Selenium supplementation of lactating dairy cows: effects on milk production and total selenium content and speciation in blood, milk and cheese

Forty multiparous Holstein cows were used in a 16-week continuous design study to determine the effects of either selenium (Se) source, selenised yeast (SY) (derived from a specific strain of Saccharomyces cerevisiae CNCM I-3060) or sodium selenite (SS), or Se inclusion rate in the form of SY in the diets of lactating dairy cows on the Se concentration and speciation in blood, milk and cheese. Cows received ad libitum a total mixed ration (TMR) with a 1 : 1 forage : concentrate ratio on a dry matter (DM) basis. There were four diets (T1 to T4), which differed only in either source or dose of Se additive. Estimated total dietary Se for T1 (no supplement), T2 (SS), T3 (SY) and T4 (SY) was 0.16, 0.30, 0.30 and 0.45 mg/kg DM, respectively. Blood and milk samples were taken at 28-day intervals and at each time point there were positive linear effects of Se in the form of SY on the Se concentration in blood and milk. At day 112, blood and milk Se values for T1 to T4 were 177, 208, 248 and 279 ± 6.6 and 24, 38, 57 and 72 ± 3.7 ng/g fresh material, respectively, and indicate improved uptake and incorporation of Se from SY. In whole blood, selenocysteine (SeCys) was the main selenised amino acid and the concentration of selenomethionine (SeMet) increased with the increasing inclusion rate of SY. In milk, there were no marked treatment effects on the SeCys content, but Se source had a marked effect on the concentration of SeMet. At day 112, replacing SS (T2) with SY (T3) increased the SeMet concentration of milk from 36 to 111 ng Se/g and its concentration increased further to 157 ng Se/g dried sample as the inclusion rate of SY increased further (T4) to provide 0.45 mg Se/kg TMR. Neither Se source nor inclusion rate affected the keeping quality of milk. At day 112, milk from T1, T2 and T3 was made into a hard cheese and Se source had a marked effect on total Se and the concentration of total Se comprised as either SeMet or SeCys. Replacing SS (T2) with SY (T3) increased total Se, SeMet and SeCys content in cheese from 180 to 340 ng Se/g, 57 to 153 ng Se/g and 52 to 92 ng Se/g dried sample, respectively. The use of SY to produce food products with enhanced Se content as a means of meeting the Se requirements is discussed.     

Lymphocyte functions in dairy cows in hot environment

This study was carried out to ascertain the effects of intense high environmental temperatures (HET) on lymphocyte functions in periparturient dairy cows. The study was undertaken from the beginning of March through the end of July 2003 in a commercial dairy unit located approximately 40 km north of Rome. Thirty-four Holstein cows were utilised in the study. Twenty-two of these cows gave birth in spring (SP cows), from 28 March to 30 April. The remaining 12 cows gave birth in summer (SU cows), between 15 June and 2 July. The two groups of cows were balanced for parity and were fed the same rations. Blood samples were taken 4, 3, 2 and 1 week before calving, and 1, 2 and 4 weeks after calving, in order to evaluate peripheral blood mononuclear cell (PBMC) function in vitro, and to determine plasma cortisol concentrations. After isolation, the PBMC were stimulated with mitogens and their response in terms of DNA synthesis and IgM secretion was measured. During spring, either the day (9–20 h) or the night (21–8 h) temperature humidity index (THI) was below the upper critical THI (72) established for dairy cows. During summer, the mean daily THI values were 79.5±2.9 during the day and 70.1±4.7 during the night. Furthermore, during summer, three heat waves (a period of at least 3 consecutive days during which there were less than 10 recovery hours) occurred. Recovery hours were intended hours with a THI below 72. The first heat wave lasted 5 days, the second 6 days, and the third 15 days. Compared to the SP cows, over the entire periparturient period the extent of DNA synthesis and IgM secretion levels were lower (P ranging from <0.01 to 0.0001) and higher (P<0.01) respectively, in the SU cows. Before calving, the SU cows also presented higher (P<0.01) concentrations of plasma cortisol compared to the SP cows. This study indicates that the effects of HET on the immune response depend on the specific immune function under consideration, and that neuroendocrinal changes due to HET may play a role in the perturbation of immune functions.     

