Global losses due to dairy cattle diseases: A comorbidity-adjusted economic analysis

An economic simulation was carried out over 183 milk-producing countries to estimate the global economic impacts of 12 dairy cattle diseases and health conditions: mastitis (subclinical and clinical), lameness, paratuberculosis (Johne's disease), displaced abomasum, dystocia, metritis, milk fever, ovarian cysts, retained placenta, and ketosis (subclinical and clinical). Estimates of disease impacts on milk yield, fertility, and culling were collected from the literature, standardized, meta-analyzed using a variety of methods ranging from simple averaging to random-effects models, and adjusted for comorbidities to prevent overestimation. These comorbidity-adjusted disease impacts were then combined with a set of country-level estimates for lactational incidence or prevalence or both, herd characteristics, and price estimates within a series of Monte Carlo simulations that estimated and valued the economic losses due to these diseases. It was estimated that total annual global losses are US$65 billion (B). Subclinical ketosis, clinical mastitis, and subclinical mastitis were the costliest diseases modeled, resulting in mean annual global losses of approximately US$18B, US$13B, and US$9B, respectively. Estimated global annual losses due to clinical ketosis, displaced abomasum, dystocia, lameness, metritis, milk fever, ovarian cysts, paratuberculosis, and retained placenta were estimated to be US$0.2B, US$0.6B, US$0.6B, US$6B, US$5B, US$0.6B, US$4B, US$4B, and US$3B, respectively. Without adjustment for comorbidities, when statistical associations between diseases were disregarded, mean aggregate global losses would have been overestimated by 45%. Although annual losses were greatest in India (US$12B), the United States (US$8B), and China (US$5B), depending on the measure of losses used (losses as a percentage of gross domestic product, losses per capita, losses as a percentage of gross milk revenue), the relative economic burden of these dairy cattle diseases across countries varied markedly.

Changes in adiponectin levels of subclinical ketosis cows and their effects on steroid hormone secretion and proliferation in follicular granulosa cells

In dairy cows, the occurrence of subclinical ketosis (SCK) is particularly high during early lactation. Previously, we documented alterations in the abundance of adiponectin (ADPN) in anestrus cows with SCK in comparison to cows in estrus. In the present study, 60 cows were divided into two groups: control (C, n = 30) and SCK (n = 30). Based on cow's estrus situation in two group at 55-60 days postpartum, 15 anestrus SCK cows and estrus cows were designated the SCK-A group and C-E group, respectively. The SCK-A group had downregulated serum and follicular fluid ADPN levels compared with the C-E group. The serum ADPN level was positively correlated with the insulin level and follicle growth rate, and there was a positive correlation between ADPN and glucose in the follicular fluid. Primary culture of dairy cow granulosa cells (GCs) was established to observe the effect of low glucose (Glu) and/or ADPN on GCs cyclins and proteins important for steroid synthesis. The results showed that the addition of 1 µg/mL ADPN alleviated the negative effects of low Glu treatment on the proliferation of GCs and the expression of steroid secretion related protein proteins. Treatment with LY294002 (PI3K inhibitor) four experimental GCs groups: control (0 µg/mL ADPN), 1 µg/mL ADPN, LY294002 inhibitor, and 1 µg/mL ADPN+LY294002. The results showed that ADPN promotes the secretion of steroid hormones by GCs through the PI3K-AKT. In summary, ADPN plays a crucial role in ameliorating postpartum anestrus in dairy cows with SCK.

Fatty acids promote M1 polarization of monocyte-derived macrophages in healthy or ketotic dairy cows and a bovine macrophage cell line by impairing mTOR-mediated autophagy

Excessive concentrations of free fatty acids (FFA) are the main factors causing immune dysfunction and inflammation in dairy cows with ketosis. Polarization of macrophages (the process of macrophages freely switching from one phenotype to another) into M1 or M2 phenotypes is an important event during inflammation induced by environmental stimuli. In nonruminants, mammalian target of rapamycin (mTOR)-mediated autophagy (a major waste degradation process) regulates macrophage polarization. Thus, our objective was to unravel the role of mTOR-mediated autophagy on macrophage polarization in ketotic dairy cows. We performed 4 experiments: (1) In vitro differentiated monocyte-derived macrophages from healthy dairy cows or dairy cows with clinical ketosis (CK) were treated for 24 h with 100 ng/mL LPS and 100 ng/mL IFN-γ or with 10 ng/mL IL4 and 10 ng/mL IL10; (2) Immortalized bovine macrophages were treated for 24 h with 0, 0.3, 0.6, or 1.2 mM FFA, LPS, and IFN-γ, or with IL4 and IL10; (3) Macrophages were pretreated with 2 μM 4,6-dimorpholino-N-(4-nitrophenyl)-1,3,5-triazin-2-amine (MHY1485) for 30 min before treatment with LPS and IFN-γ or IL4 and IL10; (4) Macrophages were pretreated with 100 nM rapamycin (RAPA) for 2 h before treatment with LPS and IFN-γ or IL4 and IL10. Compared with healthy cows, cows with CK had a greater mean fluorescence intensity (MFI) of CD86+, but lower MFI of CD206+ and lower number of autophagosomes and autolysosomes in macrophages. Exogenous FFA treatment upregulated protein abundance of inducible nitric oxide synthase (iNOS) and the MFI of CD86, whereas it downregulated the protein abundance of arginase 1 and the MFI of CD206. In addition, FFA increased the p-p65/p65 protein abundance and tumor necrosis factor α, IL1B, and IL6 mRNA abundance, but decreased LC3-phosphatidylethanolamine conjugate protein abundance and the number of autophagosomes and autolysosomes number. Pretreatment with MHY1485 promoted macrophage M1 polarization and inhibited macrophage M2 polarization via decreased mTOR-mediated autophagy. Activation of mTOR-mediated autophagy by pretreatment with RAPA attenuated the upregulation of inflammation in M1 macrophages that was induced by FFA. These data revealed that high concentrations of FFA promote macrophage M1 polarization in ketotic dairy cows by impairing mTOR-mediated autophagy.

Update on ketosis in dairy cattle with major emphasis on subclinical ketosis and abdominal adiposity

The metabolic changes that occur during the early post-partum period in dairy cows can indeed lead to an imbalance in energy utilization, resulting in the production of excessive ketone bodies. This can have detrimental effects on the cow's health and milk production, leading to economic losses for dairy producers. The release of non-esterified fatty acids into the blood due to increased lipolysis is a key factor in the development of ketosis. Abdominal adiposity is a key factor on these outcomes in modern dairy cows. The redirection of energy and glucose towards lactose synthesis and milk yield leaves a deficit of gluconeogenic precursors, leading to the conversion of acetyl-CoA into ketone bodies instead of entering the Krebs cycle. These ketone bodies, including acetone, acetoacetate and β-hydroxybutyrate, accumulate in the blood and can be detected in various bodily fluids, such as urine, blood and milk, allowing for diagnostic testing. Prevention is indeed crucial in managing ketosis in dairy cattle. Supplementation of propylene glycol in the diet or the use of monensin, either in the diet or in the form of a slow-release bolus, can help prevent the occurrence of ketosis. However, avoiding high body condition (subcutaneous fat) and excessive abdominal adiposity during the dry period and parturition plus an adequate cow comfort are fundamental tasks to avoid ketosis and related disorders. These interventions aim to provide additional energy sources or enhance the cow's ability to utilize energy efficiently, thus reducing the reliance on excessive lipolysis and ketone body production.

