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

Concentration of vitamin E in bovine plasma and erythrocytes

The aim of this study was to determine and compare the plasma and erythrocyte (RBCs) levels of vitamin E in cows of 3 different categories (2–3 weeks antepartum, 1–3 weeks and 2.5–3 months of lactation) and 1-month-old calves on dairy nutrition. We were interested in the degree of correlation of vitamin E in plasma and RBCs within the individual categories. Blood on EDTA was collected from 61 cows and 12 calves. As a part of the haematological examination, we determined haematocrit (HCT) immediately after the collection. We determined vitamin E from plasma and RBCs by a standard HPLC method. We compared the results of vitamin E in plasma and RBCs and correlated them. The concentration of vitamin E in the plasma and RBCs was 6.98 and 3.45 μmol/l, respectively, in cows 2–3 weeks antepartum; 1–3 weeks of lactation it was 4.98 and 3.34; 2.5–3 months of lactation 11.76 and 2.80 μmol/l; and in the case of calves 12.07 and 6.29 μmol/l. Weak correlations were observed between vitamin E in plasma and the RBC concentrations in the antepartum category R2 = 0.2076; 1–3 weeks of lactation R2 = 0.0369; 2.5–3 months of lactation R2 = 0.2403 and calves on dairy nutrition R2 = 0.4628. Vitamin E concentrations in RBCs were shown to be more stable than in plasma, where the concentrations varied. It is possible that vitamin E in RBCs could tell us more about the longer-term reserves of vitamin E in the organism. The highest concentration of vitamin E in plasma and RBCs, as well as a stronger correlation was found in calves.

Effect of Diet Supplementation with the Mycotoxin Binder Montmorillonite on the Bioavailability of Vitamins in Dairy Cows

The objective of this study was to determine the effect of the mycotoxin binder montmorillonite (MMT) supplemented in the diet of dairy cows on the bioavailability of vitamins A, D, E, B1 and B6. Six multiparous Holstein-Friesian cows were used in a crossover design with two periods. Treatments were a control diet with or without MMT. Vitamins were infused individually into the abomasum through the ruminal cannula. Blood samples were collected from the jugular vein at 0, 1, 2, 3, 4, 6, 9, 12, 24 and 48 h after the administration of each vitamin. Results showed that vitamin A reached maximal concentration (Tmax) at 5.3 h after dosing, the maximal concentration (Cmax) was 1.2 times higher than the basal concentration (Cbasal), and the area under the curve (AUC) was 739 arbitrary units. Vitamin B6 reached the Tmax at 13 h after dosing, the Cmax was 1.4 times higher than the Cbasal, and the AUC was 222 arbitrary units. No differences were observed in Cbasal, Tmax, Cmax and AUC of vitamin A and B6 between control vs. MMT-supplemented cows. Plasma concentrations of vitamins D, E and B1 had no concentration peaks, and were not affected by MMT addition. The lack of a response suggests that their plasma concentration may be tightly regulated. Results of this study do not show evidence that MMT affects the bioavailability of vitamins A and B6 in vivo.

Vitamin E and beta-carotene status of dairy cows: a survey of plasma levels and supplementation practices

