α-Tocopherol concentration and stereoisomer composition in plasma and milk from dairy cows fed natural or synthetic vitamin E around calving

The aim of this study was to compare the effects of supplementing dairy cows with 1000 IU/day of all-rac-α-tocopheryl acetate (SynAc), RRR-α-tocopheryl acetate (NatAc), or RRR-α-tocopherol (NatAlc), from approximately 3 weeks before estimated calving until 2 weeks after calving, on the concentration of α-tocopherol and its stereoisomers (RRR-, RSS-, RRS-, RSR- and the four 2S-forms of α-tocopherol) in blood and milk. An unsupplemented group was included as control. Blood samples were collected at 3, 2 and 1 weeks before estimated calving, at calving, and 3, 7 and 14 days after calving, while milk samples were taken twice within 24 h after calving and at 7 and 14 days in milk. Overall, time and treatment had significant effects on plasma α-tocopherol with higher concentrations in NatAc than in the other groups. In addition, SynAc had higher concentrations than Control, and NatAlc tended to be higher than Control. The lowest plasma concentrations were observed at calving and 3 days after calving. Independent of treatment, the concentration was higher in colostrum than in milk day 7 and 14 after calving. Analyses of the stereoisomer distribution in plasma and milk showed that, irrespective of dietary treatment, RRR-α-tocopherol was the most predominant form, constituting more than 86%, whereas the remaining part of α-tocopherol was made up by the three synthetic 2R isomers, while the 2S isomers only contributed less than 1% of the total α-tocopherol. In control cows and cows supplemented with natural vitamin E, the proportion of RRR-α-tocopherol in plasma and milk constituted more than 98% of the total α-tocopherol. In conclusion, the results indicate that daily oral supplementation of dairy cows with RRR-α-tocopheryl acetate gives the highest blood concentrations of α-tocopherol in the periparturient period. Analyses of the distribution of the individual stereoisomers of α-tocopherol further indicate that the bioavailability of RRR-α-tocopherol relative to synthetic stereoisomers in cattle is considerably higher than officially accepted until now.

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Injectable α-tocopherol for control of oxidized flavour in milk from dairy cows

Canadian Journal of Animal Science ◽

10.4141/cjas93-040 ◽

1993 ◽

Vol 73 (2) ◽

pp. 381-392 ◽

Cited By ~ 16

Author(s):

E. Charmley ◽

J. W. G. Nicholson

Keyword(s):

Dairy Cows ◽

Milk Fat ◽

Tocopheryl Acetate ◽

Tocopherol Concentration ◽

Oral Supplementation ◽

Stage Of Lactation ◽

Commercial Farms ◽

Quadratic Response ◽

Control Milk ◽

And Control

Two experiments were conducted to evaluate the use of intramuscular injections of d-α-tocopherol for control of spontaneous oxidized flavour (SOF) in milk. In exp. 1, 12 mid-lactation dairy cows were either not injected or given an intramuscular injection of 1500 or 3000 IU α-tocopherol on days 1, 8 and 15 of a 29-d experiment. Peak blood plasma and milk α-tocopherol levels were observed 1 and 3 d, respectively, after injection. In plasma there was a quadratic response (P = 0.02) in maximum α-tocopherol concentration to the level of α-tocopherol injected, but in milk the response was linear (P < 0.01). Milk fat concentration increased as level of α-tocopherol injected was increased (P < 0.01). Approximately 5% of the injected dose was excreted in milk over the 7 d following injection. In exp. 2, four commercial farms with a SOF problem in milk were used to test the efficacy of injectable α-tocopherol for control of SOF. Prior to the trial, cows with milk susceptible to oxidation were younger (P = 0.04), were at an earlier stage of lactation (P = 0.03) and tended to give more milk (P = 0.08). All cows were given an oral supplmement of 3000 IU dl-α-tocopheryl acetate per day and half were injected with 3000 IU α-tocopherol. Injection reduced the intensity of oxidized flavour (week 1, P < 0.01; week 2, P = 0.09) and elevated the levels of α-tocopherol in milk for up to 2 wk after injection (P < 0.01). α-Tocopherol injected intramuscularly can increase α-tocopherol levels in milk within 3 d and control milk oxidation. Subsequent oral supplementation can prolong these benefits. Key words: Oxidized milk, tocopherol, flavour, dairy cow

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Effect of Dietary Supplementation with Vitamin E and Selenium in Thoroughbred Horses on the Concentration of F2-isoprostanes in the Blood Plasma as a Marker of Lipid Peroxidation

Acta Veterinaria Brno ◽

10.2754/avb200877030335 ◽

2008 ◽

Vol 77 (3) ◽

pp. 335-340

Author(s):

H. Härtlová ◽

R. Rajmon ◽

A. Dörflerová ◽

L. Zita ◽

D. Řehák ◽

...

