Effect of dietary manganese on antioxidant status and expression levels of heat-shock proteins and factors in tissues of laying broiler breeders under normal and high environmental temperatures

Neurodegenerative Proteinopathies Induced by Environmental Pollutants: Heat Shock Proteins and Proteasome as Promising Therapeutic Tools

Environmental pollutants' (EPs) amount and diversity have increased in recent years due to anthropogenic activity. Several neurodegenerative diseases (NDs) are theorized to be related to EPs, as their incidence has increased in a similar way to human EPs exposure and they reproduce the main ND hallmarks. EPs induce several neurotoxic effects, including accumulation and gradual deposition of misfolded toxic proteins, producing neuronal malfunction and cell death. Cells possess different mechanisms to eliminate these toxic proteins, including heat shock proteins (HSPs) and the proteasome system. The accumulation and deleterious effects of toxic proteins are induced through HSPs and disruption of proteasome proteins' homeostatic function by exposure to EPs. A therapeutic approach has been proposed to reduce accumulation of toxic proteins through treatment with recombinant HSPs/proteasome or the use of compounds that increase their expression or activity. Our aim is to review the current literature on NDs related to EP exposure and their relationship with the disruption of the proteasome system and HSPs, as well as to discuss the toxic effects of dysfunction of HSPs and proteasome and the contradictory effects described in the literature. Lastly, we cover the therapeutic use of developed drugs and recombinant proteasome/HSPs to eliminate toxic proteins and prevent/treat EP-induced neurodegeneration.

Manganese alleviates heat stress of primary cultured chick embryonic myocardial cells via enhancing manganese superoxide dismutase expression and attenuating heat shock response

Manganese (Mn) is an essential trace element that has been shown to attenuate the adverse effects of heat stress in the heart of broiler breeders and embryos. However, the underlying molecular mechanisms involving this process remain unclear. Therefore, two experiments were conducted to investigate the possible protective mechanisms of Mn on primary cultured chick embryonic myocardial cells exposed to heat challenge. In experiment 1, the myocardial cells were exposed to 40 °C (normal temperature, NT) and 44 °C (high temperature, HT) for 1, 2, 4, 6 or 8 h. In experiment 2, the myocardial cells were preincubated with no Mn supplementation (CON), 1 mmol/L of Mn as the inorganic MnCl₂ (iMn) or organic Mn proteinate (oMn) under NT for 48 h, and then continuously incubated under NT or HT for another 2 or 4 h. The results from experiment 1 showed that the myocardial cells incubated for 2 or 4 h had the highest (P < 0.0001) heat-shock protein 70 (HSP70) or HSP90 mRNA levels than those incubated for other incubation times under HT. In experiment 2, HT increased (P < 0.05) the heat-shock factor 1 (HSF1) and HSF2 mRNA levels as well as Mn superoxide dismutase (MnSOD) activity of myocardial cells compared with NT. Furthermore, supplemental iMn and oMn increased (P < 0.02) HSF2 mRNA level and MnSOD activity of myocardial cells compared with the CON. Under HT, the HSP70 and HSP90 mRNA levels were lower (P < 0.03) in iMn group than in the CON group, in oMn group than in iMn group; and the MnSOD mRNA and protein levels were higher (P < 0.05) in oMn group than in the CON and iMn groups. These results from the present study indicate that supplemental Mn, especially oMn, could enhance the MnSOD expression and attenuate heat shock response to protect against heat challenge in primary cultured chick embryonic myocardial cells.

Neuroprotective mechanisms of multitarget 7-aminophenanthridin-6(5H)-one derivatives against metal-induced amyloid proteins generation and aggregation

Brain's metals accumulation is associated with toxic proteins, like amyloid-proteins (Aβ), formation, accumulation, and aggregation, leading to neurodegeneration. Metals downregulate the correct folding, disaggregation, or degradation mechanisms of toxic proteins, as heat shock proteins (HSPs) and proteasome. The 7-amino-phenanthridin-6(5H)-one derivatives (APH) showed neuroprotective effects against metal-induced cell death through their antioxidant effect, independently of their chelating activity. However, additional neuroprotective mechanisms seem to be involved. We tested the most promising APH compounds (APH1-5, 10-100 μM) chemical ability to prevent metal-induced Aβ proteins aggregation; the APH1-5 effect on HSP70 and proteasome 20S (P20S) expression, the metals effect on Aβ formation and the involvement of HSP70 and P20S in the process, and the APH1-5 neuroprotective effects against Aβ proteins (1 μM) and metals in SN56 cells. Our results show that APH1-5 compounds chemically avoid metal-induced Aβ proteins aggregation and induce HSP70 and P20S expression. Additionally, iron and cadmium induced Aβ proteins formation through downregulation of HSP70 and P20S. Finally, APH1-5 compounds protected against Aβ proteins-induced neuronal cell death, reversing partially or completely this effect. These data may help to provide a new therapeutic approach against the neurotoxic effect induced by metals and other environmental pollutants, especially when mediated by toxic proteins.

Natural Products of Plants and Animal Origin Improve Albumen Quality of Chicken Eggs

Albumen quality is recognized as one of the major yardsticks in measuring egg quality. The elasticity of thick albumen, a strong bond in the ovomucin-lysozyme complex, and excellent biological properties are indicators of high-quality albumen. The albumen quality prior to egg storage contribute to enhance egg’s shelf life and economic value. Evidence suggests that albumen quality can deteriorate due to changes in albumen structure, such as the degradation of β-ovomucin subunit and O-glyosidic bonds, the collapse of the ovomucin-lysozyme complex, and a decrease in albumen protein-protein interaction. Using organic minerals, natural plants and animal products with antioxidant and antimicrobial properties, high biological value, no residue effect and toxicity risk could improve albumen quality. These natural products (e.g., tea polyphenols, marigold extract, magnolol, essential oils, Upro (small peptide), yeast cell wall, Bacillus species, a purified amino acid from animal blood, and pumpkin seed meal) are bio-fortified into eggs, thus enhancing the biological and technological function of the albumen. Multiple strategies to meeting laying hens’ metabolic requirements and improvement in albumen quality are described in this review, including the use of amino acids, vitamins, minerals, essential oils, prebiotics, probiotics, organic trace elements, and phytogenic as feed additives. From this analysis, natural products can improve animal health and consequently albumen quality. Future research should focus on effects of these natural products in extending shelf life of the albumen during storage and at different storage conditions. Research in that direction may provide insight into albumen quality and its biological value in fresh and stored eggs.

