Impact of dietary manganese concentration on status criteria to determine manganese requirement in piglets.

The Mn requirement for pigs is not well established. This study aimed to find criteria for assessing growing piglet supply status for Mn and to determine whether the current Mn recommendations meet the requirements for piglets. Thirty-six weaned male castrated 27-day-old piglets (7.24 ± 0.69 kg) were randomized into six groups of six piglets each and housed individually in stainless steel metabolic cages for 42 days. The piglets were fed a diet based on skimmed milk powder and corn starch with increasing Mn concentrations (0.24; 2; 4; 8; 16; or 32 mg Mn/kg diet as-fed). In week 6, Mn0.24 led to reduced feed intake (p < 0.05). Manganese concentrations in blood, liver, kidney, lung, heart, phalanx proximalis, pancreas and skeletal muscle were influenced by the dietary Mn supply (p < 0.05). The activity of the Mn-containing superoxide dismutase in the heart as well as relative arginase activity in the liver were lower in groups Mn0.24, Mn2 and Mn4 compared with the higher supplemented groups (p < 0.05). The relative arginase activity increased clearly with enhanced dietary Mn up to 16 mg/kg and correlated with Mn concentration in the liver. Manganese concentrations in the liver, kidney and phalanx proximalis seem to be suitable biomarkers for Mn status. A 4 mg/kg dietary Mn concentration recommended by NRC (1998, Nutrient Requirements of Swine. National Academy Press, Washington DC.) did not fulfil piglet requirements. Under the conditions investigated, 16 mg Mn/kg diet were necessary to reach a plateau in specific enzyme activity and Mn concentration in organs.

Investigation into selenium requirement of growing turkeys offered a diet supplemented with two levels of vitamin E.

To evaluate dietary selenium (Se) requirement in turkeys offered a diet supplemented with two levels of vitamin E (VE), 96 newly hatched male BIG 6 chicks (58.4 +/- 4.12 g) were divided into eight groups of 12 animals each and fed maize soya diets containing 0.05, 0.10, 0.20 and 0.30 mg Se/kg from sodium selenate in combination either with the natural VE content (approximately 10 IU/kg) or with a VE addition of 50 IU/kg. Animals from all the groups were highly performant and their final body weights (1746 +/- 190 g) after 35 days on experiment were not significantly different. According to its dietary supply, Se concentration in the liver and plasma increased dose dependently. Independent of dietary VE, the activities of GPx3 in plasma and of GPx1 in liver and breast muscle increased to a larger extent in turkeys supplemented with 0.10 and 0.20 mg Se/kg in relation to animals with low marginal Se supply (0.05 mg/kg). Supplementation of 0.30 mg Se/kg only slightly increased further selenoprotein activities. 2-Thiobarbituric acid reactive substances in the liver were strongly reduced by dietary VE, but not by Se. Plasma aspartate aminotransferase (AST) and creatine kinase (CK) activities did not show muscular lesions in none of the groups. Although there were no signs of muscular lesions even in turkeys with marginal Se and moderate VE supply, the activity of selenoproteins in various organs increased up to 0.30 mg Se/kg diet, independent of VE supply. It was concluded that for growing turkeys the Se supply should meet at least a level of 0.20 mg/kg diet as currently recommended by the National Research Council and Gesellschaft für Ernährungsphysiologie. Vitamin E addition confirmed the particular function of the vitamin as a lipid antioxidant and should be taken into consideration when diets with high PUFA concentrations are fed.

Selenium requirement of growing male turkeys.

1. The aim of the experiment was to estimate the selenium requirement of growing male turkeys using the selenium concentrations in different organs and blood plasma and by fitting a continuous broken line to the activity of glutathione peroxidase in liver and plasma. 2. Newly hatched male BUT BIG 6 turkeys were fed either on the selenium deficient basal soybean-maize diets (selenium <0.010 mg/kg diet) adapted to the NRC (1994) and GfE (2004) recommendations for growing turkeys from 0 to 2 weeks (prestarter diet) and 3 to 5 weeks (starter diet) or the basal diets supplemented with 0.10, 0.15, 0.20, 0.25, 0.30, 0.35 or 0.40 mg selenium/kg diet as sodium selenate. Vitamin E was supplemented adequately in all diets. 3. After 5 weeks the weight in all groups (mean 2568 g) exceeded the expectations for the genotype investigated. Feed consumption and weight gain were however significantly reduced in the group receiving the selenium-deficient diet. 4. After 2 and 5 weeks selenium concentration and activity of glutathione peroxidase in the plasma and the organs examined were greatly influenced by selenium supplementation. 5. Under the conditions investigated, 0.30 mg Se/kg diet was necessary for fast-growing male turkeys to ensure maximum selenium accumulation in the organs examined and maximum glutathione peroxidase activity in plasma and liver.

