Effect of dietary organic selenium on milk selenium concentration and antioxidant and immune status in midlactation dairy cows

Differences in the intestinal microbiota and association of host metabolism with hair coat status in cattle

Introduction

The hair coat status of cattle serves as an easily observed indicator of economic value in livestock production; however, the underlying mechanism remains largely unknown. Therefore, the objective of the current study was to determine differences in the intestinal microbiota and metabolome of cattle based on a division of with either slick and shining (SHC) or rough and dull (MHC) hair coat in Simmental cows.

Methods

Eight SHC and eight MHC late-pregnancy Simmental cows (with similar parities, body weights, and body conditions) were selected based on their hair coat status, and blood samples (plasma) from coccygeal venipuncture and fecal samples from the rectum were collected. The intestinal microbiota (in the fecal samples) was characterized by employing 16S rRNA gene sequencing targeting the V3-V4 hypervariable region on the Illumina MiSeq PE300 platform, and plasma samples were subjected to LC-MS/MS-based metabolomics with Progenesis QI 2.3. Plasma macromolecular metabolites were examined for differences in the metabolism of lipids, proteins, mineral elements, and hormones.

Results

Notable differences between the SHC and MHC groups related to host hair coat status were observed in the host metabolome and intestinal microbiota (P < 0.05). The host metabolome was enriched in histidine metabolism, cysteine and methionine metabolism, and purine metabolism in the SHC group, and the intestinal microbiota were also enriched in histidine metabolism (P < 0.05). In the MHC group, the symbiotic relationship transitioned from cooperation to competition in the MHC group, and an uncoupling effect was present in the microbe-metabolite association of intestine microbiota-host interactions. The hubs mediating the relationships between intestinal microbiota and plasma metabolites were the intestinal bacterial genus g__norank_f__Eubacterium_coprostanoligenes_group, plasma inosine, triiodothyronine, and phosphorus, which could be used to differentiate cows' hair coat status (P < 0.05).

Conclusion

Overall, the present study identified the relationships between the features of the intestinal microbiota and host hair coat status, thereby providing evidence and a new direction (intestine microbiota-host interplay) for future studies aimed at understanding the hair coat status of cattle.

Effects of Lonicera japonica Extract with Different Contents of Chlorogenic Acid on Lactation Performance, Serum Parameters, and Rumen Fermentation in Heat-Stressed Holstein High-Yielding Dairy Cows

This examined the effects of Lonicera japonica extract (LJE) with different chlorogenic acid (CGA) contents on lactation performance, antioxidant status and immune function and rumen fermentation in heat-stressed high-yielding dairy cows. In total, 45 healthy Chinese Holstein high-yielding dairy cows, all with similar milk yield, parity, and days in milk were randomly allocated to 3 groups: (1) the control group (CON) without LJE; (2) the LJE-10% CGA group, receiving 35 g/(d·head) of LJE-10% CGA, and (3) the LJE-20% CGA group, receiving 17.5 g/(d·head) of LJE-20% CGA. The results showed that the addition of LJE significantly reduced RT, and enhanced DMI, milk yield, milk composition, and improved rumen fermentation in high-yielding dairy cows experiencing heat stress. Through the analysis of the serum biochemical, antioxidant, and immune indicators, we observed a reduction in CREA levels and increased antioxidant and immune function. In this study, while maintaining consistent CGA content, the effects of addition from both types of LJE are similar. In conclusion, the addition of LJE at a level of 4.1 g CGA/(d·head) effectively relieved heat stress and improved the lactation performance of dairy cows, with CGA serving as the effective ingredient responsible for its anti-heat stress properties.

Enhancing bovine immune, antioxidant and anti-inflammatory responses with vitamins, rumen-protected amino acids, and trace minerals to prevent periparturient mastitis

Mastitis, the inflammatory condition of mammary glands, has been closely associated with immune suppression and imbalances between antioxidants and free radicals in cattle. During the periparturient period, dairy cows experience negative energy balance (NEB) due to metabolic stress, leading to elevated oxidative stress and compromised immunity. The resulting abnormal regulation of reactive oxygen species (ROS) and reactive nitrogen species (RNS), along with increased non-esterified fatty acids (NEFA) and β-hydroxybutyric acid (BHBA) are the key factors associated with suppressed immunity thereby increases susceptibility of dairy cattle to infections, including mastitis. Metabolic diseases such as ketosis and hypocalcemia indirectly contribute to mastitis vulnerability, exacerbated by compromised immune function and exposure to physical injuries. Oxidative stress, arising from disrupted balance between ROS generation and antioxidant availability during pregnancy and calving, further contributes to mastitis susceptibility. Metabolic stress, marked by excessive lipid mobilization, exacerbates immune depression and oxidative stress. These factors collectively compromise animal health, productive efficiency, and udder health during periparturient phases. Numerous studies have investigated nutrition-based strategies to counter these challenges. Specifically, amino acids, trace minerals, and vitamins have emerged as crucial contributors to udder health. This review comprehensively examines their roles in promoting udder health during the periparturient phase. Trace minerals like copper, selenium, and calcium, as well as vitamins; have demonstrated significant impacts on immune regulation and antioxidant defense. Vitamin B12 and vitamin E have shown promise in improving metabolic function and reducing oxidative stress followed by enhanced immunity. Additionally, amino acids play a pivotal role in maintaining cellular oxidative balance through their involvement in vital biosynthesis pathways. In conclusion, addressing periparturient mastitis requires a holistic understanding of the interplay between metabolic stress, immune regulation, and oxidative balance. The supplementation of essential amino acids, trace minerals, and vitamins emerges as a promising avenue to enhance udder health and overall productivity during this critical phase. This comprehensive review underscores the potential of nutritional interventions in mitigating periparturient bovine mastitis and lays the foundation for future research in this domain.

Comparison of different organic selenium supplementations on selenium status and serum biomarkers in dairy cows

The objective of this study was to investigate the effects of two different organic selenium (Se) supplements, selenomethionine (Se-Met) and selenohomolanthionine (Se-Hlan), on the serum biochemical parameters and Se status of dairy cows. Different dietary Se supplementation treatments were set as follows: a control group (CON, adding sodium selenite at 0.3 mg Se/kg dry matter [DM]), 0.3 and 0.5 Se-Met (adding Se-Met at 0.3 and 0.5 mg Se/kg DM, respectively), as well as 0.3 and 0.5 Se-Hlan (adding Se-Hlan at 0.3 and 0.5 mg Se/kg DM, respectively). The experiment lasted 8 weeks. The serum measurements showed that both organic Se treatments resulted in higher uric acid than CON. Se-Met produced higher aspartate aminotransferase, glucose, urea, low-density lipoprotein cholesterol, and lactate dehydrogenase than Se-Hlan. Regarding the Se status, the highest milk Se values appeared in 0.5 Se-Met, with intermediate values in 0.3 Se-Met and 0.5 Se-Hlan, whereas the highest and lowest serum Se levels were presented in 0.5 Se-Met and 0.3 Se-Hlan, respectively. Our results suggest that Se-Hlan was not as efficient in boosting serum or milk Se as Se-Met and differences in serum biomarkers between Se-Met and Se-Hlan may be associated with distinct metabolic pathways for different forms of organic Se.

The Effect of Dietary Supplementation with Probiotic and Postbiotic Yeast Products on Ewes Milk Performance and Immune Oxidative Status

The administration of yeast products as feed additives has been proven to beneficially affect animal productivity through energy, oxidative, and immune status improvement. This study evaluated a combination of Saccharomyces cerevisiae live yeast (LY) with yeast postbiotics (rich in mannan-oligosaccharides (MOS) and beta-glucans) and selenium (Se)-enriched yeast on ewes' milk performance and milk quality, energy and oxidative status, and gene expression related to their immune system during the peripartum period. Ewes were fed a basal diet (BD; F:C = 58:42 prepartum and 41:59 postpartum) including inorganic Se (CON; n = 27), the BD supplemented with a LY product, and inorganic Se (AC; n = 29), as well as the combination of the LY, a product of yeast fraction rich in MOS and beta-glucans, and organic-Se-enriched yeast (ACMAN; n = 26) from 6 weeks prepartum to 6 weeks postpartum. The β-hydroxybutyric acid concentration in the blood of AC and ACMAN ewes was lower (compared to the CON) in both pre- and postpartum periods (p < 0.010). Postpartum, milk yield was increased in the AC and ACMAN Lacaune ewes (p = 0.001). In addition, the activity of superoxide dismutase (p = 0.037) and total antioxidant capacity (p = 0.034) measured via the 2,2-Azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) method was increased in the blood plasma of the ACMAN postpartum. Higher ABTS values were also found (p = 0.021), while protein carbonyls were reduced (p = 0.023) in the milk of the treated groups. The relative transcript levels of CCL5 and IL6 were downregulated in the monocytes (p = 0.007 and p = 0.026 respectively), and those of NFKB were downregulated in the neutrophils of the ACMAN-fed ewes postpartum (p = 0.020). The dietary supplementation of ewes with yeast postbiotics rich in MOS and beta-glucans, and organic Se, improved energy status, milk yield and some milk constituents, and oxidative status, with simultaneous suppression of mRNA levels of proinflammatory genes during the peripartum period.