Dietary Fructooligosaccharides Effectively Facilitate the Production of High-Quality Eggs via Improving the Physiological Status of Laying Hens

The focus of this study was to investigate the influence of prebiotics, such as fructooligosaccharides (FOS), on laying performance, egg quality, apparent fecal amino acid digestibility, jejunal morphology, hematological indices, immunological response, and antioxidant capacity in laying hens. A total of 216 healthy Hy-Line Brown laying hens aged 30 weeks were randomly assigned to one of three dietary treatments: basal diet, basal diet supplemented with 0.3 percent FOS, or 0.6 percent FOS. For 84 days, each treatment was fed the corresponding experimental diet. According to the findings, dietary supplementation with FOS enhanced laying performance and egg mass while lowering mortality rate. Albumen height, thick albumen content, Haugh unit, and eggshell thickness were also improved by the prebiotics. Prebiotics also boosted antioxidant status by increasing the activity of antioxidant enzymes, improved morphological development of the jejunum as demonstrated by significant increases in villi height, villi width, ratio of villi height to crypt depth, and reduced crypt depth. The prebiotics group showed a considerable increase in immunoglobulin M, G, and A (IgM, IgG, and IgA) levels, as well as a similar effect on complement proteins (C3). Furthermore, the apparent fecal amino acid digestibility of most essential amino acids was significantly enhanced. Conclusively, fructooligosaccharides at inclusion level of 0.6% efficiently enhanced laying performance and production of high-quality eggs while positively modulating amino acid digestibility, jejunal morphology, antioxidant status, and immune functions of the laying hens.

Manganese Mitigates Heat Stress-Induced Apoptosis by Alleviating Endoplasmic Reticulum Stress and Activating the NRF2/SOD2 Pathway in Primary Chick Embryonic Myocardial Cells

Heat stress leads to oxidative stress and induces apoptosis in various cells. Endoplasmic reticulum (ER) stress is an important apoptosis pathway. Manganese (Mn) has been shown to enhance the activity of manganese superoxide dismutase (MnSOD). To explore the potential effect of Mn on ER stress and apoptosis induced by heat stress, we examined crucial factors associated with heat stress, ER stress, and apoptosis in cultured primary chick embryonic myocardial cells that had been pretreated with 20 μM Mn for 24 h and then subjected to 4 h of heat stress. The results showed that Mn decreased (P < 0.05) heat stress-induced reactive oxygen species (ROS) production and exerted antiapoptotic effects by increasing MnSOD enzymatic activity. The heat stress-induced accumulation of intracellular calcium was dramatically reduced (P < 0.05). Mn treatment significantly decreased (P < 0.05) the expression levels of the apoptosis-related gene Bax and ER stress markers glucose-regulated protein 78 (GRP78) and CCAAT/enhancer binding protein homologous protein (CHOP) in primary chick embryonic myocardial cells. Additionally, Mn reduced oxidative stress by activating the nuclear factor E2-related factor 2 (NRF2)/SOD2 signaling pathway. Taken together, our findings indicate that Mn attenuates heat stress-induced apoptosis by inhibiting ROS generation, intracellular calcium accumulation, and the ER stress pathway and activating the NRF2/SOD2 signaling pathway to protect myocardial cells from oxidative stress during chick embryonic development.

Effect of in ovo manganese injection on the embryonic development, antioxidation, hatchability and performances of offspring broilers under normal and high temperatures

Two experiments were carried out to study the effect of in ovo manganese (Mn) injection on the embryonic development, antioxidation, hatchability, and performances of offspring broilers under normal temperature (NT) and high temperature (HT). Experiment 1 was conducted to investigate the effect of in ovo Mn injection on the embryonic hatchability of Arbor Acres broiler breeders. On D 9 of incubation, a total of 684 fertilized eggs were randomly allocated to 6 treatments: the non-injected positive control (niPC) and treatments injected with 0 (the negative control, iNC), 6.25, 12.5, 25.0, or 50.0 μg Mn/egg as Mn sulfate. Experiment 2 was conducted to investigate the effect of in ovo Mn injection on the embryonic development, antioxidation and performance of offspring broilers under NT and HT. A total of 792 fertilized eggs were randomly allocated to 6 treatments in a 1 (niPC) + 1 (iNC) + 2 (injected Mn sources: Mn sulfate and Mn proteinate) × 2 (injected Mn levels: 12.5 and 25.0 μg/egg) factorial arrangement during the embryonic stage and D1 to 28 at NT. Then, 288 birds were allotted to 12 treatments in a 6 (the above embryonic treatments) × 2 (environmental temperatures: NT-22℃ vs HT-34℃) factorial arrangement from D 29 to 42. The results showed that Mn injection affected (P < 0.03) the hatchability and the maximum level of in ovo injected Mn was 25.0 μg Mn/egg. The Mn injection upregulated (P < 0.05) Mn-containing superoxide dismutase mRNA expression in the embryonic heart compared to the iNC. Hyperthermia decreased (P < 0.05) ADG and ADFI, breast muscle percentage, plsma alkaline phosphatase activity, and red color values of breast and thigh muscles, but increased (P < 0.05) F/G, plasma aspartate aminotransferase and lactic dehydrogenase activities, total cholesterol, uric acid and triiodothyronine contents, abdominal fat, light values of breast and thigh muscles of offspring broilers. The results suggest that in ovo Mn injection can enhance antioxidant ability in the chick embryonic heart.

