Acute Heat Stress Induces Oxidative Stress and Decreases Adaptation in Young White Leghorn Cockerels by Downregulation of Avian Uncoupling Protein

Contents of Macro- and Microelements in Blood Serum and Breast Muscle of Turkey Subjected to Pre-Slaughter Transport for Various Distances

In this study, the effect of pre-slaughter handling on the content of macro- and micronutrients in blood serum and in the breast muscle of turkeys was assessed. Four different variants of pre-slaughter handling were used in the research: no transport (N-T), transport for a distance of 100 km (T-100), transport for a distance of 200 km (T-200), and transport for a distance of 300 km (T-300). In each of them, 30 female and 30 male turkeys were used. Blood was collected from the birds before slaughter, and samples of the pectoral muscle were collected after slaughter. In the obtained biological material, the content of Mg, P, Ca, Fe, Na and K was analyzed. On the basis of the obtained research results, it can be concluded that the pre-slaughter handling negatively affects the content of macro- and microelements both in the blood serum and in the pectoral muscles of experimental turkeys. Additionally, differences due to the sex of birds were observed.

Red chili powder dietary supplementation regularized the performance, hematobiochemical indices, oxidative status, and 8-hydroxy-2'-deoxyguanosine of aflatoxin B1 exposed broiler chickens

The effects of red chili powder dietary supplementation on the performance, hematobiochemical indices, oxidative status, and DNA damage in broiler chickens fed aflatoxin B1 (AFB1) contaminated diets were studied. Two hundred and forty Cobb 500 breed day-old broiler chicks were randomly distributed into control group (CONT), 0.5 mg/kg AFB1-exposed group (AFTB), 0.5 g/kg red chili pericarp powder supplementation alongside the 0.5 mg/kg AFB1 exposed group (RCPA), and 0.5 g/kg red chili seed powder supplementation alongside the 0.5 mg/kg AFB1 exposed group (RCSA). The red chili supplementation, in both pericarp powder and seed powder, positively influenced broiler performance by improving (P < 0.05) weight gain, feed intake, and feed conversion ratio, with a reduction in mortality rates compared to the AFTB group. Hematological indices showed that AFB1 exposure decreased (P < 0.05) the red blood cell count, packed cell volume, and hemoglobin (Hb) concentration, but the red chili supplementation mitigated these reductions. Additionally, total white blood cell counts were maintained (P > 0.05) in red chili-supplemented groups compared to CONT. Red chili supplementation increased (P < 0.05) the total protein and globulin concentrations and reduced (P < 0.05) liver enzyme levels compared to the AFTB group. The oxidative enzyme levels in RCPA and RCSA were similar (P > 0.05) to CONT groups. The red chili supplementations counteracted DNA damage, as reflected by similar (P > 0.05) 8-hydroxy-2'-deoxyguanosine levels recorded in RCPA, RCSA, and CONT groups levels. These findings suggest that 0.5 g/kg red chili supplementation has the potential to ameliorate the adverse effects of AFB1 exposure on broiler chickens, improving their performance and health.

Protective impacts of mitochondria enhancers against thermal stress in poultry

Heat stress (HS) is still the essential environmental agent influencing the poultry industry. Research on HS in poultry has progressively acquired growing interest because of increased attention to climate alteration. Poultry can survive at certain zone of environmental temperatures, so it could be considered homoeothermic. In poultry, the normal body temperature is essential to enhance the internal environment for growth, which is achieved by normal environmental temperature. Recently, many studies have revealed that HS could cause mitochondrial dysfunction in broilers by inducing redox dysfunction, increasing uncoupling protein, boosting lipid and protein oxidation, and oxidative stress. Moreover, HS diminished the energy suppliers supported by mitochondria activity. A novel strategy for combating the negative influences of HS via boosting the mitochondria function through enrichment of the diets with mitochondria enhancers was also described in this review. Finally, the current review highlights the mitochondria dysfunction induced by HS in broilers and attempts to boost mitochondria functionality by enriching mitochondria enhancers to broiler diets.

The Influence of Heat Stress on Chicken Immune System and Mitigation of Negative Impacts by Baicalin and Baicalein

Heat stress (HS) in poultry husbandry is an important stressor and with increasing global temperatures its importance will increase. The negative effects of stress on the quality and quantity of poultry production are described in a range of research studies. However, a lack of attention is devoted to the impacts of HS on individual chicken immune cells and whole lymphoid tissue in birds. Oxidative stress and increased inflammation are accompanying processes of HS, but with deleterious effects on the whole organism. They play a key role in the inflammation and oxidative stress of the chicken immune system. There are a range of strategies that can help mitigate the adverse effects of HS in poultry. Phytochemicals are well studied and some of them report promising results to mitigate oxidative stress and inflammation, a major consequence of HS. Current studies revealed that mitigating these two main impacts of HS will be a key factor in solving the problem of increasing temperatures in poultry production. Improved function of the chicken immune system is another benefit of using phytochemicals in poultry due to the importance of poultry health management in today's post pandemic world. Based on the current literature, baicalin and baicalein have proven to have strong anti-inflammatory and antioxidative effects in mammalian and avian models. Taken together, this review is dedicated to collecting the literature about the known effects of HS on chicken immune cells and lymphoid tissue. The second part of the review is dedicated to the potential use of baicalin and baicalein in poultry to mitigate the negative impacts of HS on poultry production.

Investigation of Spotty Liver Disease and Campylobacter hepaticus in Layer Flocks-A Field Study

Campylobacter hepaticus (C. hepaticus) was recently discovered as the causative agent of Spotty Liver Disease (SLD). SLD affects laying hens and causes significant economic losses in egg production in several countries throughout the world. Field observations reveal that cases of SLD appear with a high risk of reoccurrence, specifically in free-range and organic brown-feathered layer lines. Possible factors contributing to the development of SLD still have to be elucidated. In this field study, one free range (Flock 1) and one organic flock (Flock 2) of brown laying hens kept on farms with a history of clinical SLD were monitored for C. hepaticus colonization, clinical signs, and egg production from 16 to 79 wk of age on the first farm and from 17 to 83 wk of age on the other. The flocks showed a significant drop in egg production at 32 to 39 or 56 wk of age, respectively, which was associated with macroscopically visible liver lesions typical for SLD. Interestingly, in both cases observed clinical disease was linked to a stressful event: heat stress for Flock 1 and respiratory symptoms for Flock 2. C. hepaticus was detected by PCR during the acute phase of the disease in Flock 1. At 50 wk after the initial clinical outbreak had waned, C. hepaticus was still able to be isolated by culture in this flock. This clearly demonstrates that C. hepaticus persists either in the birds or their environment. We speculate that this long persistence may favor chronic SLD in affected flocks and the reoccurrence of SLD in subsequent flocks. Clinically less severe SLD outbreaks may be observed after re-exposure of clinically recovered flocks.

An evaluation of the thermoregulatory potential of in ovo delivered bioactive substances (probiotic, folic acid, and essential oil) in broiler chickens

Mitigating the negative effects of heat stress (HS) is a critical challenge for the global poultry industry. This study evaluated the thermoregulatory potential of 3 in ovo delivered bioactive substances using selected gut health parameters. Eggs were incubated and allotted to 5 groups, and respective bioactive substances delivered. These groups included-the noninjected, in ovo saline, in ovo folic acid (FA), in ovo probiotics (P), and in ovo essential oil (EO). At hatch, chicks were assigned to 5 new posthatch treatment combinations, including A) Negative control (NC)-noninjected eggs offered a basal corn-wheat-soybean diet, B) Antibiotics-NC + 0.05% bacitracin methylene disalicylate, C) In ovo FA-eggs injected with FA + NC diet, D) In ovo probiotics-eggs injected with probiotics + NC diet, E) In ovo + in-water EO-eggs injected with EO and supplied EO via drinking water + NC diet. Birds were raised for 28 d in 8 replicate cages/treatment (6 birds/cage) and exposed to either a thermoneutral (24°C ± 0.2) or HS challenge (31°C) condition from d 21 to d 28. The in ovo delivered FA and EO treatments reduced (P < 0.001) hatchability by at least 26% compared to NC. Induced HS reduced (P < 0.001) total plasma protein, total antioxidant capacity, and villus width in the duodenum and jejunum. Independent of HS and compared to NC, the in ovo + in-water EO treatment resulted in (P < 0.05) at least a 15% increase in villus height: crypt depth across the 3 gut sections. The in ovo + in-water EO treatment also increased the relative mRNA expression of intestinal barrier-related genes (Claudin1,3,4, Occludin, Zona occludens-2, and Mucin 2). Under HS, the in ovo + in-water EO treatment recorded a 3.5-fold upregulation of amino acid transporter gene (SLC1A1), compared to NC. Subject to further hatchability optimization, the in ovo + in-water delivery of EO show potential to afford broiler chicken thermotolerance.

