucleate(BNC)cells.However,the limited capacity to elucidate the transcriptomic dynamics of the placental natural environment has resulted in a poor understanding of both the molecular and cellular interactions between trophoblast cells and niches,and the molecular mechanisms governing trophoblast differentiation and functionalization.To fill this knowledge gap,we employed Stereo-seq to map spatial gene expression patterns at near single-cell resolution in the cow placenta at 90 and 130 days of gestation,attaining high-resolution,spatially resolved gene expression profiles.Based on clustering and cell marker gene expression analyses,key transcription factors,including YBX1 and NPAS2,were shown to regulate the heterogeneity of trophoblast cell subpopulations.Cell communication and trajectory analysis provided a framework for understanding cell-cell interactions and the differentiation of trophoblasts into BNCs in the placental microenvironment.Differential analysis of cell trajectories identified a set of genes involved in regulation of trophoblast differentiation.Additionally,spatial modules and co-variant genes that help shape specific tissue structures were identified.Together,these findings provide foundational insights into important biological pathways critical to the placental development and function in cows.

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.

Effects of omega-3 supplementation on components of the endocannabinoid system and metabolic and inflammatory responses in adipose and liver of peripartum dairy cows

Background:Dietary supplementation of omega-3 fatty acids can reduce the activation of the endocannabinoid system(ECS)by decreasing the availability of arachidonic acid,thus lowering endocannabinoids(e CBs)levels.The ECS is a modulator of energy metabolism,stress response and inflammation in mammals,yet there is little information on the roles of the ECS in transition dairy cows.During the periparturient period,the adipose tissue and liver are the main metabolic organs that participate in the adaptations of dairy cows to onset of lactation;however,exceeded adipose tissue lipolysis and accumulation of lipids in the liver have adverse effects on cows'physiology.Here we aimed to examine whether omega-3 supplementation during the transition period will modulate ECS activation and affect metabolic and inflammatory indices in postpartum dairy cows,by supplementing twenty-eight transition Holstein dairy cows with either saturated fat(CTL)or encapsulated flaxseed oil(FLX).Components of the ECS,metabolic and inflammatory markers were measured in blood,liver,and subcutaneous adipose tissue.Results:FLX supplementation reduced feed intake by 8.1%(P<0.01)and reduced plasma levels of arachidonic acid(by 44.2%;P=0.02)and anandamide(by 49.7%;P=0.03)postpartum compared to CTL.The m RNA transcription levels of the cannabinoid receptor 1(CNR1/CB1)tended to be lower(2.5 folds)in white blood cells of FLX than in CTL(P=0.10),and protein abundance of ECS enzyme monoacylglycerol lipase was higher in peripheral blood mononuclear cells of FLX than in CTL(P=0.04).In adipose tissue,palmitoylethanolamide levels were lower in FLX than in CTL(by 61.5%;P=0.02),relative m RNA transcription of lipogenic genes were higher,and the protein abundance of cannabinoid receptor 2(P=0.08)and monoacylglycerol lipase(P=0.10)tended to be higher in FLX compared to CTL.Hepatic 2-arachidonoylglycerol tended to be higher(by 73.1%;P=0.07),and interlukin-6 m RNA transcription level was 1.5 folds lower in liver of FLX than in CTL(P=0.03).Conclusions:Nutritional supplementation of omega-3 fatty acids seems to partly modulate ECS activation,which could be related to lower feed intake.The altered ECS components in blood,adipose tissue and liver are associated with moderate modulations in lipid metabolism in the adipose and inflammation in liver of peripartum dairy cows.

