Milk prostaglandins and electrical conductivity in bovine mastitis

Prostaglandin (PG) levels in milk samples from healthy and mastitic cows were determined by radioimmunoassay. In composite milk the PG levels were rather high both in healthy and mastitic samples, and the only significant difference was in thromboxane B₂ (TXB). In quarter milk samples classified according to the degree of mastitis by use of somatic cell counts, PGE₂ was 40, PGF₂15, and TXB₂ 44 per cent higher respectively in affected samples. PG levels were in good correlation with somatic cell counts (r=0.63–0.68, p<0.01) and electrical conductivity (r=0.36–0.52, p<0.01), two established criteria for diagnosis of mastitis. PGE₂ also correlated with protein, TXB₂ with fat content. PGF₂ was in a negative correlation with milk yield. The good correlation of PGs with somatic cell counts and electrical conductivity suggests that PGs might be used as markers of mastitic inflammation.     

The effect of steroidal dominance on cAMP, cGMP, progesterone and 17 beta-estradiol levels in the fluid of the largest follicle

Concentrations and mutual correlations of the cyclic adenosin monophosphate (cAMP), quanosin monophosphate (cGMP), progesterone (P4) and 17-beta-estradiol (E2) were studied in the fluid of the largest follicles in cows, in dependence on the steroid dominance: estrogen-dominant (ED), progesterone-dominant (PD) follicles. Mean cAMP and cGMP concentrations in the follicular fluid in the estrogen-dominant follicles were significantly higher than in the progesterone-dominant follicles; in both cases at P less than 0.01. Significant positive correlation between cAMP and cGMP at P less than 0.001 was stated in the evaluation of the correlations. The cAMP and cGMP concentrations were in significantly negative correlations with the P4 concentration at P less than 0.05, or P less than 0.01 and in significantly positive correlations with the E2, at P less than 0.05. The stated correlations suggest a close mutual relation between cyclic nucleotid and E2, or P4 when the follicles' quality changes.     

Prostaglandins and glutathione peroxidase in bovine mastitis

Prostaglandin (PG) levels in milk and plasma samples from mastitic cows were determined by radioimmunoassay and compared with erythrocyte glutathione peroxidase (GSH-Px) and other relevant parameters in milk and blood. The overall levels of PGE2, PGF2 alpha and thromboxane B2 (TXB2) in milk were two to four times higher than in blood plasma both in healthy and diseased animals (P less than 0.01). In mastitic milk the PG levels were 24 to 55 per cent and in blood plasma 41 to 95 per cent higher than in healthy animals. The changes were significant and largest for the PGF2 alpha values. In milk, the PG concentrations correlated with the markedly elevated cell count (r = 0.49 to 0.57), and TXB2 values also correlated with milk yield. In blood, PGE2 and PGF2 alpha correlated positively with serum albumin, and PGE2 also correlated with glutathione (GSH). PGE2 and PGF2 alpha correlated negatively with GSH-Px and gamma-glutamyl transferase. The substantial decline in GSH-Px in mastitic animals (P less than 0.01) may be related to changes in lipid peroxidation and PG formation. The possible implications of these findings in the treatment of mastitis are discussed.     

Lactoferrin concentrations in milk from normal and subclinical mastitic cows

The concentrations of lactoferrin (Lf) in quarter milk from normal lactating cows and subclinical mastitic cows were measured to determine whether the Lf concentration in milk is influenced by the age of the cow, the stage of lactation, number of milk somatic cells and the presence of pathogens. Lf concentrations in 111 quarter milk samples from 28 normal lactating cows and 270 quarter milk samples from 198 subclinical mastitic cows were measured by means of a single radial immunodiffusion test. Lf concentrations (means +/- standard deviations; logarithmic form) in normal cows and subclinical mastitic cows were 2.23 +/- 0.39 and 2.70 +/- 0.39, respectively. The mean milk Lf concentration (log) in subclinical mastitic cows was significantly (p<0.01) higher than that in normal cows. The mean milk Lf concentration (log) in normal lactating cows aged 5 years was lower than those in normal lactating cows aged 2 years (p<0.01) and 3 years (p<0.05). The results showed that the milk Lf concentration (log) is associated with age of the dairy cow (one-way analysis of variance test, p<0.01). The mean milk Lf concentration (log) in the latter lactational period tended to be higher than those in the peak and middle periods. Milk Lf concentrations (log) tended to be proportional to the level of the somatic cell count (SCC) score. Mean milk Lf concentrations (log) in subclinical mastitic cows infected with Staphylococcus aureus and with other streptococci species were significantly (p<0.01) higher than those in cows infected with coagulase-negative staphylococci and with Corynebacterium bovis.     