Optimisation of trace mineral supplementation in diets for Atlantic salmon smolt with reference to holistic fish performance in terms of growth, health, welfare, and potential environmental impacts

The aquafeed ingredient inventory is ever changing, from marine to plant based, and recently evolving to incorporate increasing amounts of low trophic, side stream and circular economy based raw materials, each one contributing with variable amounts and qualities of macro- and micronutrients. Meeting the micronutrient requirement of farmed fish for healthy and efficient growth under normal and challenging conditions is of paramount importance. In this study we run a trial based on a 2 × 4 factorial design with three replications for each dietary treatment, where Atlantic salmon smolt were fed one of 8 experimental diets supplemented with either organic or inorganic mineral premixes (copper, iron, manganese, selenium, and zinc) at four dietary inclusion levels. We saw a trend for higher growth rate in the organic mineral groups irrespective of the dietary mineral levels. Mineral digestibility was negatively correlated with increasing mineral supplementation levels for all tested minerals but Se which increased with the increasing supplementation in the inorganic and up to the 2nd inclusion level in the organic mineral groups. Increasing mineral supplementation affected retention efficiency of Zn, Mn, Cu and Fe while mineral source affected only the retention of Se which was higher in the organic mineral groups. Moreover, fish obtained higher EPA and DHA in their body and increased slaughter yield in the organic as compared to the inorganic mineral groups and corroborated that trace mineral inclusion levels play a key role on salmon fillet's technical quality. More effects from different origin and dietary inclusion levels of trace minerals were seen on fillet yield, fillet technical and nutritional quality, bone strength, skin morphology, organ mineralization and midgut transcriptome.

Efficacy of feeding hydroxy-selenomethionine on plasma and milk selenium in mid-lactation dairy cows

In this study, we aimed to determine the amount of Se transferred to milk and blood of mid- to late-lactation dairy cows when supplemental Se from hydroxy-selenomethionine (OH-SeMet) was fed compared with an unsupplemented group and a group supplemented with a seleno-yeast (SY). Twenty-four lactating Holstein cows (178 ± 43 d in milk) were used in a complete randomized block design for 91 d (7-d covariate period and 84-d treatment period). Treatments were (1) basal diet with an analyzed Se background of 0.2 mg of Se per kg as-fed (control); (2) basal diet + 0.3 mg of Se/kg as-fed from SY (SY-0.3); (3) basal diet + 0.1 mg of Se/kg as-fed from OH-SeMet (OH-SeMet-0.1); and (4) basal diet + 0.3 mg of Se/kg as-fed from OH-SeMet (OH-SeMet-0.3). During the trial, plasma and milk were analyzed for total Se, and plasma was analyzed for glutathione peroxidase activity. The mean plasma and milk Se concentrations exhibited the same relationship, where OH-SeMet-0.3 resulted in the highest values (142 µg/L of plasma and 104 µg/kg of milk), followed by SY-0.3 (134 µg/L and 85 µg/kg), OH-SeMet-0.1 (122 µg/L and 67 µg/kg), and the control group had the lowest values (120 µg/L and 50 µg/kg). The increment of Se in milk induced by OH-SeMet-0.3 (+54 µg/kg) was 54% higher than that induced by SY-0.3 (+35 µg/kg). Additionally, dietary supplementation of 0.2 mg/kg Se from OH-SeMet in the total mixed ration was estimated to be similar to 0.3 mg/kg Se from SY in the total mixed ration when considering the level of Se in the milk. There was no difference in plasma glutathione peroxidase activity between groups; however, OH-SeMet-0.3 significantly decreased somatic cell count. The results confirmed that supplementation with organic Se increases milk and plasma Se concentrations. Moreover, when administered at the same level of supplementation, OH-SeMet was shown to be more efficient than SY in improving milk quality by increasing Se content and decreasing milk somatic cell count.

Effects of organic and inorganic selenium on selenium bioavailability, growth performance, antioxidant status and meat quality of a local beef cattle in China

Selenium (Se) is an essential nutrient with multiple health benefits to humans and animals. Cattle generally require dietary Se supplementation to meet their daily requirements. The two main forms of dietary Se in cattle are organic Se and inorganic Se. Data comparing the health and productivity effects of organic Se and inorganic Se on cattle are still insufficient, and it is necessary to conduct more research to evaluate the bioavailability, nutritional value, deposition, and body functions of Se sources in different breeds and physiological stages of cattle raised in areas with different Se levels. The objectives of this study were to determine the effects of organic and inorganic sources of Se on plasma biochemical indices, Se bioavailability, deposition in body tissues and organs, growth performance, antioxidant capacity and meat quality of beef cattle raised in Se-deficient areas. Fifteen Chinese Xiangzhong Black beef cattle with an average weight of 254.5 ± 8.85 kg were assigned to three dietary groups. The three groups were fed the same basal ration and supplemented with either an inorganic [sodium selenite (SS)] or organic [selenomethionine (SM) or Se-enriched yeast (SY)] source of Se (0.1 mg/kg dry matter) for 60 days. At the end of the experiment, three cattle from each group were randomly selected and slaughtered, and samples were collected from tissues and organs for analysis. The results revealed that growth performance, slaughter performance, Se content of tissues and organs, meat quality characteristics including chemical composition, pH_45min, pH_24h, drip loss, and cooking losses did not differ (p > 0.05) due to supplementation of the different organic and inorganic sources of Se. SM and SY were more effective in increasing (p < 0.05) immunoglobulin M (IgM) concentrations in the blood and reducing (p < 0.05) malondialdehyde (MDA) content in the longissimus dorsi than SS. In conclusion, organic Se is more effective than inorganic Se in improving the immune and antioxidant capacity of Chinese Xiangzhong Black beef cattle.

Plasma and Colostrum Selenium Statuses of Properly Supplemented Belgian Blue Cows on Commercial Farms and Their Relationship with Sources of Dietary Selenium and Blood Biomarkers

Selenium (Se) is an essential trace element for the health and immunity of cattle. Double-muscled Belgian Blue cows are well known to be prone to nutritional deficiencies. Colostrum Se level is also a key factor to promote immunoglobulin intake in young calves. The main objectives of this study were to assess (1) the plasma and colostrum Se statuses of properly supplemented Belgian Blue cows on commercial farms and (2) the relationship between Se concentrations in plasma and colostrum. The secondary objectives were to assess relationships between plasma or colostrum Se concentrations and dietary Se supplementation as well as blood biomarkers. Blood and colostrum samples were collected from 49 Belgian Blue cows on five commercial farms in Belgium. They received five different rations with Se supplementation ranging from 0.5 to 2 ppm, including 20% to 83% in organic form. Results showed that the average Se concentration was 90 ± 15 µg/L in plasma and 79 ± 26 µg/L in colostrum, consistent with previous studies on well-supplemented cows. No relationship was observed between Se concentrations in plasma and colostrum, suggesting that colostrum Se testing would be a complementary indicator for improving calf Se supplementation. Relationships between plasma or colostrum Se concentrations and dietary Se or blood biomarkers emphasized the complexity of Se metabolism in observational studies under field conditions.

Different dietary sources of selenium alter meat quality, shelf life, selenium deposition, and antioxidant status in Hu lambs

Thirty-two male Hu lambs (32.31 ± 3.31 kg; 4-months-old) were randomly assigned to four treatments: (1) control (CON), (2) selenium-enriched yeast (SeY, 0.8 mg/kg), (3) selenized glucose (SeGlu, 0.8 mg/kg), and (4) sodium selenite (SS, 0.8 mg/kg) to evaluate their effects on Hu lamb production and slaughter performance, antioxidant capacity, hematological parameters, meat quality and shelf-life. The production and slaughter performances were not different (P > 0.05) among treatments. SeGlu and SeY increased (P < 0.05) the total antioxidant capacity in serum and muscle selenium content while decreasing (P < 0.05) the malondialdehyde (MDA) contents both in serum and muscle. SeGlu extended muscle shelf-life by 7.7 h compared with CON and decreased (P < 0.05) yellowness (b*) and lightness (L*) in meat stored for 24 h. In summary, the effects of SeGlu were similar to those of SeY and better than those of SS in improving serum and muscle antioxidant status, prolonging muscle shelf-life, and increasing selenium deposition in muscle.

