Plasma and liver alpha-tocopherol in dairy cows with left abomasal displacement and fatty liver

Serum retinol, β-carotene, and α-tocopherol as biomarkers for disease risk and milk production in periparturient dairy cows

The effectiveness of using serum vitamin concentrations as biomarkers to predict diseases in dairy cows during the periparturient period is not well known. The objective of this study was to evaluate the association between serum β-carotene, retinol, and α-tocopherol concentrations and periparturient cow diseases in commercial dairies. We measured serum concentrations of these vitamin-active compounds at dry-off and during close-up (approximately 3 wk before calving) and early lactation (approximately 7 d post-calving), and we examined their association with clinical diseases in the first 30 d in milk. Diseases were diagnosed by trained personnel and recorded using database software. Blood samples were taken from 353 cows from 5 different farms over a 3-yr period. Blood samples were analyzed for β-carotene, retinol, α-tocopherol, and cholesterol. We built separate mixed logistic regression models for each disease outcome: hyperketonuria, lameness, mastitis, uterine diseases (retained placenta or metritis), and an aggregate outcome. For the aggregate outcome, a cow was considered positive if she had one or more of the following: hyperketonuria, lameness, mastitis, uterine disease, pneumonia, milk fever, or displaced abomasum. Concentrations of all 3 fat-soluble vitamins decreased significantly in early lactation relative to the 2 prepartum sampling times. Serum retinol concentrations at close-up and early lactation were negatively associated with odds of developing postpartum hyperketonuria. At early lactation, cows with uterine disease had lower serum retinol concentrations than cows without uterine disease. Similarly, lower serum retinol concentrations were associated with greater odds of having any one disease in the aggregate outcome. First-test 305-d mature-equivalent milk yield was positively correlated with increased serum α-tocopherol and negatively correlated with β-carotene concentrations. This study demonstrates the potential for serum β-carotene, retinol, and α-tocopherol to serve as biomarkers for disease risk.

Evaluation of Oxidative Stress in Dairy Cows with Left Displacement of Abomasum

Simple Summary

The present study evaluated oxidative and antioxidant status in dairy cows with Left Displacement of the Abomasum (LDA), an economically important postpartum disease in cattle. The oxidant capacity of plasma measured with a test fo reactive oxygen metabolites, the d-ROMs test, was significantly higher and the plasma biological antioxidant potential (BAP), measured with the BAP test was lower in the LDA group compared with the control group. Oxidative status was assessed using an arbitrary index obtained from the ratio between d-ROMs and BAP and the results showed that cows with LDA experience an imbalance between oxidants and antioxidants.

Abstract

Left Displacement of the Abomasum (LDA) is a condition that occurs in high-producing postpartum dairy cows and it causes economic losses. Studies performed in the last decade indicate that adult dairy cows experience oxidative stress. Increasing interest in the role of oxidative status in ruminant medicine has emphasized the need to develop reliable methods to assess it. A few studies have evaluated the relationship between LDA and oxidative status, mostly through the determination of single parameters of oxidation and the determination of antioxidant status separately, with contrasting results. The aim of this study was to assess the oxidative status by the measurement of Reactive Oxygen Metabolites with d-ROMs and Biological Antioxidant Potential BAP and the calculation of the Oxidative Status index in 74 multiparous dairy cows with LDA. Each case was matched with a control herdmate. The amount of free oxygen radicals in plasma samples was determined using the d-ROMs test, the concentration of antioxidants was measured using the BAP test and the Oxidative Status index was also calculated. The concentration of d-ROMs was significantly higher in the study group compared to the control group (179 ± 37.7 U CARR and 158 ± 23.0 U CARR, respectively), while the concentration of BAP was significantly lower in the study group than in the control group (2156 ± 98.1 µmol/L vs. 2558 ± 108.5 µmol/L). The Oxidative Status index value was significantly higher in cows with LDA than in healthy cows (8.3 ± 1.51 vs. 6.2 ± 0.76). The results of this study indicated that an inbalance between oxidants and antioxidants occurred in cattle with LDA.

