In vivo and in vitro anti-inflammation of Rhapontici Radix extract on mastitis via TMEM59 and GPR161

ETHNOPHARMACOLOGICAL RELEVANCE

Rhapontici Radix ethanol extract (RRE) is derived from the dried root of Rhaponticum uniflorum (L.) DC belonging to the Asteraceae family. RRE exhibits significant anti-inflammatory and antioxidant properties; however, the potential of RRE in mastitis treatment requires further investigation.

AIM OF THIS STUDY

This research was performed to examine the protective properties of RRE against mastitis and the mechanisms underlying the effects of RRE.

MATERIAL AND METHODS

RRE components were analyzed by HPLC-MS/MS and DPPH methods. Isochlorogenic acid B (ICAB) was obtained commercially. MTT assay was utilized to assess RRE or ICAB cytotoxicity in bovine mammary alveolar (MAC-T) cells. Immunohistochemistry were used to investigate the pathological alterations in mammary tissue. The protein levels of inflammatory cytokines and mediators were analyzed using ELISA, and the expression of MAPK and NF-κB signaling pathways, as well as p65 nuclear translocation, were analyzed through Western blotting and immunofluorescence techniques, respectively. Target proteins of RRE were screened by RNA-seq and tandem mass tag analyses. Protein interaction was revealed and confirmed using co-immunoprecipitation and CRISPR/Cas9-based knockdown and overexpression of target genes.

RESULTS

ICAB was revealed as one of the main components in RRE, and it was responsible for 84.33% of RRE radical scavenging activity. Both RRE and ICAB mitigated the infiltration of T lymphocytes in the mammary glands of mice, leading to decreased levels of inflammatory mediators (COX-2 and iNOS) and cytokines (TNF-α, IL-6, and IL-1β) in lipopolysaccharide (LPS)-induced MAC-T cells. Furthermore, RRE and ICAB suppressed the LPS-induced phosphorylation of NF-κB inhibitor and p65, thereby impeding p65 nuclear translocation in mouse mammary glands and MAC-T cells. In addition, RRE and ICAB attenuated the LPS-triggered activation of c-Jun N-terminal kinase 1/2, p38, and extracellular regulated protein kinase 1/2. Importantly, co-treated with LPS and ICAB in MAC-T cells, an upregulation of G-protein coupled receptor 161 (GPR161) and transmembrane protein 59 (TMEM59) was observed; the interact between TMEM59 and was found, leading to inhibition of NF-κB activity and inflammatory cytokine production.

CONCLUSION

ICAB is a prominent antioxidant in RRE. RRE and ICAB reduce mammary inflammation via MAPK and NF-κB pathways and the interaction between TMEM59 and GPR161 mediates the control of ICAB in NF-κB signaling.

A randomized control trial to test the effect of pegbovigrastim treatment at dry-off on plasma and milk oxylipid profiles during early mammary gland involution and the postparturient period

The early period of mammary gland involution is a critical juncture in the lactation cycle that can have significant effects on milk production and mammary gland health. Pegbovigrastim (PEG) administered 1 wk prior and on the day of parturition can enhance immune function and reduce the incidence of mastitis in the early postpartum period. Oxylipids are potent metabolites of polyunsaturated fatty acids (PUFA) and are important mediators of inflammation. The objective of this study was to evaluate effects of PEG given 1 wk before and at the day of dry-off (D0) on concentrations of oxylipids in plasma and milk from 7 d before D0 to 14 d after, as well as the effects during the first 14 d of the subsequent lactation. We hypothesized that both pro- and anti-inflammatory oxylipids would vary based on initiation of mammary gland involution and that pegbovigrastim would affect oxylipid concentrations, particularly those related to leukocytes. A complete randomized blocked design was used to enroll cows into either a PEG treatment group (n = 10) or control group (n = 10; CON). Blood samples were collected -7, -2, -1, 0, 1, 2, 4, 7, and 14 d relative to dry-off and 5, 10, and 14 d postcalving. Samples were analyzed for PUFA and oxylipids in milk and plasma by ultra-performance mass spectrometry and liquid chromatography tandem quadrupole mass spectrometry, respectively. Overall, 30 lipid mediators were measured in both milk and plasma. Repeated measures analyses revealed a significant interaction of treatment by time for milk 8-iso-keto-15-prostaglandin E2, prostaglandin F2α, plasma 8,12-iso-prostaglandin Fα-VI, 11-hydroxyeicosatetraenoic acid, and 12-hydroxyheptadecatienoic acid. The majority of milk PUFA and oxylipids differed significantly during early mammary gland involution and into the early postpartum period. This study demonstrated changes in oxylipids in milk secretions and plasma during early involution, and further investigation may illuminate multiple complex processes and reveal targets for optimization of mammary gland involution.

Intramammary calcitriol treatment of mastitis alters profile of milk somatic cells and indicators of redox activity in milk

The objective of this experiment was to determine the effect of intramammary calcitriol treatment on indicators of inflammation during an intramammary bacterial infection. Lactating Holstein cows were challenged with intramammary Streptococcus uberis. At the onset of mild or moderate mastitis, cows were randomly assigned to receive 10 µg of intramammary calcitriol (CAL, n = 7) or placebo control (CON; n = 6) after every milking for 5 days. Data were analyzed by ANOVA with mixed models using the MIXED procedure of SAS with significance declared at P ≤ 0.05. Milk somatic cells, mastitis severity scores, rectal temperatures, and milk bacterial counts did not differ between treatments. Calcitriol decreased the percentage of CD11b+CD14- cells in milk compared with CON (CON = 81 vs. CAL = 61 ± 5%). Antioxidant potential and concentrations of 15-F2t- isoprostanes in milk of infected quarters also were lower in CAL compared with CON. Transcripts for the 25-hydroxyvitamin D 24-hydroxylase and inducible nitric oxide synthase were greater in milk somatic cells of CAL compared with CON, but those for β-defensin 7, metallothionein 1 A and 2 A, thioredoxin and thioredoxin reductase did not differ between treatments. Although clinical signs of severity did not differ, CAL influenced the composition of milk somatic cells and redox activity in milk of infected quarters.

Case-control exercise challenge study on the pathogenesis of high serum gamma-glutamyl transferase activity in racehorses

BACKGROUND

High serum γ-glutamyl-transferase (GGT) activity syndrome in racehorses has been associated with maladaption to exercise. Investigation of affected horses before and immediately after standard exercise may provide critical insight into the syndrome's pathophysiology.