Influence of deoxynivalenol on feed consumption by dairy cows

The present results would suggest that diets providing up to 14.6 mg kg⁻¹ concentrate or 31 mg DON per 100 kg body weight for relatively high levels of milk production did not affect feed intake or milk production over a 3 week period. Caution is suggested as DON-contaminated barley can at times contain other mycotoxins.     

Impacts of CLA and dietary concentrate proportion on blood metabolite concentration and proliferation of peripheral blood mononuclear cells of periparturient dairy cows

The study aimed to examine effects of supplemented CLA to periparturient dairy cows receiving different concentrate proportions antepartum (a.p.) to investigate CLA effects on metabolism and immune function. Compared with adapted feeding, high-concentrate diet a.p. should induce a ketogenic metabolic situation postpartum (p.p.) to better understand how CLA works. A total of 64 pregnant German Holstein cows had ad libitum access to partial mixed rations based on concentrate and roughage 3 weeks before calving until day 60 p.p. A.p., cows received 100 g/day control fat (CON) or a CLA supplement, either in a low-concentrate (20%, CON-20, CLA-20) or high-concentrate diet (60%, CON-60, CLA-60). P.p., concentrate proportion was adjusted to 50% while fat supplementation continued. After day 32 p.p., half of the animals of CLA-groups changed to CON supplementation (CLA-20-CON, CLA-60-CON). A ketogenic metabolic state p.p. was not achieved and respective impacts of CLA could not be examined. Blood samples for isolation of peripheral blood mononuclear cells (PBMC) were collected on day −21, 7, 28 and 56 relative to calving. Blood chemistry samples were taken over the entire experimental period. Mitogen-stimulated proliferation of PBMC remained unaffected. Besides serum concentrations of triglycerides, total bilirubin, total protein, albumin and IGF-1, clinical-chemical serum characteristics remained uninfluenced by treatments. No post-supplementation effect could be observed. Measured blood metabolites and mitogen-stimulated proliferation of PBMC indicate that all groups had an increased metabolic stress around calving, whereby group CLA-20 was affected more severely. Overall, supplemented CLA did not positively affect metabolism or immune function of periparturient dairy cows. However, feeding CLA in a low-concentrate diet a.p. seems to increase liver stress around calving via reduced DMI.     

Characterization of selenium status of inhabitants in the region Ústi nad orlici,czech republic by inaa of blood serum and hair and fluorimetric analysis of urine

Selenium is an essential trace element and its isufficient status may cause serious health complications for both individuals and the whole populations. To investigate the selenium status of the subpop-ulation in northeastern Bohemia represented by the region ústí nad Orlicí, 253 serum, 469 urine, and 31 hair samples from 470 randomly selected volunteers between 6 and 65 yr of age have been analyzed for selenium concentration. Serum and hair Se were detected by instrumental neutron activation analysis (means: 55 ±11 Μg Se/L sera, 0.268 ±0.040 Μg Se/g hair). Urine Se was measured by fluorimetry (12 ±5 Μg Se/L urine) with coanalyses of Lyphocheck urine, SRM Urine 2670, and Seronorm urine for quality control of the method. Results proved significant age-dependent differences, but gender differences were not significant. The frequency plot of serum Se proved maximal frequencies in adults between 55 and 70 Μg Se/L and in children in the range 45–55 Μg Se/L. The same plots of urine Se for both age groups showed maximal frequency in the limits 8–15 Μg Se/L. All indices used (Se in serum, urine, and hair) confirmed mild to severe selenium deficiency in the population of the region.     

