Elevated dietary selenium rescues mitochondrial capacity impairment induced by decreased vitamin E intake in young exercising horses.

Maintenance of mitochondrial health, which is supported in part by dietary antioxidants such as selenium (Se) and vitamin E (vitE), is pertinent to optimizing athletic performance. Deficiencies in Se and vitE negatively impact muscle health but mitochondrial adaptations to various levels of dietary Se and vitE are poorly understood. Young Quarter Horses (mean ± SD: 17.6 ± 0.9 mo) undergoing submaximal exercise training were used to test the hypothesis that a proprietary antioxidant blend containing elevated Se yeast (EconomasE, Alltech, Inc., Nicholasville, KY) would improve mitochondrial characteristics compared to Se at current requirements, even with reduced vitE intake. Horses were balanced by age, sex, body weight (BW), and farm of origin and randomly assigned to one of three custom-formulated concentrates fed at 1% BW (dry matter, DM basis) for 12 wk: 1) 100 IU vitE/kg DM and 0.1 mg Se/kg DM (CON, n = 6); 2) no added vitE plus EconomasE to provide 0.1 mg Se/kg DM (ESe1, n = 6); or 3) no added vitE plus EconomasE to provide 0.3 mg Se/kg DM (ESe3, n = 6). Samples collected at week 0 and 12 were analyzed for serum Se and middle gluteal glutathione peroxidase (GPx) and mitochondrial enzyme activities by kinetic colorimetry and mitochondrial capacities by high-resolution respirometry. Data were analyzed using mixed linear models in SAS v9.4 with repeated measures (time) and fixed effects of time, diet, and time × diet; horse(diet) served as a random effect. Serum Se tended to increase in all horses by week 12 (P = 0.08) but was unaffected by diet. Muscle GPx activity remained similar among all horses throughout the duration of the study. Mitochondrial volume density (citrate synthase [CS] activity), integrative function (cytochrome c oxidase [CCO] activity per mg protein), and integrative (per mg tissue) oxidative (P) and electron transfer (E) capacities increased from week 0 to 12 in all horses (P ≤ 0.01). Intrinsic (relative to CS) CCO activity decreased in all horses (P = 0.001), while intrinsic P and E capacities decreased only in ESe1 horses from week 0 to 12 (P ≤ 0.002). These results suggest that feeding EconomasE to provide 0.3 mg Se/kg DM may prevent adverse effects of removing 100 IU dietary vitE/kg DM on mitochondria in young horses. More research is needed to determine optimal dietary Se and vitE levels in performance horses to maximize mitochondrial energy production.

Mitochondria, colloquially referred to as the powerhouses of the cell, are essential for sustained energy production, which is particularly important for athletic performance. During exercise, reactive oxygen species (ROS) are produced as a normal byproduct of muscle contraction. ROS act as critical signaling molecules and are essential to stimulate adaptation to exercise and other stressors. However, if excess ROS are produced and not sequestered by antioxidants, they may damage cellular components such as lipids, proteins, and DNA. Selenium (Se) and vitamin E (vitE) are two primary dietary antioxidants that aid in quenching excess ROS. To evaluate the impact of Se and vitE on mitochondria, three diets differing in Se and vitE levels were provided to lightly exercising young horses for 12 wk. Skeletal muscle mitochondrial capacity was negatively impacted by the reduction of dietary vitE, which was rescued with elevated dietary Se. The results highlight the importance of determining optimal levels of minerals and vitamins in performance horse diets to ensure proper energy production during exercise.

Use of aspirin to intentionally induce gastrointestinal tract barrier dysfunction in feedlot cattle.