Mechanistic Approaches to the Application of Nano-Zinc in the Poultry and Biomedical Industries: A Comprehensive Review of Future Perspectives and Challenges

Bio-fortification is a new, viable, cost-effective, and long-term method of administering crucial minerals to a populace with limited exposure to diversified foods and other nutritional regimens. Nanotechnology entities aid in the improvement of traditional nutraceutical absorption, digestibility, and bio-availability. Nano-applications are employed in poultry systems utilizing readily accessible instruments and processes that have no negative impact on animal health and welfare. Nanotechnology is a sophisticated innovation in the realm of biomedical engineering that is used to diagnose and cure various poultry ailments. In the 21st century, zinc nanoparticles had received a lot of considerable interest due to their unusual features. ZnO NPs exhibit antibacterial properties; however, the qualities of nanoparticles (NPs) vary with their size and structure, rendering them adaptable to diverse uses. ZnO NPs have shown remarkable promise in bio-imaging and drug delivery due to their high bio-compatibility. The green synthesized nanoparticles have robust biological activities and are used in a variety of biological applications across industries. The current review also discusses the formulation and recent advancements of zinc oxide nanoparticles from plant sources (such as leaves, stems, bark, roots, rhizomes, fruits, flowers, and seeds) and their anti-cancerous activities, activities in wound healing, and drug delivery, followed by a detailed discussion of their mechanisms of action.

In silico investigation of uncoupling protein function in avian genomes

Introduction

The uncoupling proteins (UCPs) are involved in lipid metabolism and belong to a family of mitochondrial anionic transporters. In poultry, only one UCP homologue has been identified and experimentally shown to be associated with growth, feed conversion ratio, and abdominal fat according to its predominant expression in bird muscles. In endotherm birds, cell metabolic efficiency can be tuned by the rate of mitochondrial coupling. Thus, avUCP may be a key contributor to controlling metabolic rate during particular environmental changes.

Methods

This study aimed to perform a set of in-silico investigations primarily focused on the structural, biological, and biomimetic functions of avUCP. Thereby, using in silico genome analyses among 8 avian species (chicken, turkey, swallow, manakin, sparrow, wagtail, pigeon, and mallard) and a series of bioinformatic approaches, we provide phylogenetic inference and comparative genomics of avUCPs and investigate whether sequence variation can alter coding sequence characteristics, the protein structure, and its biological features. Complementarily, a combination of literature mining and prediction approaches was also applied to predict the gene networks of avUCP to identify genes, pathways, and biological crosstalk associated with avUCP function.

Results

The results showed the evolutionary alteration of UCP proteins in different avian species. Uncoupling proteins in avian species are highly conserved trans membrane proteins as seen by sequence alignment, physio-chemical parameters, and predicted protein structures. Taken together, avUCP has the potential to be considered a functional marker for the identification of cell metabolic state, thermogenesis, and oxidative stress caused by cold, heat, fasting, transfer, and other chemical stimuli stresses in birds. It can also be deduced that avUCP, in migrant or domestic birds, may increase heat stress resistance by reducing fatty acid transport/b-oxidation and thermoregulation alongside antioxidant defense mechanisms. The predicted gene network for avUCP highlighted a cluster of 21 genes involved in response to stress and 28 genes related to lipid metabolism and the proton buffering system. Finally, among 11 enriched pathways, crosstalk of 5 signaling pathways including MAPK, adipocytokine, mTOR, insulin, ErbB, and GnRH was predicted, indicating a possible combination of positive or negative feedback among pathways to regulate avUCP functions.

Discussion

Genetic selection for fast-growing commercial poultry has unintentionally increased susceptibility to many kinds of oxidative stress, and so avUCP could be considered as a potential candidate gene for balancing energy expenditure and reactive oxygen species production, especially in breeding programs. In conclusion, avUCP can be introduced as a pleiotropic gene that requires the contribution of regulatory genes, hormones, pathways, and genetic crosstalk to allow its finely-tuned function.

Effect of 3-caffeoylquinic acid on growth performance, nutrient digestibility, and intestinal functions in weaned pigs

Phenolic acid like with the 3-caffeoylquini acid (3-CQA) is formed by caffeic acid and qunic acid. This study was conducted to explore the effect of 3-CQA on growth performance and intestinal functions in weaned pigs. A total of 180 weaned pigs were randomly allocated into five treatments with 6 replicate pens per treatment (6 pigs per pen). Pigs in the control group (CON) were fed with basal diet (BD), and the others in the experimental groups were fed with BD and supplemented with 12.5, 25, 50, and 100 mg/kg 3-CQA. On day 43, the blood sample-collected pigs in the CON and optimal-dose group (only based on growth performance) were picked, and housed in metabolism cages (a total of 12 pigs, N = 6). 3-CQA increased the feed efficiency from days 21 to 42 of the trial and throughout the trial (P < 0.05). 3-CQA increased the serum concentrations of total protein, albumin, and total cholesterol (P < 0.05). Moreover, 3-CQA supplementation at 25 mg/kg increased the apparent digestibility of DM, energy, and ash (P < 0.05). Interestingly, 3-CQA decreased the crypt depth but increased the ratio of villus height to crypt depth in the jejunum and ileum (P < 0.05). Moreover, 3-CQA also increased the activities of sucrase, lactase, and catalase in the jejunal mucosa, and increased the activities of alkaline phosphatase and superoxide dismutase in the ileal mucosa (P < 0.05). 3-CQA also increased the abundance of secretory immunoglobulin A in the ileal mucosa (P < 0.05). Importantly, 3-CQA not only elevated the expression levels of critical functional genes such as the zonula occludens-1 , occludin, solute carrier family 7 , and nuclear factor erythroid 2-related factor 2 (Nrf2) in the duodenum but also elevated the expression levels of divalent metal transporter-1 and Nrf2 in the jejunum (P < 0.05). These results suggested a positive effect of 3-CQA supplementation on the growth and intestinal functions of weaned pigs. The mechanisms of action may be associated with elevated anti-oxidant capacity and improved intestinal barrier functions.

Severe heat stress modulated nuclear factor erythroid 2-related factor 2 and macrophage migration inhibitory factor pathway in rat liver

Heat stress impairs physiology and overall functionality of the body at tissue and organ level in animals. Liver being a vital organ performs more than hundreds regulatory functions of the body. Present study investigates the modulation of molecular pathways that are responsible for liver damage triggered by heat stress. Male Sprague dawley rats were exposed to heat stress (45 °C) in heat simulation chamber till core temperature reaches 40 °C and 42 °C in 25 and 42 min respectively. For in-depth evaluation of liver functions during severe heat stress, hepatic transcriptome and proteome were analysed by microarray and two dimensional gel electrophoresis respectively. Results revealed major alterations in redox status, inflammation, mitochondrial dysfunction and proteostasis related pathways. Data of molecular pathway analysis demonstrate that nuclear factor erythroid 2-related factor 2 (NRF-2) mediated oxidative stress response and macrophage migration inhibitory factor (MIF) regulated inflammatory pathways were upregulated in severe heat stressed liver. Expression levels of downstream molecules of above pathways such as heat shock protein 90AB 1, peroxiredoxin 5, Jun N-terminal kinases 1/2, heme-oxygenase 1, apolipoprotein 1 and interleukin 10 were examined and result suggested the upregulation of these genes modulates the NRF-2 and MIF regulated pathways in heat stressed liver. Irregularity in molecular signalling networks lead to mitochondrial dysfunction indicated by upregulation of ATP synthase β and peroxiredoxin 1 along with decreased levels of glucose-6-phosphate dehydrogenase and enhanced activity of cytochrome c in liver mitochondria. Thus, current study demonstrated heat induced alterations in key liver functions were regulated by NRF-2 and MIF pathways.

Duodenal Metabolic Profile Changes in Heat-Stressed Broilers

Simple Summary

Heat stress (HS) represents an environmental and socio-economic burden to the poultry industry worldwide. However, the underpinning mechanisms for HS responses are still not well defined. Here, we used a high-throughput analysis to determine the metabolite profiles in acute and chronic heat-stressed broilers in comparison with thermoneutral and pair-fed birds. The results showed that HS altered several duodenal metabolites in a duration-dependent manner and identified potential metabolite signatures.

Abstract

Heat stress (HS) is devastating to poultry production sustainability worldwide. In addition to its adverse effects on growth, welfare, meat quality, and mortality, HS alters the gut integrity, leading to dysbiosis and leaky gut syndrome; however, the underlying mechanisms are not fully defined. Here, we used a high-throughput mass spectrometric metabolomics approach to probe the metabolite profile in the duodenum of modern broilers exposed to acute (AHS, 2 h) or chronic cyclic (CHS, 8 h/day for 2 weeks) HS in comparison with thermoneutral (TN) and pair-fed birds. Ultra high performance liquid chromatography coupled with high resolution mass spectrometry (UHPLC–HRMS) identified a total of 178 known metabolites. The trajectory analysis of the principal component analysis (PCA) score plots (both 2D and 3D maps) showed clear separation between TN and each treated group, indicating a unique duodenal metabolite profile in HS birds. Within the HS groups, partial least squares discriminant analysis (PLS-DA) displayed different clusters when comparing metabolite profiles from AHS and CHS birds, suggesting that the metabolite signatures were also dependent on HS duration. To gain biologically related molecule networks, the above identified duodenal metabolites were mapped into the Ingenuity Pathway Analysis (IPA) knowledge-base and analyzed to outline the most enriched biological functions. Several common and specific top canonical pathways were generated. Specifically, the adenosine nucleotide degradation and dopamine degradation pathways were specific for the AHS group; however, the UDP-D-xylose and UDP-D-glucuronate biosynthesis pathways were generated only for the CHS group. The top diseases enriched by the IPA core analysis for the DA metabolites, including cancer, organismal (GI) injury, hematological, cardiovascular, developmental, hereditary, and neurological disorders, were group-specific. The top altered molecular and cellular functions were amino acid metabolism, molecular transport, small molecule biochemistry, protein synthesis, cell death and survival, and DNA damage and repair. The IPA-causal network predicted that the upstream regulators (carnitine palmitoyltransferase 1B, CPT1B; histone deacetylase 11, HDAC11; carbonic anhydrase 9, CA9; interleukin 37, IL37; glycine N-methyl transferase, GNMT; GATA4) and the downstream mediators (mitogen-activated protein kinases, MAPKs; superoxide dismutase, SOD) were altered in the HS groups. Taken together, these data showed that, independently of feed intake depression, HS induced significant changes in the duodenal metabolite profile in a duration-dependent manner and identified a potential duodenal signature for HS.