The effect of ensiled paulownia leaves in a high-forage diet on ruminal fermentation,methane production,fatty acid composition,and milk production performance of dairy cows

Background:The use of industrial by-products rich in bioactive compounds as animal feeds can reduce greenhouse gas production.Paulownia leaves silage(PLS)was supplemented to dairy cows'diet and evaluated in vitro(Exp.1;Rusitec)and in vivo(Exp.2,cannulated lactating dairy cows and Exp.3,non-cannulated lactating dairy cows).The study investigated the PLS effect on ruminal fermentation,microbial populations,methane production and concentration,dry matter intake(DMI),and fatty acid(FA)proportions in ruminal fluid and milk.Results:Several variables of the ruminal fluid were changed in response to the inclusion of PLS.In Exp.1,the p H increased linearly and quadratically,whereas ammonia and total volatile fatty acid(VFA)concentrations increased linearly and cubically.A linear,quadratic,and cubical decrease in methane concentration was observed with increasing dose of the PLS.Exp.2 revealed an increase in ruminal p H and ammonia concentrations,but no changes in total VFA concentration.Inclusion of PLS increased ruminal propionate(at 3 h and 6 h after feeding),isovalerate,and valerate concentrations.Addition of PLS also affected several populations of the analyzed microorganisms.The abundances of protozoa and bacteria were increased,whereas the abundance of archaea were decreased by PLS.Methane production decreased by 11%and 14%in PLS-fed cows compared to the control in Exp.2 and 3,respectively.Exp.3 revealed a reduction in the milk protein and lactose yield in the PLS-fed cows,but no effect on DMI and energy corrected milk yield.Also,the PLS diet affected the ruminal biohydrogenation process with an increased proportions of C18:3 cis-9 cis-12 cis-15,conjugated linoleic acid,C18:1 trans-11 FA,polyunsaturated fatty acids(PUFA),and reduced n6/n3 ratio and saturated fatty acids(SFA)proportion in milk.The relative transcript abundances of the 5 of 6 analyzed genes regulating FA metabolism increased.Conclusions:The dietary PLS replacing the alfalfa silage at 60 g/kg diet can reduce the methane emission and improve milk quality with greater proportions of PUFA,including conjugated linoleic acid,and C18:1 trans-11 along with reduction of SFA.

Predicting nitrogen use efficiency,nitrogen loss and dry matter intake of individual dairy cows in late lactation by including mid‑infrared spectra of milk samples

Background Nitrate leaching to groundwater and surface water and ammonia volatilization from dairy farms have negative impacts on the environment.Meanwhile,the increasing demand for dairy products will result in more pollution if N losses are not controlled.Therefore,a more efficient,and environmentally friendly production system is needed,in which nitrogen use efficiency(NUE)of dairy cows plays a key role.To genetically improve NUE,extensively recorded and cost-effective proxies are essential,which can be obtained by including mid-infrared(MIR)spectra of milk in prediction models for NUE.This study aimed to develop and validate the best prediction model of NUE,nitrogen loss(NL)and dry matter intake(DMI)for individual dairy cows in China.Results A total of 86 lactating Chinese Holstein cows were used in this study.After data editing,704 records were obtained for calibration and validation.Six prediction models with three different machine learning algorithms and three kinds of pre-processed MIR spectra were developed for each trait.Results showed that the coefficient of determination(R2)of the best model in within-herd validation was 0.66 for NUE,0.58 for NL and 0.63 for DMI.For external validation,reasonable prediction results were only observed for NUE,with R2 ranging from 0.58 to 0.63,while the R2 of the other two traits was below 0.50.The infrared waves from 973.54 to 988.46 cm−1 and daily milk yield were the most important variables for prediction.Conclusion The results showed that individual NUE can be predicted with a moderate accuracy in both within-herd and external validations.The model of NUE could be used for the datasets that are similar to the calibration dataset.The prediction models for NL and 3-day moving average of DMI(DMI_a)generated lower accuracies in within-herd validation.Results also indicated that information of MIR spectra variables increased the predictive ability of models.Additionally,pre-processed MIR spectra do not result in higher accuracy than original MIR spectra in the external validation.These models will be applied to large-scale data to further investigate the genetic architecture of N efficiency and further reduce the adverse impacts on the environment after more data is collected.