Plasma and milk metabolomics profiles in dairy cows with subclinical and clinical ketosis

Ketosis, a commonly observed energy metabolism disorder in dairy cows during the peripartal period, is distinguished by increased concentrations of BHB in the blood. This condition has a negative impact on milk production and quality, causing financial losses. An untargeted metabolomics approach was performed on plasma samples from cows between 5 and 7 DIM diagnosed as controls (CON; BHB <1.2 mM, n = 30), subclinically ketotic (SCK; 1.2 < BHB <3.0 mM, n = 30), or clinically ketotic (CK; BHB >3.0 mM, n = 30). Cows were selected from a commercial farm of 214 Holstein cows (average 305-d yield in the previous lactation of 35.42 ± 7.23 kg/d; parity, 2.41 ± 1.12; BCS, 3.1 ± 0.45). All plasma and milk samples (n = 90) were subjected to liquid chromatography-MS-based metabolomic analysis. Statistical analyses were performed using GraphPad Prism 8.0, MetaboAnalyst 4.0, and R version 4.1.3. Compared with the CON group, both SCK and CK groups had greater milk fat, freezing point, and fat-to-protein ratio, as well as lower milk protein, lactose, solids-not-fat, and milk density. Within 21 d after calving, compared with CON, the SCK group experienced a reduction of 2.65 kg/d in milk yield, while the CK group experienced a decrease of 7.7 kg/d. Untargeted metabolomics analysis facilitated the annotation of a total of 5,259 and 8,423 metabolites in plasma and milk. Differentially affected metabolites were screened in CON versus SCK, CON versus CK, and SCK versus CK (unpaired t-test, false discovery rate <0.05; and absolute value of log(2)-fold change >1.5). A total of 1,544 and 1,888 differentially affected metabolites were detected in plasma and milk. In plasma, glycerophospholipid metabolism, pyrimidine metabolism, tryptophan metabolism, sphingolipid metabolism, amino sugar and nucleotide sugar metabolism, phenylalanine metabolism, and steroid hormone biosynthesis were identified as important pathways. Weighted gene co-expression network analysis (WGCNA) indicated that tryptophan metabolism is a key pathway associated with the occurrence and development of ketosis. Increases in 5-hydroxytryptophan and decreases in kynurenine and 3-indoleacetic acid in SCK and CK were suggestive of an impact at the gut level. The decrease of most glycerophospholipids indicated that ketosis is associated with disordered lipid metabolism. For milk, pyrimidine metabolism, purine metabolism, pantothenate and CoA biosynthesis, amino sugar and nucleotide sugar metabolism, nicotinate and nicotinamide metabolism, sphingolipid metabolism, and fatty acid degradation were identified as important pathways. The WGCNA indicated that purine and pyrimidine metabolism in plasma was highly correlated with milk yield during the peripartal period. Alterations in purine and pyrimidine metabolism characterized ketosis, with lower levels of these metabolites in both milk and blood underscoring reduced efficiency in nitrogen metabolism. Our results may help to establish a foundation for future research investigating mechanisms responsible for the occurrence and development of ketosis in peripartal cows.

Lipolysis inhibition as a treatment of clinical ketosis in dairy cows: Effects on adipose tissue metabolic and immune responses

Dairy cows with clinical ketosis (CK) exhibit excessive adipose tissue (AT) lipolysis and systemic inflammation. Lipolysis in cows can be induced by the canonical (hormonally induced) and inflammatory lipolytic pathways. Currently, the most common treatment for CK is oral propylene glycol (PG); however, PG does not reduce lipolysis or inflammation. Niacin (NIA) can reduce the activation of canonical lipolysis, whereas cyclooxygenase inhibitors such as flunixin meglumine (FM) can limit inflammation and inhibit the inflammatory lipolytic pathway. The objective of this study was to determine the effects of including NIA and FM in the standard PG treatment for postpartum CK on AT function. Multiparous Jersey cows (n = 18; 7.1 ± 3.8 DIM) were selected from a commercial dairy. Inclusion criteria were CK symptoms (lethargy, depressed appetite, and drop in milk yield) and high blood levels of BHB (≥1.2 mmol/L). Cows with CK were randomly assigned to one of 3 treatments: (1) PG: 310 g administered orally once per day for 5 d, (2) PG+NIA: 24 g administered orally once per day for 3 d, and (3) PG+NIA+FM: 1.1 mg/kg administered IV once per day for 3 d. Healthy control cows (HC; n = 6) matched by lactation and DIM (±2 d) were sampled. Subcutaneous AT explants were collected at d 0 and d 7 relative to enrollment. To assess AT insulin sensitivity, explants were treated with insulin (1 µL/L) during lipolysis stimulation with a β-adrenergic receptor agonist (isoproterenol, 1 µM). Lipolysis was quantified by glycerol release in the media. Lipid mobilization and inflammatory gene networks were evaluated using quantitative PCR. Protein biomarkers of lipolysis, insulin signaling, and AT inflammation, including hormone-sensitive lipase, protein kinase B (Akt), and ERK1/2, were quantified by capillary immunoassays. Flow cytometry of AT cellular components was used to characterize macrophage inflammatory phenotypes. Statistical significance was determined by a nonparametric t-test when 2 groups (HC vs. CK) were analyzed and an ANOVA test with Tukey adjustment when 3 treatment groups (PG vs. PG+NIA vs. PG+NIA+FM) were evaluated. At d 0, AT from CK cows showed higher mRNA expression of lipolytic enzymes ABHD5, LIPE, and LPL, as well as increased phosphorylation of hormone-sensitive lipase compared with HC. At d 0, insulin reduced lipolysis by 41% ± 8% in AT from HC, but CK cows were unresponsive (-2.9 ± 4%). Adipose tissue from CK cows exhibited reduced Akt phosphorylation compared with HC. Cows with CK had increased AT expression of inflammatory gene markers, including CCL2, IL8, IL10, TLR4, and TNF, along with ERK1/2 phosphorylation. Adipose tissue from CK cows showed increased macrophage infiltration compared with HC. By d 7, AT from PG+NIA+FM cows had a more robust response to insulin, as evidenced by reduced glycerol release (36.5% ± 8% compared with PG at 26.9% ± 7% and PG+NIA at 7.4% ± 8%) and enhanced phosphorylation of Akt. By d 7, PG+NIA+FM cows presented lower inflammatory markers, including ERK1/2 phosphorylation, and reduced macrophage infiltration, compared with PG and PG+NIA. These data suggest that including NIA and FM in CK treatment improves AT insulin sensitivity and reduces AT inflammation and macrophage infiltration.