Change of zinc mobilization and gene expression of key zinc transport proteins between the yolk sac membrane and liver of duck embryonic developing

Zinc (Zn) deposition in egg yolk is essential for the rapid growth and complete development of the avian embryo. Thus, it is crucial to obtain maximal Zn mobilization at an appropriate time during development in favor of the survival of avian embryos. The aim of this study was to study the developmental change of Zn mobilization and gene expression related to key Zn transport proteins between the yolk sac membrane and embryonic liver from the incubation d 17 (E17) to d 32 (E32) during duck embryonic developing. The weights of duck embryo, embryo without yolk sac, and embryonic liver increased as well as the yolk sac weight decreased linearly (P < 0.0001) when incubation day increased. The Zn concentration in the yolk sac did not change from E17 to E29 and only declined significantly from E29 to E32 of duck embryos, while hepatic Zn level decreased linearly as with the increased incubation time (P < 0.01). When the incubation day increased, the decreased Zn amount in the yolk sac and the increased Zn amount in the embryonic liver were observed (P < 0.0001). The calculated transfer-out rate of Zn in the yolk sac and transfer-in rate of Zn in livers were both increased from E23-26 to E29-32 (P < 0.01). Among E17, E23 and E29, the solute carrier family 39 member (ZIP) of ZIP10, ZIP13, and ZIP14 genes mRNA expressions were increased in yolk sac membrane but were decreased in the embryonic liver, while metallothionein 1 mRNA expression was increased both in the yolk sac membrane and liver (P < 0.05). In conclusion, yolk sac membrane and embryonic liver tissues displayed the similar developmental patterns of Zn mobilization and metallothionein 1 mRNA expression from E17 to E32 during duck embryonic developing. The appropriate time of the maximal rate of Zn mobilization were observed between E29 and E32 of duck embryo, associated with the significant changes of gene expression related to some key Zn transport proteins on E29 in yolk sac membrane and liver tissues.

Organic zinc and manganese and 25-hydroxycholecalciferol improves eggshell thickness in late-phase laying hens

The aim of this study was to evaluate the effects of organic micromineral zinc (Zn) and manganese (Mn) and 25-hydroxycholecalciferol supplementation in late-phase laying hens' diets on performance, egg quality, lipid stability of fresh and stored eggs, and bone quality. The treatments were a basal diet and diets supplemented with 32 mg Zn-Met/kg diet; 26 mg Mn-Met/kg diet; 32 mg Zn-Met/kg diet and 26 mg Mn-Met/kg diet; 1500 IU 25-hydroxycholecalciferol/kg diet; 32 mg Zn-Met/kg diet; 26 mg Mn-Met/kg diet; and 1500 IU 25-hydroxycholecalciferol/kg diet. On performance, the birds supplemented with organic manganese had the lowest feed intake. Regarding egg quality, the birds supplemented with Zn-Met and Mn-Met, with 25-hydroxycholecalciferol alone, and with Zn-Met, Mn-Met and 25-hydroxycholecalciferol presented a greater eggshell thickness than those receiving the basal diet. Lipid stability of the yolk varied only according to storage time. No effect of supplementation was observed on bone quality. Supplementation with Zn-Met and Mn-Met, or associated with 25-hydroxycholecalciferol, or 25-hydroxycholecalciferol alone, improved eggshell thickness in aged white layers. However, the associated or isolated supplementation with these nutrients did not influence performance, lipid stability of fresh and stored egg yolk or bone quality.

Effect of Maternal Marginal Zinc Deficiency on Development, Redox Status, and Gene Expression Related to Oxidation and Apoptosis in an Avian Embryo Model

Maternal severe zinc (Zn) deficiency resulted in growth retardation and high mortality during embryonic development in human. Therefore, this study is aimed at evaluating the effect of maternal marginal Zn deficiency on the development and redox status to avoid severe Zn deficiency using an avian model. A total of 324 laying duck breeders at 214 days old were randomly allotted into 3 dietary Zn levels with 6 replicates of 18 ducks per replicate. The birds were fed experimental diets including 3 dietary supplemental Zn levels of 0 mg/kg (maternal Zn-deficient group, 29.2 mg Zn/kg diet), 60 mg/kg (maternal Zn-adequate group), and 120 mg/kg (maternal Zn-high group) for 6 weeks. Dietary Zn levels had on effect on egg production and fertility (P > 0.05), whereas dietary Zn deficiency decreased breeder plasma Zn concentration and erythrocytic alkaline phosphatase activity at week 6 and inhibited erythrocytic 5′-nucleotidase (5′-NT) activity at weeks 2, 4, and 6 (P < 0.05), indicating that marginal Zn-deficient status occurred after Zn depletion. Maternal marginal Zn deficiency increased embryonic mortality and contents of superoxide anion radical, MDA, and PPC and reduced MT content and CuZnSOD activity in duck embryonic livers on E29. The MDA content was positively correlated with embryonic mortality. Maternal marginal Zn deficiency increased BCL2-associated X protein and Caspase-9 mRNA expressions as well as decreased B-cell lymphoma-2 and MT1 mRNA and signal AKT1 and ERK1 protein expressions (P < 0.05). Breeder plasma Zn concentration and erythrocytic 5′-NT activities at week 6 were positively correlated with GSH-Px activity and GPx, MT1, and BCL2 mRNA expressions in embryonic livers on E29. In conclusion, erythrocytic 5′-NT activity could be more rapid and reliable to monitor marginal Zn-deficient status. Marginal Zn deficiency impaired hatchability and antioxidant defense system and then induced oxidative damage and apoptosis in the embryonic liver, contributing to the greater loss of duck embryonic death.

Regulation of bone phosphorus retention and bone development possibly by related hormones and local bone-derived regulators in broiler chicks

BACKGROUND

Phosphorus is essential for bone mineralization in broilers, however, the underlying mechanisms remain unclear. We aimed to investigate whether bone phosphorus retention and bone development might be regulated by related hormones and local bone-derived regulators in broilers.