Technical note: Rapid field test for the quantification of vitamin E, β-carotene, and vitamin A in whole blood and plasma of dairy cattle

Fast and easy tests for quantifying fat-soluble vitamins such as vitamin E and vitamin A, as well as β-carotene, in whole blood without a need to preprocess blood samples could facilitate assessment of the vitamin status of dairy cattle. The objective of this study was to validate a field-portable fluorometer/spectrophotometer assay for the rapid quantification of these vitamins in whole blood and plasma of dairy cows and calves. We measured the concentrations of vitamin E and β-carotene in whole blood and plasma from 28 dairy cows and 11 calves using the iCheck test (BioAnalyt GmbH, Teltow, Germany) and compared the results with the current analytical standard (HPLC) in 2 independent laboratories, one at the University of Potsdam (Germany) and at one at DSM Nutritional Products Ltd. (Kaiseraugst, Switzerland). For vitamin A, the HPLC measurements were done only in the laboratory in Germany. The whole-blood concentrations of vitamin E as determined by iCheck (blood-hematocrit-corrected) ranged from 1.82 to 4.99 mg/L in dairy cows and 0.34 to 3.40 mg/L in calves. These findings were moderately correlated (R² = 0.66) with the values assessed by HPLC in dairy cattle (cows + calves). When calves were excluded, the correlation was higher (R² = 0.961). The β-carotene and vitamin A values obtained by the reference method HPLC were highly correlated with the iCheck methods in whole blood (R² = 0.99 and 0.88, respectively). In plasma, we observed strong correlations between the concentrations assessed by iCheck and those of HPLC for vitamin E (R² = 0.97), β-carotene (R² = 0.98), and vitamin A (R² = 0.92) in dairy cattle (cows + calves). For vitamin E, β-carotene, and vitamin A, we compared the relationship between the differences obtained by the iCheck assay and the HPLC measurements, as well as the magnitude of measurements, using Bland-Altman plots to test for systematic bias. For all 3 vitamins, the differences values were not outside the 95% acceptability limits; we found no systematic error between the 2 methods for all 3 analytes.

Short communication: Associations between blood fatty acids, β-hydroxybutyrate, and α-tocopherol in the periparturient period in dairy cows: An observational study

The objective of the present study was to examine the relationships between blood concentrations of fatty acids, β-hydroxybutyrate (BHB), and α-tocopherol during the periparturient period in dairy cows. Blood samples were collected from 131 cows belonging to 4 different commercial dairy farms in southeastern Europe (Greece and Italy). We determined blood concentrations of fatty acids, BHB, and α-tocopherol at dry-off, at calving, and 30d postpartum. Results indicated that fatty acid concentrations were low at dry-off, reached maximum value at calving, and then declined at 30d postpartum. In fact, fatty acid concentrations at 30d postpartum were 50% lower than at calving. In contrast, BHB concentrations were low at dry-off, increased by 27% at calving, and continued to increase by another 20% at 30d postpartum. Overall, we found a weak correlation between fatty acids and BHB throughout the periparturient period. Concentrations of α-tocopherol were lowest at calving, and we detected no differences in α-tocopherol concentrations at dry-off or 30d postpartum. Negative correlations between fatty acids and α-tocopherol were highly significant at 30d postpartum and approached the level of significance at dry-off. However, both correlations became nonsignificant following the adjustment of α-tocopherol with cholesterol, indicating that the correlations were a reflection of changes in lipid transport. We found significant negative correlations (strong at dry-off and weak at 30d postpartum) between BHB and α-tocopherol after adjustment with cholesterol. The physiological basis for the negative correlations between BHB and α-tocopherol, especially that at dry-off, is not known and should not be taken to imply a cause-effect relationship. However, it opens the door to investigating the effects of vitamin E on liver function in dairy cows.

