Radical Response: Effects of Heat Stress-Induced Oxidative Stress on Lipid Metabolism in the Avian Liver

Effects of triclosan on lipid metabolism and underlying mechanisms in the cyprinid fish Squalidus argentatus

The ubiquitous presence of the disinfectant triclosan (TCS) has raised global concerns regarding its potential threat to aquatic organisms. However, the effects of TCS on lipid metabolism in fish and its underlying mechanisms remain unclear. This study investigated the effect of environmentally relevant levels of TCS on the lipid metabolism in the cyprinid fish Squalidus argentatus. Our results showed that the lipid metabolism in the cyprinid fish S. argentatus was perturbed by 28-day exposure to TCS, as evidenced by higher levels of lipid accumulation in both the liver and blood. To elucidate the mechanisms underlying toxicity, we evaluated oxidative stress, inflammatory status, and lipase activity in the liver. Our findings indicated increased ROS-specific fluorescence intensity, superoxide dismutase (SOD) activity, and malondialdehyde (MDA) content in the livers of S. argentatus exposed to TCS, suggesting oxidative damage. Additionally, TCS treatment induced the production of proinflammatory cytokines in the liver of S. argentatus exposed to TCS, which suppressed hepatic lipase activity. Intestinal tissue morphology, inflammation, and blood lipopolysaccharide (LPS) levels were also examined. Significant increases in goblet cell count and MDA levels were observed in the intestinal tract. After 28 days of TCS exposure, the serum LPS levels were significantly elevated. 16S rRNA sequencing was conducted to analyze the effects of TCS on the diversity and composition of the intestinal microbiota. Transcriptomic analysis was performed to reveal global molecular alterations following TCS exposure. In conclusion, our results indicate that TCS may disrupt the lipid metabolism in S. argentatus by (i) inducing hepatic oxidative stress and inflammation, which suppress lipoprotein lipase activity, (ii) affecting the production of beneficial metabolites and endotoxins by dysregulating gut microbiota composition, and (iii) altering the expression levels of lipid metabolism-related pathways.

Betaine and feed restriction as potential mitigation strategies against heat stress in two strains of laying hens

Climate change is increasingly manifesting in temperate regions. Laying hens are highly sensitive to heat stress and mitigation strategies should be implemented to reduce the negative effects. The goal of this experiment was to evaluate the effects of betaine in drinking water (0.55 g/L) and 4 h feed restriction during peak heat stress on laying performance, egg quality, blood gas parameters, body temperature (Tb), and oxidative stress in 2 different breeds of laying hens. Therefore, 448 ISA Brown hens (25 wk) and 448 Lohmann LSL classic laying hens (26 wk) were housed in 128 cages (7 hens/cage). Thermoneutral (TN) data was collected for 21 d before cyclic heat stress (HS) (21d; 32 ± 2°C; 6 h daily). During HS, hens were divided into 4 treatments: 1) feed restriction (FR), 2) betaine supplementation in drinking water (BET), 3) feed restriction and betaine supplementation in drinking water (FR-BET), or 4) control (CON). The effects were evaluated after 1 wk of HS (acute heat stress; AHS) and 3 wk of HS (chronic heat stress; CHS). Laying rate and egg mass (EM) diminished during CHS but decreased more in white than brown hens (2.78% and 1.94%; -1.57% and -0.81%, respectively; P = 0.004) and remained unaltered by BET or FR. During AHS, average daily feed intake (ADFI) increased compared to TN, but the increase was higher in white than brown hens (6.36% and 2.62%, respectively; P = 0.001). Egg shell quality deteriorated during AHS and CHS, but was most affected in white hens, FR or BET did not impact this. Blood pCO2, HCO3- and base excess significantly decreased during AHS and CHS, but pH and iCa were unaltered. Blood glucose increased in white hens during AHS compared to TN (P < 0.001), while plasma malondialdehyde increased in brown hens (P < 0.001). Results indicated that laying hens experienced HS, but breed differences were observed and white hens were generally most affected. FR affected feed conversion ratio negatively during CHS. However, FR and BET could not improve laying performance, egg quality, Tb, or blood parameters during HS.

Modulation of liver metabolism and gut microbiota by Alhagi-honey alleviated heat stress-induced liver damage

Alhagi-honey (AH) is a well-established traditional ethnic medicine with advantageous effects against diarrhea and headaches. We aimed to explore the preventive effect of AH on liver damage induced by heat stress (HS) and its underlying mechanism. HS models were established by thermostat, and mice were treated at 39 ℃ for 10 h, lasting for 7 days. Hematoxylin-eosin (H&E) staining and Periodic Acid-Schiff (PAS) staining were used for histological observation, and transmission electron microscopy (TEM) was used for ultrastructure examination of hepatocytes. Gut microbiota (GM) composition and liver metabolites were respectively analyzed by 16S rRNA sequencing and non-targeted metabolome sequencing. AH pretreatment alleviated liver damage caused by heat stress in mice. The main manifestation was that AH alleviated serum aspartate transferase (AST) and aspartate transaminase (ALT). It was found that AH improved symptoms of hepatocyte damage. In addition, the relative abundance of f_Rikenellaceae, g_Incertae_Sedis and s_Staphylococcus_Orisratti, g_Lachnoclostridium, g_GCA-900066575, and s_Alistipes_inops were modified by AH and these bacterial genera showed association with 6 metabolites (2- (3,4-dihydroxyphenyl) acetamide, 3-hydroxy-3-methylpentanedioic acid, PC (17:0/17:1), Y-L-Glutamy-L-glutamic acid, L-Isoleucine, 5-Methyluridine, 8,8-dimethyl-2-phenyl-4H,8H-pyrano [2, 3-h] chromen-4-one). The Pearson analysis also showed a strong correlation between these microbes and 2 risk indicators (AST and ALT) of liver damage. AH alleviated HS-induced liver damage by regulating liver metabolism and maintaining normal GM. It demonstrated that AH held potential as a prophylactic drug for the prevention of HS-induced liver damage.

Long-term arsenic exposure decreases mice body weight and liver lipid droplets

Arsenic (As) is a widespread global pollutant, and there is significant controversy surrounding its complex relationship with obesity, primarily focused on short-term exposure. Recognizing the prolonged nature of dietary arsenic exposure, this study involved feeding mice with arsenic-contained food for 14 months. The results showed that mice exposed to arsenic developed a non-alcoholic fatty liver condition, characterized by a light-yellow hue on the liver surface and various pathological alterations in the liver cells, including enlarged nuclei, cellular necrosis, inflammatory infiltration, dysfunctional mitochondria, and endoplasmic reticulum disorganization. There were also disruptions in biochemistry indices, with a significant increase in total cholesterol (TC) level and a decrease in high-density lipoprotein (HDL) level. However, some contradictory observations occurred, such as a significant decrease in body weight, triglyceride (TG) level, and the numbers of lipid droplets. Several genes related to lipid metabolism were tested, and a model was used to explain these discrepancies. Besides, examinations of the colon revealed compromised intestinal barrier function and signs of inflammation. Fecal 16S rRNA sequencing and pseudo-targeted metabolomics revealed disruptions in internal homeostasis, such as modules, nodes, connections, and lipid-related KEGG pathways. Fecal targeted metabolomics analyses of short-chain fatty acids (SCFAs) and bile acids (BAs) demonstrated a significant upregulation in three primary bile acids (CA, CDCA, TCDCA), four secondary bile acids (TUDCA, DCA, LCA, GUDCA), and total SCFAs level. Oxidative stress and inflammation were also evident. Additionally, based on correlation analysis and mediation analysis, it was assumed that changes in the microbiota (e.g., Dubosiella) can impact the liver metabolites (e.g., TGs) through alterations in fecal metabolites (e.g., LPCs). These findings provide a theoretical reference for the long-term effect of arsenic exposure on liver lipid metabolism.