OBJECTIVES

To investigate blood biomarker changes in actively competing racehorses with high GGT activity associated with an exercise challenge.

STUDY DESIGN

Case-control study.

METHODS

High GGT case (age: 2-3 years) and normal GGT control (age: 2-7 years) pairs (3 Thoroughbred, 4 Standardbred pairs) at least 3 months into their training/racing season were included. Horses with a recent history of high GGT activity (≥50 IU/L) without additional biochemical evidence of liver disease were identified by veterinarians. Horses were tested again in the week prior to a planned exercise challenge to confirm persistent increases in GGT activity. Controls from the same stable with similar training/racing intensity and serum GGT activity ≤36 IU/L were matched with each case. Blood samples were obtained immediately before, 15 and 120 min after exercise. Pre-exercise serum samples were analysed for baseline select serum chemistries, selenium and vitamin E concentrations. Cortisol concentration and markers of oxidative status were measured in serum or plasma for all time points. Individual serum bile acid and coenzyme Q10 concentrations, plasma lipid mediator (fatty acids, oxylipids, isoprostanes) concentrations and targeted metabolomics analyses were performed using liquid chromatography-mass spectrometry. Serum viral PCR for equine hepaci- and parvovirus was performed in each animal.

RESULTS

Cases had higher baseline concentrations of total glutathione, taurocholic acid, cortisol and cholesterol concentrations and higher or lower concentrations of specific oxylipid and isoprostane mediators, but there were no case-dependent changes after exercise.

MAIN LIMITATIONS

Small sample size.

CONCLUSIONS

Results indicated that glutathione metabolism was altered in high GGT horses. Enhanced glutathione recycling and mild cholestasis are possible explanations for the observed differences.

Effects of PUFA-Rich Dietary Strategies on Ruminants' Mammary Gland Gene Network: A Nutrigenomics Review

Although the inclusion of polyunsaturated fatty acids (PUFAs) in ruminants' diets appears to be a well-documented strategy to enrich milk with PUFAs, several gene networks that regulate milk synthesis and mammary gland homeostasis could be impaired. The objective of this literature review is to assess the effects of nutritional strategies focused on enriching milk with PUFAs on gene networks regulating mammary gland function and lipogenesis, as well as the impact of feed additives and bioactive compounds with prominent antioxidant potential on immune-oxidative transcriptional profiling, as a part of mammary gland homeostasis and health. The findings support the conclusion that PUFAs' inclusion in ruminants' diets more strongly downregulate the stearoyl-CoA desaturase (SCD) gene compared to other key genes involved in de novo fatty acid synthesis in the mammary gland. Additionally, it was revealed that seed oils rich in linoleic and linolenic acids have no such strong impact on networks that regulate lipogenic homeostasis compared to marine oils rich in eicosapentaenoic and docosahexaenoic acids. Furthermore, ample evidence supports that cows and sheep are more prone to the suppression of lipogenesis pathways compared to goats under the impact of dietary marine PUFAs. On the other hand, the inclusion of feed additives and bioactive compounds with prominent antioxidant potential in ruminants' diets can strengthen mammary gland immune-oxidative status. Considering that PUFA's high propensity to oxidation can induce a cascade of pro-oxidant incidences, the simultaneous supplementation of antioxidant compounds and especially polyphenols may alleviate any side effects caused by PUFA overload in the mammary gland. In conclusion, future studies should deeply investigate the effects of PUFAs on mammary gland gene networks in an effort to holistically understand their impact on both milk fat depression syndrome and homeostatic disturbance.

The impact of environmental and nutritional stresses on milk fat synthesis in dairy cows

Stress reduces milk and milk components synthesis and increases maintenance requirements of cows. The major stress-related alterations involve enhanced secretion of glucocorticoids and increased sympathetic nervous system activity, which results in biochemical and physiologic changes. In dairy cows exposed to social (ie housing conditions, overstocking, regrouping, feed delivery), physiological (ie initiation of lactation and parturition), or physical (ie heat or cold stress) stressors, responses involve alterations in energy balance and nutrient partitioning. The capacity of the animal to synthesize milk fat largely depends on the availability of substrates for lipid synthesis from the diet, ruminal fermentation or adipose tissue stores, all of which can be altered under stress conditions. Indeed, milk fat concentration is particularly responsive to diet and environment modifications, where a wide range of nutritional and non-nutritional factors influence milk fat output. Milk fat synthesis is an energy demanding process, and extremely sensitive to stress factors during lactation and the involvement of multiple organs. Recent studies examining social, physical, and physiological stressors have provided important insights into how differences in milk yield and milk components may be associated with biological responses to stress factors in dairy cows. This review focuses primarily on the role of stress sources and indicators to which the dairy cow is exposed in regulating milk fat synthesis. We will review the role of nutritional and non-nutritional factors on milk fat synthesis in dairy cows under stress conditions.

Changes in the lipidome of water buffalo milk during intramammary infection by non-aureus Staphylococci

This study aimed to determine the lipidome of water buffalo milk with intramammary infection (IMI) by non-aureus staphylococci (NAS), also defined as coagulase-negative staphylococci, using an untargeted lipidomic approach. Non-aureus Staphylococci are the most frequently isolated pathogens from dairy water buffalo milk during mastitis. A total of 17 milk samples from quarters affected by NAS-IMI were collected, and the lipidome was determined by liquid chromatography-quadrupole time-of-flight mass spectrometry. The results were compared with the lipidome determined on samples collected from 16 healthy quarters. The study identified 1934 different lipids, which were classified into 15 classes. The abundance of 72 lipids changed in NAS-IMI milk compared to healthy quarters. Significant changes occurred primarily in the class of free fatty acids. The results of this study provided first-time insight into the lipidome of dairy water buffalo milk. Moreover, the present findings provide evidence that NAS-IMI induces changes in water buffalo milk's lipidome.