Selenium in serum and whole blood in patients with surgical interventions

Selenium values of serum and whole blood were determined for two groups of patients undergoing large surgical interventions (e.g., gastrectomy) and receiving a total parenteral nutrition (TPN). All patients showed low selenium values at the beginning of TPN. The first group received a supplementation of selenium, and it was established that selenium levels normalized after 6–7 d. The balances of selenium turned out to be positive in all cases. The second group, which was not administered selenium supplementation, showed significantly lower values of selenium. It can, therefore, be concluded that a substitution of selenium prior to large surgical interventions following TPN clearly helps patients combat the increase in the oxidant stress reactions.     

Research note: Effect of duration of the collection period on the estimated digestibility in dairy cows

A digestion trial was performed with 14 lactating Friesian dairy cows to compare the estimated digestibility of crude nutrients after collecting the faeces for 5, 7 and 9 d. The experimental ration consisted of grass silage (7.3 kg DM) and concentrate (10.9 kg DM). Animals were adapted to the ration for 14 d. There was no effect of the duration of the collection period on the estimated mean digestibility of crude nutrients and on the respective standard deviation. In consequence, in digestibility trials with cows the collection period must not exceed 5 d.     

Increased hair selenium concentration in hyperlipidemic patients

Selenium is an essential trace element with potential anti‐atherogenic and antioxidant effects. Experimental data suggest that selenium might be beneficial in the prevention of atherosclerosis and its complications, whereas human epidemiological studies have yielded conflicting results. Data on hair selenium status in hyperlipidemic patients are still lacking. Therefore, we analysed selenium concentrations by X‐ray fluorescence in the hair of 81 statin‐naïve patients with newly diagnosed Fredrickson‐type IIa and IIb hyperlipoproteinemia and compared their data with 43 healthy volunteers. We also assessed the frequency of other classical risk factors of atherosclerosis. Hair selenium levels were found to be significantly higher in hyperlipidemic patients compared with volunteers with normal lipid levels. Also, a significantly increased number of traditional atherosclerosis risk factors were observed in hyperlipidemic patients with hair selenium concentrations above the median in contrast to those with below. Our results suggest that high hair selenium status might be associated with adverse blood lipid profile together with an increased number of traditional risk factors in a selenium‐deplete population. These findings warrant further investigations to study the impact of selenium supplementation on the incidence of cardiovascular events.     

Selenium levels in human plasma and hair in northern poland

The aim of this study was to (1) estimate the concentration of selenium in the plasma of 146 residents (65 men and 81 women) and in the hair of 34 persons from the Gdańsk region in northern Poland, aged 19–70 and (2) compare the obtained results with data corresponding to healthy populations living in different European countries. Selenium in plasma was determined by atomic absorption spectrometry using the hydride generation method. The mean selenium concentration in plasma of the investigated persons was 73.3 ± 14.1 μg/L, 76.7 ± 13.2 μg/L in men, and 70.4 ± 14.7 μg/L in women. No age — dependent differences in plasma selenium were found in the investigated population. In 20% of the investigated persons, the selenium level in plasma was lower than 60 μg/L. The mean selenium concentration in hair was 0.30 ± 0.11 μg/g. A positive, statistically significant correlation between selenium concentrations in the plasma and hair of the investigated persons was found. The obtained results indicate that the selenium level in significant part of this population is suboptimal and should be elevated by supplementation with this element.     

Selenium and glutathione peroxidases in blood of patients with different stages of chronic renal failure

In patients with chronic renal failure (CRF) Se concentration in blood components is usually lower as compared with healthy controls. One of the five known forms of Se-dependent glutathione peroxidases (GSH-Px), the plasma GSH-Px, is synthesized primarily in the kidney. In CRF patients, plasma GSH-Px activity is reduced and the reduction increases with the progress of the disease.

The Se concentration in blood components was measured spectrofluorometrically with 2,3-diaminonaphthalene as complexing reagent. Activities of GSH-Px in red cells and in plasma were assayed by the coupled method with t-butyl hydroperoxide as substrate. The study group consisted of 150 patients in different stages of CRF. The results were compared with the values for 30 healthy subjects.