Zinc concentrations in skimmed milk and whole milk samples from healthy and mastitic cows

Zinc concentrations were determined in skimmed milk and whole milk samples from healthy and mastitic cows. During spontaneous and induced mastitis, a marked decrease of Zn concentration in skimmed milk from the mastitic quarters was observed. Seemingly, there are 2 mechanisms involved in the lowering of Zn concentration in skimmed milk from mastitic quarters: a decline in Zn probably as a consequence of decreases in plasma Zn concentrations and an abrupt redistribution of Zn in the inflamed quarters.     

Pathophysiologic features of swine dysentery: cyclic nucleotide-independent production of diarrhea

Net electrolyte and water transport and unidirectional Na+ fluxes were examined in ligated colonic loops of clinically normal pigs and in pigs with swine dysentery (etiologic agent Treponema hyodysenteriae) in the presence or absence of theophylline. In normal pigs, theophylline abolished net Na+ absorption via a reduction in the lumen-to-blood flux, decreased Cl- absorption, and increased HCO3- accumulation in the lumen. In infected pigs, all net ion transport was abolished, with the addition of theophylline producing little effect. The absence of net Na+ absorption in infected pigs was also the result of a decreased lumen-to-blood flux. Seemingly, colonic malabsorption may be the primary transport alteration in swine dysentery. Concentrations of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) were measured in samples of colonic mucosa from normal and infected pigs after in vitro exposure to a Ringer's solution containing 0 or 20 mM theophylline. Basal values of cAMP or cGMP did not increase in infected colonic mucosa. There was a diminished capacity of the infected mucosa to respond to theophylline. Alterations in ion transport in conjunction with measurements of cAMP and cGMP indicated that the pathogenic mechanism(s) in swine dysentery were not similar to those of Salmonella, Shigella, Vibrio cholerae, or Escherichia coli diarrhea.     

Effects of long-term administration of recombinant bovine somatotropin on the concentration of metabolites in milk in different stages of lactation in crossbred Holstein cattle

Effects of long‐term treatment with recombinant bovine somatotropin (rbST) on concentrations of cellular metabolites in the milk of 87.5% crossbred Holstein cattle were performed. The peak milk yield of rbST‐treated animals was 22% higher (P < 0.05) than that of the control animals in early lactation. The mammary glucose uptake of rbST‐treated animals increased in early lactation, but decreased in mid and late lactation, while plasma glucose concentrations were not affected. Lactose and milk triacylglycerol secretion of rbST‐treated animals significantly increased (P < 0.05) when compared with those of control animals in early lactation. The concentrations of milk glucose of rbST‐treated animals significantly increased in early and mid‐lactation (P < 0.05). The concentrations of milk galactose markedly increased (P < 0.05) whereas the concentrations of milk uridine 5′‐diphosphoglucose (UDP‐glucose) and UDP‐galactose showed no significant changes as lactation advances in both groups. The concentrations of isocitrate, 2‐oxoglutarate and citrate in milk from both groups showed no significant changes throughout experiment. The concentration of glucose‐6‐phosphate (G6P), glucose‐1‐phosphate and cyclic adenosine 3,5′monophosphate in milk from both groups markedly decreased as lactation advances exception in early lactation of rbST‐treated animals, which G6P was not affected. These findings suggest that prolonged rbST treatment exerts its galactopoietic action at least in early lactation through both intramammary and extra‐mammary changes. Increases in the concentrations of glucose and G6P in milk maintained the level of pretreatment in early lactation associated with increases in milk yields during rbST administration, reflect their concentrations in the cytosol or Golgi vesicles of mammary cells, which would be one of the factors regulating intermediary metabolites in the lactose biosynthetic pathway.     