Form of dietary selenium affects mRNA encoding cholesterol biosynthesis and immune response elements in the early luteal phase bovine corpus luteum

Widespread regions of the southeast United States have soils, and hence forages, deficient in selenium (Se), necessitating Se supplementation to grazing cattle for optimal immune function, growth, and fertility. We have reported that supplementation with an isomolar 1:1 mix (MIX) of inorganic (ISe) and organic (OSe) forms of Se increases early luteal phase (LP) progesterone (P4) above that in cows on ISe alone. Increased early LP P4 advances embryonic development. Our objective was to determine the effect of form of Se on the transcriptome of the early LP corpus luteum (CL) with the goal of elucidating form of Se-regulated processes affecting luteal steroidogenesis and function. Non-lactating, 3-yr-old Angus-cross cows underwent 45-d Se-depletion, then repletion periods, and then at least 90 d of supplementation (TRT) with 35 ppm Se/d as either ISe (n = 5) or MIX (n = 5). CL were then recovered on day 7 of the estrous cycle, total RNA isolated, and the effect of TRT on the luteal transcriptome evaluated using bovine gene 1.0 ST arrays (Affymetrix, Inc., Santa Clara, CA). The abundance of transcripts in each CL was subjected to one-way ANOVA using Partek Genomic Suite software to determine TRT effects. Microarray analysis indicated a total of 887 transcripts that were differentially expressed and functionally annotated, with 423 and 464 up- and down-regulated (P < 0.05) in MIX vs. ISe CL, respectively. Bioinformatic analysis (Ingenuity Pathway Analysis) revealed the top TRT-affected canonical pathways to include seven specific to cholesterol biosynthesis and two to inflammatory responses. Results from the microarray analysis were corroborated by targeted real-time PCR. MIX CL had increased (P < 0.05) abundance of transcripts regulating cholesterol biosynthesis including DHCR7, DHCR24, and CYP51A1 (fold changes of 1.65, 1.48, and 1.40, respectively), suggesting MIX-induced increases in P4 to be due, in part, to increased availability of substrate to luteal cells. In addition, MIX CL had increased (P < 0.05) abundance of immune-response transcripts including C1QC, FAS, ILR8B, and IL1R1 (fold changes of 2.30, 1.74, 1.66, and 1.63, respectively). SREBF1 mRNA was also increased (1.32-fold, P < 0.05) in the MIX CL, which increases cholesterol synthesis and stimulates IL1B, linking effects of form of supplemental Se (TRT) on cholesterol biosynthesis and immune function in the CL.

Serum and Hair Trace Element and Mineral Levels in Dairy Cows in Relation to Daily Milk Yield

The objective of the present study was to assess hair and serum trace element and mineral levels in dairy cows in relation to daily milk yield. A total of 70 healthy 5-6-year-old Simmental cows were divided into two groups (n = 35) with high and low daily milk yield using median as a cut-off value. Hair and serum trace element and mineral content was evaluated using inductively coupled plasma mass-spectrometry. A nearly twofold difference in daily milk yield (43.8 ± 9.7 vs 21.3 ± 7.1 L/day, p < 0.001) was significantly associated with 11% lower hair Cu (p = 0.043) and 35% higher Se levels (p = 0.058) content when compared animals with lower daily milk yield. Serum trace element levels were found to be more tightly associated with milk productivity in dairy cows. Particularly, serum levels of Se and Zn were found to be 73 and 35% higher in cows with higher milk productivity in comparison to animals with lower milk production, respectively. Serum Co levels also tended to increase with higher milk productivity. Serum minerals including Ca, Mg, and P were also found to be higher in highly productive cows by 6%, 14%, and 71%, respectively. The overall regression model based on serum trace element and mineral levels accounted for 38% of daily milk production variability. Generally, improvement of essential trace element and mineral supply, as well as prevention of copper overload in dairy cows, may be considered the potential tool for modulation of milk productivity.

Effects of Hydroxyselenomethionine with Symmetrical and Chelated Chemical Structure on Lactation Performances, Anti-Oxidative Status and Immunities, Selenium Transfer Efficiencies for Early-Lactating Dairy Cows

The current study was conducted to investigate effects of hydroxyselenomethionine (HMBSe) with symmetrical and chelated chemical structure, a novel organic selenium (Se) source, on lactation performance, anti-oxidative status and immunities, and transfer efficiencies for early lactation dairy cows compared with that of sodium selenite (SS). Forty-five multiparous early-lactating dairy cows with similar days in milk, 56.0 d and milk yield 36.1 kg/d, were fed with same basal diet containing 0.04 mg of Se/kg of dry matter (DM) basis. They were assigned to 1 of 3 treatments according to one-way ANOVA design: control (basal diet, without Se supplementation), SS (0.30 mg of Se/kg of DM), or HMBSe (0.30 mg of Se/kg of DM). The experiment lasted for 9 weeks, with the first week as adaptation. Results showed that the organic HMBSe cows increased the milk yield, 4% fat-corrected milk yield, the numbers of red blood cells in whole blood, Se concentrations in milk and serum, ratio of milk to serum significantly (P < 0.01); feed efficiency, energy-corrected milk yield, contents of superoxide dismutase in serum, hemoglobin, and the numbers of white blood cells in whole blood significantly (P < 0.05) compared to control and SS. Moreover, HMBSe cows had trends to increase glutathione peroxidase activities (P = 0.09), total antioxidant capacity (P = 0.06), and had trends to decrease the contents of malonaldehyde (P = 0.07) in serum compared to control and SS. In conclusion, HMBSe was more effective on the lactation performances, anti-oxidative status, and immunities and Se transfer efficiencies for early-lactating dairy cows compared to control and SS, which was very meaningful to develop the enriched Se milk products.

Role of Selenium and Vitamins E and B9 in the Alleviation of Bovine Mastitis during the Periparturient Period

Mastitis (inflammation of the mammary gland) commonly occurs in dairy cattle during the periparturient period (transition period), in which dairy cattle experience physiological and hormonal changes and severe negative energy balance, followed by oxidative stress. To maintain successful lactation and combat negative energy balance (NEB), excessive fat mobilization occurs, leading to overproduction of reactive oxygen species (ROS). Excessive fat mobilization also increases the concentrations of nonesterified fatty acids (NEFA) and β-hydroxybutyric acid (BHB) during the periparturient period. In addition, the excessive utilization of oxygen by cellular respiration in the mammary causes abnormal production of oxidative stress (OS). OS impairs the immunity and anti-inflammatory efficiency of periparturient dairy cattle, increasing their susceptibility to mastitis. To alleviate oxidative stress and subsequent mastitis, antioxidants are supplemented to dairy cattle from an external source. Extensive studies have been conducted on the supplementation of selenium (Se) and vitamins E and B9 to mitigate mastitis during the transition period in dairy cattle. Altogether, in the current review, we discuss the research development on bovine mastitis and its major causes, with special emphasis on oxidative stress during the transition period. Moreover, we discuss the antioxidant, immunoregulatory, and anti-inflammatory properties of Se and vitamins E and B9 and their role in the control of bovine mastitis in periparturient dairy cattle.

Effects of Selenium as a Dietary Source on Performance, Inflammation, Cell Damage, and Reproduction of Livestock Induced by Heat Stress: A Review

Heat stress as a result of global warming has harmful consequences for livestock and is thus becoming an urgent issue for animal husbandry worldwide. Ruminants, growing pigs, and poultry are very susceptible to heat stress because of their fast growth, rapid metabolism, high production levels, and sensitivity to temperature. Heat stress compromises the efficiency of animal husbandry by affecting performance, gastrointestinal health, reproductive physiology, and causing cell damage. Selenium (Se) is an essential nutritional trace element for livestock production, which acts as a structural component in at least 25 selenoproteins (SELs); it is involved in thyroid hormone synthesis, and plays a key role in the antioxidant defense system. Dietary Se supplementation has been confirmed to support gastrointestinal health, production performance, and reproductive physiology under conditions of heat stress. The underlying mechanisms include the regulation of nutrient digestibility influenced by gastrointestinal microorganisms, antioxidant status, and immunocompetence. Moreover, heat stress damage to the gastrointestinal and mammary barrier is closely related to cell physiological functions, such as the fluidity and stability of cellular membranes, and the inhibition of receptors as well as transmembrane transport protein function. Se also plays an important role in inhibiting cell apoptosis and reducing cell inflammatory response induced by heat stress. This review highlights the progress of research regarding the dietary supplementation of Se in the mitigation of heat stress, addressing its mechanism and explaining the effect of Se on cell damage caused by heat stress, in order to provide a theoretical reference for the use of Se to mitigate heat stress in livestock.