Culling rate in dairy cattle has increased considerably, thereby reducing cowś longevity and raising sustainability concerns worldwide. In the last decades, feeding systems have changed towards larger inclusion of preserved forages and reduced fresh herbage, which may limit vitamin E and beta-carotene dietary supply to dairy cows. Because of higher oxidative stress, engendered by greater milk production of modern genetics, the requirement for these nutrients is increased. Therefore, this study aimed to assess the current status of vitamin E and beta-carotene of commercial dairy cows. Blood vitamin E and beta-carotene concentrations were measured in 2 467 dairy cows from 127 farms in Belgium, Germany, Iberia and The Netherlands, that were visited once. Five cows were randomly selected per lactation stage per farm: Dry (between 30 and 1 day(s) before calving), Very-early (from calving until 15 days in milk (DIM)), Early (between 16 and 119 DIM), and Mid-late (from 120 DIM onwards). In addition, a survey was conducted to retrieve data on vitamin E and beta-carotene supplementation and feeding practices. Vitamin E and beta-carotene blood concentrations dropped considerably around calving. Among all surveyed cows, more than 75 and 44% were deficient in vitamin E and beta-carotene (i.e., blood concentration below 3.0 and 3.5 mg/l, respectively). Of the Very-early group, more than 97 and 78% of the cows were deficient in vitamin E and beta-carotene, respectively, with respective blood concentrations of 1.15 and 2.71 mg/l, which was significantly lower than the other lactation stages. Vitamin E and beta-carotene blood concentrations, as well as their supplementation levels, significantly varied among countries. Vitamin E and beta-carotene blood concentrations were positively related to the total estimated daily intakes of vitamin E and beta-carotene. Therefore, blood concentrations of vitamin E and beta-carotene depend on their respective level of intake, which is generally below recommendations and varies greatly between countries. Supplementation could contribute to provide cows with adequate amounts of vitamin E and beta-carotene all along the lactation, to ensure their lifetime performance and improve their fertility.

The Physiological Roles of Vitamin E and Hypovitaminosis E in the Transition Period of High-Yielding Dairy Cows

Simple Summary

In high-yield cows, most production diseases occur during transition periods. Alpha-tocopherol, the most biologically active form of vitamin E, declines in blood and reaches the lowest levels (hypovitaminosis E) around calving. Hypovitaminosis E is associated with the incidence of peripartum diseases. Therefore, many studies which have been published for more than 30 years have investigated the effects of α-tocopherol supplementation. This α-tocopherol deficiency was thought to be caused by complex factors. However, until recently, the physiological factors or pathways underlying hypovitaminosis E in the transition period have been poorly understood. In the last 10 years, the α-tocopherol-related genes expression, which regulate the metabolism, transportation, and tissue distribution of α-tocopherol in humans and rodents, has been reported in ruminant tissues. In this paper, we discuss at least six physiological phenomena that occur during the transition period and may be candidate factors predisposing to a decreased blood α-tocopherol level and hypovitaminosis E with changes in α-tocopherol-related genes expression.

Abstract

Levels of alpha-tocopherol (α-Toc) decline gradually in blood throughout prepartum, reaching lowest levels (hypovitaminosis E) around calving. Despite numerous reports about the disease risk in hypovitaminosis E and the effect of α-Toc supplementation on the health of transition dairy cows, its risk and supplemental effects are controversial. Here, we present some novel data about the disease risk of hypovitaminosis E and the effects of α-Toc supplementation in transition dairy cows. These data strongly demonstrate that hypovitaminosis E is a risk factor for the occurrence of peripartum disease. Furthermore, a study on the effectiveness of using serum vitamin levels as biomarkers to predict disease in dairy cows was reported, and a rapid field test for measuring vitamin levels was developed. By contrast, evidence for how hypovitaminosis E occurred during the transition period was scarce until the 2010s. Pioneering studies conducted with humans and rodents have identified and characterised some α-Toc-related proteins, molecular players involved in α-Toc regulation followed by a study in ruminants from the 2010s. Based on recent literature, the six physiological factors: (1) the decline in α-Toc intake from the close-up period; (2) changes in the digestive and absorptive functions of α-Toc; (3) the decline in plasma high-density lipoprotein as an α-Toc carrier; (4) increasing oxidative stress and consumption of α-Toc; (5) decreasing hepatic α-Toc transfer to circulation; and (6) increasing mammary α-Toc transfer from blood to colostrum, may be involved in α-Toc deficiency during the transition period. However, the mechanisms and pathways are poorly understood, and further studies are needed to understand the physiological role of α-Toc-related molecules in cattle. Understanding the molecular mechanisms underlying hypovitaminosis E will contribute to the prevention of peripartum disease and high performance in dairy cows.