Terminalia bellirica and Andrographis paniculata dietary supplementation in mitigating heat stress-induced behavioral, metabolic and genetic alterations in broiler chickens

BACKGROUND

Heat stress (HS) is one of the most significant environmental stressors on poultry production and welfare worldwide. Identification of innovative and effective solutions is necessary. This study evaluated the effects of phytogenic feed additives (PHY) containing Terminalia bellirica and Andrographis paniculata on behavioral patterns, hematological and biochemical parameters, Oxidative stress biomarkers, and HSP70, I-FABP2, IL10, TLR4, and mTOR genes expression in different organs of broiler chickens under chronic HS conditions. A total of 208 one-day-old Avian-480 broiler chicks were randomly allocated into four treatments (4 replicate/treatment, 52 birds/treatment): Thermoneutral control treatment (TN, fed basal diet); Thermoneutral treatment (TN, fed basal diet + 1 kg/ton feed PHY); Heat stress treatment (HS, fed basal diet); Heat stress treatment (HS, fed basal diet + 1 kg/ton feed PHY).

RESULTS

The findings of the study indicate that HS led to a decrease in feeding, foraging, walking, and comfort behavior while increasing drinking and resting behavior, also HS increased red, and white blood cells (RBCs and WBCs) counts, and the heterophile/ lymphocyte (H/L) ratio (P < 0.05); while both mean corpuscular volume (MCV), and mean corpuscular hemoglobin (MCH) were decreased (P < 0.05). In addition, HS negatively impacted lipid, protein, and glucose levels, liver and kidney function tests, and oxidative biomarkers by increasing malondialdehyde (MDA) levels and decreasing reduced glutathion (GSH) activity (P < 0.05). Heat stress (HS) caused the upregulation in HSP70, duodenal TLR4 gene expression, and the downregulation of I-FABP2, IL10, mTOR in all investigated tissues, and hepatic TLR4 (P < 0.05) compared with the TN treatment. Phytogenic feed additives (PHY) effectively mitigated heat stress's negative impacts on broilers via an improvement of broilers' behavior, hematological, biochemical, and oxidative stress biomarkers with a marked decrease in HSP70 expression levels while all tissues showed increased I-FABP2, IL10, TLR4, and mTOR (except liver) levels (P < 0.05).

CONCLUSION

Phytogenic feed additives (PHY) containing Terminalia bellirica and Andrographis paniculata have ameliorated the HS-induced oxidative stress and improved the immunity as well as the gut health and welfare of broiler chickens.

Protected biofactors and antioxidants reduce the negative consequences of virus and cold challenge by modulating immunometabolism via changes in the interleukin-6 receptor signaling cascade in the liver

Protected biofactors and antioxidants (PBA), and protected biofactors and antioxidants with protected organic acids and essential oils (PBA+POAEO) have been shown to have benefits in stressed or challenged birds. Here, we describe the immunometabolic changes observed in the liver of Ross 308 broilers during feed supplementation and brief physiological stress. These studied additives contain protected essential oils, organic acids, and vitamins which may have protective effects on the liver. Thus, we aimed to determine the signaling changes induced by these supplements and the resultant immunometabolic effects in the liver. All birds received a 2X dose of live bronchitis vaccine at d 0 and a 48-h cold challenge by reducing the temperature from 30 to 32°C, to 20 to 23°C on d 3 to 5. Control birds were fed a standard diet without supplementation. Liver samples were collected to evaluate the effects of these treatments on cytokine gene expression and protein phosphorylation via kinome peptide array. ANOVA was used for statistical analysis of the gene expression data (significance at a p-value of 0.05), and PIIKA2 was used for statistical evaluation and comparative analysis of the kinome peptide array data. At d 15, the kinome peptide array analysis and gene expression data showed stimulation of the interleukin 6 receptor (IL-6R) signal transduction for host protection via heightened immune response while inducing immune modulation and reducing inflammation in both supplement treated groups. Significant changes were observed via IL-6R signaling in the metabolic profiles of both groups compared to control and no significant differences when compared to each other. In the liver, these 2 feed additives induced immunometabolic changes predominantly via the IL-6 receptor family signaling cascade. Differences between the 2 treated groups were predominantly in the metabolic pathways, centered around the mTOR pathway and the proteins AMPK, mTOR and S6K, with a more anabolic phenotype following the addition of essential oils.

Oxidative stress in poultry production

Oxidative stress (OS) is a major concern that impacts the overall health of chickens in modern production systems. It is characterized by an imbalance between antioxidant defence mechanisms and the production of reactive oxygen species (ROS). This literature review aims to provide a comprehensive overview of oxidative stress in poultry production, with an emphasis on its effects on growth performance, immune responses, and reproductive outcomes. This review highlights the intricate mechanisms underlying OS and discusses how various factors, including dietary components, genetic predispositions, and environmental stressors can exacerbate the production of ROS. Additionally, the impact of oxidative stress on the production performance and physiological systems of poultry is examined. The study also emphasizes the relationship between oxidative stress and poultry diseases, highlighting how impaired antioxidant defenses increase bird's susceptibility to infections. The review assesses the existing approaches to reducing oxidative stress in chickens in response to these challenges. This includes managing techniques to lower stress in the production environment, antioxidant supplements, and nutritional interventions. The effectiveness of naturally occurring antioxidants, including plant extracts, minerals, and vitamins to improve poultry resistance to oxidative damage is also examined. To improve the antioxidant defenses of poultry under stress conditions, the activation of cellular homeostatic networks termed vitagenes, such as Nuclear Factor Erythroid 2-Related Factor 2 (Nrf2) is necessary for the synthesis of protective factors that can counteract the increased production of ROS and RNS. Future studies into novel strategies for managing oxidative stress in chicken production would build on these research advances and the knowledge gaps identified in this review.

Fumonisin distorts the cellular membrane lipid profile: A mechanistic insight

Monitoring modifications in membrane lipids in association with external stimuli/agents, including fumonisins (FUMs), is a widely employed approach to assess cellular metabolic response/status. FUMs are prevalent fusariotoxins worldwide that have diverse structures with varying toxicity across species; nevertheless, they can induce metabolic disturbances and disease, including cancer. The capacity of FUMs to disrupt membrane lipids, demonstrated across numerous species and organs/tissues, is ascribed to a multitude of factors/events, which range from direct to indirect effects. Certain events are well established, whereas the potential consequences of others remain speculative. The most notable effect is their resemblance to sphingoid bases, which impacts the synthesis of ceramides leading to numerous changes in lipids' composition that are not limited to sphingolipids' composition of the membranes. The next plausible scenario involves the induction of oxidative stress, which is considered an indirect/secondary effect of FUMs. Additional modes of action include modifications of enzyme activities and nuclear signals related to lipid metabolism, although these are likely not yet fully comprehended. This review provides in-depth insight into the current state of these events and their potential mechanistic actions in modifying membrane lipids, with a focus on long-chain fatty acids. This paper also presents a detailed description of the reported modifications to membrane lipids by FUMs.