Milk selenium content and speciation in response to supranutritional selenium yeast supplementation in cows

The effects of selenium (Se) yeast supplementation on performance, blood biochemical and antioxidant parameters, and milk Se content and speciation were evaluated. Thirty-six mid-lactation Holstein dairy cows were randomly assigned to 1 of 3 treatments: 1) control (basal diet containing Se at 0.11 mg/kg DM), 2) basal diet + 0.5 mg supplemental Se/kg DM (SY-0.5), and 3) basal diet + 5 mg supplemental Se/kg DM (SY-5). Selenium was supplemented as Se yeast. The trial consisted of a 1-week pretrial period and an 8-week experimental period. Milk somatic cell score decreased with SY-5 supplementation (P < 0.05), but other performance parameters were not affected (P > 0.05). The serum Se concentration increased with the increasing levels of Se yeast supplementation (P < 0.05), however, blood biochemical parameters showed few treatment effects. The antioxidant capacity of dairy cows was improved with Se yeast supplementation reflected in increased serum glutathione peroxidase activity (P < 0.05) and total antioxidant capacity (P = 0.08), and decreased malondialdehyde concentration (P < 0.05). Milk total Se concentration increased with Se dose (P < 0.05). Also, the selenomethionine concentration increased with Se dose from 13.0 ± 0.7 μg/kg in control to 33.1 ± 2.1 μg/kg in SY-0.5 and 530.4 ± 17.5 μg/kg in SY-5 cows (P < 0.05). Similarly, selenocystine concentration increased from 15.6 ± 0.9 μg/kg in control and 18.9 ± 1.1 μg/kg in SY-0.5 to 22.2 ± 1.5 μg/kg in SY-5 cows (P < 0.05). In conclusion, Se yeast is a good organic Se source to produce Se-enriched cow milk with increased Se species including selenomethionine and selenocystine. The results can provide useful information on milk Se species when a high dose Se yeast was supplemented in the cow diet.

Effects of Supranutritional Selenium Nanoparticles on Immune and Antioxidant Capacity in Sprague-Dawley Rats

The present study was conducted to investigate the effects of supranutritional selenium nanoparticles (SeNPs) on immune and antioxidant capacity in rats. Forty male Sprague-Dawley (SD) rats were randomly divided into four groups and given intragastric administration of SeNPs at doses of 0, 0.2, 0.4, and 0.8 mg Se/kg BW, respectively, for 2 weeks. Serum immune parameters, serum and organic tissues (liver, heart, kidney) antioxidant indices, and liver mRNA expression of glutathione peroxidase 1 (GPx1) and glutathione peroxidase 4 (GPx4) were examined. The results showed that supranutritional doses of 0.4 and 0.8 mg Se/kg BW SeNPs promoted the immune responses in serum. SeNPs administration improved antioxidant capacity in the liver and kidney, and the best improvement on antioxidant capacity was found in the kidney. Furthermore, intragastric administration of SeNPs upregulated mRNA expression of GPx1 and GPx4 in the liver. The results obtained indicated that SeNPs administration at supranutritional levels had beneficial effects on immune and antioxidant capacity and supplemental SeNPs at dose of 0.4 mg Se/kg BW exhibited the best response in SD rats.

The Antioxidant Properties of Selenium and Vitamin E; Their Role in Periparturient Dairy Cattle Health Regulation

Dairy cattle experience health risks during the periparturient period. The continuous overproduction of reactive oxygen species (ROS) during the transition from late gestation to peak lactation leads to the development of oxidative stress. Oxidative stress is usually considered the main contributor to several diseases such as retained placenta, fatty liver, ketosis, mastitis and metritis in periparturient dairy cattle. The oxidative stress is generally balanced by the naturally available antioxidant system in the body of dairy cattle. However, in some special conditions, such as the peripariparturient period, the natural antioxidant system of a body is not able to balance the ROS production. To cope with this situation, the antioxidants are supplied to the dairy cattle from external sources. Natural antioxidants such as selenium and vitamin E have been found to restore normal health by minimizing the harmful effects of excessive ROS production. The deficiencies of Se and vitamin E have been reported to be associated with various diseases in periparturient dairy cattle. Thus in the current review, we highlight the new insights into the Se and vitamin E supplementation as antioxidant agents in the health regulation of periparturient dairy cattle.

Revisiting the Effects of Different Dietary Sources of Selenium on the Health and Performance of Dairy Animals: a Review

Selenium (Se) is one of the most important essential trace elements in livestock production. It is a structural component in at least 25 selenoproteins such as the iodothyronine deiodinases and thioredoxin reductases as selenocysteine at critical positions in the active sites of these enzymes. It is also involved in the synthesis of the thyroid hormone and influences overall body metabolism. Selenium being a component of the glutathione peroxidase enzyme also plays a key role in the antioxidant defense system of animals. Dietary requirements of Se in dairy animals depend on physiological status, endogenous Se content, Se source, and route of administration. Most of the dietary Se is absorbed through the duodenum in ruminants and also some portion through the rumen wall. Inorganic Se salts such as Na-selenate and Na-selenite have shown lower bioavailability than organic and nano-Se. Selenium deficiency has been associated with reproductive disorders such as retained placenta, abortion, early embryonic death, and infertility, together with muscular diseases (like white muscle disease and skeletal and cardiac muscle necrosis). The deficiency of Se can also affect the udder health particularly favoring clinical and subclinical mastitis, along with an increase of milk somatic cell counts in dairy animals. However, excessive Se supplementation (5 to 8 mg/kg DM) can lead to acute toxicity including chronic and acute selenosis. Se is the most vital trace element for the optimum performance of dairy animals. This review focuses to provide insights into the comparative efficacy of different forms of dietary Se (inorganic, organic, and nano-Se) on the health and production of dairy animals and milk Se content.

Nano-selenium Supplementation Increases Selenoprotein (Sel) Gene Expression Profiles and Milk Selenium Concentration in Lactating Dairy Cows

Supplementation with selenium is common for dairy cows, but the importance of selenium source is not clear. This study aimed to compare nano-selenium (Nano-Se) and sodium selenite supplements for dairy cows on lactation performance, milk Se levels and selenoprotein (Sel) gene expression. Twelve multiparous Holstein cows were randomly divided into two groups: a control group fed a basal diet plus 0.30 mg Se/kg of DM as sodium selenite or Nano-Se for 30 days. Dry matter intake, milk yield and composition were not affected by dietary Se source (P > 0.05); however, the milk total Se levels and milk glutathione peroxidase (GSH-Px) activities were higher with Nano-Se supplementation than sodium selenite (P < 0.05). At the end of the experiment, Nano-Se supplementation significantly increased plasma Se levels and GSH-Px activity, compared with the sodium selenite supplement. The mRNA expression levels of glutathione peroxidase 1, 2 and 4; thioredoxin reductase 2 and 3; and selenoproteins W, T, K and F were markedly upregulated (P < 0.05) in the mammary gland of the Nano-Se group. Thus, the source of selenium plays an important role in the antioxidant status and in particular the Sel gene expression in the mammary glands of dairy cows, both being stimulated by nano sources.

Can Moderate Levels of Organic Selenium in Dairy Cow Feed Naturally Enrich Dairy Products?

Simple Summary

Milk and dairy products, such as cheese and yogurt, can be useful sources of selenium-enriched products to increase human Se intake. We studied the effect of dairy cow feed supplementation with inorganic plus organic Se on milk yield, and on the Se enrichment of milk and dairy products to obtain naturally enriched products. Two groups of lactating cows were assigned to two feeding treatments, both with 0.240 mg Se/kg of ration dry matter: One was supplemented with inorganic Se, the other with a 60/40 ratio of inorganic Se/organic Se. The results showed that the inclusion of inorganic plus organic Se did not affect the yield or basic chemical composition of milk; however, the Se content of milk was higher with inorganic plus organic Se supplementation. Cheese from cows fed inorganic plus organic Se had a higher Se content, although this effect was not observed for yogurt. At a moderate level in the diet, sodium selenite plus Se yeast may be more effective than only inorganic Se, increasing the Se concentration in milk and cheese.

Abstract

This work studied the effect of dairy cow ration supplementation with inorganic plus organic Se on metabolic status, milk yield, and the quality of milk and dairy products, especially its Se content. Twenty multiparous Holstein Friesian lactating cows were assigned to two feeding treatments. The cows were fed with 22.5 kg dry matter (DM) of total mixed ration (11.75 kg DM of forage plus 10.75 kg DM of concentrate) by head. There were two different concentrates with the same Se content (0.240 mg/kg of ration DM) but with different Se sources: The control (CON) was supplemented with inorganic Se (sodium selenite); and the other (IOSe) was supplemented with sodium selenite plus organic Se (Sel-Plex^®), at 0.144 and 0.096 mg Se/kg of ration DM, respectively. The results indicated that, in general, the IOSe treatment did not modify the metabolic profile, and even decreased the total oxidant status (p < 0.05) and did not lead to a deterioration of quality and yield of milk. However, milk and cheese from IOSe had higher Se content (an increase of 29.7% and 38.2%, respectively) than CON (p < 0.01), but this effect was not observed in yogurt. In general, physical or sensorial parameters of cheeses did not show differences between treatments. Moderate inorganic plus organic Se supplementation may be more effective than inorganic Se, increasing the Se content in milk and cheese, without causing a deterioration in quality or productive parameters.