Keyword(s):

Vitamin E ◽

Blood Plasma ◽

Plasma Concentrations ◽

Tocopheryl Acetate ◽

Control Group ◽

Individual Values ◽

Large Variability ◽

Thoroughbred Horses ◽

The Individual ◽

Experimental Group

The objective of this study was to assess the effect of vitamin E and selenium (Se) supplementation on the plasma levels of F2-isoprostanes as a marker of oxidative stress in horses in their training period. Twelve healthy 3-year-old English thoroughbred horses were divided into two groups: control (n = 6) and experimental (n = 6). Feeding rations were adapted to a moderate workload. The horses of the experimental group received supplements of DL-α-tocopheryl acetate E (2 250 mg/day/horse) and of sodium selenite (0.5 mg/day/horse). The plasma concentrations of both antioxidants and F2-isoprostanes were monitored on days 0, 44 and 70. After 70 days of supplementation, the concentrations of selenium in the experimental group were significantly higher (P < 0.05) compared to the beginning of the experiment (mean ± SE: 135.81 ± 10.19 μg l -1 vs. 98.70 ± 10.88 μg l -1), as well as to the control group (day 0: 101.78 ± 11.06 μg l -1, day 70: 108.18 ± 7.77 μg l -1). In the horses of the experimental group, plasma α-tocopherol levels significantly increased from the 44th day of supplementation compared to the beginning of the study as well to the control group (5.23 ± 0.52 mg l -1 vs. 2.45 ± 0.25 mg l -1 or 3.46 ± 0.34 mg l -1, respectively). The plasma concentration of F2-isoprostanes tended to be lower in the experimental group at the end than at the beginning of monitoring (156.8 ± 12.89 pg l -1 vs. 170.3 ± 60.8 pg l -1), although the control group showed the opposite trend (181.2 ± 15.67 pg l -1 vs. 137.0 ± 47.05 pg l -1). Nevertheless, none of these differences were significant because of the large variability of the individual values. It can be stated that supplementation of the diet used with selenium and vitamin E caused a non-significant decrease of F2-isoprostane concentration in the blood plasma only, and a significant increase of plasma concentrations of these antioxidants. The variation of isoprostane levels probably reflected rather the individual responses of the horses' organisms to the training workload.

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Dose-response effect of dietary vitamin E concentration on meat quality characteristics in light-weight lambs

Animal Science ◽

10.1017/s1357729800058422 ◽

2001 ◽

Vol 73 (3) ◽

pp. 451-457 ◽

Cited By ~ 30

Author(s):

C.J. López-Bote ◽

A. Daza ◽

M. Soares ◽

E. Berges

Keyword(s):

Vitamin E ◽

Meat Quality ◽

Dietary Treatment ◽

Quality Characteristics ◽

Tocopheryl Acetate ◽

Light Weight ◽

Tocopherol Concentration ◽

Quadratic Effect ◽

Linear Effect ◽

Line Analysis

AbstractThe research was carried out to evaluate the effect of different dietary α-tocopheryl acetate (DTA) concentrations in light-weight lambs on muscle α-tocopherol accumulation and on quality characteristics of stored meats. Thirty-two Manchego lambs were randomly distributed to four groups and given diets containing four levels of DTA (20, 270, 520 and 1020 mg/kg diet) for 6 weeks. Lambs were slaughtered at live weights ranging from 23·5 to 26·4 kg. A linear (P < 0·001) and quadratic (P < 0·001) effect of dietary supplementation level was observed on muscular α-tocopherol concentration, which fitted the following equation: mg muscle α-tocopherol per kg muscle = 1·78(s.e. 0·18) + 7·08 (s.e.0·89)(1 - e00012DTA)) (P < 0·001, R2 = 0·99). There was a linear effect (P < 0·001) of muscle vitamin E concentration on thiobarbituric acid reactive substance on day 0 of storage, but a linear plus quadratic effect (P < 0·001) on days 3, 6 and 9. Broken line analysis of data at day 9 of storage indicated a target muscle α-tocopherol concentration of 5·4 mg/kg. Evolution of surface redness of lamb chops also showed a linear and quadratic effect of dietary treatment on days 3 and 6 of storage, but only a linear effect on day 9. Broken line analysis of data at 3 and 6 days indicated a target α-tocopherol concentration in the range 5·3 to 5·6 mg/kg muscle for optimum red colour stability. Surface luminosity showed no effect of dietary treatment at days 0, 3 and 6 of storage but a linear (P < 0·01) plus quadratic (P < 0·05) effect on day 9 of storage. Broken line analysis at this point indicated a target muscle α-tocopherol concentration of 3·2 mg/kg. It is concluded that the effectiveness of dietary α-tocopheryl acetate supplementation depends on the meat quality attribute assessed. A significant positive effect for lipid oxidation can be reached even at the lower supplementation level utilized in this experiment (270 mg/kg diet). However, considering the protecting effect at different storage times and particularly the effect on meat surface redness, the optimum level would be in the range 5·3 to 5·6 mg/kg muscle, which correspond to a dietary inclusion of 550 to 625 mg α-tocopheryl acetate/kg diet.