Mechanisms underlying reproductive responses of Japanese quails to heat stress conditions

Exposure to heat stress can cause a significant increase in the death rate and disease susceptibility of poultry birds, ultimately impacting the profitability of the poultry industry. Despite being a more economical choice, Japanese quails (Coturnix japonica) are not immune to the harmful effects of heat stress. Quails may experience negative effects on their reproductive performance due to excessive reactive molecules caused by heat stress. However, they have developed various mechanisms to maintain their reproductive abilities in such conditions. The neuroendocrine system in birds plays a vital role in regulating their reproductive responses to thermal stress, and it is also connected to other environmental factors such as photoperiod that can impact their reproductive performance. Hormones are crucial in the complex interactions necessary for sexual maturation and reproductive responses to heat stress in Japanese quails living in stressful thermal conditions.

Using Thermal Signature to Evaluate Heat Stress Levels in Laying Hens with a Machine-Learning-Based Classifier

Infrared thermography has been investigated in recent studies to monitor body surface temperature and correlate it with animal welfare and performance factors. In this context, this study proposes the use of the thermal signature method as a feature extractor from the temperature matrix obtained from regions of the body surface of laying hens (face, eye, wattle, comb, leg, and foot) to enable the construction of a computational model for heat stress level classification. In an experiment conducted in climate-controlled chambers, 192 laying hens, 34 weeks old, from two different strains (Dekalb White and Dekalb Brown) were divided into groups and housed under conditions of heat stress (35 °C and 60% humidity) and thermal comfort (26 °C and 60% humidity). Weekly, individual thermal images of the hens were collected using a thermographic camera, along with their respective rectal temperatures. Surface temperatures of the six featherless image areas of the hens' bodies were cut out. Rectal temperature was used to label each infrared thermography data as "Danger" or "Normal", and five different classifier models (Random Forest, Random Tree, Multilayer Perceptron, K-Nearest Neighbors, and Logistic Regression) for rectal temperature class were generated using the respective thermal signatures. No differences between the strains were observed in the thermal signature of surface temperature and rectal temperature. It was evidenced that the rectal temperature and the thermal signature express heat stress and comfort conditions. The Random Forest model for the face area of the laying hen achieved the highest performance (89.0%). For the wattle area, a Random Forest model also demonstrated high performance (88.3%), indicating the significance of this area in strains where it is more developed. These findings validate the method of extracting characteristics from infrared thermography. When combined with machine learning, this method has proven promising for generating classifier models of thermal stress levels in laying hen production environments.

High-energy and high-amino acid diet enhances production performance and antioxidant capacity in yellow-feathered broilers under heat stress

This study investigated the ameliorating effects of high-energy and high-amino acid (HEHA) diets on heat stress (HS) in yellow-feathered broilers. Broilers aged 35 d were randomly assigned to 3 groups: control and HS groups fed the basic normal diet, and the HEHA group fed the HEHA diet (basal diet + 100 kcal/kg AME + 15 % DAAs). The HS and HEHA groups were exposed to cyclic HS (30 ± 1 to 34 ± 1 ℃) for 2 wk, while the control group was maintained at 26 ± 1 ℃. The results indicated that the HEHA diet significantly alleviated HS-induced feed intake and body weight loss. HEHA feeding mitigated the increase in body temperature during HS. Compared with observations in the HS group, the HEHA diet reduced the levels of ALT, Alb, and corticosterone in the serum and downregulated the gene expression of HSP27 and HSP60 in the liver. Moreover, the HEHA group showed higher GSH-px activity in the serum and SOD and GSH-Px activity in the jejunal mucosa than that of the HS group. HEHA supplementation also reduced MDA levels in the liver. In conclusion, the HEHA diet improved the production performance of broilers under HS by increasing their antioxidant capacities. These findings suggest an effective strategy to combat HS in poultry production.

Green Light Mitigates Cyclic Chronic Heat-Stress-Induced Liver Oxidative Stress and Inflammation via NF-κB Pathway Inhibition in Geese

Heat stress (HS) induces various physiological disorders in poultry, negatively impacting feed intake, feed efficiency, and growth performance. Considering the documented anti-stress and growth-promoting benefits of monochromatic green light in poultry, we aimed to investigate its effects on cyclic chronic HS-induced oxidative stress (OS) and inflammation in geese. We established three treatment groups-geese exposed to white light (W), white light with HS treatment (WH), and green light with HS treatment (GH)-treated over a six-week period with daily HS sessions. The results revealed that cyclic chronic HS induced liver OS and inflammation, leading to hepatocellular injury and reduced growth performance and feed intake. In comparison, the growth performance of geese under green light significantly improved. Additionally, liver index, serum, liver malondialdehyde (MDA), interleukin-6 (IL-6), interleukin-8 (IL-8), and tumour necrosis factor-α (TNF-α) levels were reduced. Serum total antioxidant capacity (T-AOC), liver catalase (CAT), and superoxide dismutase (SOD) activity were enhanced, reducing hepatic OS and inflammation. Liver transcriptomic analysis indicated that green light alleviates cyclic chronic HS-induced liver injury and promotes geese growth performance by suppressing NF-κB pathway activation.

Effects of essential oils on heat-stressed poultry: A review

While certain animal species are sensitive to heat stress, poultry particularly modern breeds, are more susceptible to high ambient temperatures. This has major implications for the poultry industry, as heat stress causes large financial losses. These economic losses will probably increase as a consequence of a predicted rise in global temperatures. Heat stress adversely affects various aspects of poultry, including physiological responses, growth and production performance, meat quality, egg quality, and reproductive activities. These effects occur through specific molecular and metabolic pathways. To mitigate the impacts of heat stress, it is crucial to go beyond administrative practices and implement dietary interventions during high ambient temperature. Such interventions aim to optimize the development of stressed bird species in terms of performance, health, and profitability. Essential oils have shown promising in mitigating the negative effects of heat stress and improved antioxidant status, growth and yield performance, as well as meat and egg quality in poultry. They actively participate in certain metabolic and molecular pathways that help to counteract the effects of heat stress. The article discusses the impacts of essential oil supplementation on the relationships between antioxidant enzyme activity, these molecular, and metabolic pathways, as well as various parameters such as growth and yield performance, and product quality heat-stressed poultry.

Heat stress upregulates arachidonic acid to trigger autophagy in sertoli cells via dysfunctional mitochondrial respiratory chain function

As a key factor in determining testis size and sperm number, sertoli cells (SCs) play a crucial role in male infertility. Heat stress (HS) reduces SCs counts, negatively impacting nutrient transport and supply to germ cells, and leading to spermatogenesis failure in humans and animals. However, how HS affects the number of SCs remains unclear. We hypothesized that changes in SC metabolism contribute to the adverse effects of HS. In this study, we first observed an upregulation of arachidonic acid (AA), an unsaturated fatty acid after HS exposure by LC-MS/MS metabolome detection. By increasing ROS levels, expression of KEAP1 and NRF2 proteins as well as LC3 and LAMP2, 100 µM AA induced autophagy in SCs by activating oxidative stress (OS). We observed adverse effects of AA on mitochondria under HS with a decrease of mitochondrial number and an increase of mitochondrial membrane potential (MMP). We also found that AA alternated the oxygen transport and absorption function of mitochondria by increasing glycolysis flux and decreasing oxygen consumption rate as well as the expression of mitochondrial electron transport chain (ETC) proteins Complex I, II, V. However, pretreatment with 5 mM NAC (ROS inhibitor) and 2 µM Rotenone (mitochondrial ETC inhibitor) reversed the autophagy induced by AA. In summary, AA modulates autophagy in SCs during HS by disrupting mitochondrial ETC function, inferring that the release of AA is a switch-like response, and providing insight into the underlying mechanism of high temperatures causing male infertility.