Effects of Oral Administration of Propylene Glycol and Ca-P-Mg Mixture on Milk Quality and SCC of Dairy Cows after Birth

In order to further study the postpartum care technology of dairy cows,the effects of oral administration of propylene glycol or Ca-P-Mg mixture and compound oral rehydration salts on milk quality and SCC of dairy cows after birth were investigated. The results showed that the milk fat and dry matter contents in the dairy cows administered with Ca-P-Mg mixture and compound oral rehydration salts were higher than those in the dairy cows administered with propylene glycol（P 〈0.05）. However, there were no significant differences in milk sugar and protein contents and SCC between the two administration groups.

Heat stress affects dairy cow health status through blood oxygen availability

Background Rises in global warming and extreme weather occurrence make the risk of heat stress(HS)induced by high ambient temperatures more likely in high-yielding dairy cows,resulting in low milk quality and yield.In ani-mals,oxygen is involved in many physiological and metabolic processes,but the effects of HS on oxygen metabolism remain unclear.Thus,the current study aimed to investigate how oxygen metabolism plays a role in health status of dairy cows by measuring the milk yield,milk composition,and blood biochemical variables of cows under different levels of HS:none(No-HS),mild(Mild-HS),and moderate HS(Mod-HS).Results The HS significantly increased rectal temperature(Ptreat<0.01)and respiration rate(Ptreat<0.01).Under Mod-HS,greater Na+(P<0.05)and lower total CO_(2),and pH(P<0.05)were observed relative to those under No-HS and Mild-HS.Oxygen concentrations in both coccygeal artery and mammary vein(Ptreat<0.01)were lower under Mod-HS than under No-HS.Coccygeal vein concentrations of heat shock protein 90(HSP90)(P<0.05)increased during Mod-HS compared with those in cows under No-HS.Malondialdehyde increased during Mod-HS,and glu-tathione peroxidase(P<0.01)increased during Mild-HS.Coccygeal vein concentrations of vascular endothelial growth factor(P<0.01),heme oxygenase-1(P<0.01),and hypoxia-inducible factor 1α(P<0.01)were greater in cows under Mod-HS than those under No-HS.Red blood cell count(P<0.01)and hemoglobin concentration(P<0.01)were lower in the coccygeal vein of dairy cows under Mild-and Mod-HS than those of cows under No-HS.Conclusions Exposure to HS negatively impacts the health status and lactation performance of dairy cows by limit-ing oxygen metabolism and transportation.However,the specific mechanism by which HS affects mammary function in cows remains unclear and requires further exploration.

Association of residual feed intake with abundance of ruminal bacteria and biopolymer hydrolyzing enzyme activities during the peripartal period and early lactation in Holstein dairy cows

Background: Residual feed intake(RFI) in dairy cattle typically calculated at peak lactation is a measure of feed efficiency independent of milk production level. The objective of this study was to evaluate differences in ruminal bacteria, biopolymer hydrolyzing enzyme activities, and overall performance between the most-and the leastefficient dairy cows during the peripartal period. Twenty multiparous Holstein dairy cows with daily ad libitum access to a total mixed ration from d-10 to d 60 relative to the calving date were used. Cows were classified into most-efficient(i.e. with low RFI, n = 10) and least-efficient(i.e. with high RFI, n = 10) based on a linear regression model involving dry matter intake(DMI), fat-corrected milk(FCM), changes in body weight(BW), and metabolic BW.Results: The most-efficient cows had ~ 2.6 kg/d lower DMI at wk 4, 6, 7, and 8 compared with the least-efficient cows. In addition, the most-efficient cows had greater relative abundance of total ruminal bacterial community during the peripartal period. Compared with the least-efficient cows, the most-efficient cows had 4-fold greater relative abundance of Succinivibrio dextrinosolvens at d-10 and d 10 around parturition and tended to have greater abundance of Fibrobacter succinogenes and Megaspheara elsdenii. In contrast, the relative abundance of Butyrivibrio proteoclasticus and Streptococcus bovis was lower and Succinimonas amylolytica and Prevotella bryantii tended to be lower in the most-efficient cows around calving. During the peripartal period, the most-efficient cows had lower enzymatic activities of cellulase, amylase, and protease compared with the least-efficient cows.Conclusions: The results suggest that shifts in ruminal bacteria and digestive enzyme activities during the peripartal period could, at least in part, be part of the mechanism associated with better feed efficiency in dairy cows.

