Changes in Vitamin C Concentrations in Plasma and Milk from Dairy Cows After an Intramammary Infusion of Escherichia coli

Dietary vitamin C in pre-parturient dairy cows and their calves: blood metabolites, copper, zinc, iron, and vitamin C concentrations, and calves growth performance

The aim of this study was to evaluate the effects of dietary vitamin C supplementation on blood parameters of pre-parturient (PP) dairy cows and growth performance and immune system of their newborn calves. Forty PP cows (at approximately 21 days before calving and an average weight 791 ± 50 kg) were allocated into two experimental treatments: (1) basal diet without vitamin C supplementation (CO) and (2) basal diet with 20 g of vitamin C supplementation from 21 days before calving to parturition (VC). After parturition, the experiment continued by grouping the calves into four dietary treatments with 8 calves in each treatment. The experimental treatments were (1) control calves with no vitamin C supplementation and from cows that received no vitamin C supplement (CON), (2) calves supplemented with 600 mg of vitamin C per day and from cows that received no vitamin C supplement (CVC), (3) calves supplemented with no vitamin C and from cows that received 20 g of vitamin C per day (MVC), and (4) calves supplemented with 600 mg of vitamin C per day and from cows that received 20 g of vitamin C per day (CMVC). Serum concentrations of glucose, HDL and LDL, cholesterol, triglycerides, total protein, and albumin of cows were not affected by vitamin C supplementation during pre-parturient period. However, cows that received VC diet had lower (P < 0.05) malondialdehyde (MDA) and aspartate aminotransferase (AST) concentrations, higher total antioxidant capacity (TAC), and vitamin C concentration in their blood compared to CO cows. Vitamin C supplementation had no effect on plasma iron, copper, and zinc concentrations of PP cows. Similarly, vitamin C supplementation had no effect on total feed intake and feed conversion ratio (FCR) of suckling calves. However, calves in the CMVC group had higher (P < 0.05) overall daily weight gain compared to the other groups. Calves in the CVC and CMVC groups had lower (P < 0.05) blood MDA concentration on days 7 and 21. The highest (P < 0.05) blood TAC level was recorded in CMVC calves. Control group calves had lower (P < 0.05) blood superoxide dismutase activity compared to the other calves. Blood levels of alanine aminotransferase on days 7 and 21 and aspartate aminotransferase on day 7 were higher (P < 0.05) for calves in the CON and MVC groups. Based on the results, vitamin C supplementation had positive health effects on the oxidative parameters of PP dairy cows and also improved the performance and health status of the calves.

Grape seed extract and chromium nicotinate reduce impacts of heat stress in Simmental × Qinchuan steers

To assess the impacts of grape seed extract (GSE) fed with or without chromium nicotinate (CN) on beef steers under heat stress conditions, 40 Simmental × Qinchuan steers (400 ± 10 days old; 410 ± 8.0 kg) were randomly assigned to one of four diets (n = 10 per group): basal diet (CON group); basal diet + 33 mg/day CN (CN group); basal diet + 65 mg/kg DM GSE (GSE group); and basal diet + 33 mg/day CN + 65 mg/kg DM GSE (CN + GSE group). This study was conducted in summer and the steers were housed in outdoor shaded pens (10 steers/pen) and fed individually. The experiment lasted for 35 days, the first 7 days for diet and housing condition adaptation. The amount of feed intake was recorded daily; individual bodyweight was recorded on Days 8, 22, and 36. On Day 36 before feeding, six steers per group were slaughtered for collection of blood and tissue samples. Average daily liveweight gain and dry matter intake of steers were increased by the GSE, CN, and CN + GSE treatments (P &lt; 0.05). Dietary treatments increased the activities of glutathione peroxidase and total superoxide dismutase in plasma (P &lt; 0.05) and plasma concentration of interleukin 10 on Days 22 and 36 (P &lt; 0.05), whereas decreased plasma concentration of tumour necrosis factor-α on Day 22 (P &lt; 0.05). Overall, supplementation of GSE alone or with CN had positive effects on the growth performance of steers under heat stress conditions.