Pomegranate (Punica granatum) By-Product Extract Influences the Oxylipids Profile in Primary Bovine Aortic Endothelial Cells in a Model of Oxidative Stress

Aerobic metabolism produces reactive oxygen species (ROS) as a natural by-product that can play a significant role in cell signaling and homeostasis. Excessive and uncontrolled production of ROS, however, can lead to oxidative stress that causes damage to immune cells and is related to several diseases in dairy cattle. Endothelial cells are essential for optimal immune and inflammatory responses but are especially sensitive to the damaging effects of ROS. Accordingly, investigating antioxidant strategies that can mitigate the detrimental impact of ROS on endothelial functions could impact compromised host defenses that lead to increased disease susceptibility. The objective of this study was to test the antioxidant effect of different concentrations (20, 40, 60, 80 μg/ml) of pomegranate by-product extract (PBE) on bovine aortic endothelial cells (BAECs). A model of oxidative stress was developed using in vitro exposure of BAEC to 2,2′-azobis (2-amidinopropane) dihydrochloride (AAPH) to induce the formation of ROS. The BAEC were then analyzed for cell viability, ROS production, fatty acids profile, and oxylipids formation. The BAECs viability did not change after different concentrations of PBE and remained up to 80% over control; whereas, intracellular ROS showed a reduction passing from 20 to 50% with increasing PBE concentration from 20 to 80 μg/ml, respectively. The PBE extract clearly demonstrated efficacy in reducing the concentrations of pro-inflammatory oxylipids with a concomitant enhancement of anti-inflammatory oxylipids. In particular, the pro-inflammatory 13-hydroxyoctadecadienoic acid and its derived anti-inflammatory 13-hydroperoxoctadecaienoic acid were found lower and higher, respectively, in PBE+AAPH treated cells than AAPH treatment. Data from the present study support in vivo future experimental use of pomegranate by-product extract to study its potential beneficial effect against oxidative stress conditions in dairy cattle.

Defining Fatty Acid Changes Linked to Rumen Development, Weaning and Growth in Holstein-Friesian Heifers

After birth, as effectively monogastric animals, calves undergo substantial physiological changes to become ruminants by 3 months of age and reach sexual maturity at approximately 15 months of age. Herein, we assess longitudinal metabolomic changes in Holstein-Friesian (HF) heifers from birth until sexual maturity during this developmental process. Sera from 20 healthy, HF heifers were sampled biweekly from 2 weeks of age until 13 months of age and then monthly until 19 months of age. Sera were assessed using flow infusion electrospray high-resolution mass spectrometry (FIE-HRMS) on a Q Exactive hybrid quadrupole-Orbitrap mass spectrometer for high-throughput, sensitive, non-targeted metabolite fingerprinting. Partial least squares discriminant analysis (PLS-DA) and unsupervised hierarchical clustering analysis (HCA) of the derived metabolomes indicated changes detectable in heifers’ sera over time. Time series analyses identified 30 metabolites that could be related to rumen development and weaning at ~3 months of age. Further time series analysis identified 40 metabolites that could be correlated with growth. These findings highlight the role of acetic acid and 3-phenylpropionate (3-PP) in rumen development and growth, suggest that weaning induces elevated levels of fatty acyls in response to a post-weaning stress-induced innate immune response and demonstrate the utilization of fatty acyls in growth. The identified metabolites offer serum metabolites which could inform the nutrition and healthy development of heifers.

Role of Selenium and Vitamins E and B9 in the Alleviation of Bovine Mastitis during the Periparturient Period

Mastitis (inflammation of the mammary gland) commonly occurs in dairy cattle during the periparturient period (transition period), in which dairy cattle experience physiological and hormonal changes and severe negative energy balance, followed by oxidative stress. To maintain successful lactation and combat negative energy balance (NEB), excessive fat mobilization occurs, leading to overproduction of reactive oxygen species (ROS). Excessive fat mobilization also increases the concentrations of nonesterified fatty acids (NEFA) and β-hydroxybutyric acid (BHB) during the periparturient period. In addition, the excessive utilization of oxygen by cellular respiration in the mammary causes abnormal production of oxidative stress (OS). OS impairs the immunity and anti-inflammatory efficiency of periparturient dairy cattle, increasing their susceptibility to mastitis. To alleviate oxidative stress and subsequent mastitis, antioxidants are supplemented to dairy cattle from an external source. Extensive studies have been conducted on the supplementation of selenium (Se) and vitamins E and B9 to mitigate mastitis during the transition period in dairy cattle. Altogether, in the current review, we discuss the research development on bovine mastitis and its major causes, with special emphasis on oxidative stress during the transition period. Moreover, we discuss the antioxidant, immunoregulatory, and anti-inflammatory properties of Se and vitamins E and B9 and their role in the control of bovine mastitis in periparturient dairy cattle.

Oxylipids are associated with higher disease risk in postpartum cows

Postpartum diseases are a major animal welfare and economic concern for dairy producers. Dysregulated inflammation, which may begin as soon as the cessation of lactation, contributes to the development of postpartum diseases. The ability to regulate inflammation and mitigate postpartum health diseases relies, in part, on the production of inflammatory mediators known as oxylipids. The objective of this study was to examine associations between oxylipids and postpartum diseases. Plasma samples were collected from 16 cattle via coccygeal venipuncture at the following time points: 6 d before dry-off; dry-off (d 0); 1, 2, 6, and 12 d after dry-off; 14 ± 3 d before the expected calving date; and 7 ± 2 d after calving. After calving, cows were grouped according to if clinical disease was undetected throughout the sampling period (n = 7) or if they developed a disease postpartum (n = 9). Liquid chromatography-tandem mass spectrometry was used to analyze plasma concentrations of 63 oxylipid species. Of the 32 oxylipids detected, concentrations of 7 differed between cows with no detected disease and diseased cows throughout the sampling period. Thus, a variable oxylipid profile was demonstrated through 2 major physiological transitions of a lactation cycle. Further, the information gained from this pilot study using a small number of animals with diverse diseases from a single herd suggests that it may be possible to use oxylipids at early mammary involution to alert dairy producers of cows at risk for disease after calving. Future studies should be performed in larger populations of animals, including cows from diverse geographies and dairying styles, and focus on specific diseases to evaluate the utility of oxylipids as biomarkers. Furthermore, it is important to determine the clinical implications of variable oxylipid concentrations throughout the lactation cycle and if the oxylipid profile can be modulated to improve inflammatory outcomes.