Invited review: Inflammation during the transition to lactation: New adventures with an old flame

For dairy cattle, the first several weeks of lactation represent the highest-risk period in their lives after their own neonatal period. Although more than 50% of cows during this period are estimated to suffer from at least one subclinical disorder, the complicated admixture of normal adaptations to lactation, infectious challenges, and metabolic disorders has made it difficult to determine which physiological processes are adaptive and which are pathological during this time. Subacute inflammation, a condition that has been well documented in obesity, has been a subject of great interest among dairy cattle physiologists in the past decade. Many studies have now clearly shown that essentially all cows experience some degree of systemic inflammation in the several days after parturition. The magnitude and likely persistence of the inflammatory state varies widely among cows, and several studies have linked the degree of postpartum inflammation to increased disease risk and decreased whole-lactation milk production. In addition to these associations, enhancing postpartum inflammation with repeated subacute administration of cytokines has impaired productivity and markers of health, whereas targeted use of nonsteroidal anti-inflammatory drugs during this window of time has enhanced whole-lactation productivity in several studies. Despite these findings, many questions remain about postpartum inflammation, including which organs are key initiators of this state and what signaling molecules are responsible for systemic and tissue-specific inflammatory states. Continued in vivo work should help clarify the degree to which mild postpartum inflammation is adaptive and whether the targeted use of anti-inflammatory drugs or nutrients can improve the health and productivity of dairy cows.

Oxidative stress and antioxidant status in dairy cows during prepartal and postpartal periods

The aim of the present study was to evaluate the indicators of oxidative stress (malondialdehyde [MDA]) and antioxidant status (ferric reducing ability of plasma [FRAP]; superoxide dismutase [SOD]; glutathione peroxidase [GSH-Px]; selenium [Se]; vitamin E) in dairy cows of the Slovak Pied cattle from 3 weeks before parturition to 9 weeks after parturition. The mean MDA concentration was significantly (P < 0.001) higher in the cows 1 week after calving compared to the cows 3, 6, and 9 weeks after calving. The lowest mean FRAP value was found in the cows 3 weeks after parturition. The SOD activities were increased during the whole monitored time (ANOVA, P < 0.001). A significant (P < 0.05) decrease of GSH-Px activities was recorded in the cows 1 week after calving compared to the weeks 6 and 9 after calving. Statistical multiple comparison test showed no significant changes in Se between the examined groups. The lowest mean vitamin E concentration was found in the first week after parturition. Significantly positive correlations (P < 0.05) were recorded between Se and vitamin E (r = 0.897), SOD and GSH-Px (r = 0.903), while Se and GSH-Px had no significantly positive correlation (r = 0.520). Significant changes between MDA and indicators of oxidative stress (SOD, GSH-Px, vitamin E) confirm that during parturition and onset of lactation, oxidative stress occurs in dairy cows. Exposure of peripartal cows to oxidative stress may cause an increased incidence of metabolic diseases.

The role of liver biopsy in detection of hepatic oxidative stress

The goal of the current paper is to explore the role of liver biopsy as a tool in detection of hepatic oxidative stress, with brief notes on different types of free radicals, antioxidants, hepatic and blood oxidative stress, and lipid peroxidation. Hepatic oxidative stress was investigated for many years in human and animals, but most of the studies performed in animals were concerned with studying oxidative status in the liver tissues after slaughtering or euthanasia. However, in human medicine, a large number of studies were implemented to investigate the status of antioxidants in liver biopsy specimens. Similar studies are required in animals, as the changes in hepatic antioxidants and formation of lipid peroxide give a good idea about the condition of the liver. On the other hand, hepatic disease may present without significant effect on blood oxidative status, and, consequently, the best way to detect the status of hepatic oxidants and antioxidants is through measuring in liver biopsy. Measuring antioxidants status directly in the liver tissues gives an accurate estimation about the condition of the liver, permits the diagnosis of hepatic dysfunction, and helps to determine the degree of deterioration in the hepatic cells.