METHODS

Broilers were fed diets containing different levels of non-phytate phosphorus (NPP) 0.15%, 0.25%, 0.35%, 0.45% and 0.55% or 0.15%, 0.22%, 0.29%, 0.36% and 0.43% from 1 to 21 or 22 to 42 days of age. Serum and tibia samples were collected for determinations of bone phosphorus retention and bone development parameters, related hormones and local bone-derived regulators of broiler chickens on d 14, 28 and 42, respectively.

RESULTS

Tibia ash phosphorus, total phosphorus accumulation in tibia ash (TP_TA), bone mineral concentration (BMC), bone mineral density (BMD), bone breaking strength (BBS), and ash on d 14, 28 or 42, serum 1,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃) on d 28 and 42, mRNA expressions of tibia fibroblast growth factor 23 (FGF23) and dentin matrix protein 1 (DMP1) on d 14 and 28 increased linearly or quadratically (P < 0.05), while serum parathyroid hormone (PTH) on d 28, tibia alkaline phosphatase (ALP) on d 14, 28 and 42, bone gal protein (BGP) on d 14, and mRNA expression of tibia phosphate-regulating gene with homologies to endopeptidases on the X chromosome (PHEX) on d 14 and 28 decreased linearly or quadratically (P < 0.04) as dietary NPP level increased. TP_TA, BMC, BMD, and ash on d 28 and 42, BBS on d 28, and ash phosphorus on d 42 were positively correlated (r = 0.389 to 0.486, P < 0.03) with serum 1,25(OH)₂D₃. All of the above parameters were positively correlated (r = 0.380 to 0.689, P < 0.05) with tibia DMP1 mRNA expression on d 14, 28 and 42, but negatively correlated (r = - 0.609 to - 0.538, P < 0.02) with serum PTH on d 28, tibia ALP on d 14, 28 and 42, and BGP on d 14. TP_TA, BMC and ash on d 14 and BMD on d 28 were negatively correlated (r = - 0.397 to - 0.362, P < 0.03) with tibia PHEX mRNA expression, and BMD on d 28 was positively correlated (r = 0.384, P = 0.04) with tibia FGF23 mRNA expression.

CONCLUSIONS

These results suggested that bone phosphorus retention and bone development parameters had moderate to strong correlations with serum PTH and 1,25(OH)₂D₃ and tibia DMP1, PHEX, FGF23, ALP and BGP in broilers during the whole growth period, and thus they might be partly regulated by these related hormones and local bone-derived regulators.

Severe pantothenic acid deficiency induces alterations in the intestinal mucosal proteome of starter Pekin ducks

BACKGROUND

Pantothenic acid deficiency (PAD) results in growth depression and intestinal hypofunction of animals. However, the underlying molecular mechanisms remain to be elucidated. Mucosal proteome might reflect dietary influences on physiological processes.

RESULTS

A total of 128 white Pekin ducks of one-day-old were randomly assigned to two groups, fed either a PAD or a pantothenic acid adequate (control, CON) diet. After a 16-day feeding period, two ducks from each replicate were sampled to measure plasma parameters, intestinal morphology, and mucosal proteome. Compared to the CON group, high mortality, growth retardation, fasting hypoglycemia, reduced plasma insulin, and oxidative stress were observed in the PAD group. Furthermore, PAD induced morphological alterations of the small intestine indicated by reduced villus height and villus surface area of duodenum, jejunum, and ileum. The duodenum mucosal proteome of ducks showed that 198 proteins were up-regulated and 223 proteins were down-regulated (> 1.5-fold change) in the PAD group compared to those in the CON group. Selected proteins were confirmed by Western blotting. Pathway analysis of these proteins exhibited the suppression of glycolysis and gluconeogenesis, fatty acid beta oxidation, tricarboxylic acid cycle, oxidative phosphorylation, oxidative stress, and intestinal absorption in the PAD group, indicating impaired energy generation and abnormal intestinal absorption. We also show that nine out of eleven proteins involved in regulation of actin cytoskeleton were up-regulated by PAD, probably indicates reduced intestinal integrity.

CONCLUSION

PAD leads to growth depression and intestinal hypofunction of ducks, which are associated with impaired energy generation, abnormal intestinal absorption, and regulation of actin cytoskeleton processes. These findings provide insights into the mechanisms of intestinal hypofunction induced by PAD.

Zinc alleviates the heat stress of primary cultured hepatocytes of broiler embryos via enhancing the antioxidant ability and attenuating the heat shock responses

Zinc (Zn) has been shown to attenuate the adverse effects of heat stress on broilers, but the mechanisms involving this process remain unclear. We aimed to investigate possible protective mechanisms of Zn on primary cultured hepatocytes of broiler embryos subjected to heat stress. Three experiments were conducted. In Exp. 1, hepatocytes were treated with 0, 50, 100, 200, or 400 μmol/L added Zn as inorganic Zn sulfate (iZn) for 12, 24 or 48 h. In Exp. 2, cells were exposed to 40 °C (a normal temperature [NT]) and 44 °C (a high temperature [HT]) for 1, 2, 4, 6, or 8 h. In Exp. 3, cells were preincubated with 0 or 50 μmol/L Zn as iZn or organic Zn lysine chelate (oZn) for 8 h under NT, and then incubated with the same Zn treatments under NT or HT for 4 or 6 h. The biomarkers of antioxidative status and heat stress in cells were measured. The results in Exp. 1 indicated that 50 μmol/L Zn and 12 h incubation were the optimal conditions for increasing antioxidant ability of hepatocytes. In Exp. 2, the 4 or 6 h incubation under HT was effective in inducing heat shock responses of hepatocytes. In Exp. 3, HT elevated (P < 0.01) malondialdehyde content and expressions of heat shock protein 70 (HSP70) mRNA and protein, as well as HSP90 mRNA. However, Zn supplementation increased (P < 0.05) copper zinc superoxide dismutase (CuZnSOD) activity and metallothionein mRNA expression, and effectively decreased (P < 0.05) the expressions of HSP70 mRNA and protein, as well as HSP90 mRNA. Furthermore, oZn was more effective (P < 0.05) than iZn in enhancing CuZnSOD activity of hepatocytes under HT. It was concluded that Zn (especially oZn) could alleviate heat stress of broiler hepatocytes via enhancing their antioxidant ability and attenuating heat shock responses.