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Re-evaluation of the vitamin E requirements of juvenile tilapia (Oreochromis niloticus ✕ O. aureus)

Animal Science ◽

10.1017/s135772980005205x ◽

2001 ◽

Vol 72 (3) ◽

pp. 529-534 ◽

Cited By ~ 32

Author(s):

S. Y. Shiau ◽

L. F. Shiau

Keyword(s):

Lipid Peroxidation ◽

Vitamin E ◽

Oreochromis Niloticus ◽

Control Diet ◽

Dietary Treatment ◽

Dietary Lipid ◽

Tocopheryl Acetate ◽

Dietary Vitamin ◽

Feeding Trial ◽

Protein Deposition

AbstractA 10-week feeding trial was conducted to re-evaluate the level of dietary vitamin E (DL- α-tocopheryl acetate) that was adequate for juvenile tilapia Oreochromis niloticus ✕ O. aureus given diets containing two dietary lipid concentrations. Purified diets with eight levels of vitamin E (0, 25, 50, 75, 100, 150, 200, 400 mg/kg diet) at either 50 or 120 g lipid per kg were each given to three replicate groups of tilapia (mean weight: 0·69 (s.e.0·02) g) reared in a closed, recirculating system. Food efficiency and protein deposition were significantly (P < 0·05) higher in fish given 50 mg vitamin E per kg diet and 75 mg/kg diet in the 50 and 120 g lipid per kg groups respectively, compared with fish given the unsupplemented control diet. Mortality of fish was not affected by dietary treatment. Weight gain and liver microsomal ascorbic acid-stimulated lipid peroxidation data analysed by broken-line regression indicated that the optimum dietary vitamin E requirements in juvenile tilapia are 42 to 44 mg vitamin E per kg and 60 to 66 mg vitamin E per kg in 50 and 120 g lipid per kg diets, respectively.

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Biopotency of vitamin E in barley

British Journal Of Nutrition ◽

10.1079/bjn19840100 ◽

1984 ◽

Vol 52 (2) ◽

pp. 335-349 ◽

Cited By ~ 25

Author(s):

R. V. Juhani Hakkarainen ◽

Jouko T. Työppönen ◽

Saifeldin Hassan ◽

Gösta Bengtsson ◽

S. R. Lennart Jönsson ◽

...

Keyword(s):