Se concentrations in whole blood and plasma of the entire group of patients were significantly lower (p < 0.01) as compared with the healthy subjects. In the incipient stage, however, the Se levels in all blood components were non-significantly lower. In whole blood and plasma the Se levels gradually decreased, reaching in the end stage values that were lower by 29 to 32% (p < 0.0001) as compared with the control group. Total protein and albumin levels in plasma of patients were significantly lower (p < 0.0001) as compared with healthy subjects and they decreased linearly with the progress of the disease. Positive and highly significant correlations were noted between total plasma protein and plasma Se concentrations (p < 0.0001) as well as between plasma albumin and plasma Se concentrations (p < 0.0001).

Red cell GSH-Px activity in the entire group of patients was lower (p < 0.05) than in the control group and did not change significantly with the progress of the disease. In plasma, however, GSH-Px activity of the entire group was lower by 33% (p < 0.0001) as compared with healthy subjects and decreased gradually with increasing renal failure. Highly significant, inverse correlations were seen between creatinine levels and plasma GSH-Px activities (p < 0.0001) as well as between urea nitrogen levels and plasma GSH-Px activities (p < 0.0001) when all stages of the disease were included.

In conclusion, patients with CRF exhibit lower Se levels in blood components as compared with healthy subjects. In whole blood and plasma these levels decrease with the progress of the disease. Plasma GSH-Px activity in patients was extremely reduced and it dramatically decreased with the progress of the illness.     

Selenium, boron, and germanium deficiency in the etiology of Kashin-Beck disease

Concentrations of selenium (Se), boron (B), and germanium (Ge) were determined in scalp hair of children with Kashin-Beck disease (KBD), in healthy children in KBD-disease endemic areas, and in healthy children in non-KBD areas. Mean Se, B, and Ge concentrations were low in children with KBD; in hair of healthy children in KBD areas, Se levels were normal but B and Ge levels were lower than in KBD-free areas. The hair levels of B and Ge were unaffected by selenium supplementation. It is suggested that B and Ge deficiency may be contributing factors in the etiology of KBD.     

Silent blood chimaerism in a mare confirmed by DNA marker analysis of hair bulbs

Microsatellite DNA markers in a mare's hair bulbs not concordant with markers in her blood confirmed the hypothesis of chimaerism which had been proposed to explain the apparent parentage exclusion of the mare from her suckling foal. Parentage analysis for this foal based on genetic markers not originating from blood cells of its dam supported a parentage verification conclusion.     

Microencapsulated sodium selenite supplementation in dairy cows: effects on selenium status

The objective of this study was to compare the efficiency of transfer of selenium (Se) to plasma and milk from inorganic sodium selenite, either free or microencapsulated, and from selenized yeast in dairy cows. The study consisted of an in situ-nylon bags incubation, and in an in vivo experiment to compare the Se status of cows supplemented with either sodium selenite, microencapsulated sodium selenite, or Se yeast. Thirty dairy cows, divided in five groups, were fed the following diets: the control group (CTR) received a total mixed ration supplemented with sodium selenite in order to have 0.3 mg/kg DM of total Se; 0.3M and 0.5M groups received the same control diet supplemented with lipid microencapsulated sodium selenite to provide 0.3 and 0.5 mg/kg DM of total Se, respectively; 0.3Y and 0.5Y groups received selenized yeast to provide 0.3 and 0.5 mg/kg of total Se, respectively. Cows were fed the supplements for 56 days during which milk, blood, and fecal samples were collected weekly to conduct analysis of Se and glutathione peroxidase (GSH-px) activity. Se concentration in the nylon bags was assessed to 72%, 64%, and 40% of the initial value (time 0) after 4, 8, and 24 h of incubation, respectively. In vivo, cows supplemented with 0.3 mg/kg of microencapsulated Se had higher milk Se concentration compared to CTR. The increment was more pronounced at the highest inclusion rate (0.5 mg/kg, 0.5M group). GSH-px activity was not significantly affected by treatments. The results indicate that lipid microencapsulation has the potential to protect nutrients from complete rumen reduction and that Se from microencapsulated selenite is incorporated in milk more efficiently than the free form. Microencapsulated sodium selenite was shown to be comparable to Se-yeast in terms of availability and incorporation in milk when fed at 0.3 mg/kg DM, whereas the inclusion in the diet at 0.5 mg/kg DM resulted in higher plasma and milk concentrations than selenized yeast.     

