Espen Govasmark

Status of selenium and vitamin E on Norwegian organic sheep and dairy cattle farms

Herbage selenium (Se) concentration is generally low in Norway. It is unknown whether feeding practices on Norwegian organic farms fulfil the dietary needs of Se and vitamin E for sheep and dairy cattle. Therefore we analysed Se in soil and herbage, and Se and vitamin E in animal blood in the indoor feeding season at 14 organic dairy and 14 organic sheep farms. The herbage Se concentration was low. Approximately 50 and 35% of all samples in the first and second cut, respectively, had Se concentrations below the detection limit of 0.01 mg/kg dry matter (DM). The median (10th, 90th percentile) Se concentrations were <0.01 (<0.01, 0.03) and 0.02 (<0.01, 0.06) mg/kg DM in the first and second cuts, respectively. Whole blood Se concentrations were 0.10 (0.04, 0.15) μg/g in dairy cattle and 0.14 (0.03, 0.26) μg/g in sheep. Vitamin E concentrations were 4.2 (2.7, 8.4) mg/l in dairy cattle and 1.3 (0.9, 2.4) mg/l in sheep. None of the soil or plant variables explained the variation in herbage Se concentration, although Se in soil and plant tended to be correlated. Herbage Se concentration was inadequate to meet the dietary Se requirements. Vitamin E requirement was only met in dairy herds. We recommend Se and vitamin E supplementation to ruminants on organic farms.

Characterization of Selenium Incorporation into Wheat Proteins by Two-Dimensional Gel Electrophoresis–Laser Ablation ICP MS followed by capillary HPLC–ICP MS and Electrospray Linear Trap Quadrupole Orbitrap MS

A method has been developed for a rapid and precise location of selenium-containing proteins in large two-dimensional (2D) electrophoresis gels. A sample was divided into four aliquots which were analyzed in parallel by 1D isoelectric focusing electrophoresis (IEF)-laser ablation (LA) inductively coupled plasma mass spectrometry (ICP MS), 1D sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS PAGE)-LA ICP MS, and, in duplicate, by 2D IEF-PAGE. On the basis of the 1 D electropherograms obtained, areas supposed to contain the largest concentrations of Se were subjected to LA ICP MS imaging to locate precisely the position of Se-containing proteins which were then identified in the parallel 2D gel by electrospray Orbitrap MS/MS. The method was applied to the identification and semiquantitative determination of selenium storage proteins in wheat. MS evidence is presented for the Se-S substitution in plants not only in methionine but also in cysteine.

Effect of short-term versus long-term grassland management and seasonal variation in organic and conventional dairy farming on the composition of bulk tank milk

Bulk tank milk from 28 dairy farms was sampled every second month for 2 yr to assess the effects of grassland management, production system and season on milk fatty acid (FA) composition, concentrations of fat-soluble vitamins, Se, and milk sensory quality. Grassland management varied in terms of time since establishment. Short-term grassland management (SG) was defined as establishment or reseeding every fourth year or more often, and long-term grassland management (LG) was defined as less frequent establishment or reseeding. Fourteen organic (ORG) dairy farms with either short-term or long-term grassland management were paired with 14 conventional (CON) farms with respect to grassland management. Within ORG farms, SG farms differed from LG farms in herbage botanical composition, but not in concentrate FA concentrations, dry matter intake, or milk yield. Within CON farms, herbage composition, concentrate FA concentrations, dry matter intake, and milk yield showed no or insignificant variations. The ORG farms differed from CON farms in herbage botanical composition, concentrate FA concentrations, concentrate intake, and milk yield. Compared with ORG-LG farms, ORG-SG farms produced milk fat with higher proportions of C10:0 and C12:0 associated with higher herbage proportions of legumes (Fabaceae) and lower proportions of other dicotyledon families. Compared with milk from CON farms, milk fat from ORG farms had higher proportions of most saturated FA and all n-3 FA, but lower proportions of C18:0 and C18:1 cis-9 associated with higher forage proportion and differences in concentrations of FA in concentrates. Compared with the outdoor-feeding periods, the indoor feeding periods yielded milk fat with higher proportions of most short-chain and medium-chain FA and lower proportions of most C18-FA associated with grazing and higher forage proportions. Milk concentrations of α-tocopherol and β-carotene were lower during the grazing periods. Inclusion of fishmeal in organic concentrates may explain higher Se concentrations in organically produced milk. Milk sensory quality was not affected in this study. In conclusion, grassland management had minor effects on milk composition, and differences between ORG farms and CON farms may be explained by differences in concentrate intake and concentrate FA concentrations. Milk produced on ORG farms versus CON farms and milk produced during the outdoor versus indoor feeding periods had potential health benefits due to FA composition. In contrast, the higher milk-fat proportions of saturated FA in milk from ORG farms may be perceived as negative for human health.