Stress negatively affects the gastrointestinal tract (GIT) barrier function, resulting in compromised animal health. A deeper understanding of how diet and stress impacts the GIT barrier function in feedlot cattle is needed. Aspirin decreases mucus production and mucosal repair in the GIT and could be used as a model for GIT barrier dysfunction research. The objective of this study was to evaluate the effectiveness of aspirin to induce GIT barrier dysfunction in beef cattle. In experiment 1, sixteen crossbred heifers (425.0 ± 8.6 kg) were allotted to 0, 50, 100, or 200 mg/kg body weight (BW) aspirin doses based on BW. Experiment 1 consisted of two periods separated by 4 wk where four heifers per treatment received the same aspirin dose during each period. Heifers were fed a 49.4% corn silage and 50.6% concentrate diet. The 200 mg/kg BW aspirin treatment was dosed as a 100 mg/kg BW aspirin oral bolus 36 and 24 h prior to Cr-ethylenediaminetetraacetic acid (EDTA) dosing (1 liter; 180 mM). The 50 and 100 mg/kg BW aspirin treatments were dosed as an oral bolus 24 h prior to Cr-EDTA dosing. Urine was collected every 3 h for 48 h and analyzed for Cr. Serum was collected at 0 and 48 h and analyzed for lipopolysaccharide-binding protein (LBP), interleukin-6, serum amyloid A (SAA), haptoglobin, and aspartate aminotransferase. In experiment 2, sixteen crossbred steers (576.0 ± 14.2 kg) fed a similar diet were allotted by BW to the 0 and 200 mg/kg BW aspirin treatments (eight steers/treatment) and were slaughtered 24 h after the last dose. Jejunal tissues were collected, and claudin (CLDN) 1, 2, and 3, occludin, and zonula occludens tight junction messenger ribonucleic acid (mRNA) expression was determined. Data were analyzed using the MIXED procedure of SAS. Urinary Cr excretion increased linearly at hours 3, 6, 9, and 12 (P ≤ 0.04) as aspirin dose increased from 0 to 200 mg/kg. Aspirin linearly increased Cr absorption (P = 0.02) and elimination (P = 0.04) rates and linearly decreased mean retention time of Cr (P = 0.02). Aspirin increased SAA (P = 0.04) and tended to increase LBP (P = 0.09) in serum but did not affect any other serum inflammatory marker (P ≥ 0.19). Aspirin tended to increase jejunal CLDN-1 mRNA expression (P = 0.10) but did not affect the mRNA expression of other genes regulating tight junction function (P ≥ 0.20). Results from this study indicate that aspirin disrupts the GIT barrier function in beef cattle and has a potential as a model in GIT permeability research.

Effects of Docosahexaenoic Acid-Rich Microalgae Supplementation on Metabolic and Inflammatory Parameters in Horses With Equine Metabolic Syndrome.

Much of the equine population is obese and therefore predisposed to the development of additional health concerns such as equine metabolic syndrome (EMS). However, pharmacologic treatments for EMS are limited. Omega-3 fatty acid supplementation is a therapeutic strategy in humans with metabolic dysfunction that improves insulin sensitivity and reduces inflammation, but the effects of omega-3 fatty acid supplementation in horses with EMS are unclear. Therefore, in this pilot study, 10 mixed-sex and mixed-breed horses with EMS were fed a docosahexaenoic acid (DHA)-rich microalgae containing 16 g DHA/horse/d or served as controls for 46 days. Inflammatory status was measured using serologic enzyme-linked immunosorbent assay and in peripheral blood mononuclear cells (PBMCs) using flow cytometry and reverse transcription polymerase chain reaction. Circulating fatty acids, triglyceride, leptin, and adiponectin concentrations were also determined. Insulin and glucose dynamics were assessed with oral sugar test (OST) and frequently sampled intravenous glucose tolerance testing. Postsupplementation, treated horses had an increase in many circulating fatty acids, including DHA (P < .001). Treated horses also had lower serum triglycerides postsupplementation (P = .02) and a trend (P = .07) for reduced PBMC tumor necrosis factor α. Interestingly, after 46 days, control horses had an increase in insulin responses to the OST (P = .01), whereas treated horses did not (P = .69). These pilot data indicate that DHA-rich microalgae supplementation alters circulating fatty acids, modulates metabolic parameters, and may reduce inflammation in horses with EMS.

Effect of a hydrolyzed mannan- and glucan-rich yeast fraction on performance and health status of newly received feedlot cattle1.