Heat stress on microbiota composition, barrier integrity, and nutrient transport in gut, production performance, and its amelioration in farm animals

Livestock species experience several stresses, particularly weaning, transportation, overproduction, crowding, temperature, and diseases in their life. Heat stress (HS) is one of the most stressors, which is encountered in livestock production systems throughout the world, especially in the tropical regions and is likely to be intensified due to global rise in environmental temperature. The gut has emerged as one of the major target organs affected by HS. The alpha- and beta-diversity of gut microbiota composition are altered due to heat exposure to animals with greater colonization of pathogenic microbiota groups. HS also induces several changes in the gut including damages of microstructures of the mucosal epithelia, increased oxidative insults, reduced immunity, and increased permeability of the gut to toxins and pathogens. Vulnerability of the intestinal barrier integrity leads to invasion of pathogenic microbes and translocation of antigens to the blood circulations, which ultimately may cause systematic inflammations and immune responses. Moreover, digestion of nutrients in the guts may be impaired due to reduced enzymatic activity in the digesta, reduced surface areas for absorption and injury to the mucosal structure and altered expressions of the nutrient transport proteins and genes. The systematic hormonal changes due to HS along with alterations in immune and inflammatory responses often cause reduced feed intake and production performance in livestock and poultry. The altered microbiome likely orchestrates to the hosts for various relevant biological phenomena occurring in the body, but the exact mechanisms how functional communications occur between the microbiota and HS responses are yet to be elucidated. This review aims to discuss the effects of HS on microbiota composition, mucosal structure, oxidant-antioxidant balance mechanism, immunity, and barrier integrity in the gut, and production performance of farm animals along with the dietary ameliorations of HS. Also, this review attempts to explain the mechanisms how these biological responses are affected by HS.

Effects of manganese and Bacillus subtilis on the reproductive performance, egg quality, antioxidant capacity, and gut microbiota of breeding geese during laying period

This experiment was conducted to investigate the effects of manganese (Mn) and Bacillus subtilis (BS) on the production performance, egg quality, antioxidant capacity, and gut microbiota of breeding geese during laying period. A total of 120 forty-six-week-old breeding geese (Wulong) were randomly assigned to 1 of 6 treatment diets formulated to supply 10, 20, and 30 mg/kg Mn with 5 × 109 CFU/kg or 2.5 × 109 CFU/kg BS for a 10-wk trial. Results showed that dietary supplementation with 20 and 30 mg/kg Mn could decrease the daily feed intake (DFI) of geese. Moreover, 30 mg/kg Mn significantly increased the laying rate. Besides, although Mn addition had no obvious effect on egg quality, 5 × 109 CFU/kg BS was found to elevate the hatching egg hatching rate and eggshell thickness. For the serum hormones, 30 mg/kg Mn promoted estradiol secretion, while 5 × 109 CFU/kg BS increased the level of follicle-stimulating hormone. Furthermore, 20 and 30 mg/kg Mn and 5 × 109 CFU/kg BS significantly enhanced the total antioxidant capacity by increasing the activity of total superoxide dismutases or decreasing the content of malondialdehyde. Dietary supplementation with 5 × 109 CFU/kg BS also increased the intestinal villus height and upregulated the abundance of Fusobacteria, Fusobacteriaceae, Fusobacterium, and Faecalibacterium in cecal content. In addition, 20 and 30 mg/kg Mn elevated the levels of Bacteroidetes, Bacteroidaceae, Bacteroides, and Ruminococcaceae but decreased Streptococcaceae. Importantly, an interaction effect was observed between Mn and BS on the DFI, egg mass, average egg size, and the abundance of Bacteroides as well as Faecalibacterium. In conclusion, dietary inclusion of Mn and BS could improve the production performance, egg quality, antioxidant capacity, intestinal structure, as well as gut microbiota. Supplementation of 30 mg/kg Mn and 5.0 × 109 CFU/kg BS provided the optimal effect.

Manganese increases Aβ and Tau protein levels through proteasome 20S and heat shock proteins 90 and 70 alteration, leading to SN56 cholinergic cell death following single and repeated treatment

Manganese (Mn) produces cholinergic neuronal loss in basal forebrain (BF) region that was related to cognitive dysfunction induced after single and repeated Mn treatment. All processes that generate cholinergic neuronal loss in BF remain to be understood. Mn exposure may produce the reduction of BF cholinergic neurons by increasing amyloid beta (Aβ) and phosphorylated Tau (pTau) protein levels, altering heat shock proteins' (HSPs) expression, disrupting proteasome P20S activity and generating oxidative stress. These mechanisms, described to be altered by Mn in regions different than BF, could lead to the memory and learning process alteration produced after Mn exposure. The research performed shows that single and repeated Mn treatment of SN56 cholinergic neurons from BF induces P20S inhibition, increases Aβ and pTau protein levels, produces HSP90 and HSP70 proteins expression alteration, and oxidative stress generation, being the last two effects mediated by NRF2 pathway alteration. The increment of Aβ and pTau protein levels was mediated by HSPs and proteasome dysfunction. All these mechanisms mediated the cell decline observed after Mn treatment. Our results are relevant because they may assist to reveal the processes leading to the neurotoxicity and cognitive alterations observed after Mn exposure.