Vitamin E ◽

Chemical Reduction ◽

Tocopheryl Acetate ◽

Dietary Vitamin ◽

Total Vitamin ◽

Tissue Samples ◽

Chemical Determination ◽

The Individual ◽

Dose Responses ◽

Liver Storage

1. Investigations were carried out to establish the total biopotency of the natural vitamin E isomers in barley compared with that of DL-α-tocopheryl acetate.2. The chick was used as an experimental animal. Prevention of nutritional encephalomalacia (NE) and chick liver-storage and plasma-storage assays of vitamin E were the methods used in the study. The individual tocopherols and tocotrienols, both in the tissue samples and in the grain and barley oil, were analysed using high-pressure liquid chromatography (HPLC) with fluorescence detection. The diagnosis of NE was based on careful clinical and histopathological observations.3. It can be concluded from the results that full protection against NE in the chicks was obtained with a supplementation level of 7.5 mg DL-α-tocopheryl acetate/kg diet (i.e. a total vitamin E content of 11.20 mg/kg diet) or with a supplement of 8.7 g barley oil/kg diet (i.e. a total vitamin E content of 22.99 mg from barley oil/kg diet). This gave a biopotency factor of 0.49 for barley for prevention of NE of the chicks, as compared to that of DL-α-tocopheryl acetate.4. Using regression analysis a statistically linear relationship could be observed between the total dietary vitamin E level and the response, as measured by the total vitamin E content in the liver and plasma, both in the groups supplemented with DL-a-tocopheryl acetate and in the groups supplemented with corresponding amounts of vitamin E in barley oil. The liver and plasma responses to the total vitamin E in the barley-oil diet compared with those of the DL-a-tocopheryl acetate reference diet gave identical values for the regression coefficients, i.e. in both liver-storage and plasma-storage assays the value for slopes of dose-response lines was 0.37. This means that the biopotency of the total vitamin E in barley was 37% of that of dietary DL-a-tocopheryl acetate. Thus, barley is not as rich a source of vitamin E as could be supposed on the basis of the chemical determination of its total vitamin E content.5. It was possible to verify this experimentally established biopotency of 0.37 for the total vitamin E in barley by converting the chemically determined amounts of the vitamin E isomers in barley into DL-α-tocopheryl acetate equivalents by multiplying them with internationally accepted potency factors for the individual natural isomers (DL-α-tocopheryl acetate 1.00, D-α-tocopherol 1.49, D-β-tocopherol 0.60, D-gamma;-tocopherol 0.1 5, D-α-tocotrienol 0.37).6. In spite of the high proportion of α- and β-tocotrienols in the barley-oil diets (about 60% of the total vitamin E content), only traces of these isomers could be detected in the plasma and none could be detected in the liver. On the other hand, calculation of the individual hiopotencies for the different isomers in the barley-oil diet by comparing the dose responses, diet: liver, separately for each isomer with those of DL-α-tocopheryl acetate, resulted in biopotency values for α- and β-tocopherol which were twice as high as the internationally accepted conversion factors. These results of the present study tempted the authors to draw the conclusion that there may have been a chemical reduction of the α- and β-tocotrienols to the corresponding tocopherols before entering the liver.

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The absorption of vitamin E is influenced by the amount of fat in a meal and the food matrix

British Journal Of Nutrition ◽

10.1079/bjn20041249 ◽

2004 ◽

Vol 92 (4) ◽

pp. 575-579 ◽

Cited By ~ 71

Author(s):

Yvonne M. Jeanes ◽

Wendy L. Hall ◽

Susan Ellard ◽

Elizabeth Lee ◽

John K. Lodge

Keyword(s):

Vitamin E ◽

Intervention Studies ◽

Tocopheryl Acetate ◽

Limited Information ◽

Healthy Individuals ◽

Food Matrix ◽

High Fat ◽

Low Fat ◽

Tocopherol Concentration ◽

Skimmed Milk

Vitamin E absorption requires the presence of fat; however, limited information exists on the influence of fat quantity on optimal absorption. In the present study we compared the absorption of stable-isotope-labelled vitamin E following meals of varying fat content and source. In a randomised four-way cross-over study, eight healthy individuals consumed a capsule containing 150 mg 2H-labelled RRR-α-tocopheryl acetate with a test meal of toast with butter (17·5 g fat), cereal with full-fat milk (17·5 g fat), cereal with semi-skimmed milk (2·7 g fat) and water (0 g fat). Blood was taken at 0, 0·5, 1, 1·5, 2, 3, 6 and 9 h following ingestion, chylomicrons were isolated, and 2H-labelled α-tocopherol was analysed in the chylomicron and plasma samples. There was a significant time (P<0·001) and treatment effect (P<0·001) in 2H-labelled α-tocopherol concentration in both chylomicrons and plasma between the test meals. 2H-labelled α-tocopherol concentration was significantly greater with the higher-fat toast and butter meal compared with the low-fat cereal meal or water (P<0·001), and a trend towards greater concentration compared with the high-fat cereal meal (P=0·065). There was significantly greater 2H-labelled α-tocopherol concentration with the high-fat cereal meal compared with the low-fat cereal meal (P<0·05). The 2H-labelled α-tocopherol concentration following either the low-fat cereal meal or water was low. These results demonstrate that both the amount of fat and the food matrix influence vitamin E absorption. These factors should be considered by consumers and for future vitamin E intervention studies.