Role of diacylglycerol O-acyltransferase 1 (DGAT1) in lipolysis and autophagy of adipose tissue from ketotic dairy cows

High-yielding dairy cows in early lactation often encounter difficulties in meeting the energy requirements essential for maintaining milk production. This is primarily attributed to insufficient dry matter intake, which consequently leads to sustained lipolysis of adipose tissue. Fatty acids released by lipolysis can disrupt metabolic homeostasis. Autophagy, an adaptive response to intracellular environmental changes, is considered a crucial mechanism for regulating lipid metabolism and maintaining a proper cellular energy status. Despite its close relationship with aberrant lipid metabolism and cytolipotoxicity in animal models of metabolic disorders, the precise function of diacylglycerol o-acyltransferase 1 (DGAT1) in bovine adipose tissue during periods of negative energy balance is not fully understood, particularly regarding its involvement in lipolysis and autophagy. The objective of the present study was to assess the effect of DGAT1 on both lipolysis and autophagy in bovine adipose tissue and isolated adipocytes. Adipose tissue and blood samples were collected from cows diagnosed as clinically ketotic (n = 15) or healthy (n = 15) following a veterinary evaluation based on clinical symptoms and serum concentrations of BHB, which were 3.19 mM (interquartile range = 0.20) and 0.50 mM (interquartile range = 0.06), respectively. Protein abundance of DGAT1 and phosphorylation levels of unc-51-like kinase 1 (ULK1), were greater in adipose tissue from cows with ketosis, whereas phosphorylation levels of phosphoinositide 3-kinase (PI3K), protein kinase B (AKT), and mammalian target of rapamycin (mTOR) were lower. Furthermore, when adipocytes isolated from the harvested adipose tissue of 15 healthy cows were transfected with DGAT1 overexpression adenovirus or DGAT1 small interfering RNA followed by exposure to epinephrine (EPI), it led to greater ratios and protein abundance of phosphorylated hormone-sensitive triglyceride lipase (LIPE) to total LIPE and adipose triglyceride lipase (ATGL), while inhibiting the protein phosphorylation levels of ULK1, PI3K, AKT, and mTOR. Overexpression of DGAT1 in EPI-treated adipocytes reduced lipolysis and autophagy, whereas silencing DGAT1 further exacerbated EPI-induced lipolysis and autophagy. Taken together, these findings indicate that upregulation of DGAT1 may function as an adaptive response to suppress adipocytes lipolysis, highlighting the significance of maintaining metabolic homeostasis in dairy cows during periods of negative energy balance.

Invited review: Ketone biology-The shifting paradigm of ketones and ketosis in the dairy cow

Ketosis is currently regarded as a major metabolic disorder of dairy cows, reflective of the animal's efforts to adapt to energy deficit while transitioning into lactation. Currently viewed as a pathology by some, ketosis is associatively implicated in milk production losses and peripartal health complications that increase the risk of early removal of cows from the herd, thus carrying economic losses for dairy farmers and jeopardizing the sustainability of the dairy industry. Despite decades of intense research in the mitigation of ketosis and its sequelae, our ability to lessen its purported effects remains limited. Moreover, the association of ketosis to reduced milk production and peripartal disease is often erratic and likely mired by concurrent potential confounders. In this review, we discuss the potential reasons for these apparent paradoxes in the light of currently available evidence, with a focus on the limitations of observational research and the necessary steps to unambiguously identify the effects of ketosis on cow health and performance via controlled randomized experimentation. A nuanced perspective is proposed that considers the dissociation of ketosis-as a disease-from healthy hyperketonemia. Furthermore, in consideration of a growing body of evidence that highlights positive roles of ketones in the mitigation of metabolic dysfunction and chronic diseases, we consider the hypothetical functions of ketones as health-promoting metabolites and ponder on their potential usefulness to enhance dairy cow health and productivity.

Exploring vaginal discharge scoring to assess clinical metritis severity: Comparison between intrauterine dextrose and systemic antibiotics treatments

The objectives of this study were to assess: 1) differences in the metabolic status, systemic inflammation, daily milk yield, and daily rumination time between Holstein dairy cows with different vaginal discharge scores (VDS) in the first 7±3 DIM, and 2) effects of intrauterine dextrose infusion on metabolic status, systemic inflammation, daily milk yield and daily rumination time in dairy cows with VDS4 and VDS5. Cows (n=641) from a farm located in central Pennsylvania were screened at 7±3 DIM (study d 0) to assess vaginal discharge scores. Vaginal discharge was scored using a five-point scale (i.e., 1- clear fluid, 2- <50% white purulent fluid, 3- >50% white purulent fluid, 4- red-brownish fluid without fetid smell, and 5- fetid red-brownish watery fluid). Cows with VDS4 and VDS5 were blocked by parity and randomly assigned to one of two treatment groups: 1) CONV (VDS4 n=15; VDS5 n= 23): two injections of ceftiofur (per label; 6.6 mg/Kg) 72 h apart; and 2) DEX (VDS4 n=15; VDS5 n=22): three intrauterine infusions of a 50% dextrose solution (1 L/cow) every 24 h. Cows that presented a VDS 1, 2, and 3 were categorized as normal vaginal discharge animals (NOMVDS; n=35) and were randomly selected and matched by parity to CONV and DEX cows. Daily milk yield and rumination time for the first 150 DIM were collected from on-farm computer records. Blood samples were collected to assess haptoglobin (HP) and β-hydroxybutyrate (BHB) concentrations at study d 0, d 7, and d 14 relative to enrollment. Subclinical ketosis was defined as having a BHB concentration >1.2 mmol/dL at any of the sampling points. The data were analyzed using the MIXED and GLIMMIX procedures of SAS as a randomized complete block design. When comparing cows with different VDS (i.e., NOMVDS, VDS4, VDS5) separately, cows with VDS5 had the highest concentration of HP at enrollment compared to cows with VDS4 and NOMVDS; however, cows with VDS4 had higher concentrations of HP compared to cows with NOMVDS. Cows with VDS4 or VDS5 had a higher incidence of subclinical ketosis compared to cows with NOMVDS (p=0.005; VDS4= 62.08±9.16%; VDS5=74.44±6.74%; NOMVDS=34.36±8.53%). Similarly, daily milk yield (p<.0001; VDS4=30.17±1.32 kg/d; VDS5=27.40±1.27 kg/d; NOMVDS=35.14±1.35 kg/d) and daily rumination time (p=0.001; VDS4=490.77±19.44 min; VDS5=465±16.67 min; NOMVDS=558.29±18.80 min) was lower for cows with VDS4 and VDS5 compared to cows with NOMVDS at 7±3 days in milk. When analyzing HP concentration between treatment groups in cows with VDS4 (p=0.70), VDS5 (p=0.25), or VDS4 and VDS5 combined (p=0.31), there was no difference in HP concentration by study d 14 between treatment groups. Interestingly, when only cows with VDS4 were considered for treatment, both treatments, DEX and CONV, increased the daily milk yield to the levels of NOMVDS cows by 14 days in milk. On the other hand, when only cows with VDS5 were considered for treatment, cows treated with DEX produced, on average, 4.48 kg/d less milk in the first 150 days in milk compared to cows treated with CONV or cows that had NOMVDS. Similarly, when cows with either VDS4 or VDS5 were considered for treatment, DEX treatment also impaired milk yield. These results suggest that cows with either VDS 4 or 5 have an altered inflammatory status, and decreased milk yield and rumination compared to cows with NOMVDS. Furthermore, DEX treatment may have similar effects on daily milk yield and metabolic status compared to CONV in cows with VDS4, while DEX is not recommended for cows with VDS5.