The effect of selenium sources and supplementation on neutrophil functions in dairy cows

Selenium (Se), an essential micronutrient, is believed to enhance neutrophil functions. This study aimed to compare the effects of supplemented organic (Sel-Plex®) and inorganic (sodium selenite) Se on neutrophil functions in high-producing dairy cows, during the periparturient period. Twenty-five Holstein cows were randomly allocated to five dietary treatments as follows: control diet (basal diet without Se supplementation), IN 0.3 (basal diet supplemented with inorganic Se at 0.3 mg/kg dry matter (DM)), IN 0.5 (inorganic Se at 0.5 mg/kg DM), OR 0.3 (organic Se at 0.3 mg/kg DM) and OR 0.5 (organic Se at 0.5 mg/kg DM). Some evaluated parameters included neutrophil functions and plasma Se concentrations in cows and plasma Se concentrations in calves. Neutrophil phagocytosis did not significantly differ among the five groups. However, organic Se supplementation significantly increased (P < 0.01) the respiratory burst of neutrophils when compared to cows fed IN 0.3 and the control diet. In comparison to inorganic Se, neutrophil apoptosis was decreased (P < 0.01) when cows were fed organic Se or the control diets. These effects of organic Se on respiratory burst activities and apoptosis of neutrophils were in a dose-dependent manner. Calf plasma Se concentrations were higher (P < 0.05) when cows were fed OR 0.5 and IN 0.5.     

Selenium contentrations in human renal cortex, liver, and hair in Northern Poland

The aim of this study was to (1) determine the selenium concentration in the renal cortex, liver, and hair in 64 residents from northern Poland (Gdańsk region) aged 17–81 yr, who died suddenly, and (2) assess whether a correlation between the selenium concentration in hair and in the renal cortex and liver occurs. Selenium was determined by atomic absorption spectrometry using the hydride generation method. The mean selenium concentration in the renal cortex, liver, and hair in the investigated persons was 0.791±0.191 μg/g (wet weight), 0.289±0.084 μg/g (wet weight), and 0.443±0.128 μg/g, respectively. No age-dependent differences in selenium level in the investigated tissues was found. Also, no correlation between the selenium concentrations in hair and in renal cortex and liver was assessed.     

Serum and hair levels of zinc, selenium, iron, and copper in children with iron-deficiency anemia

In the present study, the serum and hair levels of zinc, selenium, and copper were determined in children with iron-deficiency anemia (IDA). A total of 52 anemic children aged 1–4 yr constituted the study group. Fortysix healthy children acted as controls. The copper and zinc levels were measured with an atomic absorption spectrophometer. Serum and hair selenium was determined by a spectroflourometric method. The serum zinc and selenium concentrations in the IDA group were found to be significantly lower and serum copper significantly higher than those in the controls (p<0.05). Lower iron, zinc, and selenium concentrations (p<0.001) but not copper were found in hair (p>0.05).     

植物硒同化的研究进展及其耐硒突变体的筛选

简要叙述了高等植物对硒元素吸收、同化的过程和特点。对近年来植物硒蛋白存在状态、硒相关突变体的筛选和应用硒代谢关键酶基因的转基因植物研究等方面的最新进展作了扼要综述。在此基础上对植物硒营养研究的发展提出了几点设想。     