Cellular and exosome mediated molecular defense mechanism in bovine granulosa cells exposed to oxidative stress

Various environmental insults including diseases, heat and oxidative stress could lead to abnormal growth, functions and apoptosis in granulosa cells during ovarian follicle growth and oocyte maturation. Despite the fact that cells exposed to oxidative stress are responding transcriptionally, the potential release of transcripts associated with oxidative stress response into extracellular space through exosomes is not yet determined. Therefore, here we aimed to investigate the effect of oxidative stress in bovine granulosa cells in vitro on the cellular and exosome mediated defense mechanisms. Bovine granulosa cells were aspirated from ovarian follicles and cultured in DMEM/F-12 Ham culture medium supplemented with 10% exosome-depleted fetal bovine serum. In the first experiment sub-confluent cells were treated with 5 μM H₂O₂ for 40 min to induce oxidative stress. Thereafter, cells were subjected to ROS and mitochondrial staining, cell proliferation and cell cycle assays. Furthermore, gene and protein expression analysis were performed in H₂O₂-challenged versus control group 24 hr post-treatment using qRT-PCR and immune blotting or immunocytochemistry assay, respectively. Moreover, exosomes were isolated from spent media using ultracentrifugation procedure, and subsequently used for RNA isolation and qRT-PCR. In the second experiment, exosomes released by granulosa cells under oxidative stress (StressExo) or those released by granulosa cells without oxidative stress (NormalExo) were co-incubated with bovine granulosa cells in vitro to proof the potential horizontal transfer of defense molecules from exosomes to granulosa cells and investigate any phenotype changes. Exposure of bovine granulosa cells to H₂O₂ induced the accumulation of ROS, reduced mitochondrial activity, increased expression of Nrf2 and its downstream antioxidant genes (both mRNA and protein), altered the cell cycle transitions and induced cellular apoptosis. Granulosa cells exposed to oxidative stress released exosomes enriched with mRNA of Nrf2 and candidate antioxidants. Subsequent co-incubation of StressExo with cultured granulosa cells could alter the relative abundance of cellular oxidative stress response molecules including Nrf2 and antioxidants CAT, PRDX1 and TXN1. The present study provide evidences that granulosa cells exposed to oxidative stress conditions react to stress by activating cascades of cellular antioxidant molecules which can also be released into extracellular environment through exosomes.

Structure, chaperone-like activity and allergenicity profile of bovine caseins upon peroxynitrite modification: New evidences underlying mastitis pathomechanisms

Mastitis, an inflammatory reaction frequently develops in response to intra-mammary bacterial infection‌‌, may induce the generation of peroxynitrite (PON)‌ which is a highly potent reactive oxygen and nitrogen species. Caseins as the intrinsically unfolded proteins seem feasible substrates to react with PON. Therefore, in the current study, structural and functional aspects of both β-casein (β-CN) and whole casein fraction (WCF) were evaluated after PON modification, using a variety of techniques. Modification of the bovine caseins with PON results in an important enhancement in the carbonyl, nitrotryptophan, nitrotyrosine and dityrosine content of these proteins‌. The results of fluorescence and far UV-CD assessments suggested significant structural alteration of caseins upon PON-modification. The chaperone-like activity of β-casein was significantly altered after PON modification. The results of scanning electron microscopy suggest that bovine caseins display unique morphological features after treatment with PON. Also, the PON-modified caseins preserved their allergenicity profile and displayed partial resistance against digestion by the pancreatic proteases. Ascorbic acid, an important antioxidant component of milk, was also capable to significantly prevent the PON-induced structural damages in bovine milk caseins. In conclusion, our results suggest that PON may have significant role in the structural and functional alteration of milk caseins. Also, the PON-induced structural damaging effects of caseins might be effectively prevented by a sufficient level of milk antioxidant components particularly by ascorbic acid.