Genetic Background of Blood β-Hydroxybutyrate Acid Concentrations in Early-Lactating Holstein Dairy Cows Based on Genome-Wide Association Analyses

Ketosis is a common metabolic disorder in the early lactation of dairy cows. It is typically diagnosed by measuring the concentration of β-hydroxybutyrate (BHB) in the blood. This study aimed to estimate the genetic parameters of blood BHB and conducted a genome-wide association study (GWAS) based on the estimated breeding value. Phenotypic data were collected from December 2019 to August 2023, comprising blood BHB concentrations in 45,617 Holstein cows during the three weeks post-calving across seven dairy farms. Genotypic data were obtained using the Neogen Geneseek Genomic Profiler (GGP) Bovine 100 K SNP Chip and GGP Bovine SNP50 v3 (Illumina Inc., San Diego, CA, USA) for genotyping. The estimated heritability and repeatability values for blood BHB levels were 0.167 and 0.175, respectively. The GWAS result detected a total of ten genome-wide significant associations with blood BHB. Significant SNPs were distributed in Bos taurus autosomes (BTA) 2, 6, 9, 11, 13, and 23, with 48 annotated candidate genes. These potential genes included those associated with insulin regulation, such as INSIG2, and those linked to fatty acid metabolism, such as HADHB, HADHA, and PANK2. Enrichment analysis of the candidate genes for blood BHB revealed the molecular functions and biological processes involved in fatty acid and lipid metabolism in dairy cattle. The identification of novel genomic regions in this study contributes to the characterization of key genes and pathways that elucidate susceptibility to ketosis in dairy cattle.

Prepartum behaviors as early indicators for postpartum energy associated biomarkers status in Holstein dairy cows

Our main aim was to investigate the predictive value of prepartum behaviors such as total daily rumination (TDR), total daily activity (TDA) and dry matter intake (DMI) as early indicators to detect cows at risk for hyperketonemia (HYK), hypoglycemia (HYG) or high non-esterified fatty acid (NEFA) status in the first (wk1) and second week (wk2) postpartum. In a case control study, 64 Holstein cows were enrolled 3 weeks before the expected time of calving and monitored until 15 days in milk (DIM). Postpartum blood samples were taken at D3 and D6 for wk1 and at D12 and D15 for wk2 to measure beta-hydroxybutyrate, NEFA and glucose concentration. Ear-mounted accelerometers were used to measure TDR and TDA. DMI and milk yield were obtained from farm records. Relationships between the average daily rate of change in prepartum TDR (ΔTDR), TDA (ΔTDA), and DMI (ΔDMI) with postpartum HYK, HYG and NEFA status in wk1 and wk2 post-partum were evaluated using linear regression models. Models were adjusted for potential confounding variables, and covariates retained in the final models were determined by backward selection. No evidence was found to support the premise that prepartum ΔTDR, ΔTDA or ΔDMI predicted postpartum HYK, HYG or NEFA status in wk1 or in wk2. Overall, prepartum ΔTDR, ΔTDA and ΔDMI were not effective predictors of HYK, HYG or NEFA status in the first 2 weeks postpartum.

Circulating exosome-mediated AMPKα-SIRT1 pathway regulates lipid metabolism disorders in calf hepatocytes

Subclinical ketosis (SCK) in dairy cows is often misdiagnosed because it lacks clinical signs and detection indicators. However, it is highly prevalent and may transform into clinical ketosis if not treated promptly. Due to the negative energy balance, a large amount of fat is mobilized, producing NEFA that exceeds the upper limit of liver processing, which in turn leads to the disturbance of liver lipid metabolism. The silent information regulator 1 (SIRT1) is closely related to hepatic lipid metabolism disorders. Exosomes as signal transmitters, also play a role in the circulatory system. We hypothesize that the circulating exosome-mediated adenosine 5'-monophosphate (AMP)-activated protein kinase alpha (AMPKα)-SIRT1 pathway regulates lipid metabolism disorders in SCK cows. We extracted the exosomes required for the experiment from the peripheral circulating blood of non-ketotic (NK) and SCK cows. We investigated the effect of circulating exosomes on the expression levels of mRNA and protein of the AMPKα-SIRT1 pathway in non-esterified fatty acid (NEFA)-induced dairy cow primary hepatocytes using in vitro cell experiments. The results showed that circulating exosomes increased the expression levels of Lipolysis-related genes and proteins (AMPKα, SIRT1, and PGC-1α) in hepatocytes treated with 1.2 mM NEFA, and inhibited the expression of lipid synthesis-related genes and protein (SREBP-1C). The regulation of exosomes on lipid metabolism disorders caused by 1.2 mM NEFA treatment showed the same trend as for SIRT1-overexpressing adenovirus. The added exosomes could regulate NEFA-induced lipid metabolism in hepatocytes by mediating the AMPKα-SIRT1 pathway, consistent with the effect of transfected SIRT1 adenovirus.

Prediction of key milk biomarkers in dairy cows through milk mid-infrared spectra and international collaborations

At the individual cow level, suboptimum fertility, mastitis, negative energy balance, and ketosis are major issues in dairy farming. These problems are widespread on dairy farms and have an important economic impact. The objectives of this study were (1) to assess the potential of milk mid-infrared (MIR) spectra to predict key biomarkers of energy deficit (citrate, isocitrate, glucose-6 phosphate [glucose-6P], free glucose), ketosis (β-hydroxybutyrate [BHB] and acetone), mastitis (N-acetyl-β-d-glucosaminidase activity [NAGase] and lactate dehydrogenase), and fertility (progesterone); (2) to test alternative methodologies to partial least squares (PLS) regression to better account for the specific asymmetric distribution of the biomarkers; and (3) to create robust models by merging large datasets from 5 international or national projects. Benefiting from this international collaboration, the dataset comprised a total of 9,143 milk samples from 3,758 cows located in 589 herds across 10 countries and represented 7 breeds. The samples were analyzed by reference chemistry for biomarker contents, whereas the MIR analyses were performed on 30 instruments from different models and brands, with spectra harmonized into a common format. Four quantitative methodologies were evaluated to address the strongly skewed distribution of some biomarkers. Partial least squares regression was used as the reference basis, and compared with a random modification of distribution associated with PLS (random-downsampling-PLS), an optimized modification of distribution associated with PLS (KennardStone-downsampling-PLS), and support vector machine (SVM). When the ability of MIR to predict biomarkers was too low for quantification, different qualitative methodologies were tested to discriminate low versus high values of biomarkers. For each biomarker, 20% of the herds were randomly removed within all countries to be used as the validation dataset. The remaining 80% of herds were used as the calibration dataset. In calibration, the 3 alternative methodologies outperform the PLS performances for the majority of biomarkers. However, in the external herd validation, PLS provided the best results for isocitrate, glucose-6P, free glucose, and lactate dehydrogenase (coefficient of determination in external herd validation [R2v] = 0.48, 0.58, 0.28, and 0.24, respectively). For other molecules, PLS-random-downsampling and PLS-KennardStone-downsampling outperformed PLS in the majority of cases, but the best results were provided by SVM for citrate, BHB, acetone, NAGase, and progesterone (R2v = 0.94, 0.58, 0.76, 0.68, and 0.15, respectively). Hence, PLS and SVM based on the entire dataset provided the best results for normal and skewed distributions, respectively. Complementary to the quantitative methods, the qualitative discriminant models enabled the discrimination of high and low values for BHB, acetone, and NAGase with a global accuracy around 90%, and glucose-6P with an accuracy of 83%. In conclusion, MIR spectra of milk can enable quantitative screening of citrate as a biomarker of energy deficit and discrimination of low and high values of BHB, acetone, and NAGase, as biomarkers of ketosis and mastitis. Finally, progesterone could not be predicted with sufficient accuracy from milk MIR spectra to be further considered. Consequently, MIR spectrometry can bring valuable information regarding the occurrence of energy deficit, ketosis, and mastitis in dairy cows, which in turn have major influences on their fertility and survival.