Tryptophan Alleviates Acute Heat Stress-Induced Impairment of Antioxidant Status and Mitochondrial Function in Broilers

Heat stress has been considered as a critical risk factor for decreasing performance and causing oxidative stress in broilers. The tryptophan (TRP) derivative 5-hydroxytryptophan has been reported to protect membrane fluidity in broilers suffering from oxidative stress. Therefore, this experiment was conducted to investigate the effects of dietary TRP supplementation on antioxidant status and mitochondrial function-related genes expressions in broilers exposed to acute heat stress (34 ± 1°C, 24 h). Female Arbor Acres broilers (19-d-old, n = 180) were randomly assigned to 1 of 3 treatments. Broilers were fed a basal diet and in the thermoneutral conditions (TN, 23 ± 1°C) was considered as the TN group. Broilers were fed a basal diet and exposed to acute heat stress (HS, 34 ± 1°C) was regarded as the HS group. Broilers were fed a basal diet supplemented with 0.18% L-tryptophan and under HS conditions was treated as the HS + TRP groups. Heat stress led to increased malondialdehyde (MDA) concentration (P < 0.05), while it elevated catalase (CAT), glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), and total antioxidant capacity activities (T-AOC) (P < 0.05) compared with the TN group. Nevertheless, compared with the HS group, TRP supplementation increased SOD activity (P < 0.05). The effects of acute heat stress were associated with increased mRNA abundance for redox-related genes (P < 0.05), and reduced mRNA levels for mitochondrial function-related genes (P < 0.05). Notably, the effects of acute heat stress on mitochondrial function-related genes expressions were reversed by TRP treatment. Collectively, dietary 0.18% TRP supplementation beneficially protects against acute heat stress-induced oxidation stress and mitochondrial dysfunction by regulating antioxidant states and increasing mitochondrial function-related genes expressions in broilers.

Zinc Methionine Improves the Growth Performance of Meat Ducks by Enhancing the Antioxidant Capacity and Intestinal Barrier Function

This study was conducted to investigate the effects of zinc methionine (Zn-Met) on the growth performance, antioxidant capacity and intestinal barrier function of meat ducks. Three hundred and sixty 1-day-old male Cherry Valley ducks were randomly divided into 6 groups with 6 replicates (10 birds each), and fed diets with 0, 30, 60, 90, 120 or 150 mg/kg Zn for 35 d. The results indicated that dietary supplementation with Zn-Met substantially increased the average daily gain (ADG), and reduced the feed to gain ratio (F/G) during 1–35 d (P &lt; 0.05). Dietary Zn-Met markedly increased the activity of superoxide dismutase (SOD), catalase (CAT) and glutathione (GSH), and reduced the malondialdehyde (MDA) content in the jejunum (P &lt; 0.05). The mRNA expression levels of critical antioxidant enzymes such as SOD, CAT, and nuclear factor erythroid 2-related factor 2 (Nrf2) were increased by Zn in the jejunum (P &lt; 0.05). Supplementation with 60, 90, 120, and 150 mg/kg of Zn significantly reduced the diamine oxidase (DAO) activity in the serum (P &lt; 0.05). Different levels of Zn can increase the mRNA expression of occluding (OCLN) and zonula occludens-1 (ZO-1) in the jejunum (P &lt; 0.05). Diets supplemented with zinc significantly increased the content of mucin2 (MUC2), secretory immunoglobulin A (sIgA), immunoglobulin A (IgA) and immunoglobulin G (IgG) in the jejunum of meat ducks (P &lt; 0.05). The 16S rRNA sequence analysis indicated that 150 mg/kg of Zn had a higher relative abundance of Verrucomicrobia and Akkermansia in cecal digesta (P &lt; 0.05). In conclusion, Zn-Met improved the growth performance of meat ducks by enhancing intestinal antioxidant capacity and intestinal barrier function. This study provides data support for the application of Zn-Met in meat duck breeding.

Sericin Alleviates Thermal Stress Induced Anxiety-Like Behavior and Cognitive Impairment Through Regulation of Oxidative Stress, Apoptosis, and Heat-Shock Protein-70 in the Hippocampus

Exposure to heat stress (HS) has adverse effects on brain function, leading to anxiety-like behavior and memory impairment. Sericin is a silk derived protein with various neurobiological activities. The present study has investigated the effects of sericin on anxiety and cognitive impairments, in HS-received mice. The adult male mice were exposed to HS (43 ºC, 15 min once a day for 14 days) and simultaneously treated with 100, 150, and 200 mg/kg/day of sericin through oral gavage. Elevated plus-maze and Lashley III Maze tests were used to evaluate anxiety and learning and memory, respectively. The hippocampal BAX, BCL-2, caspase3, caspase9 and heat-shock protein-70 (HSP-70) were evaluated by western blotting and oxidative stress markers including malondialdehyde (MDA), total antioxidant capacity (TAC), super oxide dismutase (SOD) as well as glutathione peroxidase (GPx) were evaluated by spectroscopy method. The serum was collected for the analysis of the corticosterone levels. Treatment with sericin in higher doses reversed anxiety-like behavior and cognitive deficit induced by HS. Moreover, heat exposure increased serum corticosterone, hippocampal MDA, apoptotic proteins and HSP-70 levels. Sericin administration decreased serum corticosterone and enhanced hippocampal antioxidant defense and attenuated apoptosis and HSP-70 levels. The results show that the protective effects of sericin against HS-mediated cognitive dysfunction and anxiety-like behavior is possibly through suppressing HSP-70, oxidative stress and apoptosis.

Effect of chlorogenic acid on intestinal inflammation, antioxidant status, and microbial community of young hens challenged with acute heat stress

Heat stress in poultry is deleterious to productive performance. Chlorogenic acid (CGA) exerts antibacterial, anti-inflammatory, and antioxidant properties. This study was conducted to evaluate the effects of dietary supplemental CGA on the intestinal health and cecal microbiota composition of young hens challenged with acute heat stress. 100-day-old Hy-line brown pullets were randomly divided into four groups. The control group (C) and heat stress group (HS) received a basal diet. HS + CGA₃₀₀ group and HS + CGA₆₀₀ group received a basal diet supplemented with 300- and 600-mg/kg CGA, respectively, for 2 weeks before heat stress exposure. Pullets of HS, HS + CGA₃₀₀ , and HS + CGA₆₀₀ group were exposed to 38°C for 4 h while the control group was maintained at 25°C. In this study, dietary CGA supplementation had effect on mitigate the decreased T-AOC and T-SOD activities and the increasing of IL-1β and TNFα induced by acute heat stress. Dietary supplementation with 600 mg/kg CGA had better effect on increasing the relative abundance of beneficial bacterial genera, such as Rikenellaceae RC9_gut_group, Ruminococcaceae UCG-005, and Christensenellaceae R-7_group, and deceasing bacteria genera involved in inflammation, such as Sutterella species. Therefore, CGA can ameliorate acute heat stress damage through suppressing inflammation and improved antioxidant capacity and cecal microbiota composition.

High ambient temperature exposure during late gestation disrupts glycolipid metabolism and hepatic mitochondrial function tightly related to gut microbial dysbiosis in pregnant mice

As global warming intensifies, emerging evidence has demonstrated high ambient temperature during pregnancy negatively affects maternal physiology with compromised pregnant outcomes; however, little is known about the roles of gut microbiota and its underlying mechanisms in this process. Here, for the first time, we explored the potential mechanisms of gut microbiota involved in the disrupted glycolipid metabolism via hepatic mitochondrial function. Our results indicate heat stress (HS) reduces fat and protein contents and serum levels of insulin and triglyceride (TG), while increases that of non-esterified fatty acid (NEFA), β-hydroxybutyric acid (B-HBA), creatinine and blood urea nitrogen (BUN) (P < 0.05). Additionally, HS downregulates both mitochondrial genes (mtDNA) and nuclear encoding mitochondrial functional genes with increasing serum levels of malondialdehyde (MDA) and 8-hydroxydeoxyguanosine (8-OHdG) (P < 0.05). Regarding microbial response, HS boosts serum levels of lipopolysaccharide (LPS) (P < 0.05) and alters β-diversity (ANOSIM, P < 0.01), increasing the proportions of Escherichia-Shigella, Acinetobacter and Klebsiella (q < 0.05), while reducing that of Ruminiclostridium, Blautia, Lachnospiraceae_NK4A136_group, Clostridium VadinBB60 and Muribaculaceae (q < 0.05). PICRUSt analysis predicts that HS upregulates 11 KEGG pathways, mainly including bile secretion and bacterial invasion of epithelial cells. The collective results suggest that microbial dysbiosis due to late gestational HS has strong associations with damaged hepatic mitochondrial function and disrupted metabolic profiles.