Comparative iTRAQ Proteomics Reveals Multiple Effects of Selenium Yeast on Dairy Cows in Parturition

The effects of prepartum dietary supplementation with selenium yeast on low abundant plasma proteins in postpartum dairy cows are not known. In this study, 24 healthy parturient dairy cows were divided into two groups (group C, a control group, and group T, a selenium treatment group). Low abundance proteins were extracted from plasma samples of calving cows, and 542 proteins were identified by isobaric tags for relative and absolute quantitation (iTRAQ) proteomic analysis. Dietary supplementation with selenium yeast caused differential abundance of 48 proteins with a fold change of more than 1.2 or less than 0.83 (p < 0.05); 14 proteins were upregulated and 34 were downregulated. The top five gene ontology (GO) enrichment terms for the differentially expressed proteins were protein homotetramerization (or tetramerization), defense response to bacteria or fungus, acute-phase reactions, nucleotide catabolic process, and positive regulation of lipid metabolic process. All proteins involved in acute-phase reactions were downregulated, indicating that selenium ameliorates systemic inflammation. The vast majority of proteins involved in the defense response to microorganisms were downregulated, thereby affecting innate immunity. The decreased abundance of apolipoprotein A-I and apolipoprotein C-II, critical proteins for positive regulation of lipid metabolism, indicated that selenium may optimize lipid metabolism. The iTRAQ results showed that prenatal supplementation with yeast selenium can relieve systemic inflammation after parturition. Moreover, selenium may reduce the effects of metabolic diseases, which can improve glyconeogenesis and prevent ketosis and fatty liver.

Effect of Lonicera japonica extract on lactation performance, antioxidant status, and endocrine and immune function in heat-stressed mid-lactation dairy cows

Here, we examined the effects of Lonicera japonica extract (LJE) on lactation performance, antioxidant status, and endocrine and immune function in heat-stressed mid-lactation dairy cows. Twenty-four healthy Chinese Holstein mid-lactation dairy cows, all with similar milk yield (30.0 ± 1.0 kg/d), parity (2.5 ± 0.3), and days in milk (105 ± 5 d) were allocated to 4 groups using a randomized complete block design: a negative control group (without LJE supplementation; CON) and groups that received LJE at 14, 28, and 56 g/d. The experiment lasted 10 wk over a hot summer, with a pre-feeding period of 2 wk. Cows were exposed to heat stress, as the average temperature-humidity index was greater than 72. The results showed that LJE had no effect on respiration rate; however, it reduced the rectal temperature of dairy cows experiencing heat stress in both a linear and quadratic manner; the lowest (39.03°C) was recorded for the LJE-28 group, lower than the CON group. Supplementation with LJE did not affect dry matter intake, milk yield, or milk composition. The majority of biochemical parameters in serum were unaffected by supplementation with different amounts of LJE; the exception was creatinine, which was reduced quadratically. Compared with the CON group, serum triiodothyronine concentrations increased significantly in the LJE-28 group. Addition of LJE to the diet increased thyroxine concentrations quadratically; values peaked at 18.62 ng/mL in the LJE-28 group. Furthermore, supplementation with increasing amounts of LJE quadratically increased the activity of glutathione peroxidase and total antioxidant capacity in serum but decreased concentration of malondialdehyde. Although we detected no differences in the concentrations of IgA, IgM, or cytokines, dairy cows in the LJE-28 group had higher IgG and IL-4 concentrations than did cows in the CON group. Supplementation with LJE increased concentrations of IgG and IL-4 in the serum quadratically but decreased that of IL-2. Finally, heat shock protein 72 concentrations in the serum tended to fall quadratically as the amount of LJE increased. In summary, LJE had no negative effects on lactation performance but helped to alleviate heat stress by improving antioxidant status and promoting endocrine and immune functions. Supplementation with LJE at 28 g/d is recommended for lactating dairy cows experiencing heat stress during hot summers.

The protective effect of selenium on the lipopolysaccharide-induced oxidative stress and depressed gene expression related to milk protein synthesis in bovine mammary epithelial cells

The objective of this study was to determine the effects of selenium (Se) on antioxidative function and the synthesis of milk protein in bovine mammary epithelial cells (BMECs). Two experiments were conducted using a single-factor completely randomized design study. In part I, BMECs were randomly divided into seven groups: control (without Se) and six Se treatments (10, 20, 50, 100, 150, and 200 nmol/L). In part II, based on the results of part I, we used lipopolysaccharide (LPS) as the induced stress source to analyze the protective effect of Se on LPS-induced oxidative damage and the influence on milk protein synthesis of BMECs. BMECs were randomly divided into eight groups: control (without Se and LPS), LPS treatment (only LPS), and six Se treatments with LPS (LS10 to LS200). Treatment of BMECs with Se was found to significantly improve cell proliferation and antioxidant function. LPS could induce oxidative damage which significantly inhibited cell proliferation and antioxidant function in BMECs. Se had a protective effect on the oxidative damage of BMECs induced by LPS. Additionally, our results indicated that LPS damage downregulated the gene expression of milk protein synthesis. Se effectively relieved the inhibition due to LPS-induced oxidative damage on the synthesis of milk protein, and Se concentrations of 50 to 200 nmol/L showed the best effect. In conclusion, Se at concentrations of 50 to 100 nmol/L is better for antioxidant function but had no effect on milk protein synthesis in healthy BMECs. Se ameliorated the damage caused by LPS-induced by improving levels of antioxidant markers and upregulating milk protein synthesis and the expression of genes associated with milk protein in BMECs.

Evaluation of male infertility treatment following Rhus coriaria extract administration on rats exposed to morphine

Morphine is the most common analgesic drug that is widely used in post-operative interventions. This drug causes free radical accumulation leading to spermatogenesis failure. Antioxidant agents like Sumach (Rhus coriaria) neutralize cellular free radicals. In this study, the properties of antioxidative, modulative of inflammatory cytokines, and apoptotic genes following Sumach extract administration on morphine-induced fertility destruction in male Wistar rats was evaluated. Sixty-four animals were grouped (n = 8) including; 1: control, 2: morphine, 3-5: Sumach (200, 400, 800 mg/kg), and 6-8: morphine + Sumach. Hydroalcoholic extract of Sumach seeds was prepared. Treatments with Sumach extract were applied orally and intraperitoneally daily for 8 weeks. The P53, Bcl2 and caspase-3 genes expression were measured by real-time PCR. Cytokines involved in inflammation were evaluated by ELISA. Sperm parameters, total antioxidant capacity (TAC), testosterone, and germinal layer height (GLH) were assessed. All parameters (investigated in this study) in Morphine group reduced significantly than the control group (P ˂ 0.01) (except P53 and caspase-3 genes expression and inflammatory cytokine which were improved). All factors in Sumach and Sumach + Morphine groups were significantly enhanced compared to the Morphine group (P ˂ 0.01) (except P53 and caspase-3 genes expression and inflammatory cytokine which were declined). Morphine disrupted the physiological function of male fertility system. Besides, all doses of Sumach showed no therapeutic changes compared to the control group. Sumach with anti-infertility features compensates the toxic effect of Morphine administration.

Comparison of Selenium Source in Preventing Oxidative Stress in Bovine Mammary Epithelial Cells

Oxidative stress can cause cell damage. Hydroxy-selenomethionine (HMSeBA) is an organic Se source with emerging antioxidant advantages. The objective of this study was to compare the effects of HMSeBA, selenomethionine (SeMet) and sodium selenite (SS) on the antioxidant response and the ability to resist oxidative stress in bovine mammary epithelial cells (BMEC). The BMEC were treated with 0 (Control), 20, 50, 100 and 150 nM HMSeBA, 100 nM SeMet and100 nM SS for 48 h. The results showed that HMSeBA and SeMet treatments had higher glutathione peroxidase (p < 0.01) and catalase (p = 0.01) activities and mRNA abundance of GPX3 (p = 0.02), but lower superoxide dismutase activity compared with SS (p = 0.04). The catalase activity (p < 0.05) and mRNA abundance of GPX3 (p = 0.04) changed in a quadratic manner with the increase of HMSeBA levels. To assess the potential protection of different Se sources against oxidative stress on BMEC, 0 or 50 μM H2O2 was added to BMEC culture for 3 h after Se pre-treatment for 48 h. The results showed that HMSeBA and SeMet, which did not differ (p > 0.05), but further decreased malondialdehyde and reactive oxygen species production compared with SS (p < 0.05). In conclusion, HMSeBA showed an enhanced cellular antioxidant status to resist oxidative damage induced by H2O2 when compared with SS, whereas the effects were similar to SeMet.