The rumen microbiota contributed to the development of mastitis induced by subclinical ketosis

BACKGROUND

Mastitis is a serious disease which affects animal husbandry, particularly in cow breeding. The etiology of mastitis is complex and its pathological mechanism is not yet fully understood. Our previous research in clinical investigation has revealed that subclinical ketosis can increase the number of somatic cell counts (SCC) in milk, although the underlying mechanism remains unclear. Recent studies have further confirmed the significant role of mastitis.

RESULTS

In this study, we aimed to examine the SCC, rumen microbiota, and metabolites in the milkmen of cows with subclinical ketosis. Additionally, we conducted a rumen microbiota transplant into mice to investigate the potential association between rumen microbiota disturbance and mastitis induced by subclinical ketosis in dairy cows. The study has found that cows with subclinical ketosis have a higher SCC in their milk compared to healthy cows. Additionally, there were significant differences in the rumen microbiota and the level of volatile fatty acid (VFA) between cows with subclinical ketosis and healthy cows. Moreover, transplanting the rumen microbiota from subclinical ketosis and mastitis cows into mice can induce mammary inflammation and liver function damage than transplanting the rumen flora from healthy dairy cows.

CONCLUSIONS

In addition to the infection of mammary gland by pathogenic microorganisms, there is also an endogenous therapeutic pathway mediated by rumen microbiota. Targeted rumen microbiota modulation may be an effective way to prevent and control mastitis in dairy cows.

Associations among post-partum rumen fill and motility, subclinical ketosis and fertility in Holstein dairy cows

This prospective observational study aimed to investigate the association of rumen fill and motility in post-partum Holstein cows with their future reproductive performance and subclinical ketosis (SCK). The study population consisted of two independent data sets: the first (DS1) included 237 cows from 6 herds and the second one (DS2) 709 cows from 9 herds. Rumen Fill Score (RFS) was transformed into a 3 level-trait, representing very low, low and adequate dry matter intake, respectively. A binary Rumen Contraction Score (RCS) was defined as: 0: <2 contractions/2 min, impaired rumen motility and 1: ≥2 contractions/2 min, normal rumen motility. A combined binary trait based on RFS and RCS (RFCS) was also established, representing unsatisfactory and satisfactory rumen function. Three SCK traits were defined, based on 3 different thresholds, SCK_I: BHB≥1,000 mmol/L, SCK_II: BHB≥1,100 mmol/L and SCK_III: BHB≥1,200 mmol/L. Scores were assessed and blood samples collected on day 7 (DS1) or day 8 (DS2), postpartum. Kaplan-Meier survival analysis, multivariable Cox proportional hazards models and Generalized Linear Mixed Models were performed to evaluate the association of rumen and SCK traits with reproduction. Herd, parity, calving season and several postparturient diseases were also included as potential explanatory variables. Mean days from calving to pregnancy after the 1st artificial insemination (AI) and from calving to pregnancy (all AIs) were shorter for levels of rumen traits representing adequate DMI and normal rumen motility; in most cases these differences were statistically significant in both datasets. Cows with adequate DMI and normal rumen motility (only in DS2) had greater hazard (hazard ratio [HR] = 1.84 and 1.61, for RFS and RFCS, respectively) and odds (odds ratio [OR] = 2.49 and 1.98, for RFS and RFCS, respectively) for pregnancy at 1st AI. Assessment of the association of examined rumen traits with hazard and odds for pregnancy at all AIs yielded statistically significant results in both datasets. For RFS, RCS and RFCS, HRs ranged from 1.57 to 3.31 and ORs from 1.95 to 4.83. No statistically significant associations with hazard and odds for pregnancy at 1st or all AIs were detected, for any of the 3 SCK traits, in either dataset. Overall, the combined RFCS trait constantly identified more than twice the number of cows with future reproductive problems than a positive SCK blood test.

Comparison of insulin infusion protocols for management of canine and feline diabetic ketoacidosis

OBJECTIVE

Describe the use of fixed-rate intravenous insulin infusions (FRIs) in cats and dogs with diabetic ketoacidosis (DKA) and determine if this is associated with faster resolution of ketosis compared to variable-rate intravenous insulin infusions (VRIs). Secondary objectives were to evaluate complication rates, length of hospitalization (LOH), and survival to discharge (STD).

DESIGN

Randomized clinical trial (January 2019 to July 2020).

SETTING

University veterinary teaching hospital and private referral hospital.

ANIMALS

Dogs and cats with DKA and venous pH <7.3, blood glucose concentration >11 mmol/L (198 mg/dL), and β-hydroxybutyrate (BHB) concentration >3 mmol/L were eligible for inclusion. Patients were randomly assigned to receive either FRI or VRI.

INTERVENTIONS

Neutral (regular) insulin was administered IV as an FRI or VRI. For FRI, the rate was maintained at 0.01 IU/kg/h. For VRI, the dose was adjusted according to blood glucose concentration.

MEASUREMENTS AND RESULTS

Sixteen cats and 20 dogs were enrolled. Population characteristics, mean insulin infusion rate, time to resolution of ketosis (BHB <0.6 mmol/L), complications, LOH, and STD were evaluated. In cats, overall resolution of ketosis was low (9/16 [56.3%]), limiting comparison of protocols. In dogs, resolution of ketosis was high (19/20 dogs [95.0%]) but the time to resolution in the FRI group was not different than that in the VRI group (P = 0.89), despite a 25% higher average insulin infusion rate in the FRI group (P = 0.04). The incidence of complications was low and did not differ between protocols. In cats, LOH and STD did not differ between protocols. All cats that died (5/16) did so within 78 hours and none had resolution of ketosis. Dogs receiving FRI had a shorter LOH (P = 0.01) but STD did not differ between protocols. Six dogs (30.0%) did not survive to hospital discharge but all had resolution of ketosis.