Anti-inflammation of epicatechin mediated by TMEM35A and TMPO in bovine mammary epithelial cell line cells and mouse mammary gland

Epicatechin (EC) has significant antiinflammation, antioxidation, and anticancer activities. It also provides a new alternative treatment for mastitis, which can result in great economic losses in the dairy industry if left untreated. The purpose of this study was to investigate the anti-inflammatory effects of EC on mastitis and the underlying mechanism using in vivo and in vitro systems. The use of ELISA and immunohistochemistry assays showed that EC treatment at 1.5, 7.5, 15, and 30 mg/mL decreased protein expression of inflammatory mediators, including cyclooxygenase-2 and inducible nitric oxide synthase; inflammatory cytokines, which were composed of IL-1β, TNF-α, and IL-6 in lipopolysaccharide (LPS)-stimulated bovine mammary epithelial cell line (MAC-T); and mouse mammary gland, together with reduced filtration of T lymphocytes in the mouse mammary gland. Furthermore, EC treatment reduced LPS-induced phosphorylation levels of p65 and inhibitor of NF-κB, and blocked nuclear translocation of p65 as revealed by western blot and immunofluorescence test in MAC-T cells and the mouse mammary gland. Epicatechin also attenuated LPS-induced phosphorylation levels of mitogen-activated protein kinase members (i.e., p38, c-Jun N-terminal kinase 1/2 and extracellular regulated protein kinases 1/2). Using RNA-seq and tandem mass tag analyses, upregulation of TMEM35A and TMPO proteins was disclosed in MAC-T cells cotreated with LPS and EC. Although clustered regularly interspaced short palindromic repeats/Cas9-based knockdown of TMEM35A and TMPO attenuated abundance of phosphorylated (p)-p65, p-p38, TNF-α, and iNOS, overexpression of TMEM35A reversed EC-mediated effects in TMPO knockdown cells. Moreover, interaction between TMEM35A and TMPO was detected using the co-immunoprecipitation method. In conclusion, our data demonstrated that EC inhibited LPS-induced inflammatory response in MAC-T cells and the mouse mammary gland. Importantly, TMEM35A mediated the transmembrane transport of EC, and the interaction between TMEM35A and TMPO inhibited MAPK and NF-κB pathways.

Inhibition of 20-hydroxyeicosatetraenoic acid biosynthesis by vitamin E analogs in human and bovine cytochrome P450 microsomes

Dairy cattle are predisposed to disease around the time of calving due to dysfunctional inflammatory responses. Oxylipids are lipid-derived mediators that regulate all aspects of the inflammatory response, and shifts in oxylipid profiles are correlated with disease risk. For example, 20-hydroxyeicosatetraenoic acid (HETE) is an oxylipid derived from cytochrome P450 enzymes (CYP450) found at significantly greater concentrations around calving and during clinical disease. Biosynthesis of 20-HETE occurs almost exclusively from two specific CYP450 of which CYP450 family four sub-family F member two (CYP4F2) is the major contributor to 20-HETE production in humans. To further study the activities of 20-HETE and potentially reduce its production in vivo, mitigation methods must be explored. Additional substrates of CYP4F2, such as vitamin E, are known to both increase and decrease the metabolism of other CYP4F2 substrates. This study aimed to determine whether vitamin E analogs may reduce the production of 20-HETE through competition for CYP4F2 activity in human CYP4F2, bovine-kidney and bovine-mammary microsomes. Gamma-tocopherol reduced 20-HETE production from human and bovine-kidney microsomes (35.3% and 27.5%, respectively) whereas γ-tocotrienol only reduced 20-HETE production from human microsomes (40.1%). Finally, bovine-mammary microsomes did not produce a quantifiable amount of 20-HETE, suggesting basal mammary CYP4F2 activity may not be a significant contributor to 20-HETE found in milk. Together, these data show that analogs of vitamin E can reduce the production of 20-HETE, potentially through competition with arachidonic acid for metabolism by CYP4F2, posing a potential means for limiting 20-HETE production during clinical diseases of dairy cattle.

A proposed modulatory role of the endocannabinoid system on adipose tissue metabolism and appetite in periparturient dairy cows

To sustain the nutrient demands of rapid fetal growth, parturition, and milk synthesis, periparturient dairy cows mobilize adipose tissue fatty acid stores through lipolysis. This process induces an inflammatory response within AT that is resolved as lactation progresses; however, excessive and protracted lipolysis compounds the risk for metabolic and inflammatory diseases. The suppression of lipolytic action and inflammation, along with amplification of adipogenesis and lipogenesis, serve as prospective therapeutic targets for improving the health of periparturient dairy cows. Generally, the activation of cannabinoid receptors by endocannabinoids enhances adipogenesis and lipogenesis, suppresses lipolysis, and increases appetite in mammals. These biological effects of activating the endocannabinoid system open the possibility of harnessing the endocannabinoid system through nutritional intervention in dairy herds as a potential tool to improve dairy cows' health, although much is still to be revealed in this context. This review summarizes the current knowledge surrounding the components of the endocannabinoid system, elaborates on the metabolic effects of its activation, and explores the potential to modulate its activity in periparturient dairy cows.

Bacteriophages isolated from dairy farm mitigated Klebsiella pneumoniae-induced inflammation in bovine mammary epithelial cells cultured in vitro

Background

Klebsiella pneumoniae, an environmental pathogen causing mastitis in dairy cattle, is often resistant to antibiotics. K. pneumoniae was used as the host bacteria to support bacteriophage replication; 2 bacteriophages, CM8-1 and SJT-2 were isolated and considered to have therapeutic potential. In the present study, we determined the ability of these 2 bacteriophages to mitigate cytotoxicity, pathomorphological changes, inflammatory responses and apoptosis induced by K. pneumoniae (bacteriophage to K. pneumoniae MOI 1:10) in bovine mammary epithelial cells (bMECs) cultured in vitro.

Results

Bacteriophages reduced bacterial adhesion and invasion and cytotoxicity (lactate dehydrogenase release). Morphological changes in bMECs, including swelling, shrinkage, necrosis and hematoxylin and eosin staining of cytoplasm, were apparent 4 to 8 h after infection with K. pneumoniae, but each bacteriophage significantly suppressed damage and decreased TNF-α and IL-1β concentrations. K. pneumoniae enhanced mRNA expression of TLR4, NF-κB, TNF-α, IL-1β, IL-6, IL-8, caspase-3, caspase-9 and cyt-c in bMECs and increased apoptosis of bMECs, although these effects were mitigated by treatment with either bacteriophage for 8 h.

Conclusions

Bacteriophages CM8-1 and SJT-2 mitigated K. pneumoniae-induced inflammation in bMECs cultured in vitro. Therefore, the potential of these bacteriophages for treating mastitis in cows should be determined in clinical trials.