Bioaccessibility of Se from Se-enriched wheat and chicken meat.

Selenium (Se) is an essential trace element to animals and humans as Se is incorporated in a series of organic molecules, such as 30 mammalian selenoproteins or seleno-enzymes, which are vital for the basic functions of life. To increase the Se intake in Se-deficient areas, food and feed can be enriched using Se fertilizers or supplements. The aim of this study is to investigate the distribution, speciation, bioaccessibility, and bioavailability of Se in Se-enriched wheat (SW) grain and in Se-enriched chicken meat products using commercial enzymes and human gastric juices (HGJs). Results from the present work show that Se in wheat is bioaccessible and bioavailable, and that SW flour or bran can serve as a valuable dietary source of Se to humans. However, the bioaccessibility studies using commercial enzymes and HGJs for wheat flour, bran, and chicken meat digestion suggests that the use of commercial enzymes overestimate Se bioavailability. Furthermore, the use of NaCl or Tris-HCl to extract Se proteins from enriched products was not suited for bioaccessibility studies. The SW flour or bran can, however, serve as a valuable dietary source of Se to humans.

Factors affecting the concentration of Zn, Fe and Mn in herbage from organic farms and in relation to dietary requirements of ruminants

To obtain a general picture of the herbage zinc, iron and manganese concentrations and their relation to dietary requirements of ruminants on organic farms, we analysed soil and herbage samples from four regions in Norway. The soil median Zn, Fe and Mn concentrations were 0.18, 13 and 0.84 mg/L, respectively. The herbage median (10th–90th percentile) Zn, Fe and Mn concentrations (mg/kg) in herbage in the first cut were 19 (14–34), 50 (36–88), 34 (22–86) and in the second cut 21 (16–37), 84 (52–171) and 66 (36–205), respectively. The results of mixed model analysis of herbage Zn, Fe and Mn indicate that soil pH, soil texture, soil mineral concentration and botanical composition are the most influencing factors. We conclude that Zn, Fe and Mn did not limit plant growth, and that the herbage concentrations, except for Zn, were sufficient to meet the dietary needs of ruminants on organic dairy farms.

Turnover of Se in adequately fed chickens using Se‐75 as a tracer

Inorganic selenium (Se) in the form of selenite is applied to livestock to avoid Se deficiency. Selenite is, however, an artificial Se source in diets of unsupplemented chickens. It is therefore hypothesized that organic Se sources, such as Se-enriched yeast and wheat, could be a more suitable Se supply in animal nutrition, although information on the transition of Se from organic Se sources in fast-growing chickens is scarce. In this work, chickens were fed a low Se diet (0.27 ± 0.01 mg Se/kg, Se-enriched yeast) until 20 days of age, after which the Se concentration was increased to maximum concentration allowed by the poultry industry in Europe (0.5 p.p.m. Se). At the same time, a daily contribution of carrier-free (75)Se tracer from labelled wheat was administered from day 20 to 27. The chickens showed S and Se homeostasis, as the concentration of S and Se in liver, blood or kidney remained about constant, and steady state of S and Se in the other organs was reached 1 day after the diet shift. The uptake of (75)Se was readily seen in all organs. After 1 week, the depuration of the (75)Se tracer was followed, and biological half-lives and retention in individual organs were determined. The shortest biological half-lives were observed in major metabolic organs, the liver, kidney and pancreas with half-lives close to 4 days. There was a significant (p < 0.05) uptake in lung, brain and muscle that reached steady state when the administration of (75)Se was terminated. The half-life of (75)Se in heart was 9 days and 7 days in blood. The longest half-lives were observed in muscle (12 days), brain and lungs (13 days). All half-lives were shorter than in Se deplete animals.