Serum progesterone concentration in pyometritic and normal postpartum dairy cows

Two studies were conducted to evaluate the concentration of serum progesterone in pyometritic cows and relate it to palpation of ovarian structures per rectum . In Trial 1, serum samples from 34 pyometritic cows were assayed for progesterone. Mean serum progesterone concentrations were 6.8 +/- 0.7 ng/ml. In Trial 2, each of 54 pyometritic cows was paired with a control cow on the basis of days post partum (18-50 days). Mean concentration of progesterone was 9.7 +/- 1.0 ng/ml for the pyometritic cows and 5.7 +/- 0.8 ng/ml in control cows (P<0.005). Progesterone concentration was greater (P<0.005) in both groups of cows with palpable corpora lutea (CLs). Ninety-six percent of the pyometritic cows had palpable CLs compared to 57% of the control group. Comparing serum progesterone only in cows with a palpable CL, the mean concentration was still greater (P<0.005) in the pyometritic group (10.6 +/- 1.0 ng/ml) than the control group (6.6 +/- 1.0 ng/ml). Compatability of rectal palpation findings and concentrations of serum progesterone were 92.6% for the pyometritic group and 72.2% for the control group. Progesterone concentration increased (P<0.05) by increased days post partum in Trial 2 (n=54) but not in Trial 1 (n=23). In both Trials 1 and 2, uterine size due to pyometra increased (P<0.05) with increased days post partum. No other associations were found.     

Mercury and selenium concentrations in maternal and neonatal scalp hair: relationship to amalgam-based dental treatment received during pregnancy

Mercury and selenium concentrations were determined in scalp hair samples collected postpartum from 82 term pregnancy mothers and their neonates. Maternal mercury and selenium had median concentrations of 0.39 μg/g (range 0.1–2.13 μg/g) and 0.75 μg/g (range 0.1–3.95 μg/g), respectively, and corresponding median neonatal values were 0.24 μg/g (range 0.1–1.93 μg) and 0.52 μg/g (range (0.1–3.0 μg/g). Amalgam-based restorative dental treatment received during pregnancy by 27 mothers (Group I) was associated with significantly higher mercury concentrations in their neonates (p<0.0001) compared to those born to 55 mothers (Group II) whose most recent history of such dental treatment was dated to periods ranging between 1 and 12 yr prior to pregnancy. In the Group I mother/neonate pairs, amalgam removal and replacement in 10 cases was associated with significantly higher mercury concentrations compared to 17 cases of new amalgam emplacement. Selenium concentrations showed no significant integroup differences. However, the selenium/mercury molar ratio values were lowest in the Group I neonates, compared to their mothers and to the Group II mother/neonate pairs. This ratio decreased as mercury concentration increased, and this interrelation was statistically significant in both groups of mother/neonate pairs. The data from this preliminary study suggest that amalgam-based dental treatment during pregnancy is associated with higher prenatal exposure to mercury, particularly in cases of amalgam removal and replacement. The ability of a peripheral biological tissue, such as hair, to elicit such marked differences in neonatal mercury concentrations provides supporting evidence of high fetal susceptibility to this form of mercury exposure. The data are discussed in relation to the differences between maternal and fetal mercury metabolisms and to mercury—selenium metabolic intereactions in response to mercury exposure.     

Selenium levels in blood of Upper Silesian population

The selenium status and the relationship of whole-blood selenium and plasma homocysteine are reported for healthy human subjects living in Upper Silesia. A total of 1063 individuals (627 male and 436 female) examined for whole-blood selenium were subdivided into six groups according to age; the youngest included adolescents (n=143) aged 10–15 yr, and the oldest were centenarians (n=132). The mean Se content was relatively low (62.5±18.4 μg/L), and it tended to be higher in men (65.9±17.2 μg/L) than in women (57.5±18.9 μg/L). Selenium levels appeared to be age dependent, as the highest values were observed in young and middle-age adults (21–40 yr), whereas they were significantly lower in adolescents and in the elderly. In more than 40% of apparently healthy adults (aged 21–69 yr), the Se concentration was within the range 60–80 μg/L (i.e., below the lower limit of the nutritional adequacy range [80 μg/L]). A significant inverse correlation between whole-blood selenium and plasma total homocysteine was detected in a smaller population sample of middle-aged and elderly persons (n=204).