Estimation of the selenium requirement of growing guinea pigs (Cavia porcellus).

The aim of the study was to determine the selenium (Se) requirement of guinea pigs as a species unable to synthesize ascorbic acid. Forty-nine male guinea pigs (average weight 208 +/- 3.5 g) were divided into an initial status group and six experimental groups. The animals received a Se deficient Torula yeast based basal diet (<0.02 mg Se and 26 mg alpha-tocopherol/kg) or a Se addition of 0.05, 0.10, 0.15, 0.20 and 0.25 mg/kg diet as sodium selenate for 10 weeks. There was no significant difference in weight gain (final weight 643 +/- 21 g) between the groups and no clinical symptoms of Se deficiency occurred. With the exception of the testes, there was an increasing Se concentration in liver, plasma and haemolysate dependent on supplementation level. Glutathione peroxidase was determined in the plasma and Se dependent glutathione peroxidase (GPx1) in haemolysate, liver, kidney, heart and lung. Thioredoxin reductase (TR) activity was measured in liver, kidney and heart and deiodinase activity in the liver. A phospholipid hydroperoxide reducing activity with Se influence was determined in liver, kidney, heart, testes and brain. With the exception of GPx1 activity in heart and haemolysate and TR activity in the kidney, all enzymes already reached their maximal activity at 0.05 mg Se/kg diet. The activities of GPx1 and TR were used as parameters for broken line analysis and a Se requirement of 0.080 mg Se/kg diet was derived as sufficient for growing guinea pigs adequately supplied with vitamin E.

Effect of dietary phytate on magnesium bioavailability and liver oxidant status in growing rats.

Male albino rats (initial average weight 60 g) were fed semi-synthetic diets based on casein, corn starch and sunflower oil over 21 days. All diets were supplemented with 300 mg magnesium from MgSO4x7H2O and 0,7.5 and 15 g phytic acid (PA) from sodium phytate per kg. The addition of PA to the diets resulted in a dose-dependent decrease of apparent Mg absorption and Mg concentration in the plasma and femur. Impaired Mg bioavailability due to 15 g PA/kg diet was accompanied by an increase of hepatic thiobarbituric acid reactive substances and protein carbonyls as well as by a moderate decline in liver reduced glutathione (GSH) levels. The liver homogenates of rats receiving the diets with 7.5 and 15 g PA/kg, respectively, were much more susceptible to iron-induced lipid peroxidation than those of the controls. Hepatic antioxidative enzymes [superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSHPx), glucose-6-phosphate dehydrogenase (G6PDH)], alpha-tocopherol concentration and phenyl-N-tert-butylnitrone (PBN) adducts using electron spin resonance spectroscopy remained unchanged by the different dietary treatments. Under the conditions of a marginal dietary Mg supply, phytate had pro-oxidative rather than antioxidative effects in the case of liver metabolism.

Effect of microbial phytase on zinc bioavailability and cadmium and lead accumulation in growing rats.

This study evaluated the effect of increasing levels of dietary microbial phytase on the bioavailability of zinc and the accumulation of cadmium and lead in growing rats. Five groups of seven albino rats (initial average weight 47 g) were housed individually and fed phytate-rich diets (7 g/kg) based on maize, soya bean meal, corn starch and soya bean oil over a 4-week experimental period. The basal diet contained 24 mg zinc (native concentration), 10 mg lead as Pb(CH3COO)2.3H2O and 5 mg cadmium as CdCl2 per kg and was supplemented with 0, 250, 500, 1000 and 2000 U phytase from Aspergillus niger per kg diet. Supplementation of microbial phytase significantly increased apparent zinc absorption. Differences in zinc bioavailability due to supplementation of the diet with microbial phytase were evident in zinc concentration in plasma, femur and testes as well as in the percentage unsaturated plasma zinc binding capacity and the activity of the zinc metalloenzyme alkaline phosphatase. Cadmium concentrations in liver and kidneys were not significantly altered in response to the different dietary treatments. There was a tendency for femur lead concentration to be increased in response due to the phytase supplementation.

Metallothionein and zinc as potential antioxidants in radical-induced lipid peroxidation in cultured hepatocytes.