Selenium Concentration in Spring Wheat and Leaching Water as Influenced by Application Times of Selenium and Nitrogen

ABSTRACT Selenium (Se) deficiency in Scandinavian soils is a common problem, and crops generally contain inadequate amounts to meet human need. This study shows a relationship of the Se concentration in spring wheat (Triticum aestivum L., c.v. ‘Helena’) and leaching water with timing of nitrogen (N) [as ammonium nitrate (NH4NO3)] and Se [as sodium selenate (Na2SeO4)] application. Ammonium-nitrate was applied by two methods (i) whole amount at sowing and (ii) in split application as 75% at sowing and 25% at stem elongation. Selenate was applied at cereal growth stages after sowing, e.g., tillering, stem elongation, head emergence, and milking. Split N application in comparison to one N application increased the grain protein content from 12.1 to 13.7 mg g− 1, and grain Se was increased from 0.8 to 1.1 mg kg− 1 when Se was applied at stem elongation and from 0.6 to 0.9 mg kg− 1 when applied at heading. The highest Se concentration in plant was achieved with the split N application and Se application at stem elongation or heading. Selenium leaching losses increased with increasing selenium concentration in the wheat grains. No differences in Se leaching losses were obtained with split N application. Applying selenate and ammonium-nitrate together after tillering increased the grain Se concentration, but did not affect the potential leaching of Se, and thus could be considered as an appropriate time of application of these elements.

Copper, molybdenum and cobalt in herbage and ruminants from organic farms in Norway

To evaluate the animal nutritional status of copper, molybdenum and cobalt on Norwegian organic farms, soil, herbage and animal blood samples were collected from 27 dairy and sheep farms and analysed for Cu, Mo and Co. The herbage median (10th–90th percentile) Cu, Mo, and Co concentrations (mg/kg DM) and the Cu:Mo ratio in the first cut were 5.3 (3.9–6.8), 1.5 (0.6–4.8), <0.05 (<0.05–0.08) and 3.8 (1.1–8.3) and in the second cut 7.0 (5.7–9.3), 3.3 (1.6–10.1), 0.06 (<0.05–0.15) and 2.0 (0.8–5.2), respectively. The results of mixed model analyses of herbage Cu and Mo indicated that soil pH, soil organic matter content, herbage botanical composition, yield and phenological stage of timothy at harvest mostly influenced the herbage micronutrient concentration. We conclude that plant growth was not limited by the supply of Cu, Mo or Co, but the herbage mineral nutrient concentration alone was not balanced to meet the dietary needs of ruminants. Supplements of mineral nutrient mixtures and/or concentrates fortified with Cu and Co are required to ensure sufficient supply for ruminants.

Iodine concentration in Norwegian milk has declined in the last decade

Abstract To evaluate the iodine (I) level in Norwegian milk, the I concentration was determined in 104 dairy tanker milk samples collected from 19 milk tours in different areas of Norway, throughout the year 2008. The I concentration in milk from indoor feeding was 122 µg L−1 and higher than in milk from the summer season, being 92 µg L−1. The weighted average mean I concentration throughout the year was 114 µg L−1 milk. The results showed that the I concentration in milk from the winter season 2008 has been reduced to nearly the half during the last decade, from 232 µg I L−1 in milk collected in the winter season in 2000. The I concentration in milk from the summer season is at the same level as a decade ago. The reason for the reduction in I in milk produced during the winter season is not known.

Translocation and re-translocation of selenium taken up from nutrient solution during vegetative growth in spring wheat

BACKGROUND Selenium (Se) is an essential micronutrient for humans, but the Se level in food plants in northern Europe is generally inadequate to meet human nutritional requirements. Commonly, food plant Se fortification is achieved by selenate fertilisation, but the effect of nitrogen (N) and sulphur (S) supply on the translocation and re-translocation of Se is unknown. Therefore the effect of N and S supply on ⁷⁵selenate/⁷⁵Se translocation and re-translocation during vegetative growth in spring wheat (Triticum aestivum) was studied. RESULTS The ⁷⁵Se activity in wheat varied from 148 to 549, from 277 to 1815 and from 171 to 1343 Bq ⁷⁵Se in plants exposed at Zadoks growth stages Z1.4, Z1.5 and Z1.6 respectively. Approximately 85% of the plant ⁷⁵Se was translocated into young leaves. High N supply enhanced the re-translocation of ⁷⁵Se from the stem to maturing leaves, while S inhibited this process. The relative proportion of ⁷⁵Se in L4, L5 and L6 increased with increasing N supply at low sulfate concentrations. CONCLUSION Selenium in the stem is more re-transportable than Se in the leaves, and the re-translocation is dependent on sulfate supply. When the sulfate supply is sufficient for plant development, less ⁷⁵Se is re-translocated from older to growing leaves.