Mechanism Underlying the Protective Effect of Selenium on NO-Induced Oxidative Damage in Bovine Mammary Epithelial Cells

This experiment was conducted to investigate the effects and mechanism of selenium (Se) on antioxidant and immune function of bovine mammary epithelial cells (BMEC) damaged by nitric oxide (NO). The third-generation BMEC was randomly divided into eight treatments with six replicates. The BMEC in the control group was cultured in the medium without Se and diethylenetriamine/NO (DETA/NO) for 30 h. For the DETA/NO group and Se protection group BMEC were exposed to different concentrations of Se (0, 10, 20, 50, 100, 150, and 200 nmol/L) for 24 h, followed by treatment with DETA/NO (1000 μmol/L) for 6 h. Compared with the control group, DETA/NO decreased proliferation rate and activity of thioredoxin reductase (TrxR; P < 0.05). Additionally, DETA/NO decreased the gene expression of both nuclear factor-E2-related factor 2 (Nrf2) and TrxR, as well as the protein expression level of TrxR. However, the activity, and expression levels of inducible nitric oxide synthase (iNOS), as well as the concentration and gene expression level of interleukin-1β (IL-1β) and the concentration of NO significantly increased (P < 0.05). The gene expression levels of indexes related to the mitogen-activated protein kinase (MAPK) signaling pathway showed similar changes. Treatment of BMEC with Se significantly reversed DETA/NO-induced changes in a linear or quadratic dose-dependent manner (P < 0.05), with greatest benefit at 50 nmol/L. These data suggests that Se improves the antioxidant function of BMEC, and protects cells from DETA/NO-induced oxidative damage, primarily by enhancing the activity of TrxR and decreasing the concentration of NO through modulation of Nrf2 and MAPK signaling pathways.

Revisiting Oxidative Stress and the Use of Organic Selenium in Dairy Cow Nutrition

In commercial animals production, productive stress can negatively impact health status and subsequent productive and reproductive performance. A great body of evidence has demonstrated that as a consequence of productive stress, an overproduction of free radicals, disturbance of redox balance/signaling, and oxidative stress were observed. There is a range of antioxidants that can be supplied with animal feed to help build and maintain the antioxidant defense system of the body responsible for prevention of the damaging effects of free radicals and the toxic products of their metabolism. Among feed-derived antioxidants, selenium (Se) was shown to have a special place as an essential part of 25 selenoproteins identified in animals. There is a comprehensive body of research in monogastric species that clearly shows that Se bioavailability within the diet is very much dependent on the form of the element used. Organic Se, in the form of selenomethionine (SeMet), has been reported to be a much more effective Se source when compared with mineral forms such as sodium selenite or selenate. It has been proposed that one of the main advantages of organic Se in pig and poultry nutrition is the non-specific incorporation of SeMet into general body proteins, thus forming an endogenous Se reserve that can be utilized during periods of stress for additional synthesis of selenoproteins. Responses in ruminant species to supplementary Se tend to be much more variable than those reported in monogastric species, and much of this variability may be a consequence of the different fates of Se forms in the rumen following ingestion. It is likely that the reducing conditions found in the rumen are responsible for the markedly lower assimilation of inorganic forms of Se, thus predisposing selenite-fed animals to potential Se inadequacy that may in turn compromise animal health and production. A growing body of evidence demonstrates that organic Se has a number of benefits, particularly in dairy and beef animals; these include improved Se and antioxidant status and better Se transfer via the placenta, colostrum, and milk to the newborn. However, there is a paucity in the data concerning molecular mechanisms of SeMet assimilation, metabolism and selenoprotein synthesis regulation in ruminant animals, and as such, further investigation is required.

Bioefficacy of hydroxy-selenomethionine as a selenium supplement in pregnant dairy heifers and on the selenium status of their calves

This study aimed to determine the effects of supplementing pregnant heifers with the organic selenium (Se) source 2-hydroxy-4-methylselenobutanoic acid (HMSeBA) during the last 8 wk of pregnancy on dam and calf Se status. A total of 42 in-calf heifers were recruited to the study and randomly allocated to 1 of 3 treatments; a negative control (Con), sodium selenite (NaSe), or HMSeBA. Animals were blocked by body weight, body condition score, and expected calving date before treatment allocation. Following enrollment, all animals underwent a 7-wk wash-out period, after which they received their respective supplements, top-dressed daily onto a basal diet for the last 8 wk of pregnancy. Heifer blood samples were taken at weekly intervals from enrollment until 2 wk before expected calving date and as soon as possible after calving for determination of whole-blood glutathione peroxidase activity (GSH-Px) and plasma Se and malondialdehyde (MDA) concentrations. Selenized AA were determined in plasma samples taken at 3 wk precalving. A colostrum sample was taken as close to parturition as possible for determination of colostrum total Se, selenized AA, and IgG concentration. Calves were blood sampled as close to birth as possible for determination of whole-blood GSH-Px activity and plasma Se and MDA concentrations. Differences in whole-blood GSH-Px activity did not become apparent until calving; GSH-Px activity was lowest in Con heifers but similar between NaSe and HMSeBA heifers. Plasma Se was lowest in unsupplemented heifers and greatest in those supplemented with HMSeBA; this was attributable to greater selenomethionine concentrations in the plasma of HMSeBA heifers. Colostrum Se was lowest in Con heifers and greatest in HMSeBA heifers. The greater Se concentration of HMSeBA heifers was attributable to a greater proportion of total Se comprising selenocysteine; the reason for this is not known. There was no effect of supplementation on colostrum IgG concentration. Plasma Se was lowest in calves born to Con heifers and greatest in those born to HMSeBA heifers. There were no effects of treatment on calf whole-blood GSH-Px activity or plasma MDA concentration. The enhanced Se status associated with HMSeBA supplementation is likely a consequence of selenomethionine supply and may confer benefits to both the dam and her calf postpartum.

Effect of hydroxyselenomethionine on lactation performance, blood profiles, and transfer efficiency in early-lactating dairy cows

The current study investigated the effects of hydroxyselenomethionine (HMBSe), a novel organic selenium (Se) additive, on lactation performance, blood profiles, antioxidative status, and transfer efficiency of Se in early-lactation dairy cows. Sixty multiparous early-lactating dairy cows with similar days in milk (57 d; standard deviation = 9.9) and milk yield (36.5 kg/d; standard deviation = 1.42) were fed a basal diet containing 0.04 mg of Se/kg (dry matter basis). These cows were assigned to 1 of 4 groups following a randomized complete block design as follows: control (basal diet) or HMBSe addition (0.1, 0.3, or 0.5 mg of Se/kg of dry matter). The experiment lasted for 13 wk, with the first week as adaptation. The results showed that milk yields (raw, protein, and lactose) and feed efficiency were improved in a quadratic manner following increased dietary HMBSe addition, whereas energy-corrected milk, 4% fat-corrected milk, and total solid yields tended to be enhanced quadratically. In terms of whole-blood variables, red blood cell and white blood cell levels were increased quadratically, whereas hemoglobin concentration increased linearly with increased HMBSe addition. Plasma nonesterified fatty acid concentrations tended to increase linearly along with HMBSe addition. Plasma superoxide dismutase activity increased quadratically with increased HMBSe addition. The total antioxidant capacity in plasma tended to improve quadratically when cows were fed more HMBSe. Moreover, plasma malondialdehyde concentrations of dairy cows tended to decrease in a quadratic manner when dietary HMBSe increased. The Se concentrations in milk, plasma, and milk/plasma ratio increased linearly following increased HMBSe addition. In conclusion, HMBSe improved lactation performance, health status, and milk Se concentrations in early-lactating dairy cows.

The impact of organic vs. inorganic selenium on dairy goat productivity and expression of selected genes in milk somatic cells

The aim of this study was to determine the effect of diet supplemented with selenized yeast (Se-yeast) on milk yield and milk composition of goats and expression of casein and mammary-gland-immune system genes in milk somatic cells (MSC). Twenty-four dairy goats in their second to fourth lactations were divided into control and experimental groups, balanced according to lactation number and breed (Polish White or Fawn Improved). Morning milk and blood samples were collected four times during lactation (on the 21st, 70th, 120th, 180th day after kidding). The control and experimental groups were fed diets with 0.7 mg inorganic Se/goat/day (sodium selenite) or 0.6 mg organic Se/goat/day (selenized yeast), respectively. Milk, fat and protein yields during lactation as well as average somatic cell count, fat, protein and lactose contents in milk were evaluated. Microelements in milk and blood serum and biochemical parameters in blood serum were determined at the beginning and the end of the experiment. The expression levels of the genes encoding αS1-casein (CSN1S1), αS2-casein (CSN1S2), κ-casein (CSN3), interleukin 8 (IL-8), serum amyloid A3 (SAA3), interleukin 1β (IL-1β), bactenecin 7.5 (BAC7.5), bactenecin 5 (BAC5), β2-defensin (GBD2), hepcidin (HAMP), chemokine 4 (CCL4), tumour necrosis factor α (TNFα), toll-like receptor 2 (TLR2), cathelicidin-7 (MAP34) and cathelicidin-6 (MAP28) were determined in MSC. Milk, fat, and protein yields were higher and somatic cell count (SCC expressed as natural logarithm) was lower in the milk of goats fed organic Se. The Se concentration in milk was twice as high in the organic vs. inorganic treatment groups at the end of the experiment, while there were no differences in studied biochemical parameters between groups. The transcript levels of CSN1S2 and BAC7.5 were higher and IL-8 was lower in MSC of Se-yeast treated groups. Such results may indicate better health status of mammary glands of goats treated with organic Se as well as positive impact of selenized yeast on the goat's milk composition. Differences in the IL-1β and IL-8 transcript levels were also noted between the stages of lactation, with the highest expression at the peak of lactation (day 70), highlighting the metabolic burden at this time. We concluded that the Se-yeast supplementation improved the productivity and health status of goats and could have significant economic impact on farmer's income.