Water amino acid-chelated trace mineral supplementation decreases circulating and intestinal HSP70 and proinflammatory cytokine gene expression in heat-stressed broiler chickens

Heat stress (HS) is a financial and physiological burden on the poultry industry and the mitigation of the adverse effects of HS is vital to poultry production sustainability. The purpose of this study was, therefore, to determine the effects of an amino acid-chelated trace mineral supplement on growth performance, stress and inflammatory markers, and meat quality in heat-stressed broilers. One day-old Cobb 500 male broilers (n = 480) were allocated into 12 environmental chambers (24 floor pens) and divided into two groups: one group supplemented with amino acid-chelated trace mineral in drinking water and one control group. On day 28, birds were subjected to chronic heat stress (HS, 2 wk, 35 °C and 20% to 30% RH) or maintained at thermoneutral condition (TN, 24 °C) in a 2 × 2 factorial design. Feed intake (FI), water consumption, and body weight were recorded. At day 42, serum fluorescein isothiocyanate dextran (FITC-D) levels, blood gas, electrolyte, and stress markers were measured. Jejunum samples were collected to measure gene expression of stress, inflammation, and tight junction proteins. The rest of the birds were processed to evaluate carcass traits. HS resulted in an increase in core body temperature, which increased water intake and decreased FI, body weight, and feed efficiency (P < 0.05). HS reduced carcass yield and the weight of all parts (P < 0.05). HS significantly increased levels of circulating corticosterone (CORT), heat shock protein 70 (HSP70), interleukin 18 (IL-18), tumor necrosis factor alpha, C-reactive protein, and nucleotide-binding oligomerization domain leucine-rich repeat and pyrin domain-containing 3 expression. HS significantly increased serum FITC-D levels and the expression of HSP70 and IL-18 in the jejunum. Although it did not affect the growth performance, amino acid-chelated trace mineral supplementation reversed the effect of HS by reducing CORT and FITC-D levels and the expression of stress and proinflammatory cytokines in the circulation and the jejunum. However, it upregulated these parameters in birds maintained under TN conditions. Together, these data indicate that the amino acid-chelated trace mineral might alleviate stress and inflammation and improve gut integrity in heat-stressed but not thermoneutral broilers.

Estimation of dietary manganese requirement for laying duck breeders: effects on productive and reproductive performance, egg quality, tibial characteristics, and serum biochemical and antioxidant indices

This study was aimed at estimating the dietary manganese (Mn) requirement for laying duck breeders. A total of 504 Longyan duck breeders (body weight: 1.20 ± 0.02 kg) aged 17 wk were randomly allocated to 6 treatments. The birds were fed with a basal diet (Mn, 17.5 mg/kg) or diets supplemented with 20, 40, 80, 120, or 160 mg/kg of Mn (as MnSO₄·H₂O) for 18 wk. Each treatment had 6 replicates of 14 ducks each. As a result of this study, dietary Mn supplementation did not affect the productive performance of laying duck breeders in the early laying period (17–18 wk), but affected egg production, egg mass, and feed conversion ratio (FCR) from 19 to 34 wk (P < 0.05), and there was a linear and quadratic effect of supplement level (P < 0.05). The proportion of preovulatory ovarian follicles increased (P < 0.01) linearly and quadratically, and atretic follicles (weight and percentage) decreased (P < 0.05) quadratically with dietary Mn supplementation. The density and breaking strength of tibias increased (quadratic; P < 0.05), the calcium content of tibias decreased (linear, quadratic; P < 0.01), and Mn content increased (linear, quadratic; P < 0.001) with increase in Mn. The addition of Mn had a quadratic effect on serum contents of estradiol, prolactin, progesterone, luteinizing hormone, and follicle-stimulating hormone (P < 0.001). Dietary Mn supplementation decreased serum contents of total protein (linear, P < 0.05), glucose (quadratic, P < 0.05), total bilirubin, triglycerides, total cholesterol, low-density lipoprotein cholesterol, and calcium (linear, quadratic; P < 0.05). The serum total antioxidant capacity and total and Mn-containing superoxide dismutase activities increased (linear, quadratic; P < 0.001), and malondialdehyde content decreased (linear, quadratic; P < 0.001) in response to Mn supplemental levels. The dietary Mn requirements, in milligram per kilogram for a basal diet containing 17.5 mg/kg of Mn, for Longyan duck breeders from 19 to 34 wk of age were estimated to be 84.2 for optimizing egg production, 85.8 for egg mass, and 95.0 for FCR. Overall, dietary Mn supplementation, up to 160 mg/kg of feed, affected productive performance, tibial characteristics, and serum biochemical and antioxidant status of layer duck breeders. Supplementing this basal diet (17.5 mg/kg of Mn) with 85 to 95 mg/kg of additional Mn was adequate for laying duck breeders during the laying period.

Relative bioavailability of selenium yeast for broilers fed a conventional corn-soybean meal diet

The present study was conducted to assess the relative bioavailability of selenium (Se) as Se yeast (SY) relative to sodium selenite (SS) for broilers fed a conventional corn-soybean meal diet. A total of 360 one-d-old Arbor Acres commercial broilers were randomly assigned to 5 treatments with 6 replicates per treatment in a completely randomized design involving a 2 (Se sources: SY and SS) × 2 (added Se levels: 0.20 and 0.40 mg Se/kg) factorial design of treatments plus 1 (a Se-unsupplemented control diet) for 42 days. The results showed that Se concentrations in plasma, liver, heart, breast muscle, pancreas and kidney of broilers on d 21 and 42, glutathione peroxidase (GSH-Px) activity in the pancreas on d 21 as well as in the breast muscle and pancreas on d 42, and GSH-Px mRNA levels in the liver, heart, breast muscle and pancreas on d 21 increased linearly (p < .03) as levels of added Se increased. Furthermore, a difference (p ≤ .05) between SY and SS was detected for Se concentrations in plasma, liver, heart, breast muscle, pancreas and kidney, GSH-Px activity in pancreas on both d 21 and 42, as well as pancreatic GSH-Px mRNA level on d 21. Based on slope ratios from the multiple linear regressions of the above indices, the Se bioavailabilities of SY relative to SS (100%) were 111%-394% (p ≤ .05) when calculated from the Se concentrations in plasma, liver, heart, breast muscle, pancreas, kidney and GSH-Px activities in pancreas on d 21 and 42, as well as GSH-Px mRNA level in pancreas on d 21. The results from this study indicated that the Se from SY was more available for enhancing the Se concentrations in plasma or tissues and the expression and activity of GSH-Px in pancreas of broilers than the Se from SS.