Rat hepatocytes were isolated by a two-step collagenase perfusion technique and introduced to the hydroxyl radical (OH)-generating xanthine-xanthine oxidase-iron (X/XO/Fe) system. The amount of thiobarbituric acid reactive substances (TBA) and thiobarbituric acid bound malondialdehyde (TBA-MDA) were assayed in homogenates after different phases of cultivation. The effects on lipid peroxidation of supplemented metallothionein (MT) ranging from 25 to 75 microM and zinc ranging from 14.5 to 77.8 microM, as well as the effect of a Zn-pretreatment for 18 h were investigated. The addition of X/XO/Fe resulted in a 3 to 4-fold increase in the levels of TBA and TBA-MDA. These results show that X/XO/Fe initiated the lipid peroxidation in the hepatocyte cell system. High doses of supplemented MT inhibited the production of TBA and TBA-MDA. Neither Zn nor the Zn-pretreatment, which resulted in an increase of intracellular MT, had any effect on TBA and TBA-MDA levels. This study suggests that MT can act as an antioxidant in high concentrations via the cysteinyl groups of the protein. The postulated protective effects of Zn via its release from the oxidized MT can be ruled out.

Induction of metallothionein by exposure to normobaric 100% oxygen atmosphere in rats with different zinc supply.

The objective of this study was to determine the effects of an oxygen enriched environment on the induction of the metalloprotein metallothionein (MT) and its relation to zinc metabolism in rats supplied with different levels of dietary zinc. Male albino rats were fed purified diets based on maize starch, egg white, saccharose and soybean oil differing in the concentration of zinc (1; 20; 100; 500 mg Zn/kg diet). At a dietary zinc supply of 1 mg/kg, the rats developed a zinc deficiency indicated by visual and biochemical parameters. At the end of the 37-day feeding period, half of the rats were exposed to 100% oxygen for 12 h. The oxygen treatment significantly reduced plasma zinc in the zinc supplemented rats and reduced it in tendency in the zinc deficient rats. The MT concentration was increased in the zinc supplemented groups in the liver, kidney and lung. The oxygen treatment elevated the metallothionein concentration in the two high zinc supplemented groups (100 and 500 mg Zn/kg diet) in the liver. The response of the zinc concentration in plasma and of hepatic metallothionein levels to oxygen exposure indicates a role of metallothionein in zinc distribution or interactions with other trace elements to support antioxidant capacity, rather than an impact on direct scavenging activity of free radicals.

Supplemental phytic acid and microbial phytase change zinc bioavailability and cadmium accumulation in growing rats.

Three groups of individually housed albino rats (n = 6 each, initial average weight = 47 g) were fed diets based on egg white and corn starch over a 4-week period. All diets were supplemented with 15 mg/kg of Zn and 5 mg/kg of Cd. Group I (Control) was fed the basal diet free of phytic acid (PA) and phytase. By replacing corn starch by 0.5% PA (as NaPA) in groups II and III, a molar PA/Zn ratio of 33 was obtained. In group III, 2000 U of microbial phytase per kg diet were added. Addition of PA to diet (group II) resulted in a significant decrease in growth and zinc status. The negative effect of dietary PA on growth and zinc status was considerably counteracted by the supplementation of 2000 U microbial phytase (group III). In group I the highest apparent zinc absorption (58.2%) was measured. The addition of 0.5% PA (group II) significantly decreased apparent zinc absorption to 23.4%. In rats receiving the phytase-enriched diet (group III) 46.5% of ingested zinc was apparently absorbed. Liver cadmium concentration in rats fed the diet containing PA was significantly higher than that in the control group, whereas phytase supplementation lowered liver cadmium accumulation. In tendency similar effects were obtained for kidney cadmium accumulation.

Liver and colon oxidant status in growing rats fed increasing levels of dietary iron.

A study with four groups, each with 9 individually-housed, male albino rats (clinical average weight = 65 g), was undertaken to examine the effect of increasing dietary iron levels on the oxidant status in liver and colon of growing rats. The basal maize/soya diet contained 70 mg iron per kg and was supplemented with 200 (group II), 500 (group III) and 2000 (group IV) mg Fe/kg from iron (II) fumarate. Liver-Fe was closely correlated (r = 0.997) with dietary Fe intake. Feeding diets supplemented with 500 and 2000 mg Fe/kg over 28 days resulted in significantly elevated TBA-RS in liver homogenates. Vitamin E in the liver was about 20% lower in group IV compared to the controls. Liver SOD, G6PDH and CAT activities were not influenced by dietary iron, whereas liver GSHPx was decreased in groups III and IV. TBA-RS in the colon mucosa significantly increased only at a dietary iron supply of 2000 mg per kg. Iron-enriched diets caused a moderate dose-dependent enhancement in the concentration of methane sulfinic acid in feces samples, which was formed by the reaction of hydroxyl radicals and dimethyl sulfoxide. Liver was more sensitive than the colon mucosa to iron-induced lipid peroxidation. Compared with the recommended iron requirements of growing rats very high dietary iron levels were necessary to induce oxidative stress.