Molecular and Cellular Responses of DNA Methylation and Thioredoxin System to Heat Stress in Meat-Type Chickens

Heat stress (HS) causes molecular dysfunction that adversely affects chicken performance and increases mortality. The responses of chickens to HS are extremely complex. Thus, the aim of this study was to evaluate the influence of acute and chronic exposure to HS on the expression of thioredoxin-peroxiredoxin system genes and DNA methylation in chickens. Chickens at 14 d of age were divided into two groups and reared under either constant normal temperature (25 °C) or high temperature (35 °C) in individual cages for 12 days. Five birds per group at one and 12 days post-HS were euthanized and livers were sampled for gene expression. The liver and Pectoralis major muscle were sampled for cellular analysis. mRNA expression of thioredoxin and peroxiredoxins (Prdx) 1, 3, and 4 in the liver were down-regulated at 12 days post-HS compared to controls. The liver activity of thioredoxin reductase (TXNRD) and levels of peroxiredoxin1 (Prdx1) at 12 days post-HS were significantly decreased. The results reveal that there was a significant decrease in DNA methylation at 12 days post HS in liver tissues. In conclusion, pathway of thioredoxin system under HS may provide clues to nutritional strategies to mitigate the effect of HS in meat-type chicken.

Identification of key Genes and Pathways Associated With Thermal Stress in Peripheral Blood Mononuclear Cells of Holstein Dairy Cattle

The objectives of the present study were to identify key genes and biological pathways associated with thermal stress in Chinese Holstein dairy cattle. Hence, we constructed a cell-model, applied various molecular biology experimental techniques and bioinformatics analysis. A total of 55 candidate genes were screened from published literature and the IPA database to examine its regulation under cold (25°C) or heat (42°C) stress in PBMCs. We identified 29 (3 up-regulated and 26 down-regulated) and 41 (15 up-regulated and 26 down-regulated) significantly differentially expressed genes (DEGs) (fold change ≥ 1.2-fold and P < 0.05) after cold and heat stress treatments, respectively. Furthermore, bioinformatics analyses confirmed that major biological processes and pathways associated with thermal stress include protein folding and refolding, protein phosphorylation, transcription factor binding, immune effector process, negative regulation of cell proliferation, autophagy, apoptosis, protein processing in endoplasmic reticulum, estrogen signaling pathway, pathways related to cancer, PI3K- Akt signaling pathway, and MAPK signaling pathway. Based on validation at the cellular and individual levels, the mRNA expression of the HIF1A gene showed upregulation during cold stress and the EIF2A, HSPA1A, HSP90AA1, and HSF1 genes showed downregulation after heat exposure. The RT-qPCR and western blot results revealed that the HIF1A after cold stress and the EIF2A, HSPA1A, HSP90AA1, and HSF1 after heat stress had consistent trend changes at the cellular transcription and translation levels, suggesting as key genes associated with thermal stress response in Holstein dairy cattle. The cellular model established in this study with PBMCs provides a suitable platform to improve our understanding of thermal stress in dairy cattle. Moreover, this study provides an opportunity to develop simultaneously both high-yielding and thermotolerant Chinese Holstein cattle through marker-assisted selection.

Antioxidant Resveratrol Increases Lipolytic and Reduces Lipogenic Gene Expression under In Vitro Heat Stress Conditions in Dedifferentiated Adipocyte-Derived Progeny Cells from Dairy Cows

Heat stress (HS) induces oxidative stress by increasing reactive oxygen species (ROS), and the polyphenol resveratrol (RSV) has been shown to have antioxidant properties by reducing ROS. Hence, we aimed to examine the effects of RSV, HS and their interaction on bovine adipocytes. We generated bovine dedifferentiated adipocyte-derived progeny (DFAT) cells from subcutaneous adipose tissue and examined the effects of RSV (100 µM), heat conditions: isothermal (ISO-37 °C), short heat (SH-41.2 °C for 1 h) and long HS (LH-41.2 °C for 16 h), and their interaction on gene expression in DFAT-cells. In medium of DFAT-cells treated with RSV, malondialdehyde levels were reduced and oxygen-radical absorbance-capacity levels were increased compared to control. Treating DFAT-cells with RSV increased the relative mRNA expression of stress-induced-phosphoprotein-1 (STIP1) and the expression of hormone-sensitive-lipase (LIPE) and perilipin-1 (PLIN1), whereas it reduced the expressions of fatty-acid-synthase (FASN) and of pro-inflammatory chemotactic-C-C-motif-chemokine-ligand-2 (CCL2) also under HS. Moreover, reduced protein abundance of FASN was found in RSV-treated DFAT-cells compared to controls. Molecular docking of RSV with FASN confirmed its possible binding to FASN active site. This work demonstrates that RSV has an antioxidant effect on bovine DFAT cells and may induce adipose lipolysis and reduce lipogenesis also under in vitro HS conditions.

Protective effects of dietary synbiotic supplementation on meat quality and oxidative status in broilers under heat stress

This study evaluated protective effects of synbiotic on meat quality and oxidative status of breast muscle in heat-stressed broilers. Twenty 2-day-old broilers were allocated in a 2×2 factorial design, and the main factors consisted of synbiotic level (0 (basal diet) or 1.5 g/kg synbiotic) and temperature (thermoneutral or high temperature), resulting in 4 treatments. From 22 to 42 days, chickens were raised at thermoneutral temperature (22 °C) or subjected to cyclic high temperature (heat stress, HS) by keeping them at 32-33 °C for 8 h and 22 °C for rest 16 h daily. Cyclic HS decreased relative weight, redness (45 min), and pH values (45 min and 24 h) but increased contents of moisture and ether extract, lightness (45 min and 24 h), drip loss (24 h and 48 h), and cooking loss in breast muscle of broilers compared with those under thermoneutral temperature. It also increased malondialdehyde content and mRNA abundances of heat shock protein 70 (HSP70) and HSP90 but decreased glutathione (GSH) concentration and activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), as well as mRNA abundances of nuclear factor (erythroid 2)-like 2 (Nrf2), NAD(P)H quinone dehydrogenase 1 (NQO1), GSH-Px, and copper and zinc superoxide dismutase in breast muscle in broilers. Dietary synbiotic supplementation was effective in increasing weight and reducing lightness (45 min), drip loss (24 h and 48 h) and cooking loss of breast muscle in heat-stressed broilers compared with those fed the basal diet. It also reduced malondialdehyde content and HSP70 mRNA abundance and increased GSH-Px activity, GSH content, and mRNA abundances of Nrf2, NQO1 and GSH-Px in breast muscle of heat-stressed broilers. These results suggested that synbiotic supplementation at a level of 1.5 g/kg could ameliorate compromised meat quality and oxidative status in broilers under cyclic HS.

Av-UCP single nucleotide polymorphism affects heat production during cold exposure in chicks

OBJECTIVE

Uncoupling protein one (UCP1) is involved in thermogenesis, especially in non-shivering heat production. In chickens, a single nucleotide polymorphism (SNP) of the av-UCP (avian UCP) gene has been reported to be associated with body weight gain and increased abdominal fat. The purpose of this study was to examine the relationship between the av-UCP gene SNP and heat production in chicks.

METHODS

C/C and T/T male chicks (Rhode Island Red) of av-UCP gene SNP (g. 1270, C > T) were exposed to a low temperature environment (16 °C for 15 min) and their physiological responses were compared.

RESULTS

After cold exposure, mean rectal temperatures of C/C chicks were higher than those of T/T chicks. In pectoral muscle, genes expression of av-UCP and carnitine palmitoyltransferase-1 were higher in C/C chicks than T/T chicks. Hypothalamic expression levels of thyrotropin-releasing hormone and proopiomelanocortin genes were higher in C/C chicks than T/T chicks. Expression of hypothalamic corticotropin-releasing hormone, arginine vasotocin, brain-derived neurotrophic factor and neuropeptide Y genes did not differ between C/C and T/T chicks. In addition, plasma free fatty acid levels in C/C chicks were lower than those of T/T chicks.