15-F2t-Isoprostane Concentrations and Oxidant Status in Lactating Dairy Cattle with Acute Coliform Mastitis

Background

Severe mammary tissue damage during acute coliform mastitis in cattle is partially caused by oxidative stress. Although considered a gold standard biomarker in some human conditions, the utility of 15‐F_2t‐Isoprostanes (15‐F_2t‐Isop) in detecting oxidative stress in dairy cattle has not been validated.

Hypothesis

Concentrations of 15‐F_2t‐Isop in plasma, urine, and milk correlate with changes in oxidant status during severe coliform mastitis in cattle.

Animals

Eleven lactating Holstein‐Friesian dairy cows in their 3rd–6th lactation.

Methods

A case–control study using cows with acute coliform mastitis and matched healthy controls were enrolled into this study. Measures of inflammation, oxidant status, and redox status in plasma and milk samples were quantified using commercial assays. Plasma, urine, and milk 15‐F_2t‐Isop were quantified by liquid chromatography/tandem mass spectrometry (LC‐MS/MS) and ELISA assays. Data were analyzed by Wilcoxon rank sum tests (α = 0.05).

Results

Plasma 15‐F_2t‐Isop quantified by LC‐MS/MS was positively correlated with systemic oxidant status (r = 0.83; P = .01). Urine 15‐F_2t‐Isop quantified by LC‐MS/MS did not correlate with systemic oxidant status, but was negatively correlated with redox status variables (r = −0.83; P = .01). Milk 15‐F_2t‐Isop quantified by LC‐MS/MS was negatively correlated (r = −0.86; P = .007) with local oxidant status. Total 15‐F_2t‐Isop in milk quantified by a commercial ELISA (cbELISA) was positively correlated with oxidant status in milk (r = 0.98; P < .001).

Conclusions and Clinical Importance

Free plasma 15‐F_2t‐Isop quantified by LC‐MS/MS and total milk 15‐F_2t‐Isop quantified by cbELISA are accurate biomarkers of systemic and mammary gland oxidant status, respectively. Establishing reference intervals for free and total 15‐F_2t‐Isops for evaluating oxidative stress in dairy cows should currently be based on the LC‐MS/MS method.

Effects of supplementation with a phytobiotics-rich herbal mixture on performance, udder health, and metabolic status of Holstein cows with various levels of milk somatic cell counts

This study evaluated the effects of dietary supplementation of a novel phytobiotics-rich herbal mixture (PRHM) on feed intake, performance, udder health, ruminal fermentation, and plasma metabolites in cows with moderate or high somatic cell counts (SCC) in the milk. Twenty-four Holstein dairy cows (117 ± 26 d in milk and 46.3 ± 4.7 kg of milk/d at the start of the experiment) were blocked by parity and days in milk and split into 2 groups, based on SCC in the milk; 12 cows were with moderate SCC (260,000<SCC <500,000 cells/mL), whereas 12 other cows had high levels of SCC (>500,000 cells/mL) in the milk. Within each SCC group, cows were blocked by milk yield and parity, and were randomly assigned to 2 different feeding regimens. Half of the cows in each SCC group (n=6) were supplemented with PRHM (185 g/cow per day, providing 12.4 g of phenolic compounds per day), and the other half (n=6) were not supplemented in their diets. The experiment lasted 36 d, whereby the first 24 d were used for adaptation to the diets and the last 12 d for sampling. Data showed that supplementation of PRHM decreased somatic cell score in the milk, indicating improved udder health of cows with high initial SCC, but not in cows with moderate SCC. Also, cows supplemented with PRHM consumed more feed DM, produced greater amounts of milk, and showed an improvement of feed utilization efficiency. However, these cows also lost more back-fat thickness during the experiment. Supplementation of PRHM increased fat- and energy-corrected milk yields in cows with high initial SCC, but not in cows with moderate SCC. Supplementation of PRHM decreased milk fat content, whereas other milk components were not affected by PRHM feeding. The PRHM supplementation decreased the acetate-to-propionate ratio in the rumen fluid, but increased β-hydroxybutyrate and cholesterol concentration in the plasma, irrespective of the initial SCC level in the milk. Other plasma metabolites and liver enzymes were not affected by PRHM supplementation. Apparent nutrient digestibility did not differ among treatments. Overall, supplementation of PRHM seems to be an effective strategy to enhance performance and lower SCC, particularly in cows having high SCC levels in the milk. Further research is warranted to evaluate long-term effects of PRHM supplementation, especially with regard to metabolic health status and reproduction.