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Vitamin E and Selenium Decreased Cortisol in Cattle

Folia Veterinaria ◽

10.2478/fv-2020-0037 ◽

2020 ◽

Vol 64 (4) ◽

pp. 49-54

Author(s):

P. Mudroň

Keyword(s):

Vitamin E ◽

Abdominal Surgery ◽

Dairy Cows ◽

Serum Vitamin ◽

Selenium Concentration ◽

Serum Cortisol ◽

Average Concentration ◽

Tocopheryl Acetate ◽

Control Group ◽

Stress Changes

AbstractTwenty dairy cows with left abomasal displacement were used to investigate the effects of vitamin E and selenium treatment on blood cortisol in dairy cows stressed by omentopexy. The cows were randomly divided into two groups. Ten hours before surgery 6 g of DL-α-tocopheryl acetate (6 mg.kg−1) and 67 mg of natrium selenite (0.1 mg.kg−1) in a volume of 40 ml were administered subcutaneously to 10 cows; the control animals (n = 10) received an equivalent volume of injectable water (40 ml). The injection of vitamin E and selenium produced a rapid rise (P < 0.05) in blood α-tocopherol and selenium concentrations. The serum vitamin E increased several times ten hours after vitamin E and Se injection and raised continuously to the highest average concentration of 21.6 mg.l−1 at hour 24 after the surgery. The highest selenium concentration was seen ten hours after selenium administration with holding the increased concentrations in comparison to initial ones during the whole study. Serum cortisol increased in both groups after surgery. The highest cortisol concentrations were reached at one hour after surgery in the experimental and control group (56.7 ± 28.8 and 65.3 ± 26.1 μg.l−1, respectively). A return to the levels similar to the initial ones was recognized 24 hours after the surgery. The ANOVA revealed a significant effect of vitamin E and selenium injection on serum cortisol (P < 0.05). In conclusion, we have demonstrated that abdominal surgery resulted in typical stress changes with a weaker cortisol response to the abdominal surgery in animals treated with vitamin E and selenium.

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Effects of concomitant selenium and vitamin E administration on thyroid hormone metabolism in broilers

Journal of the Hellenic Veterinary Medical Society ◽

10.12681/jhvms.15490 ◽

2018 ◽

Vol 68 (3) ◽

pp. 355

Author(s):

A. C. PAPPAS ◽

B. M. KOTSAMPASI ◽

K. KALAMARAS ◽

K. FEGEROS ◽

G. ZERVAS ◽

...

Keyword(s):

Vitamin E ◽

Thyroid Hormone ◽

Control Diet ◽

Dietary Treatment ◽

Tocopheryl Acetate ◽

Type I ◽

Hormone Metabolism ◽

Iodothyronine Deiodinase ◽

Thyroid Hormone Metabolism ◽

Diet Control

A total of 400, as hatched, broilers were used to investigate the effect of selenium (Se) and vitamin E supplementation on thyroid hormones metabolism. There were 5 replicates of 4 dietary treatments namely: control (C), a soybean meal maize basal diet with adequate Se and vitamin E (0.3 mg Se per kg diet and 80 mg vitamin E per kg diet), control diet with Se added (Se+, with an additional 1 mg of Se per kg of diet), control diet with vitamin E added (E+, with an additional 350 mg of vitamin E per kg of diet) and Se+E+ (with additional 1 mg of Se and 350 mg of vitamin E per kg of diet). Diets were isonitrogenous and isocaloric. Zinc L-selenomethionine complex was used to increase Se content and dl-α-tocopheryl acetate to increase vitamin E content. The experiment lasted 42 days. Plasma Se concentration increased in Se+ groups, while whole blood glutathione peroxidase (GPx) activity increased in Se+, E+ and Se+E+ groups compared to control. Hepatic type I iodothyronine deiodinase (ID-I) and thyroid hormone concentrations were unaffected by any dietary treatment. It is concluded that supplementation with Se or vitamin Ε alone or in combination above animal’s requirements does not affect thyroid hormone metabolism and liver ID-I activity under the conditions examined.

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α-Tocopherol in breast milk of women with preterm delivery after a single postpartum oral dose of vitamin E

British Journal Of Nutrition ◽

10.1017/s0007114516000477 ◽

2016 ◽

Vol 115 (8) ◽

pp. 1424-1430 ◽

Cited By ~ 8

Author(s):

Jeane Franco Pires Medeiros ◽

Karla Danielly da Silva Ribeiro ◽

Mayara Santa Rosa Lima ◽

Renata Alexandra Moreira das Neves ◽

Amanda Cibely Pinheiro Lima ◽

...