A 2-part experiment was conducted to determine the effects of a blend of specialized mannan- and glucan-rich fractions of yeast (Select-TC, Alltech Inc.) on the health status and performance of steers during the first 2 mo of the feedlot period. Eighty crossbred steers were acquired from commercial sale barns in Mississippi and Georgia and transported to Purdue University. All animals were fed a corn silage-based receiving diet and were checked and treated daily for respiratory disease as needed following established treatment protocols. In Exp. 1, 64 steers (246.5 ± 4.7 kg initial weight) were blocked by BW and randomly allocated to 2 treatments to determine the impact of supplementation of a hydrolyzed mannan- and glucan-rich yeast fraction for 56 d on BW, ADG, daily DMI, and G:F: hydrolyzed yeast fed at 13 g (as-fed)/steer daily (TC) or nonsupplemented control (CON). Steers in Exp. 1 were housed in bedded pens with 2 animals per pen [n = 16 pens (32 steers)/treatment]. In Exp. 2, 16 steers (247.1 ± 5.4 kg initial BW) were similarly allotted to 2 treatments (CON and TC), individually penned, and subjected to a lipopolysaccharide (LPS) endotoxin challenge on day 62 or 63 after the start of the study to determine the animal's response to an inflammatory agent. Serum samples and rectal temperatures were taken every half an hour from -2 to 8 h relative to LPS injection from steers in Exp. 2. Data were analyzed as a complete randomized block design using the MIXED procedure of SAS. Morbidity for both experiments did not differ (P ≥ 0.16). Weight, ADG, DMI, and G:F did not differ among treatments (P ≥ 0.32) in Exp. 1. After the LPS infusion in Exp. 2, rectal temperatures (P = 0.03) and serum NEFA concentration (P = 0.04) were decreased in TC compared with CON steers. Concentrations of blood urea nitrogen (P = 0.31), glucose (P = 0.70), insulin (P = 0.57), and cortisol (P = 0.77) did not differ by treatment after LPS administration. Serum IL-6 concentrations were decreased (P < 0.0001), and interferon-γ concentrations tended to be greater (P = 0.07) in TC compared with CON steers after LPS infusion. Serum cytokine and metabolite results indicate that Select-TC improved health and metabolic status of LPS-challenged cattle, but this did not result in quantifiable improvements in performance in the conditions observed in this study.

Skeletal muscle and liver gene expression profiles in finishing steers supplemented with Amaize.

Our main objective was to evaluate the effects of feeding α-amylase (Amaize, Alltech Inc., Nicholasville, KY, USA) for 140 days on skeletal muscle and liver gene transcription in beef steers. Steers fed Amaize had lower average daily gain (p = .03) and gain:feed ratio (p = .05). No differences (p > .10) in serum metabolites or carcass traits were detected between the two groups but Amaize steers tended (p < .15) to have increased 12th rib fat depth. Microarray analysis of skeletal muscle revealed 21 differentially expressed genes (DEG), where 14 were up-regulated and seven were down-regulated in Amaize-fed steers. The bioinformatics analysis indicated that metabolic pathways involved in fat formation and deposition, stress response, and muscle function were activated, while myogenesis was inhibited in Amaize-fed steers. The quantitative PCR results for liver revealed a decrease (p < .01) in expression of fatty acid binding protein 1 (FABP1) and 3-hydroxybutyrate dehydrogenase 1 (BDH1) with Amaize. Because these genes are key for intracellular fatty acid transport, oxidation and ketone body production, data suggest a reduction in hepatic lipid catabolism. Future work to investigate potential positive effects of Amaize on cellular stress response, muscle function, and liver function in beef cattle appears warranted.

Performance, insulin sensitivity, carcass characteristics, and fatty acid profile of beef from steers fed microalgae.