Supplemental sodium phytate and microbial phytase influence iron availability in growing rats.

Five groups of individually housed albino rats (n = 7 each, initial average weight = 42 g) were fed diets based on corn starch and casein over a 4-week period. All diets were supplemented with 35 mg/kg of iron from FeSO4 x 7 H2O. Group I (control) was fed the basal diet free of phytic acid (PA) and phytase. By replacing corn starch by 7.5 g (groups II and IV) and 15 g phytic acid (groups III and V) from sodium phytate per kg diet, molar PA/iron ratios of 18 and 36 were obtained. In groups IV and V, 1000 U phytase from Aspergillus niger per kg diet were added. Food conversion efficiency ratio and growth rate as well as iron in plasma and spleen, hemoglobin, red blood cell count and erythrocyte zinc protoporphyrin were not influenced by the different dietary treatments. Dietary phytate reduced apparent iron absorption in groups II and III. Furthermore hematocrit, transferrin saturation and iron concentration in liver and femur were lowered in rats fed diets with PA, while total and latent iron-binding capacity of plasma increased. Microbial phytase supplementation (groups IV and V) partly counteracted the antinutritive effects of phytic acid on iron availability.

Cadmium accumulation, zinc status, and mineral bioavailability of growing rats fed diets high in zinc with increasing amounts of phytic acid.

Five groups of individually housed albino rats (n = 7, initial average weight = 48 g) were fed diets based on egg albumen and cornstarch (basal diet 8.2 g Ca, 6.0 g P, 0.7 g Mg, 225 mg Zn, 150 mg Fe, 60 mg Mn, 8 mg Cu, and 5 mg Cd) over a 4-wk period. Group I (control) was fed the basal diet free of phytic acid (PA). In groups II, III, IV, and V, cornstarch was replaced by 3.5, 7.0, 10.5, and 14.0 g sodium phytate/kg diet, respectively. Daily gain, feed efficiency, Zn status (Zn in plasma, femur, testes, liver and kidneys, activity of the plasma alkaline phosphatase) and apparent absorption of Zn, Fe, Cu, and Mn remained unchanged by the different dietary treatments. PA decreased apparent Mg absorption significantly and apparent absorption of Ca in tendency. Increasing the amount of phytate caused a corresponding enhancement of amount of the digestible P. Cd accumulation in the liver was not significantly altered, and kidney Cd accumulation slightly increased owing to PA. In conclusion, it was shown that under conditions of high dietary Zn, PA had only little effect on the carryover of Cd in growing rats.

[Investigations in central Hessia on the occurrence of estrogenic activity content of cattle feed]. / Untersuchungen in Mittelhessen zum Vorkommen von östrogen-wirksamen Inhaltsstoffen im Rinderfutter.

In 21 farms which requested consultation for reasons of infertility problems feed samples (grass silage, n = 20; cornsilage, n = 19; hay, n = 9; cereal mixture, n = 3, brewers grains, n = 5, ensiled sugar beet tops, n = 1) were drawn for assay of free (aglycon) and glycosidic (glycosid) bound oestrogen activity. Following sample preparation and extraction, the oestrogenic activity was determined using a radioreceptorassay and only those samples leading to a 50% displacement of the 3H-estradiol-17 beta-tracer were classified as oestrogen-positive; values were expressed as ng 17 beta-estradiol equivalents per g dry matter. Selected samples clearly oestrogen-positive in the aglycone fraction were submitted to separation by HPLC and cytograms were established with the intention to allow an assignment of the oestrogenic activity to the following reference compounds, coumestrol, genistein, daidzein, formononetin, biochanin A, zeeralenon. With regard to free oestrogenic activity (aglycon) most of the grass silages were positive while-with one exception -the cornsilages were negative as were the hay-samples. The brewers grain samples were likewise positive and negative. Distinctly lower concentrations were found for the glycosidic bound oestrogenic activity with highest levels determined in hay. Results obtained after application of HPLC showed that the oestrogenic activity could particularly be attributed to daidzein and biochanin A. In the only oestrogen-positive cornsilage-sample the activity found corresponded with zearalenon. Types and concentrations of the oestrogenic activity allow the conclusion that negative effects on reproduction cannot be excluded.

Associating ECG features with firefighter's activities.