Dynamics of somatic cell count (SCC) and differential SCC during and following intramammary infections

Somatic cell count is frequently used as an indicator of intramammary infections (IMI) in dairy cattle worldwide. The newly introduced differential SCC (DSCC) can potentially contribute to detection of IMI. The purpose of this study was to investigate the dynamics of SCC and DSCC after IMI. We used a data set with monthly samples from 2 Danish dairy herds through 1 yr, using bacterial culture to identify IMI. The dynamics of SCC and DSCC with regard to IMI were assessed at quarter level following new IMI with each of 3 defined pathogen groups, major, minor, or "other" pathogens, using general additive models. Both SCC and DSCC increased after IMI, with a more pronounced increase if major or other pathogens were detected compared with minor pathogens. We found that DSCC increased after IMI with other pathogens in both herds and, in herd 2, after IMI caused by major and minor pathogens. We also estimated the duration of increased SCC and DSCC when they exceeded a threshold, done separately for each pathogen group. Major pathogens had the longest-lasting effect in both herds for both SCC and DSCC. We conclude that the magnitude and duration of response of SCC and DSCC to IMI differs between herds and causative pathogens.

Invited review: Cytochrome P450 enzyme involvement in health and inflammatory-based diseases of dairy cattle

Dairy cattle are at the greatest risk of developing diseases around the time of calving because of compromised immune responses and the occurrence of oxidative stress. Both the development of compromised immunity and oxidative stress are influenced directly or indirectly by the metabolism of polyunsaturated fatty acids (PUFA) and fat-soluble vitamins. The cytochrome P450 (CYP450) family of enzymes is central to the metabolism of both classes of these compounds, but to date, the importance of CYP450 in the health of dairy cattle is underappreciated. As certain CYP450 isoforms metabolize both PUFA and fat-soluble vitamins, potential interactions may occur between PUFA and fat-soluble vitamins that are largely unexplored. For example, one CYP450 that generates anti-inflammatory oxylipids from arachidonic acid additionally contributes to the activation of vitamin D. Other potential substrate interactions between PUFA and vitamins A and E may exist as well. The intersection of PUFA and fat-soluble vitamin metabolism by CYP450 suggest that this enzyme system could provide an understanding of how immune function and oxidant status interconnect, resulting in increased postpartum disease occurrence. This review will detail the known contributions of bovine CYP450 to the regulation of oxylipids with a focus on enzymes that may also be involved in the metabolism of fat-soluble vitamins A, D, and E that contribute to antioxidant defenses. Although the activity of specific CYP450 is generally conserved among mammals, important differences exist in cattle, such as the isoforms primarily responsible for activation of vitamin D that makes their specific study in cattle of great importance. Additionally, a CYP450-driven inflammatory positive feedback loop is proposed, which may contribute to the dysfunctional inflammatory responses commonly found during the transition period. Establishing the individual enzyme isoform contributions to oxylipid biosynthesis and the regulation of vitamins A, D, and E may reveal how the CYP450 family of enzymes can affect inflammatory responses during times of increased susceptibility to disease. Determining the potential effect of each CYP450 on disease susceptibility or pathogenesis may allow for the targeted manipulation of the CYP450 pathways to influence specific immune responses and antioxidant defenses during times of increased risk for health disorders.

Evaluation of natural plant extracts as antioxidants in a bovine in vitro model of oxidative stress

Oxidative stress contributes to many inflammatory-based diseases of dairy cattle especially during periods of increased metabolic activity such as around calving. Endothelial cells play a key role in maintaining normal inflammatory responses, but they are especially susceptible to macromolecule damage during times of oxidative stress. Therefore, bovine aortic endothelial cells (BAEC) were used to study the effect of natural tannin-based extracts on oxidative stress that may improve health and well-being of cattle. Tannins are secondary metabolites in plants with potent antioxidant activity that have been used as natural feed additives for food-producing animals. However, there is little information on how tannin-rich plant extracts may affect oxidative stress in dairy cattle. The objective of this study was to evaluate the antioxidant effect of pomegranate (Punica granatum; PMG), tara (Caesalpinia spinosa; TA), chestnut (Castanea sativa; CH), and gambier (Uncaria gambir; GM) natural extracts using an in vitro BAEC model of oxidative stress. Natural extracts were tested at a concentration of 80 μg/mL. Viability, apoptosis, intracellular reactive oxygen species, and isoprostanes were determined on cultured BAEC treated with different plant natural extracts. No changes in cell viability was detected following PMG and GM treatments. In contrast, there was a 30% reduction of BAEC viability following treatment with CH or TA extracts. Intracellular reactive oxygen species production was significantly less abundant in cells treated with natural extracts than with the lipopolysaccharide control. Moreover, antioxidant activity varied according to the tested extract, showing a reduction of 63, 45, 51, and 27% in PMG, GM, CH, and TA, respectively. The formation of isoprostanes as a consequence of lipid peroxidation after induction of oxidative stress also were significantly decreased in PMG-treated cells when compared with the untreated cells. Theses findings suggest that PMG extract has the potential to mitigate oxidative stress without detrimental effects on cell viability. Further in vitro and in vivo research is warranted to explore the antioxidant potential of PMG extract as a dietary supplement to control oxidative stress in dairy cattle.

Postpartum meloxicam administration alters plasma haptoglobin, polyunsaturated fatty acid, and oxylipid concentrations in postpartum ewes

Background

Postpartum inflammation is a natural and necessary response; however, a dysfunctional inflammatory response can be detrimental to animal productivity. The objective of this study was to determine the effects of a non-steroidal anti-inflammatory drug (meloxicam) on ewe postpartum inflammatory response, ewe plasma polyunsaturated fatty acid and oxylipid concentrations, and lamb growth.

Results

After lambing, 36 Hampshire and Hampshire × Suffolk ewes were sequentially assigned within type of birth to control (n = 17) or meloxicam orally administered on d 1 and 4 of lactation (MEL; 90 mg, n = 19). Milk and blood samples were collected on d 1 (prior to treatment) and d 4. Milk glucose-6-phosphate was not affected by MEL. Plasma haptoglobin (Hp) concentrations were less for MEL ewes; control ewes with greater d 1 Hp concentrations had elevated Hp on d 4, but this was not the case for MEL-treated ewes. Treatment with MEL increased plasma arachidonic acid concentration by more than 4-fold in ewes rearing singles but decreased concentrations of 9,10-dihydroxyoctadecenoic acid, prostaglandin F_2α, 8-iso-prostaglandin E₂, and 8,9-dihydroxyeicosatetraenoic acid. Nine oxylipids in plasma had interactions of treatment with d 1 Hp concentration, all of which revealed positive associations between d 1 Hp and d 4 oxylipid concentrations for CON, but neutral or negative relationships for MEL. MEL decreased 13-hydroxyoctadecadienoic acid:13-oxooctadecadienoic acid ratio and tended to increase 9-hydroxyoctadecadienoic acid:9-oxooctadecadienoic acid ratio (both dependent on d 1 values), indicating progressive metabolism of linoleic acid-derived oxylipids occurred by enzymatic oxidation after MEL treatment. Meloxicam reduced oxylipids generated across oxygenation pathways, potentially due to an improved redox state.