Vitamin C nutrition in cattle

Domestic animals, including ruminants, can synthesize vitamin C (VC) in their liver; as such, the dietary requirement for VC has not been confirmed in these animals. The adequacy of VC has been evaluated by quantifying VC levels in plasma, but the reported values in bovine plasma have been widely variable. Plasma VC concentration is decreased by heat stress, hepatic lesions, fattening, and infectious diseases such as mastitis in cattle. Therefore, VC supplementation is potentially beneficial for cattle with low plasma VC concentration. This review discusses the methods for determination of plasma VC concentration in cattle, VC nutrition, and the efficacy of VC supplementation in calves, dairy cattle, and beef cattle. Additionally I propose a reference range for plasma VC concentration in Japanese Black cattle.

Subclinical mastitis causes alterations in nitric oxide, total oxidant and antioxidant capacity in cow milk

The aim of this study was to investigate total antioxidant (TAC), and oxidant capacity (TOC) and nitric oxide (NO) levels in milk of cows with subclinical mastitis. Brown Swiss and Holstein breed cows were screened with California Mastitis Test (CMT) to determine mammary glands with subclinical mastitis. Moreover, somatic cell counts (SCC) were determined electronically in all milk samples. Mammary quarters were classified as healthy (n=25) or subclinical mastitis (n=35) based on CMT scores and somatic cell count (SCC: < or =200,000/ml or >200,000/ml) in milk. Nitric oxide, TOC and SCC levels were significantly higher (p<0.001, p<0.005 and p<0.001, respectively) in milk from mammary quarters with subclinical mastitis compared to those from healthy mammary quarters. In conclusion, subclinical mastitis results in higher NO concentrations, TOC and SCC, and NO and TOC were positively correlated with SCC. Moreover, alterations in NO levels and TOC in milk could be used as an alternative diagnostic tool to screen for subclinical mastitis.

Metabolic factors affecting the inflammatory response of periparturient dairy cows

Dairy cattle are susceptible to increased incidence and severity of disease during the periparturient period. Increased health disorders have been associated with alterations in bovine immune mechanisms. Many different aspects of the bovine immune system change during the periparturient period, but uncontrolled inflammation is a dominant factor in several economically important disorders such as metritis and mastitis. In human medicine, the metabolic syndrome is known to trigger several key events that can initiate and promote uncontrolled systemic inflammation. Altered lipid metabolism, increased circulating concentrations of non-esterified fatty acids and oxidative stress are significant contributing factors to systemic inflammation and the development of inflammatory-based diseases in humans. Dairy cows undergo similar metabolic adaptations during the onset of lactation, and it was postulated that some of these physiological events may negatively impact the magnitude and duration of inflammation. This review will discuss how certain types of fatty acids may promote uncontrolled inflammation either directly or through metabolism into potent lipid mediators. The relationship of increased lipid metabolism and oxidative stress to inflammatory dysfunction will be reviewed as well. Understanding more about the underlying cause of periparturient health disorders may facilitate the design of nutritional regimens that will meet the energy requirements of cows during early lactation and reduce the susceptibility to disease as a function of compromised inflammatory responses.