Brain-natriuretic peptide and cyclic guanosine monophosphate as biomarkers of myxomatous mitral valve disease in dogs

Elevations in the plasma concentrations of natriuretic peptides correlate with increased severity of myxomatous mitral valve disease (MMVD) in dogs. This study correlates the severity of MMVD with the plasma concentrations of the biomarkers N-terminal fragment of the pro-brain-natriuretic peptide (NT-proBNP) and its second messenger, cyclic guanosine monophosphate (cGMP). Furthermore, the l-arginine:asymmetric dimethylarginine (ADMA) ratio was measured as an index of nitric oxide availability. The study included 75 dogs sub-divided into five groups based on severity of MMVD as assessed by clinical examination and echocardiography.Plasma NT-proBNP and cGMP concentrations increased with increasing valve dysfunction and were significantly elevated in dogs with heart failure. The cGMP:NT-proBNP ratio decreased significantly in dogs with heart failure, suggesting the development of natriuretic peptide resistance. Although the l-arginine:ADMA ratio decreased with increasingly severe MMVD, this was largely due to the older age of the dogs with heart failure.     

牛磺鹅去氧胆酸对小鼠机体cAMP和cGMP含量的影响

为了研究牛磺鹅去氧胆酸(TCDCA)对小鼠机体环磷酸腺苷(cAMP)和环磷酸鸟苷(cGMP)含量的影响,试验用环孢菌素A诱导特异性免疫低下模型,按相应组别对应的剂量对小鼠灌胃给药7 d,获取血清;体外培养正常小鼠腹腔巨噬细胞,用MTT方法筛选TCDCA作用于腹腔巨噬细胞的最佳药物浓度;用最佳药物浓度作用于巨噬细胞后超声破碎,获取上清液;ELISA方法测定血清和上清液中cAMP和cGMP的含量。结果表明:在TCDCA高剂量(0.2 g/kg)组小鼠血清中,cAMP含量极显著高于环孢菌素A组(P<0.01);各组小鼠血清cGMP含量差异不显著(P>0.05);TCDCA促进小鼠腹腔巨噬细胞增殖的体外浓度为1μg/mL、2.5μg/mL、5μg/mL、10μg/mL;1μg/mL、2.5μg/mL、5μg/mL的TCDCA均能显著或极显著提高细胞内cAMP含量(P<0.05或P<0.01),对cGMP含量均没有显著影响。说明TC-DCA能够显著提高正常和免疫抑制小鼠血清中和正常腹腔巨噬细胞内cAMP含量。     

Plasma cholesterol levels and short-term adaptations of metabolism and milk production during feed restriction in early lactating dairy cows on pasture

Low plasma total cholesterol (TC) concentrations are characteristic during the negative energy balance in early lactating dairy cows. The objective was to investigate short-term effects of different TC concentrations during an aggravated energy deficiency through a 1-week concentrate withdrawal on adaptations of metabolism and milk production. Multiparous Holstein cows (n = 15) were investigated during 3 week beginning at 24 ± 7 DIM (mean ± SD). Cows were kept on pasture and received additional concentrate in experimental week 1 and 3, while in week 2, concentrate was withdrawn. Blood was sampled once and milk twice daily. Based on their average TC concentration during week 1 (prior to concentrate withdrawal), cows were retrospectively assigned into a high (H-Chol; n = 8, TC ≥ 3.36 mmol/L) and a low TC groups (L-Chol; n = 7, TC < 3.36 mmol/L). Concentrations of phospholipids and lipoproteins were higher in H-Chol compared to L-Chol throughout the study (p < 0.05). During concentrate withdrawal, milk yield, glucose and insulin concentrations decreased similarly in both groups, while milk fat, milk acetone and plasma BHB were higher in H-Chol compared to L-Chol (p < 0.05). Compared to initial values, plasma NEFA, TAG and VLDL increased in both groups within 2 days after concentrate withdrawal (p < 0.05). Concentrations of NEFA during week 2 were greater in L-Chol compared to H-Chol (p < 0.05). Despite reintroduction of concentrate, milk yield in H-Chol remained lower for two more days compared to week 1 (p < .05), whereas milk yield recovered immediately in L-Chol. Activity of aspartate aminotransferase was higher in H-Chol compared to L-Chol in week 2 (p < 0.05). Greater plasma TC concentrations were associated with a reduced increase of NEFA. Further research is warranted if TC concentrations are related to adipose tissue mobilization and fatty acid turnover.     