Conclusions

Postpartum MEL treatment of ewes decreased plasma concentrations of Hp and several oxylipids, with the greatest impact in ewes with biomarkers reflecting a greater inflammatory state before treatment. Anti-inflammatory strategies may help resolve excessive postpartum inflammation in some dams.

Review: Following the smoke signals: inflammatory signaling in metabolic homeostasis and homeorhesis in dairy cattle

Inflammatory cascades are a critical component of the immune response to infection or tissue damage, involving an array of signals, including water-soluble metabolites, lipid mediators and several classes of proteins. Early investigation of these signaling pathways focused largely on immune cells and acute disease models. However, more recent findings have highlighted critical roles of both immune cells and inflammatory mediators on tissue remodeling and metabolic homeostasis in healthy animals. In dairy cattle, inflammatory signals in various tissues and in circulation change rapidly and dramatically, starting just prior to and at the onset of lactation. Furthermore, several observations in healthy cows point to homeostatic control of inflammatory tone, which we define as a regulatory process to balance immune tolerance with activation to keep downstream effects under control. Recent evidence suggests that peripartum inflammatory changes influence whole-body nutrient flux of dairy cows over the course of days and months. Inflammatory mediators can suppress appetite, even at levels that do not induce acute responses (e.g. fever), thereby decreasing nutrient availability. On the other hand, inhibition of inflammatory signaling with non-steroidal anti-inflammatory drug (NSAID) treatment suppresses hepatic gluconeogenesis, leading to hypoglycemia in some cases. Over the long term, though, peripartum NSAID treatment substantially increases peak and whole-lactation milk synthesis by multiparous cows. Inflammatory regulation of nutrient flux may provide a homeorhetic mechanism to aid cows in adapting to rapid changes in metabolic demand at the onset of lactation, but excessive systemic inflammation has negative effects on metabolic homeostasis through inhibition of appetite and promotion of immune cell activity. Thus, in this review, we provide perspectives on the overlapping regulation of immune responses and metabolism by inflammatory mediators, which may provide a mechanistic underpinning for links between infectious and metabolic diseases in transition dairy cows. Moreover, we point to novel approaches to the management of this challenging phase of the production cycle.

Colostrum supplementation with n-3 fatty acids and α-tocopherol alters plasma polyunsaturated fatty acid profile and decreases an indicator of oxidative stress in newborn calves

Our objective was to characterize the effects of supplementing newborn calves with n-3 fatty acids (FA) and α-tocopherol on blood lipid profiles and oxidant status in early life. Sixteen calves received 0 or 60 mL of 1:1 fish and flaxseed oil with 200 mg of α-tocopherol in 2.8 L of colostrum within 6 h after birth. Colostrum was >22% on the Brix scale. Blood was sampled on d 1, 2, 4, 7, 14, and 21 after birth for assessment of plasma polyunsaturated FA, α-tocopherol, total serum protein, and oxidant status index, an indirect indicator of oxidative stress that examines the balance between the concentration of reactive oxygen and nitrogen species and antioxidant capacity in serum. Health was observed daily. Weight and hip height were recorded at birth, 3 wk, and 8 wk. Data were analyzed with a Mixed procedure of SAS 9.4 (SAS Institute Inc., Cary, NC). Treatment did not alter concentration of total protein in blood serum, prevalence of diarrhea or other signs of disease, or rate of growth. Feeding n-3 FA and α-tocopherol increased plasma concentrations of the n-3 FA, including α-linolenic, eicosapentaenoic, and docosahexaenoic acids, with a concomitant decrease in oxidant status index during the first week of life. Concentrations of α-tocopherol decreased with supplementation, but all calves maintained adequate concentrations. Oxidant status index of treated calves returned to the level of control calves by d 14. We conclude that a colostrum supplement of n-3 FA and α-tocopherol is safe to administer to newborn calves, reduces oxidant status in the first week of life, and may improve health and performance.

Symposium review: Late-gestation maternal factors affecting the health and development of dairy calves

Efficient production of heifers is fundamental to the productivity and sustainability of dairy farms. However, high preweaning morbidity and mortality rates are frequently reported worldwide, imposing substantial welfare and economic implications. A major contributing factor to disease susceptibility in the neonatal stage is the inability of calves to mount an effective immune response. Appreciation is now greater that exposure in utero to several stresses (nutritional, social, metabolic, and so on) during the last stages of pregnancy have downstream carryover effects in calves' health, growth, and development. Suboptimal intrauterine conditions during critical periods of development lead to changes in tissue structure and function that may have long-term consequences on the offspring's physiology and disease susceptibility. Indeed, preweaning metabolic function and growth are associated with future milk production. Thus, late-gestation carryover effects span into the lactating stage of the heifers. Nevertheless, researchers have been studying how to minimize these effects. This review will discuss the effects of maternal stress during late gestation on the offspring's growth, productivity, metabolism, and health. In addition, strategies focusing on maternal interventions that improve neonatal health will be discussed. A better understanding of the intrauterine conditions affecting calf health and growth may facilitate the design of management practices that could improve neonatal development and future cow productivity.

Lipolysis modulates the biosynthesis of inflammatory lipid mediators derived from linoleic acid in adipose tissue of periparturient dairy cows

Oxidized linoleic acid metabolites (OXLAM) are products of adipocyte lipolysis with the potential to modulate adipose tissue (AT) lipid metabolism and inflammation. In periparturient cows, linoleic acid is preferentially mobilized from AT during lipolysis by hormone-sensitive lipase (HSL) compared with other polyunsaturated fatty acids. Enzymatic and nonenzymatic reactions generate OXLAM from linoleic acid. Among OXLAM, 9-, 10-, and 12-hydroxy-octadecadienoic acids (HODE) are associated with pro-inflammatory responses, whereas 9- and 13-oxo-octadecadienoic acids (oxoODE) and 13-HODE can facilitate inflammation resolution and promote lipogenesis. This study evaluated the effect of HSL activity on OXLAM biosynthesis using subcutaneous AT explants collected from multiparous dairy cows at 10 d before and again at 10 and 24 d after calving. Explants were treated for 3 h without or with the β-adrenergic agonist isoproterenol (ISO; 1 µM; MilliporeSigma, Burlington, MA) to induce HSL activity. The contribution of HSL to OXLAM biosynthesis was determined by inhibiting its activity with CAY10499 (2 µM; Cayman Chemical, Ann Arbor, MI). After treatments, media and explants were collected for lipidomic analysis using HPLC-tandem mass spectroscopy. Results indicated that ISO increased the biosynthesis of 9-, 12-, and 13-HODE and 9-oxoODE, and this effect was reduced at 24 d after calving. Inhibiting HSL activity partially reversed ISO effects on HODE and 9-oxoODE. Our ex vivo model demonstrated for the first time a direct effect of HSL activity on the biosynthesis of OXLAM in AT, especially at 10 d before and 10 d after calving. The biosynthesis of anti-inflammatory OXLAM is limited during the first weeks after parturition and may promote AT inflammation and lipolytic responses to negative energy balance. These results indicate that HSL activity releases linoleic acid for OXLAM biosynthesis in concentrations of a magnitude that may bypass the need for the activation of phospholipases linked with the inflammatory cascade and thus supports, in part, lipolysis-driven inflammation within AT of periparturient cows.