Effects of Abdominal Surgery on Thiobarbituric acid Reactive Substances and Plasma Anti-oxidative Capacity in Dairy Cows

The present investigation was undertaken to study the effects of surgical stress on thiobarbituric acid reactive substances (TBARS) and ferric reducing ability of plasma (FRAP) in dairy cows. Ten Holstein-Friesian dairy cows, mean age 5.26 years, admitted for treatment of left abomasal displacement (omentopexy), were used in our study. Blood samples were collected from the jugular vein prior to surgery, immediately and then 15, 30, 60, 90 min, and 2, 5, 10, and 24 h after reposition of abomasum. Surgical stress resulted in a significant increase in plasma cortisol concentrations (P < 0.001) with the highest mean levels 15 min after surgery (32.4 +/- 18.1 microg/l) as well as in serum levels of glucose (P < 0.001) and non-esterified fatty acids (P < 0.001). Similarly, surgery transiently enhanced the plasma levels of TBARS (P < 0.001). The highest TBARS plasma levels (0.91 +/- 0.18 micromol/l) were recognized 60 min after reposition of abomasums. There were no significant differences in FRAP in dairy cows before and after reposition of abomasum. In conclusion, these data indicate that stress reaction caused by surgical correction of left displacement of abomasum can be associated with higher production of TBARS.

Rumen-protected choline administration to transition cows: effects on milk production and vitamin E status

We investigated the influence of rumen-protected choline (RPC) supplementation on milk production, lipid metabolism and vitamin E status in dairy cows receiving a silage-based diet. Twenty-six Italian Holstein multiparous cows were assigned by weight and average production in the previous lactation, to one of two groups: control (no RPC supplementation) and RPC (supplemented with 20 g/day rumen-protected choline chloride). Treatment began 14 days before expected calving and continued for 30 days after parturition. Choline administration significantly increased milk production during the first month of lactation and also the concentration (and total secretion) of choline in milk, but did not affect fat or protein concentrations in milk, or plasma levels of glucose, beta-hydroxybutyrate, cholesterol and non-esterified fatty acids (NEFA). However, around parturition, NEFA concentrations in plasma were lower in treated animals than in controls, suggesting improved lipid metabolism as a result of choline supplementation. Choline supplementation also increased alpha-tocopherol plasma concentrations, suggesting a novel aspect in dairy cows.

Effects of vitamin E and different energy sources on vitamin E status, milk quality and reproduction in transition cows

We investigated whether vitamin E supplementation and supplemental energy sources (fat or starch) influenced plasma and milk levels of vitamin E, and reproductive and other parameters in 28 Italian Friesian multiparous dry cows. From 14 days before expected calving to 7 days after, the animals were assigned to either basal diet (containing 1000 IU/day of vitamin E) or an extra 1000 IU/day of vitamin E (total 2000 IU). In addition they received either 0.5 kg/day of corn or 0.2 kg/day of calcium soaps. Plasma samples were collected 4 days before expected calving and 4 days after calving and analysed for alpha-tocopherol and cholesterol. Milk yield as well as the composition, somatic cell count (SCC) and alpha-tocopherol of milk were determined 7 and 14 days after calving. Milk yield and composition were unaffected by treatments. SCC was significantly lower in (SCC Log 4.62 versus Log 5.1, P < 0.01) 2000 IU/day animals than in the 1000 IU/day group. Milk alpha-tocopherol was higher (P < 0.001) in animals receiving 2000 IU/day (1.11 vs. 0.65 microgram/ml, P < 0.01). Plasma alpha-tocopherol in animals receiving 2000 IU/day was also higher (P < 0.001) than in cows receiving 1000 IU/day (4.85 vs. 3.25 micrograms/ml), but was not affected by dietary energy source. Number of services and days to conception were lower (P < 0.01) in the 2000 IU vitamin E supplemented cows. To conclude, dietary vitamin E supplementation to periparturient dairy cows increased plasma and milk vitamin E, decreased SCC in milk, and improved fertility but different energy sources had no effect on any measured variable.