Management of mastitis on organic and conventional dairy farms

This paper compares management of mastitis on organic dairy farms with that on conventional dairy farms. National standards for organic production vary by country. In the United States, usage of antimicrobials to treat dairy cattle results in permanent loss of organic status of the animal, effectively limiting treatment choices for animals experiencing bacterial diseases. There are no products approved by the US Food and Drug Administration that can be used for treatment of mastitis on organic dairy farms, and usage of unapproved products is contrary to Food and Drug Administration guidelines. In general, organic dairy farms tend to be smaller, produce less, and more likely to be housed and milked in traditional barns as compared with conventionally managed herds. It is difficult to compare disease rates between herds managed conventionally or organically because perception and detection of disease is influenced by management system. To date, no studies have been published with the defined objective of comparing animal health on organic dairy herds with that on conventional dairy herds in the United States. European studies have not documented significant differences in animal health based on adoption of organic management. Few differences in bulk tank somatic cell counts have been identified between organic and conventional herds. Farmers that have adopted organic management consistently report fewer cases of clinical mastitis, but organic farmers do not use the same criteria to detect clinical mastitis. European dairy farmers that adopt organic management report use of a variety of conventional and alternative therapies for treatment and control of mastitis. In the United States, organic farmers treat clinical mastitis using a variety of alternative therapies including whey-based products, botanicals, vitamin supplements, and homeopathy. Organic farmers in the United States use a variety of alternative products to treat cows at dry-off. Virtually no data are available that support the clinical efficacy of any of the alternative veterinary products used for treatment or prevention of mastitis. Some associations between organic management and antimicrobial susceptibility of gram-positive mastitis pathogens have been noted, but overall, few mastitis pathogens from both conventional and organic dairy herds demonstrate resistance to antibiotics commonly used for mastitis control.

Treatment practices and quantification of antimicrobial drug usage in conventional and organic dairy farms in Wisconsin

The objective of this study was to develop a method to quantify antimicrobial drug usage and treatment practices on conventional and organic dairy farms that had been recruited to represent a broad spectrum of potential exposure to antimicrobial drugs. Data on disease prevalence and treatment practices of organic (n = 20) and conventional (n = 20) farms were obtained during a farm visit using a survey instrument. A standardized estimate of antimicrobial drug usage was developed using a defined daily dose (DDD) of selected compounds. Density of antimicrobial drug usage was expressed as the number of DDD per adult cow per year. Differences in prevalence and management of selected diseases between conventional and organic farms were identified. The overall estimated prevalence of selected diseases was greater for conventional farms compared with organic farms. Organic farmers reported use of a variety of nonantimicrobial compounds for treatment and prevention of disease. Conventional farmers reported that penicillin was the compound most commonly used for dry cow therapy and cephapirin was most commonly used for treatment of clinical mastitis. On conventional farms, the estimated overall exposure to antimicrobial drugs was 5.43 DDD per cow per year composed of 3.58 and 1.85 DDD of intramammary and parenteral antimicrobial drugs, respectively. Of total intramammary antimicrobial drug usage, treatment of clinical mastitis contributed 2.02 DDD compared with 1.56 DDD attributed to the use of dry cow therapy. Of total parenteral treatments, the distribution of exposure was 0.52 (dry cow therapy), 1.43 (clinical mastitis treatment), 0.39 (treatment of foot disease), 0.14 (treatment of respiratory disease), and 0.32 (treatment of metritis) DDD. For treatments of foot infections (0.33 DDD), respiratory infections (0.07 DDD), and metritis (0.19 DDD), the mean density of ceftiofur usage was significantly greater compared with other compounds.

The effect of vitamin C supplementation on plasma concentration and urinary excretion of vitamin C in cattle

We investigated the plasma concentration and urinary excretion of vitamin C in cows supplemented with vitamin C. Five cows (mean BW = 597 kg) were allocated to a 5 x 5 Latin square design and supplemented with a vitamin C preparation coated with hydrogenated soybean oil at 0, 10, 20, 40, or 60 mg of vitamin C per kg of BW per day for 9 d. Plasma and urine samples were collected for measuring vitamin C concentration. Urinary excretion of vitamin C was expressed as the ratio of vitamin C to creatinine. Plasma vitamin C concentration and urinary vitamin C excretion increased quadratically as dietary vitamin C increased (P < 0.001); that is, the lowest dose affected neither plasma vitamin C concentration nor urinary vitamin C excretion but the plasma vitamin C concentration and urinary vitamin C excretion increased (P < 0.05) with increasing supplementation of vitamin C at greater doses. This suggests that plasma vitamin C concentration affects urinary excretion of vitamin C in cattle and that plasma vitamin C concentration exceeded the renal threshold for vitamin C in the cows receiving vitamin C at 20 mg/kg of BW per day. Furthermore, increased urinary excretion of vitamin C appears to limit plasma vitamin C concentration in response to vitamin C intake. The daily excretion of vitamin C was estimated by the reported value of daily creatinine excretion, indicating that the daily amount of vitamin C excreted into urine was more than half of supplied vitamin C. Therefore, a large part of supplied vitamin C probably escapes ruminal degradation and is absorbed but excreted into urine.