Effects of Fat Supplementation in Dairy Goats on Lipid Metabolism and Health Status

Simple Summary

There is an increasing demand for information on the nutraceutical properties of food. Due to its bioactive components and high digestibility, goat milk is an excellent functional food. Dietary fat supplementation can further enrich the value of goat milk by modifying its acidic profile. Nevertheless, animal health can also benefit from lipids supplied with rations. In this review, the relationships between dietary fats and goat health status are summarized. Particular attention is paid to describing the effects of specific fatty acids on lipid metabolism and immune functionality.

Abstract

Fat supplementation has long been used in dairy ruminant nutrition to increase the fat content of milk and supply energy during particularly challenging production phases. Throughout the years, advances have been made in the knowledge of metabolic pathways and technological treatments of dietary fatty acids (FAs), resulting in safer and more widely available lipid supplements. There is an awareness of the positive nutraceutical effects of the addition of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) to fat supplementation, which provides consumers with healthier animal products through manipulation of their characteristics. If it is true that benefits to human health can be derived from the consumption of animal products rich in bioactive fatty acids (FAs), then it is reasonable to think that the same effect can occur in the animals to which the supplements are administered. Therefore, recent advances in fat supplementation of dairy goats with reference to the effect on health status have been summarized. In vivo trials and in vitro analysis on cultured cells, as well as histological and transcriptomic analyses of hepatic and adipose tissue, have been reviewed in order to assess documented relationships between specific FAs, lipid metabolism, and immunity.

Widespread basal cytochrome P450 expression in extrahepatic bovine tissues and isolated cells

Periparturient cattle face increased risk of both metabolic and infectious diseases. Factors contributing to this predisposition include oxidized polyunsaturated fatty acids, also known as oxylipids, whose production is altered during the periparturient period and in diseased cattle. Alterations in the production of oxylipids derived from cytochrome P450 (CYP450) enzymes are over-represented during times of increased disease risk and clinical disease, such as mastitis. Many of these same CYP450 enzymes additionally regulate metabolism of fat-soluble vitamins, such as A, D, and E. These vitamins are essential to maintaining immune health, yet circulating concentrations are diminished near calving. Despite this, a relatively small amount of research has focused on the roles of CYP450 enzymes outside of the liver. The aim of this paper is to describe the relative gene expression of 11 CYP450 in bovine tissues and common in vitro bovine cell models. Eight tissue samples were collected from 3 healthy dairy cows after euthanasia. In vitro samples included primary bovine aortic and mammary endothelial cells and immortalized bovine kidney and mammary epithelial cells. Quantitative real-time-PCR was carried out to assess basal transcript expression of CYP450 enzymes. Surprisingly, CYP450 mRNA was widely expressed in all tissue samples, with predominance in the liver. In vitro CYP450 expression was less robust, with several cell types lacking expression of specific CYP450 enzymes altogether. Overall, cell culture models did not reflect expression of tissue CYP450. However, when CYP450 were organized by activity, certain cell types consistently expressed specific functional groups. These data reveal the widespread expression of CYP450 in individual organs of healthy dairy cows. Widespread expression helps to explain previous evidence of significant changes in CYP450-mediated oxylipid production and fat-soluble vitamin metabolism in organ microenvironments during periods of oxidative stress or disease. As such, these data provide a foundation for targeted functional experiments aimed at understanding the activities of specific CYP450 and associated therapeutic potential during times of increased disease risk.

Neutrophil β-defensin gene expression of postpartum dairy cows is altered by prepartum dietary cation-anion difference

The objective of this study was to evaluate expression of a cluster of genes encoding β-defensin antimicrobial peptides in neutrophils of postpartum cows in relation to prepartum dietary cation-anion difference (DCAD), vitamin D, and postpartum disease. Pregnant dry Holstein cows (28 nulliparous and 51 parous) at 255 d gestation were blocked by parity and randomly assigned to 4 prepartum diets of positive (+130 mEq/kg) or negative (-130 mEq/kg) DCAD and either 3 mg vitamin D₃ or 3 mg of 25-hydroxyvitamin D₃ per 11 kg of dry matter/d. Treatment diets were fed from 255 d of gestation until calving. Peripheral blood neutrophils of 35 parous cows were collected at 0 and 3 d after calving and stimulated with 0 or 100 ng/mL of lipopolysaccharide (LPS). Furthermore, serum Ca and incidences of postpartum diseases were recorded for all cows. The mRNA transcripts of β-defensin genes were quantified by real-time PCR, and data were analyzed with a general linear mixed model to test for fixed effects and interactions of day, level of DCAD, source of vitamin D, and incidence of disease. Effects of DCAD and vitamin D on neutrophil oxidative burst and phagocytosis were previously reported but were analyzed for effects of disease in the present study. Transcripts for DEFB1, DEFB3, DEFB4, DEFB5, DEFB7, DEFB10, and lingual antimicrobial peptide (LAP) in neutrophils were upregulated by LPS at 0 d but not at 3 d. Transcripts for DEFB4 and DEFB7 in LPS-stimulated neutrophils were greater in cows fed negative DCAD diets compared with positive DCAD. Source of vitamin D (vitamin D₃ vs. 25-hydroxyvitamin D₃) did not affect expression of β-defensins in neutrophils. Cows with postpartum subclinical hypocalcemia (serum Ca <2.0 mM) had decreased DEFB3, DEFB4, DEFB6, DEFB7, DEFB10, and LAP expression in LPS-stimulated neutrophils compared with cows that did not experience subclinical hypocalcemia. Likewise, DEFB4, DEFB6, DEFB7, DEFB10, and LAP in LPS-stimulated neutrophils at 3 d postpartum were positively associated with serum Ca at 0 d postpartum. Transcripts for DEFB7, DEFB10 and LAP also were less abundant in neutrophils from cows with metritis compared with healthy cows. In conclusion, feeding a prepartum negative DCAD to improve postpartum serum Ca resulted in greater neutrophil β-defensin expression, and greater neutrophil β-defensin expression was positively associated with postpartum health.