CONCLUSION

These results suggest that the av-UCP gene SNP affects non-shivering heat production via the hypothalamo-pituitary-thyroid axis and fatty acid metabolism in the chicken.

iTRAQ-based quantitative proteomic analyses the cycle chronic heat stress affecting liver proteome in yellow-feather chickens

Heat stress (HS) is one of the main environmental factors affecting the efficiency of poultry production. The yellow-feather chickens (YFC) as an indigenous strain of chicken is a popular poultry breed in China. Our previous study used the RNA-seq to analyze the gene expression profiles of male YFC under HS and showed that the lipid and energy metabolism pathways are activated in livers of YFC exposed to acute HS (38°C, 4 h and 25°C recovery 2 h). In this study, we used quantitative proteome analysis based on iTRAQ to study the liver response of YFC to cycle chronic HS (38 ± 1°C, 8 h/d, 7 d, CyCHS). The male YFCs treatment used the CyCHS from 22 to 28 days of age. The liver tissue samples were collected at 28 d old. A total of 39,327 unique peptides matches were detected using iTRAQ analysis and 4,571 proteins exhibited a false discovery rate of 1% or less. Forty-six significant differentially expressed proteins (DEPs) were detected in the CyCHS group compared with the control group for the liver samples, including up- and down-regulated DEPs were 18 and 28, respectively. We found that the enriched biological process terms of the DEPs expressed in the liver were related to DNA metabolic process, oxidation-reduction process, oxidative stress and gluconeogenesis. In KEGG pathway analysis. Most of the hepatic DEPs were annotated to glutathione metabolism and TCA cycle in response to CyCHS. The up-regulation of 5 DEPs (GPX1, GSTT1, GSTT1L, RRM2, and LOC100859645) in the glutathione metabolism pathway likely reflects an attempt to deal with oxidative damage by CyCHS. The down-regulation of 3 DEPs (Isocitrate dehydrogenase [IDH3A], IDH3B, and phosphoenolpyruvate carboxykinase 1) in the TCA cycle pathway contributes to the regulation mechanism of energy metabolism and probably to cope with the balance of heat production and dissipation during CyCHS in order to adapt to high temperature environments. Our results provide insights into the potential molecular mechanism in heat-induced oxidative stress and energy in YFCs and future studies will investigate the functional genes associated with the response to HS.

Transcriptome Analysis Identifies Candidate Genes and Signaling Pathways Associated With Feed Efficiency in Xiayan Chicken

Feed efficiency is an important economic factor in poultry production, and the rate of feed efficiency is generally evaluated using residual feed intake (RFI). The molecular regulatory mechanisms of RFI remain unknown. Therefore, the objective of this study was to identify candidate genes and signaling pathways related to RFI using RNA-sequencing for low RFI (LRFI) and high RFI (HRFI) in the Xiayan chicken, a native chicken of the Guangxi province. Chickens were divided into four groups based on FE and sex: LRFI and HRFI for males and females, respectively. We identified a total of 1,015 and 742 differentially expressed genes associated with RFI in males and females, respectively. The 32 and 7 Gene Ontology (GO) enrichment terms, respectively, identified in males and females chiefly involved carbohydrate, amino acid, and energy metabolism. Additionally, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis identified 11 and 5 significantly enriched signaling pathways, including those for nutrient metabolism, insulin signaling, and MAPK signaling, respectively. Protein-protein interaction (PPI) network analysis showed that the pathways involving CAT, ACSL1, ECI2, ABCD2, ACOX1, PCK1, HSPA2, and HSP90AA1 may have an effect on feed efficiency, and these genes are mainly involved in the biological processes of fat metabolism and heat stress. Gene set enrichment analysis indicated that the increased expression of genes in LRFI chickens was related to intestinal microvilli structure and function, and to the fat metabolism process in males. In females, the highly expressed set of genes in the LRFI group was primarily associated with nervous system and cell development. Our findings provide further insight into RFI regulation mechanisms in chickens.

Effects of Thermal Conditioning on Changes in Hepatic and Muscular Tissue Associated With Reduced Heat Production and Body Temperature in Young Chickens

Effects of increased summer temperatures on poultry production are becoming more pronounced due to global warming, so it is important to consider approaches that might reduce heat stress in chickens. Thermal conditioning in chickens in the neonatal period can improve thermotolerance and reduce body temperature increases when birds are exposed to high ambient temperature later in life. The objective of this study was to investigate physiological and molecular changes associated with heat production and hence body temperature regulation under high ambient temperatures in thermally conditioned chicks. Three-day-old broiler chicks (Chunky) were thermally conditioned by exposure to a high ambient temperature (40°C) for 12 h while control chicks were kept at 30°C. Four days after the treatment, both groups were exposed to 40°C for 15 or 90 min. The increase in rectal temperature during 90 min of exposure to a high ambient temperature was less in thermally conditioned than control chicks. At 15-min of re-exposure treatment, gene expression for uncoupling protein and carnitine palmitoyletransferase 1, key molecules in thermogenesis and fatty acid oxidation, were significantly higher in pectoral muscle of control chicks but not conditioned chicks. Hepatic argininosuccinate synthase (ASS) decreased and hepatic argininosuccinate lyase (ASL) increased after reexposure to a high temperature. The concentrations of hepatic arginosuccinic acid, and ASS and ASL expression, were upregulated in conditioned chicks compared with the control chicks, indicating activity of the urea cycle could be enhanced to trap more energy to reduce heat production in conditioned chicks. These results suggest thermal conditioning can reduce the increase in heat production in muscles of chickens that occurs in high ambient temperatures to promote sensible heat loss. Conditioning may also promote energy trapping process in the liver by altering the heat production system, resulting in an alleviation of the excessive rise of body temperature.

Effect of vitamin E level and dietary zinc source on performance and intestinal health parameters in male broilers exposed to a temperature challenge in the finisher period

The objective of this study was to evaluate the interaction of zinc source (ZnSO₄ vs. zinc amino acid complex) and vitamin E level (50 IU vs. 100 IU) on performance and intestinal health of broilers exposed to a temperature challenge in the finisher period. A total of 1224 day old male Ross 308 broilers were randomly distributed among 4 dietary treatments (9 replicates per treatment). Dietary treatments were organized in a 2 × 2 factorial arrangement: two sources of zinc, 60 mg/kg of Zn as ZnSO₄ .7H₂ O or 60 mg/kg of Zn as zinc amino acid complexes (ZnAA) combined with two levels of vitamin E (50 or 100 IU/kg). Zinc and vitamin E were added to a wheat/rye-based diet that was designed to create a mild nutritional challenge. From day 28 until day 36 (finisher period), all birds were subjected to chronic cyclic high temperatures (32°C ± 2°C and RH 55-65% for 6 h daily). The combination of ZnAA and 50 IU/kg of vitamin E improved weight gain in the starter (day 0-10), finisher (day 28-36) and overall period (day 0-36) and feed conversion ratio in the starter (day 0-10) and finisher phase (day 28-36). Providing Zn as ZnAA significantly improved villus length and villus/crypt ratio in the starter, grower and finisher period and decreased infiltration of T-lymphocytes and ovotransferrin leakage in the finisher period. In conclusion, providing broilers with a diet supplemented with ZnAA and a vitamin E level of 50 IU/kg, resulted in better growth performance as compared to all other dietary treatments. Interestingly, under the conditions of this study, positive effects of ZnAA on performance did not occur when vitamin E was supplemented at 100 IU/kg in feed. Moreover, providing zinc as zinc amino acid complex improved intestinal health.

Different dietary electrolyte balance values on performance, egg, and bone quality of Japanese quail (Coturnix Coturnix Japonica) under heat stress

The objective of this study was to evaluate the productive performance and quality of eggs and bones of Japanese quails that received different dietary electrolyte balance (EB) and were submitted to thermoneutrality or heat stress conditions. Eight hundred Japanese quails of 21 days of age were selected and distributed randomly in two bioclimatic chambers: thermoneutral chamber (23 °C ± 2 °C) and heat-stress chamber (33 °C ± 2 °C). The treatments were in a 2 × 5 factorial arrangement, with two temperatures and five EB levels (165, 215, 265, 315, 365 mEq/kg) with four replicates of 20 birds each. The productive performance and egg quality (in 3 cycles of 21 days) were measured. At 105 days old, the bone quality was evaluated. Data were analyzed by Minitab, and the means were compared by Tukey's test and regression test for levels (P < 0.05). Quails submitted to thermoneutrality showed better performance and egg and bone quality. The highest production rate was the EB level of 265 mEq/kg. Low values of EB (165 and 215 mEq/kg) and high values (365) impaired egg quality, and the ideal was 315 mEq/kg. Lower levels of balance provided poor bone density. In conclusion, the results of this study indicated that heat stress impairs the production and quality of quail eggs and bones. Furthermore, by using intermediate EB levels (265 and 315) mEq/kg, it is possible to improve egg production and egg quality, and using high levels increases bone mineral density.

Heat stress impacts on broiler performance: a systematic review and meta-analysis

Heat stress (HS) is a major problem in poultry business which affects chickens' performance and may trigger large economic losses. This study intends to analyze the impact of HS on broiler chickens' performance compared with those under normal condition. A literature search was performed on PubMed, Web of Science, and Cochrane Library for studies published in English up to January 17, 2020. Outcomes of body weight gain (BWG), feed intake (FI), feed conversion ratio (FCR), and mortality were calculated by weighted difference (WMD) or odds ratio (OR) with 95% confidence interval (CI). A total of 12 studies with 470 broiler chickens were included. HS significantly decreased FI (11 trials: WMD = -97.95, 95% CI: -141.70, -54.20) and BWG (7 trials: WMD = -151.40, 95% CI: -198.59, -104.21) and significantly increased FCR (9 trials: WMD = 0.17, 95% CI: 0.04, 0.29) and mortality (8 trials: OR = 3.74, 95% CI: 1.39, 10.12) compared with the control. In conclusion, HS significantly affected broiler chickens' BWG, FI, FCR, and mortality, indicating the importance to control housing temperature to avoid unnecessary costs.