Anti-inflammatory therapy in acute endotoxin-induced bovine mastitis

Acute mastitis was induced in lactating cows by intramammary challenge with 10 g of Escherichia coli lipopolysaccharide. The cows were monitored clinically prior to and for 96 hours after challenge. Milk production, complete blood counts, serum enzyme activities and milk indicators of inflammation were evaluated.Endotoxin challenge was in 7 groups of 3 cows each. Within the groups, cows were randomly assigned to 3 intravenous treatments: saline controls, steroid (one dose of dexamethasone at 0.44 mg/kg) and non-steroidal agent (two doses of flunixin meglumine at 1.1 mg/kg, 8 h apart).Anti-inflammatory therapy reduced rectal and mammary gland surface temperatures. Milk production was significantly reduced (p<0.05) in cows treated with dexamethasone. Although dexamethasone treatment produced significant increases (p<0.05) in blood leukocytes and segmented neutrophils, milk somatic cell concentrations were not significantly altered. Flunixin meglumine did not alter milk production or blood or milk leukocytes.     

Selenium and vitamin E increases polymorphonuclear cell phagocytosis and antioxidant levels during acute mastitis in riverine buffaloes

Antioxidant, antiinflammatory and phagocytic activities were studied in milk polymorphonuclear cells (PMNs) isolated from healthy buffaloes (group I) and during clinical mastitis with the treatment of Enrofloxacin alone (group II) and combined treatment with Enrofloxacin and Vitamin E plus selenium (group III). On days 0,3, 8 and 15 the milk Somatic cell count (SCC) were significantly higher in mastitic milk than in milk obtained from healthy buffaloes. In group II SCC decreased significantly on day 3 and day 8, however in group III reduction in SCC was observed on day 3, day 8 and day 15 (P < 0.05). The antiinflammatory activity was evaluated by determining nitrite plus nitrate (NOx) production in the milk PMNs before treatment and on day 8. NOx activity was significantly higher in mastitic milk than from healthy controls, both before and after treatment (P < 0.05). In group II and group III the activity decreased significantly on day 8 (P < 0.05). The Glutathione peroxidase (GSH-Px) activity was estimated in the milk polymorphonuclear cell (PMNs) supernatant. GSH-Px activity was significantly lower in mastitic buffaloes than in healthy controls, both before and after treatment (P < 0.05). In group II levels did not change in response to treatment, whereas in group III levels had increased significantly on day 8 (P < 0.05). The phagocytic activity (PA) (percentage of neutrophil that had phagocytosed 1–6 bacteria) and phagocytic index (PI) (average number of bacteria/ leukocytes counted in 100 cells) of the milk PMNs was significantly lower in mastitic buffaloes (P < 0.05). In group II the PA and PI did not change in response to treatment, whereas in group III both the parameters had increased significantly on day 8 (P < 0.05). The results of the present experiment indicated enhancement of antioxidative and cellular defense and reduction of somatic cell count in the mastitic animals treated with Enrofloxacin and Vitamin E plus Selenium as compared to the Enrofloxacin treatment alone. Hence Vitamin E plus selenium therapy may be added along with the antibiotics for effective amelioration of intramammary infection in buffaloes.     

The influence of ageing on muscarinic receptors, β-adrenoceptors and adenylate cyclase activity in the bovine lung

Muscarinic and -adrenoceptors were identified in airway epithelium, smooth muscle and lung parenchyma from Holstein-Friesian calves and cows and were characterized with [³H]quinuclidinyl benzilate and [³H]dihydroalprenolol, respectively. The muscarinic receptor density in the smooth muscle of cows (B _max=4803±245 fmol/mg protein) was 33% greater (p<0.01) than in calves. Low receptor numbers were detected in the epithelium and parenchyma. In both calves and cows, the density of epithelial -adrenoceptors was twice as high as in smooth muscle and parenchyma. The quantity of -adrenoceptors in the tracheal epithelium (B _max=994±83 fmol/mg protein) and smooth muscle (B _max=492±41 fmol/mg protein) in cows was respectively 37% (p<0.001) and 35% (p<0.01) lower than in calves. Adenylate cyclase (AC) assays indicated that the basal and the (–)-isopropylnoradrenaline- (ISO-) stimulated cAMP production were not significantly different between the calves and cows. After stimulation with NaF, significantly higher cAMP production was found in all tissues from cows. Significant correlations were found between absolute AC responses to NaF and -adrenoceptor density in epithelium (r=–0.75,p<0.001) and smooth muscle (r=–0.63,p<0.01). It seems that, in older animals, the production of cAMP is independent of the number of receptors, indicating the presence of fully active compensatory mechanisms.Abbreviations AC adenylate cyclase - cAMP intra-cellular adenosine monophosphate - G-protein GTP binding protein - GTP guanosine 5-triphosphate - ISO isopropylnoradrenaline - M muscarine - QNB quinuclidinyl benzilate     