Genetic and genomic analyses of latent variables related to the milk fatty acid profile, milk composition, and udder health in dairy cattle

The aim of this study was to perform genetic, genome-wide association (GWAS), and gene-set enrichment analyses with latent variables related to milk fatty acid profile (i.e., fatty acids factor scores; FAF), milk composition, and udder health in a cohort of 1,158 Italian Brown Swiss cows. The phenotypes under study were 12 FAF previously identified through factor analysis and classified as follows: de novo FA (F1), branched-chain FA-milk yield (F2), biohydrogenation (F3), long-chain fatty acids (F4), desaturation (F5), short-chain fatty acids (F6), milk protein and fat contents (F7), odd fatty acids (F8), conjugated linoleic acids (F9), linoleic acid (F10), udder health (F11) and vaccelenic acid (F12). (Co)variance components were estimated for factor scores using a Bayesian linear animal model via Gibbs sampling. The animals were genotyped with the Illumina BovineSNP50 BeadChip v.2 (Illumina Inc., San Diego, CA). A single marker regression model was fitted for GWAS analysis. The gene-set enrichment analysis was run on the GWAS results using the Gene Ontology and the Kyoto Encyclopedia of Genes and Genomes pathway databases to identify the ontologies and pathways associated with the FAF. Marginal posterior means of the heritabilities of the aforementioned FAF ranged from 0.048 for F12 to 0.310 for F5. Factors F1 and F6 had the highest number of relevant genetic correlations with the other traits. The genomic analysis detected a total of 39 significant SNP located on 17 Bos taurus autosomes. All latent variables produced signals except for F2 and F10. The traits with the highest number of significant associations were F11 (17) and F12 (7). Gene-set enrichment analyses identified significant pathways (false discovery rate 5%) for F3 and F7. In particular, systemic lupus erythematosus was enriched for F3, whereas the MAPK (mitogen-activated protein kinase) signaling pathway was overrepresented for F7. The results support the existence of important and exploitable genetic and genomic variation in these latent explanatory phenotypes. Information acquired might be exploited in selection programs and when designing further studies on the role of the putative candidate genes identified in the regulation of milk composition and udder health.

Mammary Gland Immunobiology and Resistance to Mastitis

The ability of dairy cattle to prevent infectious pathogens from causing mastitis is related to the efficiency of the mammary immune system. The primary roles of the bovine immune system are to prevent bacterial invasion of the mammary gland, eliminate existing infections, and restore mammary tissues to normal function. Mammary gland immunity uses a multifaceted network of physical, cellular, and soluble factors to protect the cow from the diverse array of mastitis-causing pathogens. Strategies to optimize mammary gland defenses can be an effective way to prevent the establishment of new intramammary infections and limit the use of antimicrobials to treat mastitis.

Conditions Associated with Marine Lipid-Induced Milk Fat Depression in Sheep Cause Shifts in the In Vitro Ruminal Metabolism of 1-13C Oleic Acid

Shifts in ruminal oleic acid (OA) metabolism have received little research attention but recent studies have suggested their association with marine lipid-induced milk fat depression (MFD) in ewes and cows. Measurement of specific products of OA within the complex mixture of digesta lipids is however challenging. Therefore, this in vitro trial combined the isotopic labelling technique with the use of rumen inoculum from cannulated sheep fed a diet supplemented or not with 2% of fish oil (which has been demonstrated to cause MFD in dairy ruminants) to characterize the metabolism of OA in response to ruminal alterations associated with MFD. The products of 13C-OA after 24 h of incubation were analysed by gas chromatography-combustion isotope ratio mass spectrometry (GC-C-IRMS). Numerous 13C-labeled 18:1 intermediates and oxygenated FA were detected and no elongation or desaturation of 13OA occurred. Diet supplementation with fish oil (i.e., MFD conditions) resulted in no unique metabolites of 13OA but in relevant changes in the relative contribution of specific metabolic pathways. The inhibition of 18:0 saturation caused by this treatment appeared largely attributable to increased oxygenated FA proportion, in particular the candidate milk fat inhibitor 10-oxo-18:0, and warrants further research on the association between MFD and oxygenated FA. Changes in the concentration of 13C-labeled trans 18:1 intermediates but not in cis 18:1, were also observed.

Production of 15-F2t-isoprostane as an assessment of oxidative stress in dairy cows at different stages of lactation

Oxidative stress contributes to dysfunctional immune responses and predisposes dairy cattle to several metabolic and inflammatory-based diseases. Although the negative effects of oxidative stress on transition cattle are well established, biomarkers that accurately measure oxidative damage to cellular macromolecules are not well defined in veterinary medicine. Measuring 15-F_2t-isoprostane, a lipid peroxidation product, is the gold standard biomarker for quantifying oxidative stress in human medicine. The aim of our study was to determine whether changes in 15-F_2t-isoprostane concentrations in plasma and milk could accurately reflect changes in oxidant status during different stages of lactation. Using liquid chromatography-tandem mass spectrometry, 15-F_2t-isoprostane concentrations were quantified in milk and plasma of 12 multiparous Holstein-Friesian cows that were assigned to 3 different sampling periods, including the periparturient period (1-2 d in milk; n = 4), mid lactation (80-84 d in milk; n = 4), and late lactation (183-215 d in milk; n = 4). Blood samples also were analyzed for indicators of oxidant status, inflammation, and negative energy balance. Our data revealed that 15-F_2t-isoprostane concentrations changed at different stages of lactation and coincided with changes in other gauges of oxidant status in both plasma and milk. Interestingly, milk 15-F_2t-isoprostane concentrations and other indices of oxidant status did not follow the same trends as plasma values at each stage of lactation. Indeed, during the periparturient period, systemic 15-F_2t-isoprostane increased significantly accompanied by an increase in the systemic oxidant status index. Milk 15-F_2t-isoprostane was significantly decreased during the periparturient period compared with other lactation stages in conjunction with a milk oxidant status index that trended lower during this period. The results from this study indicate that changes in 15-F_2t-isoprostane concentrations in both milk and plasma may be strong indicators of an alteration in redox status both systemically and within the mammary gland.