Heterotrophic production of microalgae biomass provides a consistent, high-quality source of docosahexaenoic acid (DHA; C22:6 n-3) in triglyceride oils that could be used as a ration supplement for feedlot steers to improve nutritional qualities of beef. Sixty Angus × Simmental steers (438 ± 6.4 kg) were allotted to two treatments (30 steers each, six pens, five steers/pen) to determine the effects of ForPLUS (DHA-rich microalgae Aurantiochytrium limacinum; 63.6% fat; 17.9% DHA; 30 mg/kg Sel-Plex; Alltech Inc.) on performance, insulin sensitivity, LM fatty acid composition, and meat quality. Steers were fed basal diets containing 45% corn, 30% distillers dried grains with solubles, 20% corn silage, and 5% supplement. Basal diets were formulated to contain 16.1% CP and 1.32 Mcal/kg NEg. Treatments were delivered to steers in a ground corn-based top-dress (454 g total/steer) and contained no microalgae for control steers or 100 g/steer daily of ForPLUS for microalgae steers. A glucose tolerance test (GTT) was performed 10 d prior to slaughter. Steers were slaughtered when a target pen BW of 621 kg was achieved. Fatty acid oxidation potential was determined by measuring thiobarbituric acid reactive substances (TBARS) on LM samples collected 24 h after slaughter and aged for 48 h or 21 d. Weight and BW gain did not differ during the study (P ≥ 0.13); however, steers fed microalgae remained in the feedlot seven more days compared to steers fed the control diet (111 vs. 104 d; P = 0.04). Overall DMI decreased (P = 0.002) and G:F increased during the second half of the study (P = 0.04) in steers fed microalgae compared to steers fed the control diet. Steers fed microalgae secreted less insulin (P = 0.01) and took longer to clear glucose (P = 0.01) during a 2-h GTT. Carcass traits did not differ between treatments (P ≥ 0.23). Microalgae had no effect on n-6 content (P = 0.67), but more than doubled the n-3 fatty acid percentage and the n-3:n-6 ratio of the LM (P < 0.0001). The percentage of n-3 fatty acids C20:5 and C22:6 were increased (P < 0.0001) 4-fold and 6.25-fold, respectively, by microalgae supplementation. Concentration of TBARS did not differ in LM aged for 48 h (P = 0.91); however, when aged for 21 d, steers fed microalgae tended to produce LM with greater TBARS concentration compared to steers fed the control diet (P = 0.08). In conclusion, DHA-rich microalgae decreased DMI of steers, and increased n-3 fatty acids and beef oxidation in steaks aged for 21 d.

Differential Gene Expression Analysis of Bovine Macrophages after Exposure to the Penicillium Mycotoxins Citrinin and/or Ochratoxin A.

Mycotoxins produced by fungal species commonly contaminate livestock feedstuffs, jeopardizing their health and diminishing production. Citrinin (CIT) and ochratoxin A (OTA) are mycotoxins produced by Penicillium spp. and commonly co-occur. Both CIT and OTA can modulate immune response by inhibiting cell proliferation and differentiation, altering cell metabolism, and triggering programmed cell death. The objective of this study was to determine the effects of sublethal exposure (i.e., the concentration that inhibited cell proliferation by 25% (IC25)) to CIT, OTA or CIT + OTA on the bovine macrophage transcriptome. Gene expression was determined using the Affymetrix Bovine Genome Array. After 6 h of exposure to CIT, OTA or CIT + OTA, the number of differentially expressed genes (DEG), respectively, was as follows: 1471 genes (822 up-regulated, 649 down-regulated), 5094 genes (2611 up-regulated, 2483 down-regulated) and 7624 genes (3984 up-regulated, 3640 down-regulated). Of these, 179 genes (88 up-regulated, 91 down-regulated) were commonly expressed between treatments. After 24 h of exposure to CIT, OTA or CIT + OTA the number of DEG, respectively, was as follows: 3230 genes (1631 up-regulated, 1599 down-regulated), 8558 genes (4167 up-regulated, 4391 down-regulated), and 10,927 genes (6284 up-regulated, 4643 down-regulated). Of these, 770 genes (247 up-regulated, 523 down-regulated) were commonly expressed between treatments. The categorization of common biological functions and pathway analysis suggests that the IC25 of both CIT and OTA, or their combination, induces cellular oxidative stress, a slowing of cell cycle progression, and apoptosis. Collectively, these effects contribute to inhibiting bovine macrophage proliferation.

Effects of a docosahexaenoic acid-rich microalgae nutritional product on insulin sensitivity after prolonged dexamethasone treatment in healthy mature horses.

OBJECTIVE: To determine effects of a microalgae nutritional product on insulin sensitivity in horses. ANIMALS: 8 healthy mature horses. PROCEDURES :Horses (n = 4/group) received a basal diet without (control diet) or with docosahexaenoic acid-rich microalgae meal (150 g/d) for 49 days (day 0 = first day of diet). On day 28, an isoglycemic hyperinsulinemic clamp procedure was performed. Horses then received dexamethasone (0.04 mg/kg/d) for 21 days. On day 49, the clamp procedure was repeated. After a 60-day washout, horses received the alternate diet, and procedures were repeated. Plasma fatty acid, glucose, and insulin concentrations and glucose and insulin dynamics during the clamp procedure were measured on days 28 and 49. Two estimates of insulin sensitivity (reciprocal of the square root of the insulin concentration and the modified insulin-to-glucose ratio for ponies) were calculated. RESULTS: Baseline glucose and insulin concentrations or measures of insulin sensitivity on day 28 did not differ between horses when fed the control diet or the basal diet plus microalgae meal. On day 49 (ie, after dexamethasone administration), the microalgae meal was associated with lower baseline insulin and glucose concentrations and an improved modified insulin-to-glucose ratio for ponies, compared with results for the control diet. CONCLUSIONS AND CLINICAL RELEVANCE: Although the microalgae meal had no effect on clamp variables following dexamethasone treatment, it was associated with improved plasma glucose and insulin concentrations and insulin sensitivity estimates. A role for microalgae in the nutritional management of insulin-resistant horses warrants investigation.