Effects of herbal dregs supplementation of Salvia miltiorrhiza and Isatidis Radix residues improved production performance and gut microbiota abundance in late-phase laying hens

The present study was designed to evaluate the effect of a mixture of Chinese medicinal residues (CMRs) consisting of Salvia miltiorrhiza residues (SMR) and Isatidis Radix residues (IRR) on productive performance, egg quality, serum lipid and hormone levels, liver and blood antioxidant capacity, oviduct inflammation levels, and gut microbiota in the late-laying stage. A total of 288 fifty-four-week-old BaShang long-tailed hens were divided into four groups. The feed trial period was 8 weeks. The control group was fed the basic diet as a CCMR group, supplemented with 3, 4, and 6% for the experimental groups LCMR, MCMR, and HCMR. The egg production rate of the MCMR group was 8.1% higher than that of the CCMR group (p < 0.05). Serum triglyceride (TG) levels of hens of the CMR-supplemented group were significantly decreased than those of the CCMR group (p < 0.05). The group supplemented with different levels of CMR had significantly higher serum HDL-C levels compared with the control group (p < 0.05). Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels were remarkably increased for the LCMR and MCMR groups and significantly decreased for the HCMR group compared to CCMR (p < 0.05). Serum and liver glutathione peroxidase (GSH-PX) activities were significantly increased, and malondialdehyde (MDA) levels were significantly decreased in the MCMR group compared to the CCMR group (p < 0.05). The expression levels of tubal inflammatory factor markers (IL-4, IL-1β, TNF-α) in the MCMR and HCMR groups were consistent with the pathological findings of the sections. As for cecal microbiota, supplementation with CMR affected the alpha diversity of the cecum microbiome at the genus level. The Shannon index was significantly higher in the MCMR group than in the CCMR and HCMR groups (p < 0.05). Supplementation with different levels of CMR mainly regulated the ratio of intestinal Firmicutes to Bacteroidetes and the abundance of phyla such as Proteobacteria. In addition, CMR supplementation at different levels in the diet enriched lipid-metabolizing bacteria, such as Bacteroides and Ruminococcus_gnavus_group. Furthermore, according to linear discriminant analysis (LDA) effect size (LEfSe) analysis, the MCMR group showed an increase in the number of short-chain fatty acid-producing bacteria Romboutsia and fiber-degrading specialized bacteria Monoglobus. Therefore, supplementation of appropriate amounts of CMR to the diet of laying hens enhanced reproductive hormone levels, hepatic antioxidant capacity, and lipid metabolism, alleviated the levels of oviductal inflammatory factors, and modulated the abundance structure of bacterial flora to improve the late-laying performance and egg quality. The results of the current study showed that CMR is a beneficial feed supplement for chickens when added in moderation.

Effects of varying dietary microalgae levels on performance, egg quality, fertility, and blood biochemical parameters of laying Japanese quails (Coturnix coturnix Japonica)

This experiment was carried out to investigate the nutritional value of Spirulina and Dunaliella (SD) combination levels (0, 0.5, 1.0, 1.5, and 2.0 g/kg) that affected the laying Japanese quail's efficiency, egg quality, fertility, and blood biological indicators. A total of 150 adult Japanese quails, aged 8 wk, were divided into 5 treatments at random, each consisting of 30 quails. There were 5 duplicates for every treatment, with 2 male and 4 female quails in each. Comparing the addition of various concentrations of a mixture of SD to the control treatment, the results showed no substantial rise in egg production, egg weight, or egg mass. When compared to the control group, final body weight (FBW) was improved with SD supplementation. The quails in control consumed more feed intake (FI) (p < 0.05), and they were different from the groups who got SD therapy in that they had a regular feed conversion ratio (FCR). The percentages of hatchability and fertility increased when SD was added to quail meals at up to 1.00 g/kg. When compared to the control quail, the quail supplemented with SD levels showed a non-significant rise in albumin%, yolk%, Haugh unit, and unit surface shell weight (USSW), as well as an increase in eggshell percentage and a drop in egg shape index (p < 0.05). Renal and hepatic enzyme functioning improved when SD was added to the diets. Additionally, lipid profile indicators were reduced by SD supplementation (except low-density lipoprotein-LDL). Moreover, compared to the control, incorporating SD led to a nonsignificant rise in immunoglobulin concentrations (IgG and IgM). In conclusion, adding SD to the diet can improve body weight, lipid profile, immunological response, and liver and kidney functions in Japanese quail.

Stress-Related Gene Expression in Liver Tissues from Laying Hens Housed in Conventional Cage and Cage-Free Systems in the Tropics

Global egg production is mainly based on cage systems, which have been associated with negative effects on the welfare of birds. Stress factors in restrictive production systems can lead to changes in gene transcription and protein synthesis, ultimately impacting the quality of poultry products. The liver serves various metabolic functions, such as glycogen storage, and plays a crucial role in animals' adaptation to environmental changes. Consequently, both internal and external conditions can influence liver functions. The aim of this study was to evaluate the gene expression of AGP, CRP, NOX4, SOD1, CAT, GPX1, SREBF1, and FXR in the liver of laying hens under two different production systems. Liver tissues from Hy-Line Brown hens housed in conventional cage and cage-free egg production systems at 60 and 80 weeks of production were used. mRNA transcript levels were determined by qPCR using the relative quantification method and ACTB as the reference gene. AGP, SOD1, and SREBF1 gene expressions were significantly higher in the conventional cage group at the 60 weeks of production. Furthermore, the mRNA levels of transcripts related to oxidative stress and lipid metabolism were higher in the group of laying hens housed in conventional cages compared to those in cage-free systems. These results suggest differential gene expression of genes related to oxidative stress in liver tissues from hens housed in conventional cages compared to cage-free systems. The conditions of the egg production system can impact the gene expression of oxidative stress and lipid synthesis genes, potentially leading to changes in the metabolism and performance of hens, including egg quality.

Turmeric essential oil improves intestinal integrity, immunological parameters, and performance of broiler chickens under cyclic heat stress

This study aimed to examine whether dietary supplementation of broiler chickens with turmeric essential could mitigate the effects of cyclic heat stress conditions. Intestinal and immunological parameters and gene expression were evaluated during the grower phase. A total of 320 21-day-old male Cobb 500 broilers were distributed according to a completely randomized design with a 4 (diet) × 2 (environment) factorial arrangement and eight replications of five birds each. Dietary treatments consisted of a basal diet without essential oil (EO, negative control) and three diets containing low (100 mg kg-1), intermediate (200 mg kg-1), or high (300 mg kg-1) levels of turmeric EO. In the heat stress group, dietary supplementation with turmeric EO at 100 and 200 mg kg-1 improved body weight, feed conversion, breast yield, and relative liver weight. These supplementation levels reduced villus width, increased villus/crypt ratio, reduced the H/L ratio, and improved hepatic (HSP70 and SREBP1) and intestinal (OCLN) gene expression in birds under heat stress. These findings support the hypothesis that turmeric EO can be used to improve or restore intestinal integrity, modulate inflammation parameters, and, consequently, enhance the performance of broilers challenged by cyclic heat stress.