Kinetics of phosphorus absorption and expressions of related transporters in primary cultured duodenal epithelial cells of chick embryos

Two experiments were conducted to investigate the kinetics of phosphorus (P) absorption and expressions of type IIb sodium-dependent phosphate cotransporter (NaP-IIb), inorganic phosphate transporters 1 and 2 (PiT-1 and PiT-2) in primary cultured duodenal epithelial cells of chick embryos. In experiment 1, the P absorptions across duodenal epithelial cell monolayers at different incubation time points (0, 10, 20, 40, 60, 80, 100 and 120 min) were compared. In experiment 2, the kinetics of P absorption was performed at 40 min after incubation of duodenal epithelial cells with the media containing 0, 0.75, 1.5, 3.0, 6.0, 12.0, 24.0 and 48.0 mmol P/L as KH₂ PO₄ , and the mRNA and protein expression levels of NaP-IIb, PiT-1 and PiT-2 in duodenal epithelial cells with the media containing 0, 6.0 and 48.0 mmol P/L were determined at 87 min after incubation. The results from experiment 1 showed that the P absorption increased linearly (p < .0001) from 0 to 80 min and the fastest increase occurred at 40 min; the asymptotic model was shown to have the best fit degree, and the optimal incubation time for saturable P absorption was determined to be 87 min. The kinetic curves of P absorption from experiment 2 demonstrated that P absorption was a mixed process of a non-saturable diffusion plus a saturable carrier-mediated transport across the duodenal epithelial cells. The high P concentration (48.0 mmol/L) decreased (p < .05) NaP-IIb and PiT-1 mRNA and protein levels and increased (p < .0001) PiT-2 mRNA level. These results indicated that the P absorption across primary cultured duodenal epithelial cell monolayers of chick embryos was a mixed process of a non-saturable diffusion plus a saturable carrier-mediated transport and could be restricted by reducing the NaP-IIb and PiT-1 expressions while increasing the PiT-2 expression at a high P concentration.

Phosphorus absorption and gene expression levels of related transporters in the small intestine of broilers

To investigate the P absorption and gene expression levels of related co-transporters, type IIb sodium-dependent phosphate co-transporter (NaPi-IIb), inorganic phosphate transporter 1 (PiT-1) and inorganic phosphate transporter 2 (PiT-2) in the small intestine of broilers, 450 1-d-old Arbor Acres male broilers were randomly allocated to one of three treatments with ten replicate cages of fifteen birds per cage for each treatment in a completely randomised design. Chickens were fed a diet with no added inorganic P (containing 0·06 % non-phytate P (NPP)) or with either 0·21 or 0·44 % NPP for 21 d. Plasma P concentration in the hepatic portal vein, mRNA and protein expression levels of NaPi-IIb, PiT-1 and PiT-2 were determined at 7, 14 and 21 d of age. The results showed that the concentration of P in plasma in the hepatic portal vein increased as dietary NPP increased (P<0·0001). At 14 and 21 d of age, the increase in dietary NPP inhibited (P<0·003) NaPi-IIb mRNA expression level in the duodenum, as well as PiT-1 mRNA and protein expression levels in the ileum, but promoted NaPi-IIb protein expression level (P<0·002) and PiT-2 mRNA and protein expression levels (P<0·04) in the duodenum. These results suggest that NaPi-IIb, PiT-1 and PiT-2 might be important P transporters in the small intestine of broilers. Higher intestinal P absorption may be achieved by up-regulating the protein expression levels of NaPi-IIb and PiT-2 and down-regulating the protein expression of PiT-1.

Relative bioavailability of ultrafine sodium selenite for broilers fed a conventional corn-soybean meal diet

The particle size of selenium (Se) sources could affect Se absorption and utilization, and thus it is hypothesized that the Se bioavailability might be higher in ultrafine sodium selenite (USSe) than in sodium selenite (SSe) for broilers because of USSe's smaller particle size. An experiment was conducted to investigate the relative bioavailability of Se as USSe relative to SSe for broiler chicks fed a conventional corn-soybean meal diet. A total of 504 one-d-old Arbor Acres commercial male broilers were randomly allotted to 1 of 7 treatments with 6 replicates per treatment in a completely randomized design involving in a 2 (Se sources) × 3 (added Se levels) factorial arrangement of treatments plus a Se-unsupplemented control diet containing 0.05 mg Se/kg by analysis for 21 d. The 2 Se sources were USSe and SSe, and the 3 added Se levels were 0.15, 0.30, or 0.45 mg Se/kg. The Se concentrations, glutathione peroxidase (GSH-Px) activities, and mRNA relative abundances in plasma, liver, or pancreas of broilers on day 14 and 21 were determined. The results showed that Se concentrations, GSH-Px activities in plasma, liver, and pancreas, and mRNA relative abundances in the liver and pancreas of broilers on day 14 and 21 increased linearly (P < 0.05) as the added Se-level increased. Furthermore, a difference (P < 0.05) between USSe and SSe was detected for GSH-Px mRNA relative abundance in the pancreas of broilers on day 14. On the basis of the slope ratios from the multiple linear regression of the pancreatic GSH-Px mRNA relative abundance of broilers at 14 d of age on daily dietary analyzed Se intake, the Se bioavailability of USSe relative to SSe (100%) was 158% (P < 0.05). The results from this study indicated that the Se from USSe was more available to broilers than the Se from SSe in enhancing the pancreatic GSH-Px mRNA expression.