Short communication: Effects of different selenium supplements on rumen fermentation and apparent nutrient and selenium digestibility of mid-lactation dairy cows

The aim of this study was to evaluate the dose-dependent effects of a hydroxy-analog of selenomethionine (HMSeBA) on rumen fermentation, apparent nutrient digestibility, and total selenium absorption in mid-lactation dairy cows, and to compare the effects with those of sodium selenite (SS). Fifty mid-lactation dairy cows with similar milk yields, days in milk, and parity were randomly assigned to 1 of 5 treatments according to a randomized complete block design. The cows were fed a basal diet containing 0.06 mg/kg dry matter (DM) of Se (control) or the same basal diet supplemented with SS, yielding 0.3 mg of Se/kg of DM (SS-0.3), or HMSeBA, yielding 0.1, 0.3, or 0.5 mg of Se/kg of DM (SO-0.1, SO-0.3, and SO-0.5, respectively), during the experimental period. The final content of Se in control, SS-0.3, SO-0.1, SO-0.3, and SO-0.5 was 0.06, 0.34, 0.15, 0.33, and 0.52 mg of Se/kg of DM. The experiment lasted for 10 wk, with a pretrial period of 2 wk. Supplementation with HMSeBA altered rumen fermentation by linearly increasing total volatile fatty acids and the molar proportions of propionate and butyrate but decreasing rumen pH, ammonia content, and the ratio of acetate to propionate. Compared with SS, HMSeBA enhanced the molar proportion of propionate in the rumen and the apparent digestibility of crude protein, neutral detergent fiber, acid detergent fiber, and selenium. We demonstrated that HMSeBA promoted rumen fermentation, apparent nutrient digestibility, and selenium absorption, implying that HMSeBA has a greater apparent absorption than SS.

Effect of Organic Selenium Supplementation on Selenium Status, Oxidative Stress, and Antioxidant Status in Selenium-Adequate Dairy Cows During the Periparturient Period

The periparturient period represents a stressful time for dairy cows as they transition from late gestation to early lactation. Oxidation stress occurs during this period owing to the increased metabolic activity. Antioxidants supplementation slightly above the suggested requirements may be beneficial in relieving this kind of stress. The objective of this study was to determine whether supplementing selenium (Se) yeast to diets with adequate Se concentrations affects Se status, oxidative stress, and antioxidant status in dairy cows during the periparturient period. Twenty multiparous Holstein cows were randomly divided into two groups with ten replicates in each group. During the last 4 weeks before calving, cows were fed Se-yeast at 0 (control) or 0.3 mg Se/kg dry matter (Se-yeast supplementation), in addition to Na selenite at 0.3 mg Se/kg dry matter in their rations. The concentrations of Se, reactive oxygen species (ROS), hydrogen peroxide (H₂O₂), hydroxyl radical, malonaldehyde (MDA), α-tocopherol and glutathione (GSH), the activities of glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) and catalase (CAT), and the total antioxidant capacity (T-AOC) in plasma or erythrocyte of dairy cows were measured at 21 and 7 days prepartum, and at 7 and 21 days postpartum. Cows fed Se-yeast supplement during the last 4 weeks of gestation had higher plasma Se and lower MDA concentrations at 7 days prepartum, and at 7 and 21 days postpartum, and had higher whole blood Se and lower plasma ROS and H₂O₂ concentrations at 7 and 21 days postpartum compared with control cows. Se-yeast supplementation increased plasma and erythrocyte GSH-Px activities and erythrocyte GSH concentration at 7 days postpartum as compared to Se-adequate control cows. Compared with control cows, the enhanced SOD and CAT activities, increased α-tocopherol and GSH concentrations, and improved T-AOC in plasma at 7 and 21 days postpartum in Se-yeast-supplemented cows were also observed in this study. The results indicate that feeding Se-adequate cows a Se-yeast supplement during late gestation increases plasma Se status, improves antioxidant function, and relieves effectively oxidative stress occurred in early lactation.

The Protective Effect of Selenium on Bovine Mammary Epithelial Cell Injury Caused by Depression of Thioredoxin Reductase

To elucidate the effect of selenium (Se) on antioxidant function of mammary glands in dairy cows and the underlying mechanism, an experiment was conducted using a single-factor completely randomized design study. Bovine mammary epithelial cells (BMECs) were randomly divided into four groups: control, Se treatment, 2,4-dinitrochlorobenzene (DNCB) inhibition, and Se prevention. Treatment of BMECs with Se was found to significantly reverse decreased cell proliferation and the expression of thioredoxin reductase (TrxR) after DNCB exposure. DNCB-induced activation of apoptosis signaling kinase-1 (ASK-1), which activates the mitogen-activated protein kinase (MAPK) pathway, was reduced in BMECs treated with Se. Additionally, our results indicated that Se treatment resulted in lower intracellular accumulation of arachidonic acid (ARA) and 15-hydroperoxyeicosatetraenoic acid (15-HPETE) due to suppressed expression of cytosolic phospholipase A₂ (cPLA₂) regulated by p38MAPK and c-Jun N-terminal kinase (JNK) in DNCB-stimulated BMECs. Taken together, these findings suggest that Se treatment improved the antioxidant function of dairy cow mammary glands and protected cells from oxidative damage primarily by increasing the activity of TrxR, inhibiting the activation of the MAPK signaling pathway, and thus decreasing the content of ARA and its related metabolites.

Supplemented Organic and Inorganic Selenium Affects Milk Performance and Selenium Concentration in Milk and Tissues in the Guanzhong Dairy Goat

Trace amounts of selenium (Se) are essential for several organisms, and deficiencies therein have adverse effects on growth, development, and reproduction; this is particularly significant in animals raised for milk and livestock production. To study the effect of Se on Guanzhong dairy goats, their diets were supplemented with different sources (inorganic or organic) and Se concentrations (0.2 or 0.4 mg Se/kg). A non-Se-fortified basal diet served as a negative control, and a sixth treatment group received both inorganic and organic Se sources (0.2 mg Se/kg diet each). Dietary Se supplementation increased milk production, with organic Se being more effective than inorganic Se. Selenium supplementation also increased Se concentration and glutathione peroxidase activity in whole blood, with organic Se more effective than inorganic Se at the same Se concentration. With increasing Se in diets, the Se content in milk increased markedly, reaching a plateau value at day 30 in all groups, and organic Se (0.4 mg/kg diet) had the best effect. In addition, dietary Se sources and concentrations markedly affected Se concentrations in different tissues and organs. Thus, organic Se supplementation of a basal diet at 0.4 mg/kg is practically applicable for Se-enriched milk and meat production in Guanzhong dairy goats.

Development of mathematical models to predict calcium, magnesium and selenium excretion from lactating Holstein cows

The aim of this study was to develop and evaluate mathematical models that predict mineral excretion, particularly calcium (Ca), magnesium (Mg) and selenium (Se), from lactating dairy cows. Mineral excretion can be affected by several dietary factors. A deficiency in Ca or Mg application to pasture, among other factors, can contribute to grass tetany or wheat pasture poisoning in cows, whereas an excess can cause runoff into water supplies. Manure application with high Se concentration can also result in runoff, causing the bioaccumulation of selenium in aquatic ecosystems, wetland habitats and estuaries, leading to toxic levels in fish. A database composed of studies relating to mineral utilisation in lactating dairy cows conducted after and including the year 2000 was compiled. A meta-analysis was conducted with the aim of creating multiple empirical equations to predict Ca, Mg and Se excretion from lactating dairy cows. Calcium intake, feed Ca content, milk yield, milk protein content and acid detergent fibre content in diet were positively and linearly related to Ca excretion. Dietary crude protein content and milk fat content were negatively related to Ca excretion. Magnesium intake, feed Mg content and milk yield were positively and linearly related to Mg excretion. Selenium content of diet and dry matter intake were linearly and positively related to Se excretion. Two sets of models were developed using or excluding the intake variable and both sets of models were evaluated with independent data originating from commercial herd or individual animals. In general, intake measurements improved prediction when evaluated with independent datasets (root mean square prediction error = 8% to 19% vs 14% to 26% of the average observed value). There were substantial mean biases, particularly those evaluated with data from a commercial farm, perhaps due to inaccurate feed intake measurements. Although there was generally good agreement between predicted and observed mineral excretion, model development and evaluation would benefit from an expanded database.