Rye-grass-derived probiotics alleviate heat stress effects on broiler growth, health, and gut microbiota

The primary aim of this study was to assess the impact of liquid (S-LAB) and lyophilized (L-LAB) probiotics sourced from Rye-Grass Lactic Acid Bacteria on broilers experiencing heat stress. The study involved 240 broiler chicks divided into six groups. These groups included a negative control (Control) with broilers raised at a normal temperature (24 °C) on a basal diet, and positive control groups (S-LAB and L-LAB) with broilers under normal temperature receiving a lactic acid bacteria supplement (0.5 mL/L) from rye-grass in their drinking water. The heat stress group (HS) comprised broilers exposed to cyclic heat stress (5-7 h per day at 34-36 °C) on a basal diet, while the heat stress and probiotic groups (S-LAB/HS and L-LAB/HS) consisted of broilers under heat stress supplemented with the rye-grass-derived lactic acid bacteria. Results indicated that heat stress without supplementation (HS) led to reduced body weight gain, T3 levels, citrulline, and growth hormone levels, along with an increased feed conversion ratio, serum corticosterone, HSP70, ALT, AST, and leptin levels. Heat stress also negatively impacted cecal microbiota, decreasing lactic acid bacteria (LABC) while increasing E. coli and coliform bacteria (CBC) counts. Probiotic supplements (S-LAB/HS and L-LAB/HS) mitigated these effects by enhancing broilers' resilience to heat stress. In conclusion, rye grass-derived S-LAB and L-LAB probiotics can effectively support broiler chickens under heat stress, promoting growth, liver function, hormonal balance, gut health, and cecal microbiome ecology. These benefits are likely mediated through improved gut health.

Eucalyptol ameliorates chlorpyrifos-induced necroptosis in grass carp liver cells by down-regulating ROS/NF-κB pathway

Chlorpyrifos (Diethoxy-sulfanylidene-(3,5,6-trichloropyridin-2-yl) oxy-λ5-phosphane, CPF) was extensively used organophosphorus pesticide, extensively deteriorating public problem with the enrichment in the water bodies. Eucalyptol (1,3,3-Trimethyl-2-oxabicyclo[2.2.2] octane, EUC), a colorless cyclic monoterpene oxide, has shown anti-inflammatory and anti-oxidation properties. To explore the effect of EUC on CPF-induced necroptosis in the grass carp liver cells (L8824 cells), we treated L8824 cells with 60 mM CPF and 5 μM EUC for 24 h. The results showed that CPF exposed lead to excessive accumulation of reactive oxygen species (ROS) and oxidative stress, activating the NF-κB and RIPK1 pathway, increasing the level of cell necroptosis. However, EUC treatment attenuated the toxic effects of CPF treatment on L8824 cells. In summary, the study demonstrated that CPF induced necroptosis and inflammation, and EUC treatment could decrease CPF-caused cell injury.

Production performance, haematological parameters, serum biochemistry, and expression of HSP-70 in broiler chickens fed dietary ascorbic acid during heat stress

An experiment was carried out to assess the efficacy of supplemental ascorbic acid (AA) on broiler chicken production performance, blood haematological profile, biochemical profile, and carcass traits under heat stress conditions. A total of 192-day-old broiler chicks were divided into four groups, each with six replicates of eight each (4 × 6 × 8). Four corn-based dietary treatments were formulated: T1 (control diet), T2 (T1 + AA at 200 mg/kg), T3 (T1 + AA at 400 mg/kg), and T4 (T1 + AA at 600 mg/kg) for a period of 42 days. Despite the high temperature and humidity, the 600 mg AA supplemental groups (T4) gained significantly (P ≤ 0.05) more body weight and had a higher feed intake and better feed conversion ratio (FCR) than the control group (T1). After 28 days of feeding the three AA-supplemented diets, antibody titres (humoral immune response) were significantly higher (P ≤ 0.05). The response to intradermally injected phyto-haemagglutinin (PHA-P), an index of the in vivo cell-mediated immune response, was found to be increased (P ≤ 0.05) in the 400 and 600 mg AA-supplemented groups after 35 days. Higher levels of AA (T4) supplementation significantly (P ≤ 0.05) improved haematological values such as haemoglobin (Hb), total erythrocyte count (TEC), total leukocyte count (TLC), and differential leukocyte count (DLC), heterophil:lymphocyte (H:L) in comparison to the control group (T1). The supplemented group improved the serum biochemical profile of the birds, with an increase (P ≤ 0.05) in total serum protein, albumin, and globulin and a decrease in serum cholesterol and corticosterone levels in the T4 group compared to the control group. Heat shock protein-70 (HSP-70) was gradually elevated after increasing the ascorbic acid concentration (P ≤ 0.05) at 14 and 21 days. As a result, it can be concluded that supplementing ascorbic acid at 600 mg/kg is beneficial for improving the performance, immunity, and blood haematological biochemical profile and upregulating the HSP-70 gene of broiler chickens under heat stress conditions.

Growth performance, blood biochemistry, and mRNA expression of hepatic heat shock proteins of heat-stressed broilers in response to rosemary and oregano extracts

The growing interest in countering the adverse effects of heat stress in poultry using phytogenic feed additives has garnered considerable attention in recent times, this research sought to examine the impact of rosemary leaves extract (RLE) and oregano leaves extract (OLE) on the growth performance, physiological responses, and hepatic mRNA expression of heat shock proteins in broiler chickens exposed to heat stress. A total of 150 male Indian River chicks, aged one day, were randomly allocated into five equally sized groups, each consisting of six replicates. The initial group was designated as the control and was provided with the basal diet. The second and third groups (R1 and R2) were administered the basal diet enriched with 50 and 100 mg/kg of rosemary leaves extract (RLE), respectively. The fourth and fifth groups (O1 and O2) were fed the basal diet supplemented with 50 and 100 mg/kg of oregano leaves extract (OLE), respectively. These chicks were reared in a controlled environmental chamber maintained at a temperature of 32±2 °C and relative humidity of 50 ± 5 %. Ferruginol was the leading component in RLE, whereas thymol was the prevalent constituent in OLE. RLE and OLE both have high DPPH• and ABTS•+ antioxidant potential. Among the experimental groups, the fourth group (O1) showed the heaviest live body weight and the lowest feed conversion ratio, indicating improved growth performance. There was a significant reduction in plasma total lipids and LDL-cholesterol levels within the R2 and O2 groups, respectively. Enhanced total antioxidant capacity and an improvement in the T3 hormone were observed in the R1 and R2 groups. In the second and fourth groups, the mRNA expression of hsp70 and 90A were both found to be significantly downregulated, respectively. In conclusion, the addition of 50 mg/kg of oregano leaves extract (OLE) to the diets of heat-stressed broilers resulted in improved hepatic heat shock proteins, along with certain physiological responses, ultimately contributing to enhanced growth performance.

The role of phytogenic feed additives in stress mitigation in broiler chickens

The increase in global temperature and consumers' welfare has increased the use of phytogenic feed additives (PFA) to mitigate the negative effects of heat stress on chickens in recent years. Various bioactive compounds capable of improving the thermotolerance of broiler chickens during exposure to thermal challenges have been identified in different plant species and parts. This review is an overview of the roles of bioactive compounds of different PFA, such as polyphenols and flavonoids, antioxidants, growth-promoting and immune-modulating agents, in heat stress management in broiler chickens. Common PFA in use, particularly in tropical environments, are also discussed. An understanding of the roles of the PFA in chickens' thermotolerance could further stimulate interest in their use, thereby improving the birds' productivity and addressing consumers' concerns. This review collates the existing data on the roles of herbs in mitigating heat stress on chickens and highlights future research perspectives.