CONCLUSIONS

FRIs can be used in veterinary species but may not hasten resolution of ketosis.

Gene association analysis of an osteopontin polymorphism and ketosis resistance in dairy cattle

The aim of this study was to identify the c.495C > T polymorphism within exon 1 of the osteopontin gene (OPN), and to analyze its association with susceptibility to ketosis in Polish Holstein-Friesian (HF) cows. The study utilized blood samples from 977 HF cows, for the determination of β-hydroxybutyric acid (BHB) and for DNA isolation. The c.495C > T polymorphism of the bovine osteopontin gene was determined by PCR-RFLP. The CT genotype (0.50) was deemed the most common, while TT (0.08) was the rarest genotype. Cows with ketosis most often had the CC genotype, while cows with the TT genotype had the lowest incidence of ketosis. To confirm the relationship between the genotype and ketosis in cows, a weight of evidence (WoE) was generated. A very strong effect of the TT genotype on resistance to ketosis was demonstrated. The distribution of the ROC curve shows that the probability of resistance to ketosis is > 75% if cows have the TT genotype of the OPN gene (cutoff value is 0.758). Results suggest that TT genotype at the c.495C > T locus of the OPN gene might be effective way to detect the cows with risk of ketosis.

Metabolic-digestive clinical disorders of lactating dairy cows were associated with alterations of rumination, physical activity, and lying behavior monitored by an ear-attached sensor

The objective of this observational cohort study was to characterize the pattern of rumination time (RT), physical activity (PA), and lying time (LT) monitored by an automated health monitoring system, based on an ear-attached sensor, immediately before, during, and after clinical diagnosis (CD) of metabolic-digestive disorders. Sensor data were collected from 820 lactating Holstein cows monitored daily from calving up to 21 DIM for detection of health disorders (HD). Cows were grouped retrospectively in the no-clinical health disorder group (NCHD; n = 616) if no HD were diagnosed, or the metabolic-digestive group (METB-DIG; n = 58) if diagnosed with clinical ketosis or indigestion only. Cows with another clinical health disorder within -7 to +7 d of CD of displaced abomasum, clinical ketosis, or indigestion were included in the metabolic-digestive plus one group (METB-DIG+1; n = 25). Daily RT, PA, and LT, and absolute and relative changes within -7 to +7 d of CD were analyzed with linear mixed models with or without repeated measures. Rumination time and PA were smaller, and LT was greater for the METB-DIG and METB-DIG+1 group than for cows in the NCHD group for most days from -7 to +7 d of CD of HD. In general, daily RT, PA, and LT differences were larger between the METB-DIG+1 and NCHD groups than between the METB-DIG and NCHD groups. In most cases, RT and PA decreased to a nadir and LT increased to a peak immediately before or after CD of HD, with a return to levels similar to the NCHD group within 7 d of CD. Absolute values and relative changes from 5 d before CD to the day of the nadir for RT and PA or peak for LT were different for cows in the METB-DIG and METB-DIG+1 group than for the NCHD group. For PA, the METB-DIG+1 group had greater changes than the METB-DIG group. For cows affected by metabolic-digestive disorders, RT, PA, and LT on the day of CD and resolution of clinical signs were different than for cows in the NCHD group, but an increase in RT and PA or a decrease in LT was observed from the day of CD to the day of resolution of clinical signs. We conclude that dairy cows diagnosed with metabolic-digestive disorders including displaced abomasum, clinical ketosis, and indigestion presented substantial alterations in the pattern of RT, PA, and LT captured by an ear-attached sensor. Thus, automated health monitoring systems based on ear-attached sensors might be used as an aid for identifying cows with metabolic-digestive disorders. Moreover, RT, PA, and LT changes after CD might be positive indicators of recovery from metabolic-digestive disorders.

Lipolysis inhibition as a treatment of clinical ketosis in dairy cows: A randomized clinical trial

Excessive and protracted lipolysis in adipose tissues of dairy cows is a major risk factor for clinical ketosis (CK). This metabolic disease is common in postpartum cows when lipolysis provides fatty acids as an energy substrate to offset negative energy balance. Lipolysis in cows can be induced by the canonical (hormonally induced) and inflammatory pathways. Current treatments for CK focus on improving glucose in blood (i.e., oral propylene glycol [PG], or i.v. dextrose). However, these therapies do not inhibit the canonical and inflammatory lipolytic pathways. Niacin (NIA) can reduce activation of the canonical pathway. Blocking inflammatory responses with cyclooxygenase inhibitors such as flunixin meglumine (FM) can inhibit inflammatory lipolytic activity. The objective of this study was to determine the effects of including NIA and FM in the standard PG treatment for postpartum CK on circulating concentrations of ketone bodies. A 4-group, parallel, individually randomized trial was conducted in multiparous Jersey cows (n = 80) from a commercial dairy in Michigan during a 7-mo period. Eligible cows had CK symptoms (lethargy, depressed appetite, and milk yield) and hyperketonemia (blood β-hydroxybutyrate [BHB] ≥1.2 mmol/L). Cows with CK were randomly assigned to 1 of 3 groups where the first group received 310 g of oral PG once per day for 5 d; the second group received PG for 5 d + 24 g of oral NIA once per day for 3 d (PGNIA); and the third group received PG for 5 d + NIA for 3 d + 1.1 mg/kg i.v. FM once per day for 3 d (PGNIAFM). The control group consisted of cows that were clinically healthy (HC; untreated; BHB <1.2 mmol/L, n = 27) matching for parity and DIM with all 3 groups. Animals were sampled at enrollment (d 0), and d 3, 7, and 14 to evaluate ketone bodies and circulating metabolic and inflammatory biomarkers. Effects of treatment, sampling day, and their interactions were evaluated using mixed effects models. Logistic regression was used to calculate the odds ratio (OR) of returning to normoketonemia (BHB <1.2 mmol/L). Compared with HC, enrolled CK cows exhibited higher blood concentrations of dyslipidemia markers, including nonesterified fatty acids (NEFA) and BHB, and lower glucose and insulin levels. Cows with CK also had increased levels of biomarkers of pain (substance P), inflammation, including lipopolysaccharide-binding protein, haptoglobin, and serum amyloid A, and proinflammatory cytokines IL-4, MCP-1, MIP-1α, and TNFα. Importantly, 72.2% of CK cows presented endotoxemia and had higher circulating bacterial DNA compared with HC. By d 7, the percentage of cows with normoketonemia were higher in PGNIAFM = 87.5%, compared with PG = 58.33%, and PGNIA = 62.5%. At d 7 the OR for normoketonemia in PGNIAFM cows were 1.5 (95% CI, 1.03-2.17) and 1.4 (95% CI, 0.99-1.97) relative to PG and PGNIA, respectively. At d 3, 7, and 14, PGNIAFM cows presented the lowest values of BHB (PG = 1.36; PGNIA = 1.24; PGNIAFM = 0.89 ± 0.13 mmol/L), NEFA (PG = 0.58; PGNIA = 0.59; PGNIAFM = 0.45 ± 0.02 mmol/L), and acute phase proteins. Cows in PGNIAFM also presented the highest blood glucose increment across time points and insulin by d 7. These data provide evidence that bacteremia or endotoxemia, systemic inflammation, and pain may play a crucial role in CK pathogenesis. Additionally, targeting lipolysis and inflammation with NIA and FM during CK effectively reduces dyslipidemia biomarkers, improves glycemia, and improves overall clinical recovery.