Guanidinoacetic acid supplementation improves feed conversion in broilers subjected to heat stress associated with muscle creatine loading and arginine sparing

It was hypothesized that dietary guanidinoacetic acid (GAA), the precursor of creatine (Cr), would be beneficial to heat-stressed finisher broilers owing to improved cellular energy status and arginine sparing effects. A total of 720 one-day-old male Ross 308 broilers were allocated to 3 treatments, 0 (control), 0.6, or 1.2 g/kg of GAA added to complete corn–soybean meal diets, and were fed for 39 D, with 12 replicates (20 birds each) per treatment. A chronic cyclic heat stress model (at a temperature of 34°C and 50 to 60% relative humidity for 7 h daily) was applied in the finisher phase (day 25–39). Samples were taken on day 26 and 39 to determine thrombocyte, white blood cell, corticosterone, protein and amino acid levels in blood and Cr, phosphocreatine (PCr), and adenosine triphosphate levels in the breast muscle. Meat quality was assessed on day 40 after overnight fasting. Guanidinoacetic acid at a dose of 1.2 g/kg decreased feed-to-gain ratio compared with the control in the grower phase (1.32 vs. 1.35, respectively; P <0.05). In the finisher period, the supplementation of 1.2 g/kg of GAA reduced feed intake compared with the control (–3.3%, P <0.05), whereas both GAA supplementation levels improved feed efficiency markedly (1.76, 1.66, and 1.67 for 0 [control], 0.6, and 1.2 g/kg of GAA, respectively, P <0.05). Mortality outcomes highlight that GAA feeding improved survival during heat stress, supported by lower panting frequency (linear effect, P <0.05). Plasma arginine was higher with increase in dietary GAA concentration on day 26 (+18.3 and + 30.8% for 0.6 and 1.2 g/kg of GAA, respectively; P <0.05). This suggests enhanced availability of arginine for other metabolic purposes than de novo GAA formation. In the breast muscle, PCr (day 39, P <0.05), free Cr (day 39, P <0.05), total Cr (both days, P <0.05), and PCr-to-adenosine triphosphate ratio (day 39, P <0.05) levels were increased with higher GAA content in diet. Guanidinoacetic acid supplementation improved feed conversion and survival during chronic cyclic heat stress, which may be associated with enhanced breast muscle energy status and arginine sparing effect.

Short chain fatty acids may improve hepatic mitochondrial energy efficiency in heat stressed-broilers

The present study was conducted to investigate the effects of four dietary fat types and two environmental temperatures on the hepatic mitochondrial energetic in male broilers exposed to heat stress. The birds were kept in two separate rooms at 24 °C or 36 °C from 32 to 42 d of age with four experimental groups in each room. The birds fed on the diets supplemented containing rich sources of long-chain saturated fatty acids (beef tallow), middle-length-chain saturated FA (coconut oil), monounsaturated FA (olive oil), or polyunsaturated FA (soybean oil) for ten days. At 36 °C, the highest body weight and lowest feed conversion ratio were recorded in the birds fed on the diets supplemented with coconut oil or beef tallow. Temperature and fat type significantly affected the activities of the mitochondrial electron transport chain complexes (P < 0.01). There was a significant interaction between the temperature and fat type (P < 0.01). Generally, electron transport chain complexes I-V enzymatic activities were decreased at 36 °C. The coconut oil-fed birds showed the highest complex I activity at both temperatures. The beef tallow-fed broilers showed the lowest complex II activity at 24 °C. In birds exposed to 36 °C, complex II activity was higher for birds fed saturated coconut oil or beef tallow than those feeding the unsaturated olive oil or soybean oil-supplemented diets. At 24 °C, the highest and lowest complex III activities were recorded for the coconut oil- and beef tallow-supplemented diets, respectively. At 36 °C, the activity of complex III was coconut oil > beef tallow > olive oil > soybean oil. At 24 °C, complex IV activity was highest in coconut oil- or soybean oil-fed broilers; and at 36 °C, complex IV showed the lowest activity in soybean oil-fed birds. The highest complex IV activity was observed in coconut oil-fed chickens followed by olive oil-fed and beef tallow-fed birds, respectively. At 24 or 36 °C, the highest and lowest complex V activity was observed in coconut oil-fed and soybean oil-fed chickens, respectively. ATP concentration and mitochondrial membrane potential were in the order of coconut oil > beef tallow > olive oil > soybean oil at both temperatures. Temperature and fat type significantly affected the avANT mRNA concentration. Exposure of broilers to 36 °C generally decreased the mRNA expression of avANT, with beef tallow- or coconut oil-supplemented birds showing a lower avANT mRNA expression than those receiving olive oil- or soybean oil-supplemented diets. These findings provide further information on the use of fat sources in the diet of heat stressed-broilers.

Cellular antioxidant enzyme activity and biomarkers for oxidative stress are affected by heat stress

Heat stress (HS) causes oxidative stress and cellular changes in an attempt to detoxify the harmful effects of reactive oxygen species (ROS). However, how ROS affect different organs in chickens under acute and chronic HS is relatively unknown. We investigated the cellular enzyme activity and biomarker changes in the liver and Pectoralis (P) major muscle in broiler chickens subjected to both acute and chronic HS. Forty-eight broiler chickens at 14 days old were randomly assigned to either 25 °C (control) or 35 °C (heat-stressed) for 12 days. Five birds per treatment at 1 and 12 days post-HS were euthanized, and the liver and P. major muscle were sampled. Superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione (GSH), glutathione reductase (GR), glutathione S-transferase (GST) activity as well as 8-hydroxy-2'-deoxyguanosine (8-OHdG), advanced glycation end product (AGE), malondialdehyde (MDA), and protein carbonyl (PCO) were analyzed as biomarkers for DNA, carbohydrate, lipid, and protein oxidation, respectively. The SOD, CAT, and GSH-GPx activity levels in the liver and the P. major muscle changed under HS; however, some of the changes were tissue-specific or dependent on the duration of the HS. There were increased liver 8-OHdG during chronic HS and also increased liver AGE levels during both acute and chronic HS indicating significant carbohydrate and DNA oxidations. In the P. major muscle, we observed significant increases in lipid peroxidation and protein oxidation which may reflect that this tissue is less resilient to oxidative damage under heat stress. We show that heat stress caused tissue-specific changes to levels of oxidation biomarkers in chicken.

Oxidative stress status and reproductive performance of sows during gestation and lactation under different thermal environments

Objective

Two experiments were conducted using 28 healthy multiparous sows to evaluate the oxidative stress status and reproductive performance of sows during gestation and lactation under different thermal environments.

Methods

Fourteen multiparous sows were used in Exp. 1 under a high thermal environment, and the other 14 multiparous sows were used in Exp. 2 under a moderate thermal environment. In both experiments, reproductive performances of sows were recorded. Plasma samples were collected on d 35, 60, 90, and 109 of gestation, and d 1 and 18 of lactation for malondialdehyde, protein carbonyls, 8-hydroxy-deoxyguanosine, immunoglobulin g (IgG), and IgM analysis.

Results

For sows in Exp. 1, plasma malondialdehyde concentration on d 109 of gestation tended to be greater (p<0.05) than it on d 18 of lactation. Plasma concentration of protein carbonyl on d 109 of gestation was the greatest (p<0.05) compared with all the other days. Plasma concentrations of 8-hydroxy-deoxyguanosine on d 109 of gestation was greater (p< 0.05) than d 18 of lactation in Exp. 1. For sows in Exp. 2, there was no difference of malondialdehyde and protein carbonyl concentration during gestation and lactation. In both Exp. 1 and 2, litter size and litter weight were found to be negatively correlated with oxidative stress indicators.

Conclusion

Sows under a high thermal environment had increased oxidative stress during late gestation indicating that increased oxidative damage to lipid, protein, and DNA could be one of the contributing factors for reduced reproductive performance of sows in this environment. This study indicates the importance of providing a moderate thermal environment to gestating and lactating sows to minimize the increase of oxidative stress during late gestation which can impair reproductive outcomes.

Evaluation of yeast culture and direct-fed microbial on gut histology and serum components of broilers challenged with suboptimal diets under heat stress

The use of antibiotics in feed for growth promotion has been restricted in many countries, thus it is of interest to investigate potential alternatives for enhancing growth performance in birds. An experiment was carried out to evaluate the concurrent use of prebiotic and probiotic on gut histology and some blood chemicals of broiler chickens during heat stress. A total of 144 day-old male Ross 308 broiler chicks were randomly divided into 3 treatments. The first treatment was a diluted diet including rice bran without probiotic or prebiotic. The other treatments were fed the diluted diets with a prebiotic (treatment 2) and concurrent use of that prebiotic along with a probiotic (treatment 3). Results showed that villus height was not influenced by feed additives. However, crypt depth significantly increased by feed additives in particular with combination of prebiotic and probiotic. The ratio of villus height to crypt depth significantly decreased in treatments fed prebiotic alone or prebiotic and probiotic together. This finding is indicating the fact that non-starch polysaccharides (NSPs) in high inclusion rate of rice bran caused to villus height erosion. It could be concluded that prebiotic and probiotic caused an increasing of enterocyte proliferation in the crypt of Liberkhun.