Severe riboflavin deficiency induces alterations in the hepatic proteome of starter Pekin ducks

Suboptimal vitamin B2 status is encountered globally. Riboflavin deficiency depresses growth and results in a fatty liver. The underlying mechanisms remain to be established and an overview of molecular alterations is lacking. We investigated hepatic proteome changes induced by riboflavin deficiency to explain its effects on growth and hepatic lipid metabolism. In all, 360 1-d-old Pekin ducks were divided into three groups of 120 birds each, with twelve replicates and ten birds per replicate. For 21 d, the ducks were fed ad libitum a control diet (CAL), a riboflavin-deficient diet (RD) or were pair-fed with the control diet to the mean daily intake of the RD group (CPF). When comparing RD with CAL and CPF, growth depression, liver enlargement, liver lipid accumulation and enhanced liver SFA (C6 : 0, C12 : 0, C16 : 0, C18 : 0) were observed. In RD, thirty-two proteins were enhanced and thirty-one diminished (>1·5-fold) compared with CAL and CPF. Selected proteins were confirmed by Western blotting. The diminished proteins are mainly involved in fatty acid β-oxidation and the mitochondrial electron transport chain (ETC), whereas the enhanced proteins are mainly involved in TAG and cholesterol biosynthesis. RD causes liver lipid accumulation and growth depression probably by impairing fatty acid β-oxidation and ETC. These findings contribute to our understanding of the mechanisms of liver lipid metabolic disorders due to RD.

Maternal dietary manganese protects chick embryos against maternal heat stress via epigenetic-activated antioxidant and anti-apoptotic abilities

Maternal heat stress induced the aberrant epigenetic patterns resulting in the abnormal development of offspring embryos. It is unclear whether maternal dietary manganese supplementation as an epigenetic modifier could protect the chick embryonic development against maternal heat stress via epigenetic mechanisms. To test this hypothesis using an avian model, a completely randomized design with a 2 (maternal normal and high environmental temperatures of 21 and 32°C, respectively) × 3 (maternal dietary manganese sources, the control diet without manganese supplementation and the control diet + 120 mg/kg as either inorganic or organic manganese) factorial arrangement was adopted. Maternal environmental hyperthermia increased mRNA expressions of heat shock proteins 90 and 70, cyclin-dependent kinase 6 and B-cell CLL/lymphoma 2-associated X protein displaying oxidative damage and apoptosis in the embryonic heart. Maternal environmental hyperthermia impaired the embryonic development associated with the alteration of epigenetic status, as evidenced by global DNA hypomethylation and histone 3 lysine 9 hypoacetylation in the embryonic heart. Maternal dietary manganese supplementation increased the heart anti-apoptotic gene B-cell CLL/lymphoma 2 expressions under maternal environmental hyperthermia and manganese superoxide dismutase enzyme activity in the embryonic heart. Maternal dietary organic Mn supplementation effectively eliminated the impairment of maternal environmental hyperthermia on the embryonic development. Maternal dietary manganese supplementation up-regulated manganese superoxide dismutase mRNA expression by reducing DNA methylation and increasing histone 3 lysine 9 acetylation of its promoter. It is suggested that maternal dietary manganese addition could protect the chick embryonic development against maternal heat stress via enhancing epigenetic-activated antioxidant and anti-apoptotic abilities.

Maternal dietary zinc supplementation enhances the epigenetic-activated antioxidant ability of chick embryos from maternal normal and high temperatures

The role of maternal dietary zinc supplementation in protecting the embryos from maternal hyperthermia-induced negative effects via epigenetic mechanisms was examined using an avian model (Gallus gallus). Broiler breeder hens were exposed to two maternal temperatures (21°C and 32°C) × three maternal dietary zinc treatments (zinc-unsupplemented control diet, the control diet + 110 mg zinc/kg inorganic or organic zinc) for 8 weeks. Maternal hyperthermia increased the embryonic mortality and induced oxidative damage evidenced by the elevated mRNA expressions of heat shock protein genes. Maternal dietary zinc deficiency damaged the embryonic development associated with the global DNA hypomethylation and histone 3 lysine 9 hyperacetylation in the embryonic liver. Supplementation of zinc in maternal diets effectively eliminated the embryonic mortality induced by maternal hyperthermia and enhanced antioxidant ability with the increased mRNA and protein expressions of metallothionein IV in the embryonic liver. The increased metallothionein IV mRNA expression was due to the reduced DNA methylation and increased histone 3 lysine 9 acetylation of the metallothionein IV promoter regardless of zinc source. These data demonstrate that maternal dietary zinc addition as an epigenetic modifier could protect the offspring embryonic development against maternal heat stress via enhancing the epigenetic-activated antioxidant ability.

Use of molecular biomarkers to estimate manganese requirements for broiler chickens from 22 to 42 d of age

The present study was carried out to evaluate dietary Mn requirements of broilers from 22 to 42 d of age using molecular biomarkers. Chickens were fed a conventional basal maize–soyabean meal diet supplemented with Mn as Mn sulphate in graded concentrations of 20 mg Mn/kg from 0 to 140 mg Mn/kg of diet for 21 d (from 22 to 42 d of age). The Mn response curves were fitted for ten parameters including heart Mn-containing superoxide dismutase (MnSOD) mRNA and its protein expression levels and the DNA-binding activities of specificity protein 1 (Sp1) and activating protein-2 (AP-2). Heart MnSOD mRNA and protein expression levels showed significant quadratic responses (P<0·01), and heart MnSOD activity showed a broken-line response (P<0·01), whereas Mn content and DNA-binding activities of Sp1 and AP-2 in the heart displayed linear responses (P<0·01) to dietary Mn concentrations, respectively. The estimates of dietary Mn requirements were 101, 104 and 94 mg/kg for full expressions of MnSOD mRNA level, MnSOD protein level and MnSOD activity in the heart, respectively. Our findings indicate that heart MnSOD mRNA expression level is a more reliable indicator than heart MnSOD protein expression level and its activity for the evaluation of Mn requirement of broilers, and about 100 mg Mn/kg of diet is required for the full expression of heart MnSOD in broilers fed the conventional basal maize–soyabean meal diet from 22 to 42 d of age.