Comparative Effects on Using Bilberry Leaves in Broiler Diet Reared under Thermoneutral Conditions vs. Heat Stress on Performance, Health Status and Gut Microbiota

The study aims to investigate the impact of dietary bilberry leaves on the performance, health status, and gut microbiota of broilers reared in both thermoneutral conditions and under heat stress. Sixty Cobb 500 broiler chicks were divided into two groups (C-TN, BL-TN) and reared in thermoneutral conditions for the first trial. For the second trial, two other groups (C-HS and BL-HS) were reared in heat stress (32 °C), with 30 chickens in each group. The experimental diets were supplemented with 1% bilberry leaves compared to the control diets. The broilers fed a diet with bilberry leaves had lower levels of cholesterol compared to the control birds. At the end of the experiment, six broilers per group were slaughtered, and intestinal contents were collected for bacteriological analyses. The results revealed that bilberry leaves increased body weight and average daily feed intake in the BL-TN group compared to the C-HS group. However, the broilers fed a bilberry leaves diet and reared in heat stress had a significantly lower average daily feed intake and average daily weight gain than the C-TN group. Additionally, the number of staphylococci colonies decreased significantly in the group fed with a BL-supplemented diet and reared in TN compared to C-TN, while lactobacilli increased significantly in BL-TN compared to C-TN. In summary, bilberry leaves can be used as a natural supplement in a broiler's diet to regulate serum cholesterol in heat stress and maintain the health of intestinal microflora in thermoneutral conditions.

Effect of chronic heat stress on the carbonylation of glycolytic enzymes in breast muscle and its correlation with the growth performance of broilers

Chronic heat stress has detrimental effects on the growth performance of broilers, and the potential mechanism is under exploration. In this study, the protein carbonyl modification was introduced to glycolytic enzymes to evaluate its relationship with the growth performance of heat-stressed (HS) broilers. A total of 144 male 28-day-old broilers were assigned to 3 treatments: the normal control group (NC, raised at 22°C with free access to feed and water), the HS group (raised at 32°C with free access to feed and water), and the pair-fed group (PF, raised at 22°C with an amount of feed equal to that consumed by the HS group on a previous day). Results showed that heat stress decreased the average daily growth, increased the feed-to-gain ratio (F/G), decreased breast muscle rate, and increased abdominal fat rate compared with the NC and PF groups (P < 0.05). Higher cloacal temperature and serum creatine kinase activity were found in the HS group than those of the NC and PF groups (P < 0.05). Heat stress increased the contents of carbonyl, advanced glycation end-products, malonaldehyde, and the activities of catalase, glutathione peroxidase, and total antioxidant capacity compared with the NC and PF groups (P < 0.05). Heat stress increased the contents of glucose and lactate, declined the glycogen content, and lowered the relative protein expressions of pyruvate kinase muscle type, lactate dehydrogenase A type (LDHA), and citrate synthase compared to those of the NC group (P < 0.05). In contrast to the NC and PF groups, heat stress intensified the carbonylation levels of phosphoglucomutase 1, triosephosphate isomerase 1, β-enolase, and LDHA, which were positively correlated with the F/G (P < 0.05). These findings demonstrate that heat stress depresses growth performance on account of oxidative stress and glycolysis disorders. It further increases the carbonylation of glycolytic enzymes, which potentially correlates with the F/G by disturbing the mode of energy supply of broilers.

Effect of dietary glycine supplementation on productive performance, egg quality, stress response, and fatty liver incidence in laying hens raised under heat stress conditions

The current experiment aimed to investigate the effect of dietary glycine (Gly) supplementation on productive performance, egg quality, stress response, and fatty liver incidence in laying hens raised under heat stress (HS) conditions. A total of two hundred eighty 24-wk-old Lohmann Brown-Lite laying hens were randomly allotted to 1 of 4 dietary treatments with 7 replicates. The negative control (NC) diet was prepared to meet or exceed the nutrient and energy requirement for Lohmann Brown laying hens, whereas the positive control (PC) diet was formulated to increase AMEn by 100 kcal/kg compared with the NC diet. Two additional diets were prepared by supplementing 0.341% and 0.683% Gly to the NC diet. All hens were exposed to cyclic HS at 31.4 ± 1.17°C for 8 h/d and 26.7 ± 1.10°C for the remaining time for a 12-wk trial. Results indicated that increasing supplementation of Gly in diets tended (linear, P = 0.088) to decrease the FCR of laying hens. Increasing supplementation of Gly in diets increased (linear, P < 0.05) eggshell lightness and decreased (linear, P < 0.05) egg yolk color. Moreover, a tendency for a quadratic association (P < 0.10) of serum aspartate aminotransferase and alanine aminotransferase concentrations with increasing supplementation of Gly was observed. Increasing supplementation of Gly in diets decreased (linear, P < 0.05) blood heterophil:lymphocyte ratio of laying hens. Hens fed the NC diet showed higher fatty liver incidence (P < 0.05) than those fed the PC diet, but increasing supplementation of Gly decreased (linear, P < 0.05) fatty liver incidence of laying hens. In conclusion, increasing supplementation of Gly up to 0.683% in diets decreases FCR, stress response, and fatty liver incidence in laying hens raised under HS conditions.

Effects and Mechanisms Investigation of Heat Stress on Egg Yolk Quality in Huaixiang Chickens

The purpose of this study was to examine the effects of high temperature on internal egg yolk quality parameters and their possible mechanisms in Huaixiang chickens. This study consisted of two treatments, and each treatment had six replicates with six birds per cage. A total of seventy-two 26-week-old female Huaixiang chickens were randomly divided into a normal-temperature group (NT) and a high-temperature group (HT) for 6 weeks. And these hens were exposed to 25 ± 2 °C and 32 ± 2 °C, respectively. Their relative humidity was maintained at 55-65%. The results showed that the HT group significantly reduced yolk weight, yolk color, and egg weight compared to the NT group (p < 0.05). Heat stress caused vacuolar degeneration of the liver and reduced the absolute liver weight (p < 0.05). Both yolk triglyceride (TG) and liver TG in the HT group were significantly higher than in the NT group (p < 0.05). However, the liver total cholesterol (TC) level in the HT group was remarkably lower than that in the NT group (p < 0.05). Additionally, heat stress remarkably enhanced SREBP-1c, ACACA, and FASN lipid metabolism-related gene mRNA expression levels in Huaixiang chicken liver after 6 weeks of heat exposure (p < 0.05). Furthermore, the HT group had remarkably reduced total amino acid, Cys, and Tyr levels in the yolk when compared with the NT group in our experiment (p < 0.05). In conclusion, heat stress causes egg yolk quality reduction and abnormal lipid metabolism in Huaixiang chickens. These findings provided novel insights into the role of high temperature on egg yolk parameters and the underlying mechanisms in Chinese indigenous laying hens.