Oxidative stress, inflammation, and glycometabolism disorder-induced erythrocyte hemolysis in selenium-deficient exudative diathesis broilers

Selenium (Se) deficiency causes injury of diversified tissues and cells, including livers, hearts, skeletal muscles, and erythrocytes. The aim of the present study is to explore the molecular mechanism of erythrocyte hemolysis due to Se deficiency in broilers. One hundred and eighty broilers (male/female, 1 day old) were randomly divided into two groups and fed with either a normal Se content diet (C group, 0.2 mg Se/kg) or a Se-deficient diet (ED group, 0.008 mg Se/kg) for 45 days. During the trial period of 15-30 days, biological properties such as osmotic fragility, fluidity, phospholipid components of cell membrane, adenosine triphosphatase activities, and antioxidant function of erythrocytes in broilers were examined. Moreover, the messenger RNA (mRNA) expressions of genes associated with inflammation, glycometabolism, and avian uncoupling protein (avUCP) were detected. We found that compared with the C group, hemolysis rate, degree of polarization, and microviscosity of erythrocytes were increased in broilers of the ED group. The composition of erythrocyte membrane lipids was changed. Meanwhile, the antioxidant function of erythrocytes was weakened and mRNA levels of inflammatory genes were stimulated by Se deficiency (p < 0.05). In addition, mRNA expressions of rate-limiting enzymes in glycometabolism were effected and avUCP mRNA level was downregulated (p < 0.05) in the ED group. It has been concluded from the results that oxidative stress, inflammatory response, and glycometabolism disorder lead to erythrocyte hemolysis by changing the structure and function of erythrocyte membrane in ED broilers suffered from Se deficiency.

Heat stress management in poultry farms: A comprehensive overview

Heat stress causes significant economic losses in poultry production, especially in tropical and arid regions of the world. Several studies have investigated the effects of heat stress on the welfare and productivity of poultry. The harmful impacts of heat stress on different poultry types include decreased growth rates, appetites, feed utilization and laying and impaired meat and egg qualities. Recent studies have focused on the deleterious influences of heat stress on bird behaviour, welfare and reproduction. The primary strategies for mitigating heat stress in poultry farms have included feed supplements and management, but the results have not been consistent. This review article discusses the physiological effects of heat stress on poultry health and production and various management and nutritional approaches to cope with it.

Effect of thermal manipulation of broilers embryos on the response to heat-induced oxidative stress

Effects of embryonic thermal manipulation (TM) on mRNA expressional levels and total antioxidant capacity of genes associated with heat-induced oxidative stress (NOX4, GpX2, SOD2, catalase, and AvUCP) in 2 breeds of broiler chicken were investigated. Fertile Cobb and Hubbard eggs (n = 1,200) were divided into 4 treatment groups: Cobb control, Cobb TM, Hubbard control, and Hubbard TM. Control groups were maintained under standard conditions (37.8°C; 56% relative humidity), whereas TM groups were incubated at 39°C and 65% relative humidity for 18 h a day from embryonic days (ED) 10 to 18. On post-hatch day 28, the broilers were subject to acute heat stress (AHS) at 40°C for 7 h. At certain intervals (0, 1, 3, 5, and 7 h), 12 chickens from each of the 4 groups were humanely euthanized, and liver samples were immediately isolated. During AHS, in both breeds, the mRNA expression levels of NOX4, GPx2, SOD2, and catalase in TM chickens were significantly lower than in controls, but AvUCP mRNA expression in the TM group was higher. The total antioxidant capacity and activity of superoxidase dismutase and catalase were significantly lower in the TM than in the control group in both breeds. The results of this study suggest that TM has a long-lasting effect on the acquisition of thermotolerance in 2 broiler chicken breeds as indicated by the reduction of system genes associated with heat-induced oxidative stress.

Oxidative Stress in the Poultry Gut: Potential Challenges and Interventions

The gastrointestinal tract (GIT) provides the biological environment for nutrient digestion and absorption, and protection from pathogens and toxins. Broilers are fast growing because of the great potential of intestinal epithelia for nutrient absorption, and efficient conversion of nutrient to muscle. Physiologically, reactive oxygen species (ROS) and reactive nitrogen species (RNS) are generated by GIT epithelial cells either from oxygen metabolism or by enteric commensal bacteria and regulate gut health. However, increased production of ROS elevates free radical production and antioxidant insults resulting in oxidative stress. Oxidative stress in poultry GIT is derived from nutritional, environmental heat stress, and pathological factors, which alters overall performance as well as meat and egg quality. Supplementation of exogenous vitamins, antioxidants, and plant extract having antioxidant properties scavenge ROS and are beneficial in mitigating oxidative stress in the GIT. This review highlights the involvement of oxidative stress in the gastrointestinal functionality of poultry and potential intervention strategies to maintain redox balance in the GIT.

Prevalence and aetiology of coccidiosis in broiler chickens in Bejaia province, Algeria

The prevalence of coccidiosis was determined and Eimeria species were identified in farms at different locations in the Bejaia region, Algeria. The study was conducted from February to December 2016. Unvaccinated birds were selected randomly. Samples from litter and faeces were collected randomly (147 and 109, respectively). Necropsy and parasitological examinations were carried out using standard methods. Of the samples examined, 93 out of the 147 litter samples and 78 out of the 109 intestinal content samples were infected with Eimeria oocysts (63.26% and 71.55%, respectively). Mixed infections with Eimeria spp. were observed in some of the positive farms, with an overall prevalence of 54.28%. Five species of Eimeria (viz. E. acervulina, E. tenella, E. maxima, E. brunetti and E. mitis) were identified with different indices. Eimeria acervulina followed by E. tenella were the predominant species infecting chickens at the farms visited (32.05% and 26.92%, respectively). Statistically, the most prevalent Eimeria spp. was E. Acervulina (p < 0.05). This study demonstrated that coccidiosis is an omnipresent parasitic intestinal disease. It could strongly decrease production performance in broiler chickens.

Saturated fatty acids may ameliorate environmental heat stress in broiler birds by affecting mitochondrial energetics and related genes

Heat stress decreases performance of poultry. The novel strategies to maintain production level, or at least minimizing the decrease in productivity during hot days need to be elucidated. This study was conducted to determine the effect of four fat types on mitochondrial energetics in heat-stressed broilers. In experiment 1, nitrogen-corrected apparent metabolizable energy (AMEn) content of four supplemental fat sources, including olive oil, soybean oil, coconut oil and beef tallow, all supplemented at 3%, 6%, and 9% in the basal diet, was evaluated. The AMEn values of fats were determined as 9738.0 ± 137.9, 8949.0 ± 159.9, 7844.0 ± 91.7, and 7368.0 ± 190.3 kcal/kg for olive oil, soybean oil, coconut oil and beef tallow, respectively. In experiment 2, birds were kept in two separated rooms under 24 °C or 36 °C from 32 to 42 d of age. Each room consisted of four experimental groups. Birds in the experimental groups were fed on beef tallow-, coconut oil-, olive oil- or soybean oil-supplemented diets (factorial arrangement with two factors of fat types and environmental temperatures). The birds reared under 24 °C had higher final body weight (P < 0.01), weight gain (P < 0.01), feed intake (P < 0.05) and lower feed conversion ratio (P < 0.01) than the birds grown under 36 °C. There was a temperature by fat type interaction effect on mitochondrial attributes. At 36 °C, in birds fed on coconut oil- or beef tallow-supplemented diets, the expression levels of avUCP and avANT mRNA were lower (P < 0.05) but that of HSP70 mRNA was higher (P < 0.01) in comparison with the birds feeding on the olive oil- or soy oil-supplemented diets. An interaction effect was recorded between the temperature and fat type for ATP concentration and mitochondrial membrane potential (P < 0.01); with significant differences between birds receiving the coconut oil- or beef tallow-supplemented diets and the birds feeding on the soy oil- or olive oil-supplemented diets. It was also found that unsaturated fatty acids had a more significant effect on avUCP and avANT mRNA expression. It can be concluded that when using fat in the diet of heat stressed-broilers, it is advisable to choose a type, which has a lower effect on the expression of avUCP and avANT, and hence reduces the metabolic heat load in the bird.

Proteomic analysis of the hypothalamus of broiler-type Taiwan country chickens in response to acute heat stress

The hypothalamus is a critical center for regulating heat retention or dissipation. This study investigated global protein changes in the hypothalamus of broiler-type Taiwan country chickens (TCCs) after acute heat stress. Twelve TCC hens aged 30 weeks were allocated to groups subjected to acute heat stress at 38°C for 2 hr without recovery, with 2 hr of recovery, and with 6 hr of recovery; a control group was maintained at 25°C. Hypothalami were collected for protein expression analysis at the end of each time point. The results showed 114 protein spots differentially expressed after acute heat stress. Most of the differentially expressed proteins were involved in cellular processes, metabolism, transport, and cellular component organization. Functional annotation analysis suggested that these proteins were related to cellular defensive responses against heat and oxidative stress, detoxification and toxin export/delivery, cytoskeleton integrity, oxygen transport, and neural development. The results of this study suggest that acute heat stress damages the hypothalamus of broiler-type TCCs through oxidative stress and provokes a series of responses to stabilize protein structures, degrade misfolded proteins, and remodel cytoskeletons for attenuating the detrimental effects by acute heat stress.