Effects of Dietary Vitamin C on Neutrophil Function and Responses to Intramammary Infusion of Lipopolysaccharide in Periparturient Dairy Cows

Neutrophil function and the severity and incidence of mastitis in dairy cows is related to the intake of many antioxidant nutrients. Because vitamin C is the major water-soluble antioxidant in mammals, we examined the effect of dietary vitamin C on neutrophil function and responses to intramammary infusion of lipopolysaccahride (LPS) in periparturient dairy cows. At 2 wk before anticipated calving, Holstein cows were fed diets that provided 0 (16 cows) or 30 (15 cows) g/d of supplemental vitamin C (phosphorylated ascorbic acid). Treatments continued until 7 d after cows received an infusion of 10 microg of LPS into one quarter of the mammary gland (on average, this occurred 32 d postcalving). Supplementation of vitamin C increased plasma concentrations of vitamin C at calving, but no differences were observed in samples taken 24 h postinfusion. Concentrations of vitamin C in milk (24 h postinfusion) and in neutrophils (calving and 24 h postinfusion) were not affected by treatment, but vitamin C concentrations in neutrophils isolated from milk were about 3 times greater than concentrations in blood neutrophils. The LPS infusion did not alter concentrations of vitamin C in plasma or milk, suggesting that the LPS model did not produce the same effects as a bacterial infection of the mammary gland with respect to antioxidant effects. Supplemental vitamin C had no effect on neutrophil phagocytosis or bacterial kill. Dietary vitamin C reduced the milk somatic cell count but did not affect the febrile response or milk production following LPS infusion.

Oxidants and antioxidants in disease: oxidative stress in farm animals

Important infectious diseases in farm animals, such as pneumonia and enteritis, are thought to be associated with the so-called oxidative stress, i.e. a chemical phenomenon involving an imbalance in the redox status of the individual animal. The specifics of oxidative stress and how it may result in disease or be prevented are complex questions with no simple answers. However, the considerable literature on the subject suggests that many researchers consider oxidative stress-related mechanisms to be important early events in disease development. A particularly intriguing aspect is that, at least theoretically, oxidative stress should be easily prevented with antioxidants yet the use of antioxidants as therapy remains controversial. The present knowledge on oxidative stress in farm animals is the topic of this review.

Plasma Vitamin C Concentration is Not Related to the Incidence of Ketosis in Dairy Cows during the Early Lactation Period

Many animals including cattle can synthesize vitamin C from glucose. The objective of this study was to investigate plasma vitamin C concentration in ketotic cows during the early lactation period because glucose supply for vitamin C synthesis might be limited in these cows. We measured plasma beta-hydroxybutyrate (BHBA) concentration in 118 cows within 2 months after parturition. Subclinical/clinical ketosis was quantitatively determined using a plasma BHBA threshold of 1,200 microM. Plasma glucose concentration was lower in the ketotic cows than in the control cows but plasma vitamin C concentration did not differ between the control and the ketotic cows. Then we measured plasma vitamin C, BHBA and glucose levels in 7 cows during the periparturient period. Plasma BHBA increased and plasma glucose decreased after parturition but plasma vitamin C did not change. These results indicate that plasma vitamin C is not related to the incidence of ketosis in the early lactation period. We suggest that ketotic cows have the ability to produce vitamin C to meet its requirement in the early lactation period although glucose supply is not sufficient for milk production. Vitamin C synthesis is possibly given a high metabolic-priority for glucose in lactating cows.