Inhibition of cluster antigen 36 protects against fatty acid-induced lipid accumulation, oxidative stress, and inflammation in bovine hepatocytes

When ketosis occurs, supraphysiological concentrations of nonesterified fatty acids (NEFA) display lipotoxicity and are closely related to the occurrence of hepatic lipid accumulation, oxidative stress, and inflammation, resulting in hepatic damage and exacerbating the progression of ketosis. However, the mechanism of these lipotoxic effects caused by high concentrations of NEFA in ketosis is still unclear. Cluster antigen 36 (CD36), a fatty acid transporter, plays a vital role in the development of hepatic pathological injury in nonruminants. Thus, the aim of this study was to investigate whether CD36 plays a role in NEFA-induced hepatic lipotoxicity in dairy cows with clinical ketosis. Liver tissue and blood samples were collected from healthy (n = 10) and clinically ketotic (n = 10) cows at 3 to 15 d in milk. In addition, hepatocytes isolated from healthy calves were treated with 0, 0.6, 1.2, or 2.4 mM NEFA for 12 h; or infected with CD36 expressing adenovirus or CD36 silencing small interfering RNA for 48 h and then treated with 1.2 mM NEFA for 12 h. Compared with healthy cows, clinically ketotic cows had greater concentrations of serum NEFA and β-hydroxybutyrate and activities of aspartate aminotransferase and alanine aminotransferase but lower serum glucose. In addition, dairy cows with clinical ketosis displayed excessive hepatic lipid accumulation. More importantly, these alterations were accompanied by an increased abundance of hepatic CD36. In the cell culture model, exogenous NEFA (0, 0.6, 1.2, or 2.4 mM) treatment could dose-dependently increase the abundance of CD36. Meanwhile, NEFA (1.2 mM) increased the content of triacylglycerol, reactive oxygen species and malondialdehyde, and decreased the activities of glutathione peroxidase and superoxide dismutase. Moreover, NEFA upregulated phosphorylation levels of nuclear factor κB (NF-κB) and the inhibitor of NF-κB (IκB) α, along with the upregulation of protein abundance of NLR family pyrin domain containing 3 (NLRP3) and caspase-1, and mRNA abundance of IL1B, IL6, and tumor necrosis factor α (TNFA). These alterations induced by NEFA in bovine hepatocytes were associated with increased lipid accumulation, oxidative stress and inflammation, which could be further aggravated by CD36 overexpression. Conversely, silencing CD36 attenuated these NEFA-induced detriments. Overall, these data suggest that CD36 may be a potential therapeutic target for NEFA-induced hepatic lipid accumulation, oxidative stress, and inflammation in dairy cows.

Subclinical ketosis leads to lipid metabolism disorder by downregulating the expression of acetyl-coenzyme A acetyltransferase 2 in dairy cows

Ketosis is a metabolic disease that often occurs in dairy cows postpartum and is a result of disordered lipid metabolism. Acetyl-coenzyme A (CoA) acetyltransferase 2 (ACAT2) is important for balancing cholesterol and triglyceride (TG) metabolism; however, its role in subclinical ketotic dairy cows is unclear. This study aimed to explore the potential correlation between ACAT2 and lipid metabolism disorders in subclinical ketotic cows through in vitro and in vivo experiments. In the in vivo experiment, liver tissue and blood samples were collected from healthy cows (CON, n = 6, β-hydroxybutyric acid [BHBA] concentration <1.0 mM) and subclinical ketotic cows (subclinical ketosis [SCK], n = 6, BHBA concentration = 1.2-3.0 mM) to explore the effect of ACAT2 on lipid metabolism disorders in SCK cows. For the in vitro experiment, bovine hepatocytes (BHEC) were used as the model. The effects of BHBA on ACAT2 and lipid metabolism were investigated via BHBA concentration gradient experiments. Subsequently, the relation between ACAT2 and lipid metabolism disorder was explored by transfection with siRNA of ACAT2. Transcriptomics showed an upregulation of differentially expression genes during lipid metabolism and significantly lower ACAT2 mRNA levels in the SCK group. Compared with the CON group in vivo, the SCK group showed significantly higher expression levels of peroxisome proliferator-activated receptor γ (PPARγ) and sterol regulator element binding protein 1c (SREBP1c) and significantly lower expression levels of peroxisome proliferator-activated receptor α (PPARα), carnitine palmitoyl-transferase 1A (CPT1A), sterol regulatory element binding transcription factor 2 (SREBP2), and 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR). Moreover, the SCK group had a significantly higher liver TG content and significantly lower plasma total cholesterol (TC) and free cholesterol content. These results were indicative of TG and cholesterol metabolism disorders in the liver of dairy cows with SCK. Additionally, the SCK group showed an increased expression of perilipin-2 (PLIN2), decreased expression of apolipoprotein B, and decreased plasma concentration of very low-density lipoproteins (VLDL) and low-density lipoproteins cholesterol (LDL-C) by downregulating ACAT2, which indicated an accumulation of TG in liver. In vitro experiments showed that BHBA induced an increase in the TG content of BHEC, decreased content TC, increased expression of PPARγ and SREBP1c, and decreased expression of PPARα, CPT1A, SREBP2, and HMGCR. Additionally, BHBA increased the expression of PLIN2 in BHEC, decreased the expression and fluorescence intensity of ACAT2, and decreased the VLDL and LDL-C contents. Furthermore, silencing ACAT2 expression increased the TG content; decreased the TC, VLDL, and LDL-C contents; decreased the expression of HMGCR and SREBP2; and increased the expression of SREBP1c; but had no effect on the expression of PLIN2. These results suggest that ACAT2 downregulation in BHEC promotes TG accumulation and inhibits cholesterol synthesis, leading to TG and cholesterol metabolic disorders. In conclusion, ACAT2 downregulation in the SCK group inhibited cholesterol synthesis, increased TG synthesis, and reduced the contents of VLDL and LDL-C, eventually leading to disordered TG and cholesterol metabolism.