Adipose tissue lipolysis and remodeling during the transition period of dairy cows

Elevated concentrations of plasma fatty acids in transition dairy cows are significantly associated with increased disease susceptibility and poor lactation performance. The main source of plasma fatty acids throughout the transition period is lipolysis from adipose tissue depots. During this time, plasma fatty acids serve as a source of calories mitigating the negative energy balance prompted by copious milk synthesis and limited dry matter intake.Past research has demonstrated that lipolysis in the adipose organ is a complex process that includes not only the activation of lipolytic pathways in response to neural, hormonal, or paracrine stimuli, but also important changes in the structure and cellular distribution of the tissue in a process known as adipose tissue remodeling. This process involves an inflammatory response with immune cell migration, proliferation of the cellular components of the stromal vascular fraction, and changes in the extracellular matrix. This review summarizes current knowledge on lipolysis in dairy cattle, expands on the new field of adipose tissue remodeling, and discusses how these biological processes affect transition cow health and productivity.

Prepartum body conditions affect insulin signaling pathways in postpartum adipose tissues in transition dairy cows

Background: Overconditioned dairy cows are susceptible to excessive lipolysis and increased insulin resistance during the transition period.The associations among body fat reserve,insulin resistance,and lipolysis in adipose tissues(AT) remain to be elucidated.Therefore,this study aimed to investigate whether excessive fat reserves influence the insulin signaling pathway in AT postpartum.Results: Twenty multiparous dairy cows were selected and assigned to one of two groups,according to prepartum body condition score(BCS): Control group(BCS = 3.0–3.5;n = 10) and Overconditioned group(BCS ≥ 4.0;n = 10).Blood samples were collected on days-14,-7,-4,-2,-1,0,1,2,4,7,and 14 relative to parturition.Subcutaneous AT were collected on day 2 following parturition for quantitative real-time polymerase chain reaction and western blot analyses.No differences were observed between the two groups in serum glucose,non-esterified fatty acids,β-hydroxybutyric acid,tumor necrosis factor(TNF)α,insulin,or leptin concentrations during the experimental period.Compared with the control cows,the overconditioned cows had lower serum triglyceride levels and higher adiponectin concentrations.In the AT postpartum,insulin receptor mRNA and protein levels were lower in the overconditioned cows than in the control cows,and no differences were found in glucose transporter 4 mRNA.Compared with the control cows,the overconditioned cows had lower mRNA levels of TNFα and higher mRNA levels of peroxisome proliferator-activated receptor gamma(PPARγ) in AT postpartum.The phosphorylated protein kinase B(AKT) content and phosphorylation rate of AKT were increased in the overconditioned cows compared with the control cows,which suggested that the downstream insulin signaling in AT was affected.Conclusions: In the present study,transition dairy cows with higher BCS did not show more fat mobilization.The changes of insulin signaling pathway in AT postpartum of overconditioned cows may be partly related to the expression of PPARγ and TNFα,and the secretion of adiponectin.

Milk production and composition and metabolic alterations in the mammary gland of heat-stressed lactating dairy cows