中草药添加剂对山羊泌乳性能的影响

本添加剂由芪、当归、川芎、王不留行等中草药组成。为观察其增乳作用，探讨其作用机理，我们对１５只泌乳５０天左右的奶山羊（试验组８只，对照组７只）进行了。将添加剂拦入精料，阶段性饲喂。在添加前后，分别测定了乳脂、乳糖、乳蛋白及乳中环核苷酸（ｃＧＭＰ和ｃＡＭＰ）的含量；进行了外周血液Ｅ玫瑰花环试验，包括总Ｅ（Ｅｔ）花环和活性Ｅ（Ｅａ）花环试验；检查了隐性乳房炎发病情况；记录了产乳量。结果发现，本添加剂增     

Dose-dependent Response to an Intratesticular Injection of Calcium Chloride for Induction of Chemosterilization in Adult Albino Rats

This study concerned the minimum and optimum effective doses of calcium chloride needed for induction of chemosterilization in male albino rats, 30 days after a single intratesticular injection of calcium chloride (CaCl₂.2H₂O) solution at 2.5, 5, 10 or 20 mg per 100 g body weight per testis. There was a significant diminution in the relative wet weight of the sex organs (p<0.01), epididymal sperm count (p<0.001), plasma concentration of testosterone (p<0.01), testicular activities of D,3-hydroxy steroid dehydrogenase (D,3-HSD), 17-hydroxy steroid dehydrogenase (17-HSD) (p<0.01), glutathione S-transferase (GST) (p<0.01), superoxide dismutase (SOD) (p<0.01), and peroxidase (p<0.01), significant elevations in testicular content of malondialdehyde (MDA) and conjugated dienes (p<0.01), along with derangement of seminiferous tubular architecture and degeneration of the Leydig cells in the testis and elevations in the concentrations in the plasma of LH and FSH (p<0.01), commencing at a dose of 5 mg, with the greatest effects at a dose of 20 mg. No significant alterations in these factors occurred at the dose of 2.5 mg in comparison to the control that received only the vehicle. There was no significant alteration in the plasma concentrations of prolactin (p>0.05), corticosterone (p>0.05) or fasting blood glucose or in the rectal temperature (p>0.05) at any of the doses relative to the control group, suggesting that this chemosterilizing procedure did not exert any chronic stress on the experimental animals. From these observations, it may be suggested that 5 mg should be considered as the minimum dose, and 10 mg or 20 mg as the optimum dose, whereas 2.5 mg was ineffective for induction of chemosterilization. There would seem to be little point in using more than 20 mg of calcium chloride for this purpose. Intratesticular injection of calcium chloride at an effective dose may be considered as an alternative to surgical castration.     

Cilostazol Improves Developmental Competence of Pig Oocytes by Increasing Intraoocyte Cyclic Adenosine Monophosphate Level and Delaying Meiotic Resumption

Cilostazol (CLZ) is a cyclic adenosine monophosphate (cAMP) modulator that influences the steady state of the meiotic stage. This study was conducted to determine the effects of CLZ treatment during in vitro maturation (IVM) on developmental competence of pig oocytes. Immature oocytes were exposed to 0 (control), 0.5, 2 and 4 μm CLZ during the first 22 h of IVM. Nuclear maturation, intraoocyte glutathione content and embryo cleavage after parthenogenesis (PA) and somatic cell nuclear transfer (SCNT) were not influenced by CLZ at any concentrations. However, 4 μm CLZ significantly (p < 0.05) improved blastocyst formation after PA (52.1% vs 38.7–46.0%) and SCNT relative to other concentrations (40.8% vs 25.0–30.7%). The mean cell numbers of SCNT blastocysts were significantly increased by 4 μm CLZ compared to the control (42.6 cells vs 35.3 cells/blastocyst). CLZ treatment significantly increased the intraoocyte cAMP level and effectively arrested oocytes at the germinal vesicle (GV) and GV break down stages compared to the control (74.5% vs 45.4%). Our results demonstrated that improved developmental competence of PA and SCNT pig embryos occurred via better synchronization of nuclear and cytoplasmic maturation induced by increased cAMP and delayed meiotic resumption after CLZ treatment.     