Hydroxy-selenomethionine: A novel organic selenium source that improves antioxidant status and selenium concentrations in milk and plasma of mid-lactation dairy cows

This study aimed to evaluate the effect of hydroxy-selenomethionine (HMSeBA), a novel organic selenium (Se) source, on milk performance, antioxidative status, and Se concentrations in the milk and plasma of mid-lactation dairy cows compared with that of sodium selenite (SS). Fifty mid-lactation dairy cows with similar days in milk, milk yield, and parity received the same basal diet containing 0.06 mg of Se/kg of DM. They were assigned to 1 of 5 treatments according to a randomized complete block design: negative control (without Se supplementation), SS supplementation (0.3 mg of Se/kg of DM; SS-0.3) or HMSeBA supplementation (0.1, 0.3, or 0.5 mg of Se/kg of DM: SO-0.1, SO-0.3, and SO-0.5, respectively). The experiment lasted for 10 wk, including a pretrial period of 2 wk. The results indicated that neither Se supplementation nor Se source affected dry matter intake, milk yield, milk composition, or blood biochemical parameters, except for milk fat percentage. Simultaneously, milk fat percentage and milk fat yield increased linearly as the quantity of HMSeBA supplementation was increased. Production of 4% FCM and ECM was elevated linearly as dietary HMSeBA increased. The SO-0.3 group showed higher serum activity of glutathione peroxidase, total antioxidant capacity, and superoxide dismutase than the SS-0.3 group, but malondialdehyde content was not affected by Se source. Furthermore, HMSeBA supplementation linearly increased the activities of serum glutathione peroxidase and superoxide dismutase, but decreased malondialdehyde content. Compared with the SS-0.3 group, the SO-0.3 group showed augmented concentrations of total Se in milk and plasma, and total Se milk-to-plasma concentration ratio. In addition, increasing doses of HMSeBA linearly increased the concentrations of total Se in the milk and plasma. This study demonstrates that HMSeBA improves antioxidant status and increases milk and plasma Se concentrations more effectively than SS, indicating that HMSeBA could replace SS as an effective organic Se source for lactating dairy cows.

Selenium-fertilized forage as a way to supplement lactating dairy cows

Fertilization with Se improves forage organic Se concentration, but comparisons with other forms of Se supplementation in feeding lactating dairy cows are scarce. Our objective was to compare the effect of Se-enriched forages to dietary sources of inorganic and organic Se. Digestibility, retention, and balance were assessed by measuring Se concentrations in feces, urine, milk, and blood. The resulting effect on antioxidant status and lactation performance of dairy cows was also determined. High-Se silages [1.72 mg of Se/kg of dry matter (DM)] were produced following a spring application of 2.5 kg/ha of Selcote Ultra, whereas low-Se silages (0.05 mg of Se/kg of DM) were produced in the Se-unfertilized portion of the same fields. After a 77±17 d period of Se depletion, 33 late-lactation primiparous Holstein cows were blocked and randomly assigned for 43 d to 1 of 4 experimental total mixed rations fed for ad libitum intake in an unbalanced randomized block design. Treatments consisted of 4 diets: control with low-Se silages, without Se supplement (0.12±0.04 mg of Se/kg of DM); ISe with low-Se silages and inorganic Se (0.80±0.14 mg of Se/kg of DM); YSe with low-Se silages and organic Se from yeast (0.70±0.11 mg of Se/kg of DM); and FSe with high-Se silages, without Se supplement (0.79±0.14 mg of Se/kg of DM). Organic Se, either as YSe or FSe, was more available and more effective to increase blood and milk Se concentrations than ISe. Moreover, FSe was more available than YSe, as cows fed FSe excreted 16 and 22% less Se (as percentage of intake) in feces and urine, respectively, had higher Se apparent absorption (17%), retention (37%), and balance (45%), and had greater concentration of Se in serum (16%) and milk (11%) than cows fed YSe. Antioxidant status (whole blood and plasma glutathione peroxidase, and milk thioredoxin reductase and malondialdehyde) was not affected by treatments. Dry matter intake, yield of actual, energy-corrected, and fat-corrected milk, as well as milk fat and lactose concentrations, were not affected by the dietary treatments. Cows fed ISe had lower milk protein concentration (3.44%) than cows fed YSe (3.58%) or FSe (3.51%). Cows fed Se-supplemented diets had a lower milk somatic cell count than cows fed the control diet. Results from the current study showed that the production of Se-enriched forages is an effective method to supplement dairy cows in Se as it was more available than YSe, and did not alter antioxidant status and performances of lactating dairy cows.

The in vitro effect of lipopolysaccharide on proliferation, inflammatory factors and antioxidant enzyme activity in bovine mammary epithelial cells

Lipopolysaccharide (LPS) was selected as a stimulus to investigate its effect on cell viability and oxidative stress in bovine mammary epithelial cells (BMEC) by detecting the cell relative growth rate (RGR), antioxidant indicators and inflammatory factors. This information was used to provide the theoretical basis for the establishment of a LPS-induced oxidative damage model. The experiment was divided into two parts. The first part used a two-factor experimental design to determine the appropriate incubation time of LPS by detecting the RGR. The third-passage BMEC were divided into 24 groups with six replicates in each group. The first factor was LPS concentration, which was 0 (control), 0.1, 1.0 and 10.0 μg/mL; the second factor was LPS incubation time (2, 4, 6, 8, 12 and 24 h). The optimum LPS incubation time was 6 h according to the results of the first part of the experiment. The second part of the experiment was conducted using a single-factor experimental design, and the third-passage cells were divided into four groups with six replicates in each group. The cells were incubated with culture medium containing different concentrations of LPS (0 [control], 0.1, 1.0 and 10.0 μg/mL) for 6 h to select the appropriate concentration of LPS to measure the antioxidant indicators and inflammatory factors. The results showed the RGR was significantly reduced as the concentration of LPS and the incubation time increased; the interaction between concentration and incubation time was also significant. The cells treated with 0.1 μg/mL of LPS for 6 h had no significant difference in the activities of glutathione peroxidase (GPx) and superoxide dismutase (SOD) (P > 0.05) compared with the cells in the control group. On the contrary, catalase (CAT) activity and malondialdehyde (MDA) content were markedly lower and higher, respectively, in the 0.1 μg/mL LPS-treated group for 6 h compared with the control group (P < 0.05). The activities of GPx, CAT and SOD in the BMEC treated with 1.0 or 10.0 μg/mL of LPS were significantly lower compared with the cells treated with 0.1 μg/mL of LPS and cells in the control group after 6 h of incubation; however, the opposite trend was detected in MDA content. There was no significant (P > 0.05) difference between the 10.0 and 1.0 μg/mL LPS-treated groups. Compared with the control group, interleukin-1, interleukin-6 and nitric oxide concentrations and the activity of inducible nitric oxide synthase in the 0.1 μg/mL LPS-treated group significantly increased (P < 0.0001), but the levels of tumour necrosis factor did not significantly change (P > 0.05). All of observed indicators were higher in the 1.0 and 10.0 μg/mL LPS-treated groups (P < 0.0001) compared with the other groups, but there was no significant (P > 0.05) difference between the 1.0 and 10.0 μg/mL LPS-treated groups. The results indicated that a concentration of 1.0 μg/mL of LPS and an incubation time of 6 h were the optimum conditions necessary to induce oxidative stress in the BMEC and establish a model for oxidative damage.

Effect of selenium on its content in milk and performance of dairy cows in ecological farming

Currently, the ecological farming is increasingly spread in the European Union. The aim of this relatively young farming method is a friendly approach to agricultural production with an emphasis to deliver healthy raw materials and food to final consumer. Selenium is included in an essential trace micronutrients which are necessary for the proper process of physiological reactions. It is a part of glutathione peroxidase, which is a powerful antioxidant. At present,  selenium-deficiency can occur in feed and food in central Europe. Selenium deficiency is one cause of the higher occurrence of cardiovascular diseases. The aim of the experiment was to study whether the addition of selenium to the diet of dairy cows in ecological farming can increase its concentration in milk and affect quantitative (milk yield) and quality (content of protein, fat, lactose, somatic cells and urea) milk indicators. The experiment included twenty cows of Holstein breed. The first experimental group of cows (n = 10) was fed with selenium in an amount of 0.3 mg.kg-1 (as selenomethionine) in the feed dose. The control group (n = 10) was not fed with the increased selenium in the feed dose. The basic feed dose contained 0.17 mg of Se/kg in the diet. For dairy cows, daily intake was of 20.5 kg of dry matter feed. The duration of the experiment was set at 45 days. The selenium concentration in milk was measured from 0.13 to 0.15 µg.mL-1 in the experimental group of cows during the evaluation. The control group of cows without the addition of selenium to the diet showed a selenium concentration below the detection limit. During the experiment, milk yield, lactose, fat and protein were not affected. A significant decrease (p <0.05) of somatic cells by 58% occurred in milk in the experimental group. The amount of urea was significantly lower in both groups in the experimental (by 52%; p <0.05) and control (50%; p <0.05). These results show that the addition of selenium may increase the selenium concentration in milk (the production of functional food). The addition of selenium reduces the amount of somatic cells, which are the indicators of inflammatory diseases of the mammary gland.