This experiment was conducted to investigate the effects of heat stress(HS) on the feed intake, milk production and composition and metabolic alterations in the mammary gland of dairy cows. Twenty Holstein cows were randomly assigned to one of two treatments according to a completely randomized design. Half of the cows were allocated to the HS group in August(summer season), and the other half were assigned to the HS-free group in November(autumn season). HS reduced(P<0.01) dry matter intake(DMI), milk yield, milk protein and milk urea nitrogen(MUN) of cows compared with HSfree control, but increased(P<0.01) milk somatic cell counts(SCC). We determined the HS-induced metabolic alterations and the relevant mechanisms in dairy cows using liquid chromatography mass spectrometry combined with multivariate analyses. Thirty-four metabolites were identified as potential biomarkers for the diagnosis of HS in dairy cows. Ten of these metabolites, glucose, lactate, pyruvate, lactose, β-hydroxybutyrate, citric acid, α-ketoglutarate, urea, creatine, and orotic acid, had high sensitivity and specificity for HS diagnoses, and seven metabolites were also identified as potential biomarkers of HS in plasma, milk, and liver. These substances are involved in glycolysis, lactose, ketone, tricarboxylic acid(TCA), amino acid and nucleotide metabolism, indicating that HS mainly affects lactose, energy and nucleotide metabolism in the mammary gland of lactating dairy cows. This study suggested that HS might affect milk production and composition by affecting the feed intake and substance metabolisms in the mammary gland tissue of lactating dairy cows.

Changes in feed intake, nutrient digestion, plasma metabolites, and oxidative stress parameters in dairy cows with subacute ruminal acidosis and its regulation with pelleted beet pulp

The objectives of this study were to 1） determine the variation of nutrient digestion, plasma metabolites and oxidative stress parameters triggered by induced subacute ruminal acidosis （SARA）; and 2） evaluate the ability of pelleted beet pulp （BP） as a replacement for ground corn to alleviate SARA. Eight Holstein-Friesian cows were fed four diets during four successive17 day periods： 1） total mixed ration （TMR） containing 0% finely ground wheat （FGW） （WO）; 2） TMR containing 10% FGW （W10）; 3） TMR containing 20% FGW （W20）; and 4） TMR containing 10% BP as a replacement for 10% ground corn （BP10）. The SARA induction protocol reduced the mean ruminal pH from 6.37 to 5.94, and the minimum ruminal pH decreased from 5.99 to 5.41 from baseline to challenge period. Mean ruminal pH increased from 5.94 to 6.05, and minimum daily ruminal pH increased from 5.41 to 5.63, when BP was substituted for corn. The apparent digestibility of nutrients was not affected by the dietary treatments, except that the digestibility of neutral detergent fibre （NDF） and acid detergent fibre （ADF） was reduced in cows fed the W20 diet compared with cows fed the W0 and W10 diets, and cows fed the BP10 diet had higher NDF and ADF digestibility than the cows fed the W20 diet. Cows fed the W20 diet had a lower plasma concentration of 13-hydroxybutyrate （BHBA）, non-esterified fatty acids （NEFA）, cholesterol, triglyceride, and total antioxidative capacity （TAC）, and a higher plasma concentration of glucose, insulin, malonaldehyde （MDA）, super oxygen dehydrogenises （SOD）, and glutathione peroxidase （GSH-Px） than cows fed the W0 diet. Substitution of BP for corn increased concentrations of plasma BHBA and TAC, but decreased concentrations of plasma MDA. Our results indicate that reduction of fibre digestion; the concomitant increase of plasma glucose and insulin; the decrease of plasma BHBA, NEFA, cholesterol, and triglyceride; and changes of plasma oxidative stress parameters are highly related to SARA induced by W20 diets. These variables may be alternative candidates for SARA diagnosis. We also suggest that the substitution of BP for corn could reduce the risk of SARA, increase fibre digestion, and improve the antioxidant status in dairy cows.

Advances in fatty acids nutrition in dairy cows: from gut to cells and effects on performance