Combination Effects of Organic and Inorganic Chromium on Production Performance, Reproductive Response, Immune Status, and Maternal Antibody Transmission in Breeder Quails Under Heat Stress

This experiment was carried out to investigate the combination effects of organic and inorganic chromium (Cr) on egg production, egg quality, reproductive response, and immune status of breeder quails and their offspring under heat stress. A total of 140 7-week-old Japanese breeder quails (120 females and 20 males) according to a completely randomized design were used in four treatment groups (five replicate and seven birds per each) lasted for 8 weeks. Quails exposed to 35 °C for 8 h/day for induction of cyclic heat stress treatments consisted of diets supplemented with (1) 1 mg CrCl₃ per kilogram of diet as control (CNT); (2) 1 mg Cr-L-Met per kilogram of diet as organic Cr (OCr); (3) 0.5 mg CrCl₃ plus 0.5 mg Cr-L-Met per kilogram of diet (ISO); (4) 1 mg CrCl₃ plus 0.5 mg Cr-L-Met per kilogram of diet (On-top). Productive performance and egg quality parameters were determined weekly. Fertility, hatchability, and embryonic mortality were measured at the end of experiment. Humoral immunity was assessed by primary and secondary antibody titer in sheep red blood cells (SRBC) and Newcastle disease (ND) tests. Cell-mediated immunity was assessed by the cutaneous basophil hypersensitivity (CBH) test to phytohemagglutinin (PHA) at days 20 and 45 of age. White blood cell count and immunoglobulin Y (IgY) content in serum and yolk of breeders and in serum and yolk residues of offspring were also measured. Results showed that maximum egg production, egg shell thickness, and Haugh unit were observed in birds fed ISO and On-top diets (P ≤ 0.05). The highest (P ≤ 0.05) antibody levels in ND test were observed in birds fed with OCr, ISO, and On-top diets. The highest cellular response (P ≤ 0.05) was in 12 h after primary PHA injection and 12 and 24 h after secondary PHA injection in birds fed with On-top diets. The highest count of heterophil and (H/L) were gained in breeder quails fed with CNT diet, and the lowest of them were reached with On-top diet (P ≤ 0.05). Results showed that the highest IgY level in serum of breeder and their offspring and that of yolk suck and egg yolk were observed in birds fed with On-top diet (P ≤ 0.05). These results suggest that extra supplemental organic Cr in combination with CrCl₃ could lead to higher egg production, egg quality, and immune status of breeder quails and their offspring.

Mitochondrial efficiency and exercise economy following heat stress: a potential role of uncoupling protein 3

Heat stress has been reported to reduce uncoupling proteins (UCP) expression, which in turn should improve mitochondrial efficiency. Such an improvement in efficiency may translate to the systemic level as greater exercise economy. However, neither the heat‐induced improvement in mitochondrial efficiency (due to decrease in UCP), nor its potential to improve economy has been studied. Determine: (i) if heat stress in vitro lowers UCP3 thereby improving mitochondrial efficiency in C2C12 myocytes; (ii) whether heat acclimation (HA) in vivo improves exercise economy in trained individuals; and (iii) the potential improved economy during exercise at altitude. In vitro, myocytes were heat stressed for 24 h (40°C), followed by measurements of UCP3, mitochondrial uncoupling, and efficiency. In vivo, eight trained males completed: (i) pre‐HA testing; (ii) 10 days of HA (40°C, 20% RH); and (iii) post‐HA testing. Pre‐ and posttesting consisted of maximal exercise test and submaximal exercise at two intensities to assess exercise economy at 1600 m (Albuquerque, NM) and 4350 m. Heat‐stressed myocytes displayed significantly reduced UCP3 mRNA expression and, mitochondrial uncoupling (77.1 ± 1.2%, P < 0.0001) and improved mitochondrial efficiency (62.9 ± 4.1%, P < 0.0001) compared to control. In humans, at both 1600 m and 4350 m, following HA, submaximal exercise economy did not change at low and moderate exercise intensities. Our findings indicate that while heat‐induced reduction in UCP3 improves mitochondrial efficiency in vitro, this is not translated to in vivo improvement of exercise economy at 1600 m or 4350 m.

Heat stress causes dysfunctional autophagy in oxidative skeletal muscle

We have previously established that 24 h of environmental hyperthermia causes oxidative stress and have implicated mitochondria as likely contributors to this process. Given this, we hypothesized that heat stress would lead to increased autophagy/mitophagy and a reduction in mitochondrial content. To address this hypothesis pigs were housed in thermoneutral (TN; 20°C) or heat stress (35°C) conditions for 1- (HS1) or 3- (HS3) days and the red and white portions of the semitendinosus collected. We did not detect differences in glycolytic muscle. Counter to our hypothesis, upstream activation of autophagy was largely similar between groups as were markers of autophagosome nucleation and elongation. LC3A/B-I increased 1.6-fold in HS1 and HS3 compared to TN (P < 0.05), LC3A/B-II was increased 4.1-fold in HS1 and 4.8-fold in HS3 relative to TN, (P < 0.05) and the LC3A/B-II/I ratio was increased 3-fold in HS1 and HS3 compared to TN suggesting an accumulation of autophagosomes. p62 was dramatically increased in HS1 and HS3 compared to TN Heat stress decreased mitophagy markers PINK1 7.0-fold in HS1 (P < 0.05) and numerically by 2.4-fold in HS3 compared to TN and BNIP3L/NIX by 2.5-fold (P < 0.05) in HS1 and HS3. Markers of mitochondrial content were largely increased without activation of PGC-1α signaling. In total, these data suggest heat-stress-mediated suppression of activation of autophagy and autophagosomal degradation, which may enable the persistence of damaged mitochondria in muscle cells and promote a dysfunctional intracellular environment.

Effects of dietary Allium hookeri root on growth performance and antioxidant activity in young broiler chickens

The objective of this experiment was to evaluate the antioxidant potential of Allium hookeri (AH) root in two forms, powdered AH root and fermented powdered AH root, to demonstrate its value as an antibiotic alternative feed additive for broiler chickens. A total of 125 male Ross-708 broiler chickens were randomly assigned to five groups (n = 25 birds/group) and fed standard diets supplemented with root or fermented root of AH at two different levels (1% or 5%). Control birds were provided with non-supplemented basal diets. Body weights was measured at days 14 and 21 of age. To monitor antioxidant activities, heme oxygenase (HMOX), aflatoxin B1 aldehyde reductase (AFAR), superoxide dismutase 1 (SOD1), and catalase (CAT) enzyme levels were quantified by real-time PCR in the jejunums 21-day-old birds. Also, serum levels of SOD, CAT, and malondialdehyde (MDA) were measured using commercial kits. The results showed greater body weight gains at day 14 in chickens fed diets supplemented with 1% AH root, as compared to the control group (p < 0.05). Up-regulated transcript levels of AFAR, HMOX1, and CAT were observed in the jejunum of chickens fed diets supplemented with AH. The serum levels SOD and CAT were significantly increased (p < 0.05) in groups treated with AH, whereas MDA levels were decreased in groups fed diets supplemented with AH, as compared to the control group. These results indicated that an optimum level of dietary AH supplementation to young broiler chickens influences growth and improves antioxidant activities.

In vitro and in vivo antioxidant activities of inulin

This study was designed to investigate the in vitro and in vivo antioxidant activities of inulin. The in vitro assays demonstrated that the antioxidant activities of inulin, including the DPPH radical scavenging activity, ABTS scavenging activity and ferric reducing power, were weak and significantly lower than those of Vitamin C (P < 0.05). The influence of dietary supplementation with inulin on the antioxidant status of laying hens was evaluated with in vivo antioxidant assays. The results indicated that inulin supplementation quadratically improved the egg production rate of the laying hens (P < 0.01). The antioxidant enzyme activities in the serum, including SOD, CAT, and GSH-Px, and the total antioxidant capacity increased quadratically as inulin levels increased (P < 0.001). The levels of MDA in the serum decreased quadratically as inulin levels increased (P < 0.001). These findings suggest that inulin has the potential to improve the antioxidant status of laying hens.

Effect of feed supplement and additives on stress mitigation in Karan Fries heifers

AIM

The objective of this study was to evaluate the effects of protected fat plus yeast, niacin, zinc, and chromium dietary supplementation on the reduction of heat stress in Karan Fries (KF) heifers during hot humid months.

MATERIALS AND METHODS

The basal ration for both the control and treatment groups was the same, containing maize as green fodder and concentrate mixture. However, the treatment group was supplemented with protected fat (2.5% of dry matter intake [DMI]), yeast (10 g/animal/day), niacin (6 g/animal/day), zinc (40 mg/kg DMI), and chromium (1.5 mg/kg DMI).

RESULT

The overall mean value of afternoon rectal temperature for control and treatment group was 103.17±0.09 and 102.72±0.10°F, respectively, and was significantly (p<0.01) lower in the treatment group. The overall mean value of afternoon respiration rate for control and treatment group was 76.35±0.56 and 73.13±0.58 breaths/min, respectively, and was also significantly (p<0.01) lower in the treatment group. The overall mean value of afternoon pulse rate for control and treatment group was 97.09±0.63 and 94.67±0.67 beats/minute, respectively, and was also significantly (p<0.01) lower in the treatment group. Finally, the mean cortisol concentration for control and treatment group was 3.94±0.05 ng/ml and 3.70±0.06 ng/ml, respectively, and was significantly (p<0.01) lower in the treatment group.

CONCLUSION

The present study shows that supplementation with the above feed additives could serve as a heat stress abatement strategy in growing KF heifers during extreme conditions in summer months.