Production of lipid mediators in mastitic milk of cow

Bovine mastitis is one of the most prevalent and costly diseases in the dairy industry. Lipid mediators are signaling molecules which coordinately and intricately modulate inflammation. They are produced from polyunsaturated fatty acids (PUFAs) in the cellular membrane via several enzymes including cyclooxygenase (COX) and lipoxygenase (LOX). In the present study, we performed comprehensive analysis of lipid production in milk obtained from clinical or subclinical mastitic cows using liquid chromatography/mass spectrometry. We detected 26, 24, and 40 kinds of lipid constantly in healthy, subclinical, and clinical mastitic milk, respectively. In clinical mastitic milk, the amount of a major n‐6 PUFA, arachidonic acid (AA), tended to increase, whereas amounts of major n‐3 PUFAs, eicosapentaenoic acid and docosahexaenoic acid, tended to decrease. The amounts of several AA‐derived lipids including COX‐catalyzed prostaglandin (PG) D₂ and PGE₂, and LOX‐catalyzed leukotriene (LT) B₄ were increased in clinical mastitic milk. Although subclinical mastitic milk represented similar trend of lipid production to healthy milk, amounts of several lipids such as LTD₄, 14,15‐dihydroxyeicosatrienoic acid, and 14‐epoxyeicosatrienoic acid changed. These findings would be helpful for better understanding of mastitis pathology and give us some insights to develop a new diagnostic and therapeutic strategy.     

ORIGINAL ARTICLE: The approach to the mechanism of calcitonin gene‐related peptide‐inducing inhibition of food intake

The aim of this study was to investigate the anorectic mechanism of calcitonin gene‐related peptide (CGRP) in rats. Intraperitoneal injection of CGRP (50 μg/kg) resulted in decline (p < 0.05) in the food intake of rats at 0.5, 1, 2 and 4 h in comparison with saline control. Compared with saline‐treated group, the levels of hypothalamic 3′,5′‐cyclic adenosine monophosphate (cAMP) and plasma glucagon were increased (p < 0.05) in CGRP‐treated group, but insulin level was decreased (p < 0.05). No significant changes (p > 0.05) in the plasma leptin were observed between two treatment groups. Calcitonin gene‐related peptide injection down regulated (p < 0.05) both neuropeptide Y (NPY) and melanin‐concentrating hormone (MCH) genes at mRNA levels, but up regulated (p < 0.05) the expression of cholecystokinin (CCK) gene. The correlations analysis showed that food intake was negatively correlated (p < 0.05) with CCK mRNA, cAMP and glucagon levels. Moreover, there existed negative correlations (p < 0.05) between MCH mRNA and glucagon levels, and positive correlations (p < 0.05) between insulin and leptin levels. The results showed that cAMP acting as the second messenger may play a vital role in the anorectic effects of CGRP. Calcitonin gene‐related peptide could stimulate anorexigenic neuropeptides (i.e. CCK) and/or inhibit orexigenic neuropeptides (i.e. NPY and MCH) expression, and ultimately suppressed food intake that was functionally coupled to cAMP/PKA pathway activation.     

Cell free mitochondrial DNA in serum and milk associated with bovine mastitis: a pilot study

Mastitis is inflammation of mammary gland affecting all the species of domestic animals. Fragments of the mitochondrial genome released from dying cells are considered surrogate markers of mitochondrial injury. We hypothesized that bovine mastitis would be associated with increased cell free mitochondrial DNA (mtDNA) content in serum and milk. Milk and serum samples were collected from sub-clinical mastitic and normal animals. Mastitis was confirmed by California mastitis test and bacterial isolation. Oxidative stress, nitric oxide and inflammatory cytokines were also estimated. Real time polymerase chain reaction was conducted in serum and milk from sub-clinical mastitic animals and compared with healthy animals targeting the mtDNA genes cytochrome b. Mastitis animals showed higher oxidative stress markers and nitric oxide along with higher level of inflammatory cytokines. Cell free mtDNA was significantly higher in serum and milk of mastitic animals comparing to that of healthy control. The higher cell free relative mtDNA content in mastitis animals indicates injury to the mammary epithelial cells and thereby releasing the mtDNA in the milk and blood. This mtDNA may be a bio-marker of oxidative stress and tissue injury in bovine mastitis.