Keyword(s):

Vitamin E ◽

Breast Milk ◽

Controlled Trial ◽

Intervention Group ◽

Relevant Information ◽

Maternal Serum ◽

Tocopheryl Acetate ◽

Control Group ◽

Mature Milk ◽

Tocopherol Concentration

AbstractWe evaluated the effect of maternal vitamin E supplementation on the α-tocopherol concentrations of colostrum, transitional milk and mature milk of women who had given birth prematurely. This longitudinal randomised-controlled trial divided eighty-nine women into two groups: a control group and a supplemented group. Blood and breast milk were collected from all the participants after delivery. Next, each woman in the supplemented group received 400 IU of RRR-α-tocopheryl acetate. Further breast milk samples were collected 24 h after the first collection, as well as 7 and 30 d after delivery. α-Tocopherol concentrations were determined by HPLC. The baseline α-tocopherol concentrations in the maternal serum of the two groups were similar: 1159·8 (sd 292·4) μg/dl (27·0 (SD 6·8) μmol/l) for the control group and 1128·3 (sd 407·2) μg/dl (26·2 (SD 9·5) μmol/l) for the supplemented group. None of the women was vitamin E deficient. Breast milk α-tocopherol concentrations increased by 60 % 24 h after supplementation in the intervention group and did not increase at all in the control group. α-Tocopherol concentration of the transitional milk in the supplemented group was 35 % higher compared with the control group. α-Tocopherol concentrations of the mature milk in both groups were similar. Maternal supplementation with 400 IU of RRR-α-tocopherol increased the vitamin E concentrations of the colostrum and transitional milk, but not of the mature milk. This study presents relevant information for the design of strategies to prevent and combat vitamin E deficiency in the risk group of preterm infants.

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EFFECTS OF REDUCING DIETARY CATION-ANION BALANCE FOR PREPARTUM DAIRY COWS WITH SPECIFIC REFERENCE TO HYPOCALCEMIC PARTURIENT PARESIS

Canadian Journal of Animal Science ◽

10.4141/cjas89-046 ◽

1989 ◽

Vol 69 (2) ◽

pp. 411-423 ◽

Cited By ~ 39

Author(s):

HÉLÈNE LECLERC ◽

ELLIOT BLOCK

Keyword(s):

Dairy Cows ◽

Control Diet ◽

Dietary Treatment ◽

Specific Reference ◽

Apparent Absorption ◽

Milk Fever ◽

Periparturient Period ◽

Hydroxy Proline ◽

Parturient Paresis ◽

Dietary Treatments

A trial was conducted to investigate the response of prepartum dairy cows to reducing the level of dietary cation-anion balance by measuring the concentration of plasma Ca, P, Mg and hydroxy proline, the apparent absorption of Ca, P and Mg and the incidence of milk fever. Twenty prepartum Holstein cows were randomly allocated to four dietary treatments designated control, diets 1, 2 and 3, with cation-anion balances [(Na + K) – (Cl + S)] of + 394, + 121, + 105 and + 62 meq kg−1 dietary dry matter (DM), respectively. Diets containing 1.38% Ca and 0.76% P (dry basis) were offered from day 45 prepartum to day 2 postpartum. Reducing the level of dietary cation-anion balance decreased the severity of the decline of plasma Ca during the periparturient period and delayed the time of observing the lowest concentration of plasma Ca. Strong negative correlations were observed during the periparturient period, particularly at parturition, between dietary cation-anion intake and the concentrations of plasma Ca and P. Apparent absorption of minerals was not influenced by dietary treatment from day 24 to day 21 prepartum. However, apparent absorption of Ca was reduced in cows fed diets 2 and 3 compared to cows fed the control diet and apparent absorption of Mg was reduced in cows fed diets 1, 2 and 3 compared to cows fed the control diet from day 7 prepartum until day 1 postpartum. Apparent absorption of phosphorus was not influenced by treatment at either time. Plasma levels of hydroxyproline were higher in cows fed diets 2 and 3 than in those fed diet 1 and the control diet from day 2 prepartum to day 1 postpartum. Results showed that reducing the level of dietary cation-anion balance influenced the concentration of plasma calcium, its apparent absorption and its resorption from bone. These effects were most accentuated during the periparturient period and may be beneficial in the prevention of milk fever. Key words: Milk fever, dairy cows, dietary anions and cations, parturient paresis

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