In this paper we associate features obtained from ECG signals with the expected levels of stress of real firefighters in action when facing specific events such as fires or car accidents. Five firefighters were monitored using wearable technology collecting ECG signals. Heart rate and heart rate variability features were analyzed in consecutive 5-min intervals during several types of events. A questionnaire was used to rank these types of events according to stress and fatigue and a measure of association was applied to compare this ranking to the ECG features. Results indicate associations between this ranking and both heart rate and heart rate variability features extracted in the time domain. Finally, an example of differences in inter personal responses to stressful events is shown and discussed, motivating future challenges within this research field.

Exercise affects tissue lymphocyte apoptosis via redox-sensitive and Fas-dependent signaling pathways.

Intensive and exhaustive exercise induces an activation of blood T-lymphocytes, which seems to be terminated by apoptotic processes in the postexercise period. Here, we report that exercise-induced T-lymphocyte apoptosis is a systemic phenomenon occurring in various lymphoid and nonlymphoid tissues. The apoptosis rate could be related to exercise intensity and type. Although in some tissues, such as the spleen and Peyer's patches, an early start of apoptosis (1-3 h postexercise) could be detected, a delayed apoptosis (24 h postexercise) was observed in lung, bone marrow, and lymph nodes. Further analysis showed a similar apoptosis distribution among lymphocyte subpopulations. We tested whether components of the extrinsic or the intrinsic apoptotic pathways or both were involved in these processes. Elevated levels of lipid peroxidation-product malondialdehyde (MDA), indicating an increased production of reactive oxygen species (ROS), were found after exercise in Peyer's patches, lung, and spleen, but not in lymph nodes. Application of N-acetyl-cysteine (NAC) prevented exercise-induced T-cell apoptosis completely in spleen and bone marrow, partially in lung and Peyer's patches, while it was ineffective in lymph nodes. Additionally, exercise addressed the Fas-mediated apoptosis. The percentage of Fas-receptor (Fas+) and Fas-ligand positive (FasL+) lymphocytes was enhanced in Peyer's patches after exercise. Moreover, FasL+ T cells were increased in the lung, while in lymph nodes Fas+ cells were increased. The critical role of Fas signaling in exercise-induced apoptosis was supported by using Fas-deficient MRL/lpr-mice. In Fas-deficient mice, exercise-induced T-lymphocyte apoptosis was prevented in spleen, lung, bone marrow, and lymph nodes, but not in Peyer's patches. These data demonstrate that exercise-induced lymphocyte apoptosis is a transient systemic process with tissue-type specific apoptosis-inducing mechanisms, whose relevance for the adaptive immune competence remains to be shown.

Deposition of copper, iron, manganese and zinc in the empty body of growing lambs of the breed German Merino Landsheep.

A growth experiment with 108 lambs (breed: German Merino Landsheep) was carried out to examine the effect of gender, body weight (BW) and feeding intensity on the deposition of Fe, Zn, Cu and Mn in the empty body (whole animal minus contents of the gastrointestinal tract and bladder). The lambs (50% female and 50% male animals) were fed at three feeding levels ('low', 'medium' and 'high' by varying daily amounts of concentrate and hay) and slaughtered at different final BWs (30, 45 or 55 kg). Six male and six female animals were killed at a BW of 18 kg representing the animals' BW at the beginning of the comparative slaughter experiment. There were significant main effects for the treatments growth rate and final weight on the daily rate of accretion of the trace elements examined. Feeding intensity had a marked influence on the accretion rate for Fe (P < 0.001), Zn (P < 0.001), Cu (P < 0.001) and Mn (P = 0.003). With increasing feeding intensity (low, medium, high) the daily deposition of these trace elements increased (4.4, 5.2, 6.6 mg/day for Fe; 4.9, 5.5, 6.9 mg/day for Zn; 0.20, 0.36, 0.44 mg/day for Cu; 0.14, 0.16, 0.21 mg/day for Mn). Heavier final BW led to increased daily retention of Zn (P < 0.001) and Mn (P = 0.002). Gender had a marked influence only on the accretion rate for Zn (P < 0.001). Ram lambs had a higher daily deposition of this element than female lambs. Related to 1000 g empty body gain, the following concentrations were found for the trace elements examined: Fe 26.1 mg, Zn 30.0 mg, Cu 1.41 mg and Mn 1.04 mg. A feeding influence was given for Zn (P < 0.001) and Cu (P = 0.039). Feeding level low had higher Zn and lower Cu concentrations. Male animals showed less Fe (P < 0.001) and Zn (P = 0.034) per kg empty body gain than females.