Biogenic Selenium Nanoparticles Synthesized with Alginate Oligosaccharides Alleviate Heat Stress-Induced Oxidative Damage to Organs in Broilers through Activating Nrf2-Mediated Anti-Oxidation and Anti-Ferroptosis Pathways

Selenium (Se) is an essential trace element for maintaining health due to its ideal antioxidant properties. We previously prepared a new type of biogenic selenium nanoparticles based on alginate oligosaccharides (SeNPs-AOS), and this study aimed to investigate the protective effects of SeNPs-AOS (Se particle size = 80 nm, Se content = 8%) on organ health in broilers challenged with HS. A total of 192 21-day-old Arbor Acres broilers were randomly divided into four groups according to a 2 × 2 experimental design, including a thermoneutral zone group (TN, raised under 23 ± 1.5 °C); TN + SeNPs-AOS group (TN group supplemented 5 mg/kg SeNPS-AOS); HS group (HS, raised under 33 ± 2 °C for 10 h/day); and HS + SeNPs-AOS group (HS group supplemented 5 mg/kg SeNPS-AOS). There were six replicates in each group (eight broilers per replicate). The results showed that SeNPs-AOS improved the splenic histomorphology, enhanced the activity of catalase (CAT) and glutathione peroxidase (GSH-Px) of the spleen, as well as upregulating the splenic mRNA expression of antioxidant-related genes in broilers under HS. In addition, SeNPs-AOS reversed the pathological changes in bursa caused by HS increased the activity of GST, GSH-Px, and CAT and upregulated the mRNA expression of Nrf2 and antioxidant-related genes in the bursa of heat-stressed broilers. In addition, dietary SeNPs-AOS improved the hepatic damage, increased the activity of GSH-Px in the liver, and upregulated the mRNA expression of antioxidant-related genes while downregulating the Keap1 gene expression of the liver in broilers during HS. Moreover, dietary SeNPs-AOS upregulated the anti-ferroptosis-related genes expression of liver in broilers under HS. In conclusion, dietary SeNPs-AOS could relieve HS-induced oxidative damage to the spleen, bursa of Fabricius and liver in broilers by upregulating the Nrf2-mediated antioxidant gene expression and SeNPs-AOS could also upregulate the expression of hepatic Nrf2-related anti-ferroptosis genes in heat-stressed broilers. These findings are beneficial for the development of new nano-antioxidants in broilers.

Influence of different heat stress models on nutrient digestibility and markers of stress, inflammation, lipid, and protein metabolism in broilers

This experiment determined the effects of different HS models and pair-feeding (PF) on nutrient digestibility and markers of stress, inflammation, and metabolism in broilers. Birds (720 total) were allocated into 12 environmentally controlled chambers and reared under thermoneutral conditions until 20 d. Until 41 d birds were exposed to 4 treatments, including: thermoneutral at 24°C (TN-al), daily cyclic HS (12 h at 24 and 12 h at 35°C; cyHS), constant HS at 35°C (coHS), and PF birds maintained at 24°C and fed to equalize FI with coHS birds (TN-coPF). At d 41, ileal digesta were collected to determine nutrient apparent ileal digestibility (AID). Blood, liver, and breast tissues were collected from 8 birds per treatment to determine the mRNA expression of stress, inflammation, and metabolism markers. An additional 8 TN-al birds were sampled after acute HS exposure at 35°C for 4 h (aHS), and 8 cyHS birds were sampled either right before or 4 h after HS initiation. Data were analyzed by 1-way ANOVA and means were separated using Tukey's HSD test. Compared with TN-al birds, AID of nitrogen and ether extract were reduced in coHS birds, and both cyHS and coHS reduced (P < 0.05) AID of total essential amino acids. TNFα and SOD2 expression were increased (P < 0.05) under aHS, coHS, and TN-coPF conditions. IL6 and HSP70 were increased (P < 0.05) under coHS and aHS, respectively. Expression of lipogenic enzymes ACCα and FASN were reduced by coHS and TN-coPF, while coHS increased the lipolytic enzyme ATGL (P < 0.05). IGF1 was lowered in coHS birds, and p70S6K and MyoG were reduced under coHS and TN-coPF (P < 0.05). Interestingly, MuRF1 and MAFbx were increased (P < 0.05) under coHS only. Overall, these results indicate that coHS has a greater impact on nutrient digestibility and metabolism than aHS and cyHS. Interestingly, increased protein degradation during HS appears to be mostly driven by HS per se and not the reduced FI.

Effect of Glucose Supplementation on Apoptosis in the Pectoralis major of Chickens Raised under Thermoneutral or Heat Stress Environment

Reduced feed intake during heat stress (HS) disrupts glucose homeostasis, thereby resulting in endoplasmic reticulum (ER) stress and triggering apoptosis in chickens. We hypothesize that glucose supplementation could reduce apoptosis in chickens raised under HS. This study comprised 456 28-day-old broiler chickens randomly assigned to four treatment combinations under glucose supplementation and HS. The treatments were TN0, TN6, HS0, and HS6 with two glucose levels (0% and 6%) and two temperature levels (25 °C (thermoneutral-TN) and 35 °C (8.00 AM to 8.00 PM, (HS)). After 7 days post-HS, the blood glucose level for the HS6 group was higher than for TN0, TN6, and HS0. We studied the mRNA expression of genes and caspase-3 activity in the four experimental groups. The expressions of GCN2, ATF4, CHOP, and FOXO3a increased during HS regardless of glucose supplementation, while PERK and MAFbx increased only under HS with glucose supplementation. We show that under TN conditions, glucose supplementation led to a significant increase in cellular apoptosis in the Pectoralis (P.) major. However, under HS with glucose, the level of apoptosis was similar to that of chickens raised under TN conditions with no glucose supplementation. The utility of glucose to curtail apoptosis under HS should be tested under other intense models of HS.

Effects of melittin on production performance, antioxidant function, immune function, heat shock protein, intestinal morphology, and cecal microbiota in heat-stressed quails

The purpose of this study was to investigate the effects of melittin on production performance, antioxidant function, immune function, heat shock protein, intestinal morphology, and cecal microbiota of heat-stressed quails. A total of 120 (30-day-old) male quails were randomly divided into 3 groups. Each group consisted of 4 replicates with 10 birds per replicate. The ambient temperature of the control group (group W) was 24°C ± 2°C. The heat stress group (group WH) and the heat stress + melittin group (group WHA2) were subjected to heat stress for 4 h from 12:00 to 16:00 every day, and the temperature was 36°C ± 2°C for 10 d. The results showed that compared with the group W, heat stress significantly decreased growth performance, serum and liver antioxidative function, immune function, intestinal villus height (VH) and villus height-to-crypt depth ratio (VH/CD), and cecal microbiota Chao and ACE index (P < 0.05). The crypt depth (CD) in the small intestine, and HSP70 and HSP90 mRNA levels in the heart, liver, spleen, and kidney were significantly increased (P < 0.05). Dietary melittin significantly increased growth performance, serum and liver antioxidative function, immune function, intestinal VH and VH/CD, and cecal microbiota Shannon index in heat-stressed quails (P < 0.05). Melittin significantly decreased small intestinal CD, and HSP70 and HSP90 mRNA levels in the viscera (P < 0.05). Furthermore, dietary melittin could have balanced the disorder of cecal microbiota caused by heat stress and increased the abundance and diversity of beneficial microbiota (e.g., Firmicutes were significantly increased). PICRUSt2 functional prediction revealed that most of the KEGG pathways with differential abundance caused by high temperature were related to metabolism, and melittin could have restored them close to normal levels. Spearman correlation analysis showed that the beneficial intestinal bacteria Anaerotruncus, Bacteroidales_S24-7_group_norank, Lachnospiraceae_unclassified, Shuttleworthia, and Ruminococcaceae_UCG-014 increased by melittin were positively correlated with average daily feed intake, the average daily gain, serum and liver superoxide dismutase, IgG, IgA, bursa of Fabricius index, and ileum VH and VH/CD. In sum, our results demonstrate for the first time that dietary melittin could improve the adverse effects of heat stress on antioxidant function, immune function, heat shock protein, intestinal morphology, and cecal microbiota in quails, consequently improving their production performance under heat stress.