Associations between days in the close-up group and milk production, transition cow diseases, reproductive performance, culling, and behavior around calving of Holstein dairy cows

The objective of experiment I was to evaluate the association between days in the close-up group (DINCU) and milk production, early lactation diseases, reproductive performance, and culling. In experiment II behavioral changes associated with DINCU were evaluated using a neck-mounted sensor (Smarttag neck, Nedap Livestock Management, Groenlo, the Netherlands). Cow-lactations of 28,813 animals from 14,155 individual cows of 2 farms in northern Germany and western Slovakia, calving between January 2015 and December 2020, were included in the study. After exclusion of cows with a gestation length <262 and >292 d and cows with >42 DINCU data from 8,794 and 19,598 nulliparous and parous cows, respectively, were available for final statistical analyses. To analyze the association between DINCU and second test-d 305-d mature-equivalent milk projection, linear mixed models were calculated. Binary data (i.e., clinical hypocalcemia, hyperketonemia, retained placenta [RP], acute puerperal metritis [APM], mastitis, left displaced abomasum [LDA], first service pregnancy risk) were analyzed using logistic regression models. To analyze the association between DINCU and culling or death during the first 300 DIM Cox proportional hazards were used. To analyze the association between DINCU and behavior 7 d before to 7 d after calving (i.e., activity, inactivity, eating, ruminating time), linear mixed models were calculated. Nulliparous cows with a short (<10 DINCU) and a long stay (>30 DINCU) in the close-up group had a lower milk production an increased risk for hyperketonemia, RP, and APM compared with nulliparous cows with DINCU between 21 to 28 d. Parous cows with a short (<10 DINCU) and a long stay (>30 DINCU) in the close-up group had a lower milk production, an increased risk for RP and mastitis, a reduced first service pregnancy risk, and an increased culling risk, compared with parous cows with DINCU between 21 to 28 d. Furthermore, the risk for clinical hypocalcemia and LDA was increased in parous cows with >30 DINCU compared with parous cows with <30 DINCU. The risk for APM was increased in parous cows with <10 DINCU compared with parous cows with >10 DINCU. In nulliparous cows no association was found between DINCU and the risk for left displaced abomasum and mastitis. In experiment II, cows with 7 and 35 DINCU had an impaired behavior around calving compared with cows with 14, 21, and 28 DINCU. During the last 7 d before parturition, these cows were more inactive and had a reduced eating and ruminating time. After calving, cows with 7 DINCU spent less time eating. In conclusion, cows with <10 DINCU and cows with >30 DINCU had a lower milk production, a higher risk to incur diseases and an impaired behavior, especially before calving.

[The lipidosis in the liver of the dairy cow: Part 2 Genetic predisposition and prophylaxis]

Hepatic lipidosis in dairy cows is the result of a disturbed balance between the uptake of non-esterified fatty acids (NEFA), their metabolism in the hepatocytes, and the limited efflux of TG as very-low-density lipoprotein (VLDL). Lipidosis and the associated risk for ketosis represents a consequence of selecting dairy cows primarily for milk production without considering the basic physiological mechanisms of this trait. The overall risk for lipidosis and ketosis possesses a genetic background and the recently released new breeding value of the German Holstein Friesian cows now sets the path for correction of this risk and in that confirms the assumed genetic threat. Ectopic fat deposition in the liver is the result of various steps including lipolysis, uptake of fat by the liver cell, its metabolism, and finally release as very-low-density lipoprotein (VLDL). These reactions may be modulated directly or indirectly and hence, serve as basis for prophylactic measures. The pertaining methods are described in order to support an improved understanding of the pathogenesis of lipidosis and ketosis. They consist of feeding a glucogenic diet, restricted feeding during the close-up time as well as supplementation with choline, niacin, carnitine, or the reduction of milking frequency. Prophylactic measures for the prevention of ketosis are also included in this discussion.

Is adenosine deaminase (ADA) activity in saliva and serum a more accurate disease detection tool than traditional redox balance parameters in early-lactating dairy cows?

Enzyme adenosine deaminase (ADA) is a marker of inflammation in domestic animals, but it is unclear whether it is a reliable marker of oxidative stress, especially in the transition period in dairy cows. This study aims to assess if ADA and redox status measurements in saliva provide the same utility to detect disease condition as that obtained from serum. Sixty-eight multiparous Holstein cows, between 2 and 3 weeks postpartum were selected. Five study groups were established: control (healthy), and cows with ketosis, mastitis, laminitis, and metritis. The parameters measured were ADA activity, total oxidants (TOS), antioxidants (TAC), and OSi ratio.Regarding redox status, no significant differences arise in both saliva and serum being the correlations negative and not significant. In saliva, ADA activity in healthy cows differs from those with pathological processes, having the lowest activities. In serum, ADA activity is similar in the healthy and ketosis cows, showing the lowest activities meanwhile animals with mastitis, laminitis, or metritis have significantly higher activities. In conclusion, the measurement of ADA activities and redox status in saliva does not give consistent results, being preferable to measure them in serum during the transition period.

Evaluating variations in metabolic profiles during the dry period related to the time of hyperketonemia onset in dairy cows

Hyperketonemia (HYK) in early lactation can have a different impact on health and productivity depending on the timing of HYK onset. While specific metabolites measured during the dry period may serve as biomarkers of HYK, the correlations between metabolites represent a challenge for the use of metabolic profiles dataset, and little has been explored on HYK. This exploratory cohort study aimed a) to characterize the correlations among metabolites measured during the late dry period in dairy cows, and b) to identify biomarkers in the late dry period associated with the onset of HYK at the first (wk1) and second (wk2) week of lactation. Individual blood samples from 440 Holstein dairy cows were collected at 21 ± 3 days before expected parturition. From each sample, 36 different metabolites were measured in serum and plasma. Hyperketonemia was diagnosed in wk1 and wk2 of lactation based on the blood concentration of beta-hydroxybutyrate (BHB > 1.2 mmol/L). Principal component analysis (PCA) was performed to reduce metabolites to a smaller number of uncorrelated components. Multivariable logistic regression models were applied to assess the associations between principal components (PC) and HYK at wk1 only (HYK+ wk1), wk2 only (HYK+ wk2), or both weeks (HYK+ wk1-2). The incidence of HYK was 16.2% in the first week, 13.0% in the second week, and 21.2% within the first two weeks of lactation. The results of PCA highlighted 10 PCs from which two were associated with HYK+ wk1 as compared with cows without HYK during the first two weeks of lactation (non-HYK); the PC a2 led by bilirubin and non-esterified fatty acids (OR = 1.29; 95%CI: 1.02-1.68), and the PC a5 led by alkaline phosphatase (ALP) and gamma-glutamyl transferase (GGT) (OR = 2.77; 95%CI: 1.61-4.97). There was no evidence of an association between any PC and HYK+ wk2 (vs. non-HYK cows). Cows with elevated PC a5 (led by ALP and GGT) in the dry period were 3.18 times more likely to be HYK+ wk1 than HYK+ wk2 (OR: 3.18, 95%CI: 1.34-8.73; P = 0.013). Overall, the main hypothesis generated by our exploratory study suggests that cows with biomarkers of liver dysfunction (ALP, GGT, bilirubin) assessed by PCA at 3 weeks before calving are more likely to develop HYK during the first week of lactation compared to the second week. In addition, results suggest that cows with HYK in both of the first two weeks of lactation had an overall metabolic disbalance during the onset of the late dry period, which based on PCs, encompass biomarkers related to glucogenic and ketogenic metabolic pathways as well as liver dysfunction and fatty liver. Further research is needed to determine the underlying mechanisms associated with the different adaptations between cows that develop HYK during the first and second week of lactation.