High producing dairy cows generally receive in the diet up to 5–6% of fat. This is a relatively low amount of fat in the diet compared to diets in monogastrics;however, dietary fat is important for dairy cows as demonstrated by the benefits of supplementing cows with various fatty acids(FA). Several FA are highly bioactive, especially by affecting the transcriptome;thus, they have nutrigenomic effects. In the present review, we provide an up-to-date understanding of the utilization of FA by dairy cows including the main processes affecting FA in the rumen,molecular aspects of the absorption of FA by the gut, synthesis, secretion, and utilization of chylomicrons;uptake and metabolism of FA by peripheral tissues, with a main emphasis on the liver, and main transcription factors regulated by FA. Most of the advances in FA utilization by rumen microorganisms and intestinal absorption of FA in dairy cows were made before the end of the last century with little information generated afterwards. However,large advances on the molecular aspects of intestinal absorption and cellular uptake of FA were made on monogastric species in the last 20 years. We provide a model of FA utilization in dairy cows by using information generated in monogastrics and enriching it with data produced in dairy cows. We also reviewed the latest studies on the effects of dietary FA on milk yield, milk fatty acid composition, reproduction, and health in dairy cows. The reviewed data revealed a complex picture with the FA being active in each step of the way, starting from influencing rumen microbiota, regulating intestinal absorption, and affecting cellular uptake and utilization by peripheral tissues, making prediction on in vivo nutrigenomic effects of FA challenging.

Month-Wise Prevalence of Subclinical Mastitis in Dairy Cows in Guangdong Province,China

To evaluate the month-wise prevalence of subclinical mastitis （SM） and its relations with climatic temperature and humidity, and to provide references for control and prevention of mastitis in dairy cows in Guangdong, China, California mastitis test method was used to determine the monthly prevalence of SM （MPSM, %） of lactating Holstein cows from 11 dairy farms in Guangdong Province, China, including about 516 cows per monthly examination. The average MPSM on a cow and a quarter basis were 30 and 13% respectively, and there was a positive linear correlation between monthly mean air temperature （MT, °C） and MPSM on a cow basis （r=0.763, P=0.004） or a quarter basis （r=0.577, P=0.049）, but there were no correlations between MT and MPSM on a cow or a quarter basis （P〉0.05）. There was a shift in MPSM trend that the highest MPSM （38.4%） was not for the hottest July with MT at 30.8°C, but for the later September at 27.9°C. The farms need to develop new housing conditions to control cowshed temperatures in the hot season to reduce the mastitis prevalences in the post-hot months.

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.

Effects of different sources of carbohydrates on intake, digestibility, chewing, and performance of Holstein dairy cows

To investigate the effects of different sources of carbohydrates on intake, digestibility, chewing, and performance, nine lactating Holstein dairy cows （day in milk= 100±21 d; body weight=645.7 ± 26.5 kg） were allotted to a 3 × 3 Latin square design at three 23-d periods. The three treatments included 34.91% （B）, 18.87% （BC）, and 18.86% （BB） barley that in treatment B was partially replaced with only corn or corn plus beet pulp in treatments BC and BB, respectively. The concentration of starch and neutral detergent soluble carbohydrate varied （22.2, 20.2, and 14.5; 13.6, 15.9, and 20.1% of DM in treatments B, BC, and BB, respectively）. Cows in treatment BB showed a higher DMI and improved digestibility of DM, NDF, and EE compared with treatments B or BC Ruminal pH was higher in cows fed on BB （6.83） compared with those that received B or BC treatments （6.62 and 6.73, respectively）. A lower proportion of propionate accompanied the higher pH in the BB group; however, a greater proportion of acetate and acetate： propionate ratio was observed compared with cows fed either on the B or BC diet. Moreover, cows fed on the BB diet showed the lowest ruminal passage rate and longest ruminal and total retention time. Eating time did not differ among treatments, rumination time was greater among cows fed on the BB diet compared with the others, whereas total chewing activity was greater than those fed on BC, but similar to those fed on B. The treatments showed no effect on milk yield. Partially replacing barley with corn or beet pulp resulted in an increase in milk fat and a lower protein concentration. Changing dietary NFC with that of a different degradability thus altered intake, chewing activity, ruminal environment, retention time or passage rate, and lactation performance. The results of this study showed that beet pulp with a higher NDF and a detergent-soluble carbohydrate or pectin established a more consistent ruminal mat than barley and corn, thus resulting in higher mean retention time and chewing activity, whereas no changes in 3.5% ECM and milk fat were observed.