Source of selenium supplementation influences testis selenium content and gene expression profiles in Single Comb White Leghorn roosters.

Spermatogenesis is a tightly regulated, selenium-dependent process. Nutritional deficiencies, including Se, have been associated with decreased fertility. During Se depletion, testes preferentially retain Se while other tissues are depleted. This study was aimed at evaluating the effect of Se source (inorganic or organic yeast derived) on testes weight, Se content, and gene expression. At 17 weeks of age, roosters were randomly assigned to one of three treatments: basal diet (control), basal diet + 0.3 mg organic Se/kg organic yeast-derived Se (YS; Sel-Plex®, Alltech Inc.), or basal diet + 0.3 mg inorganic Se /kg inorganic Se as sodium selenite (SS). At 40 weeks of age, seven roosters from each treatment were euthanized and testes removed. Testes weight did not differ between treatments, but Se content was greater (P ≤ 0.01) in YS than SS and control. Testicular differential gene expression profiling was accomplished using the Affymetrix Genechip® chicken genome array. Ingenuity® pathway analysis revealed that Se supplementation, regardless of source, results in the up-regulation of genes governing cell structure/morphology. The enrichment of such pathways was greater with YS than SS. These expression patterns suggest that aside from playing a role in antioxidant defense, Se, especially in the organic YS form, is useful for maintaining testicular cell structure.

Selenium content in blood fractions and liver of beef heifers is greater with a mix of inorganic/organic or organic versus inorganic supplemental selenium but the time required for maximal assimilation is tissue-specific.

Selenium (Se) content of feedstuffs is dependent on the Se level of the soil. Even though Se in grass and forage crops is primarily present in organic forms, Se is commonly supplemented in cattle diets in an inorganic (sodium selenite) form in geographic regions where Se soil concentrations are low. The purpose of this study was to answer two important questions about inorganic (ISe) vs organic (OSe) forms of dietary supplementation of Se (3 mg/day) to growing beef heifers (0.5 kg/day): (1) what would the effect of supplementing Se with an equal blend of ISe:OSe (Mix) have on Se tissue concentrations and (2) how long does it take for the greater assimilation with OSE to occur and stabilize? A long-term (224 day) Se dietary supplementation trial was conducted with serial sampling performed (days 28, 56, 112, and 224) to determine the length of time required to achieve Se supplement (OSE, Mix, and ISe)-dependent changes in Se assimilation in blood fractions and liver tissue. Forty maturing Angus heifers were fed a corn silage-based diet for 98 days with no Se supplementation, and then a cracked corn/cottonseed hull-based diet (basal diet) without Se supplementation for 74 days. Liver biopsies were taken for Se analysis, and heifers were fed the same diet for another 14 days. Heifers were assigned (n = 10) to one of four Se treatment groups such that basal liver Se contents were stratified among groups, and then fed enough of the basal diet (0.08 mg Se per day) and a mineral-vitamin mix that provided 0.16 (control) or 3.0 mg Se per day in ISe (sodium selenite), OSe (Sel-Plex(®)), or Mix (1:1 ISe:OSe) form to support 0.5 kg/day growth for 224 days. More Se was found in whole blood, red blood cells, serum, and liver of Mix and OSe heifers than ISe heifers, and all were greater than control. Se content either increased until day 56 then was stable (liver and plasma), or was stable until day 56 (whole blood) or day 112 (red blood cells) and then increased steadily through day 224, for all supplemental Se treatments. These data indicate that a 1:1 mix (1.5 mg Se:1.5 mg Se) of supplemental ISe and OSe is equal to 3 mg/day OSe supplementation and greater than 3 mg/day ISe supplementation. The data also indicate that Se levels stabilized in liver and plasma by 56 to 112 days whereas whole blood and red blood cell concentrations were still increasing through 224 days of supplementation, regardless of the form of supplemental Se.