Assessing phytotoxicity and cyto-genotoxicity of two insecticides using a battery of in-vitro biological assays

Intensive use of chemical pesticides in agriculture poses environmental risks and may have negative impacts on agricultural productivity. The potential phytotoxicity of two chemical pesticides, chlorpyrifos (CPS) and fensulfothion (FSN), were evaluated using Cicer arietinum and Allium cepa as model crops. Different concentrations (0-100 μgmL-1) of both CPS and FSN decreased germination and biological attributes of C. arietinum. High pesticide doses significantly (p ≤ 0.05) caused membrane damage by producing thiobarbituric acid reactive substances (TBARS) and increasing proline (Pro) content. Pesticides elevated ROS levels and substantially increased the superoxide anions and H2O2 concentrations, thus aggravating cell injury. Plants exposed to high pesticide dosages displayed significantly higher antioxidant levels to combat pesticide-induced oxidative stress. Ascorbate peroxidase (APX), guaiacol peroxidase (GPX), catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD) increased by 48%, 93%, 71%, 52% and 94%, respectively, in C. arietinum roots exposed to 100 µgFSNmL-1. Under CLSM, pesticide-exposed C. arietinum and 2',7'-dichlorodihydrofluorescein diacetate (2'7'-DCF) and 3,3'-diaminobenzidine stained roots exhibited increased ROS production in a concentration-dependent manner. Additionally, enhanced Rhodamine 123 (Rhd 123) and Evan's blue fluorescence in roots, as well as changes in mitochondrial membrane potential (ΔΨm) and cellular apoptosis, were both associated with high pesticide dose. Allium cepa chromosomal aberration (CAs) assay showed a clear reduction in mitotic index (MI) and numerous chromosomal anomalies in root meristematic cells. Additionally, a-dose-dependent increase in DNA damage in root meristematic cells of A. cepa and conversion of the super-coiled form of DNA to open circular in pBR322 plasmid revealed the genotoxic potential of pesticides. The application of CPS and FSN suggests phytotoxic and cyto-genotoxic effects that emphasize the importance of careful monitoring of current pesticide level in soil before application and addition at optimal levels to soil-plant system. It is appropriate to prepare both target-specific and slow-release agrochemical formulations for crop protection with concurrent safeguarding of agroecosystems.

Cecal microbiota composition differs under normal and high ambient temperatures in genetically distinct chicken lines

Modern broilers, selected for high growth rate, are more susceptible to heat stress (HS) as compared to their ancestral jungle fowl (JF). HS affects epithelia barrier integrity, which is associated with gut microbiota. The aim of this study was to determine the effect of HS on the cecal luminal (CeL) and cecal mucosal (CeM) microbiota in JF and three broiler populations: Athens Canadian Random Bred (ACRB), 1995 Random Bred (L1995), and Modern Random Bred (L2015). Broiler chicks were subjected to thermoneutral TN (24 °C) or chronic cyclic HS (8 h/day, 36 °C) condition from day 29 until day 56. HS affected richness in CeL microbiota in a line-dependent manner, decreasing richness in slow-growing JF and ACRB lines, while increasing richness in faster-growing L1995 and L2015. Microbiota were distinct between HS and TN conditions in CeL microbiota of all four lines and in CeM microbiota of L2015. Certain bacterial genera were also affected in a line-dependent manner, with HS tending to increase relative abundance in CeL microbiota of slow-growing lines, while decreases were common in fast-growing lines. Predictive functional analysis suggested a greater impact of HS on metabolic pathways in L2015 compared to other lines.

Replacement of Vitamin E by an Extract from an Olive Oil by-Product, Rich in Hydroxytyrosol, in Broiler Diets: Effects on Liver Traits, Oxidation, Lipid Profile, and Transcriptome

The study examines the effect of replacing vitamin E (VE) with a liquid obtained from alpeorujo, an olive oil by-product rich in hydroxytyrosol (HT), as an antioxidant in broiler chicken feeds on the gene expression, lipid profile, and oxidation in the liver. There were five diets that differed only in the substitution of supplemental VE (0 to 40 mg/kg with differences of 10 mg/kg) by HT (30 to 0 mg/kg with differences of 7.5 mg/kg). A linear decrease (p < 0.05) in α-tocopherol concentration in the liver was observed with the replacement of VE by HT. There were no significant changes in triglyceride, cholesterol, or TBARS concentrations. The hepatic transcriptome showed 378 differentially expressed genes between broilers fed HT15 (20 mg/kg VE and 15 mg/kg HT) and HT0 (40 mg/kg VE) diets (p < 0.05 and fold change less or higher than 1.3). Significant changes in cell cycle, cell nucleus activity, neuroactivity, and necroptosis pathways and functions were observed. It is concluded that the olive oil by-product, rich in HT, could be used to spare VE as an antioxidant in broiler diets without affecting liver lipid and TBARS concentrations. The differential gene expression analysis showed a potential role of olive polyphenols in enhancing the chicken immune response.

Neuroprotective Effects of Phenolic Antioxidant Tert-butylhydroquinone (tBHQ) in Brain Diseases

Human life and health are gravely threatened by brain diseases. The onset and progression of the illnesses are influenced by a variety of factors, including pathogenic causes, environmental factors, mental issues, etc. According to scientific studies, neuroinflammation and oxidative stress play a significant role in the development and incidence of brain diseases by producing pro-inflammatory cytokines and oxidative tissue damage to induce inflammation and apoptosis. Neuroinflammation, oxidative stress, and oxidative stress-related changes are inseparable factors in the etiology of several brain diseases. Numerous neurodegenerative diseases have undergone substantial research into the therapeutic alternatives that target oxidative stress, the function of oxidative stress, and the possible therapeutic use of antioxidants. Formerly, tBHQ is a synthetic phenolic antioxidant, which has been widely used as a food additive. According to recent researches, tBHQ can suppress the processes that lead to neuroinflammation and oxidative stress, which offers a fresh approach to treating brain diseases. In order to achieve the goal of decreasing inflammation and apoptosis, tBHQ is a specialized nuclear factor erythroid 2-related factor (Nrf2) activator that decreases oxidative stress and enhances antioxidant status by upregulating the Nrf2 gene and reducing nuclear factor kappa-B (NF-κB) activity. This article reviews the effects of tBHQ on neuroinflammation and oxidative stress in recent years and looks into how tBHQ inhibits neuroinflammation and oxidative stress through human, animal, and cell experiments to play a neuroprotective role in Alzheimer's disease (AD), stroke, depression, and Parkinson's disease (PD). It is anticipated that this article will be useful as a reference for upcoming research and the creation of drugs to treat brain diseases.

Transcriptome analysis of multiple tissues reveals the potential mechanism of death under acute heat stress in chicken

BACKGROUND

Acute heat stress could induce high mortality and cause huge economic losses in the poultry industry. Although many studies have revealed heat stress-induced injuries of multiple tissues, the main target tissue and molecular mechanism of death under acute heat stress was largely unknown. This study systematically compared the transcriptome data of five main visceral tissues in chickens to reveal the response of multiple tissues to acute heat stress and determine the main target tissue of acute heat stress, further revealing the injuries of main target tissue and their potential mechanism by combing pathological section and qRT-PCR technologies.

RESULTS

The transcriptome data of five visceral tissues revealed that acute heat stress broadly caused inflammatory response and damaged tissues metabolic homeostasis. Among the five tested visceral tissues, the number of differentially expressed genes in the lung was the highest, and their fold changes were the greatest, indicating that the lung was the main target tissue of acute heat stress. The results of pathological section revealed severe inflammation, emphysema and pulmonary hemorrhage in the lung under acute heat stress. Our study found that some pro-inflammatory genes, including CNTFR, FURIN, CCR6, LIFR and IL20RA, were significantly up-regulated both in the heat-stress and heat-death groups, and their fold changes in the heat-death group were significantly greater than that in the heat-stress group. We also found an anti-inflammatory gene, AvBD9, exhibiting an extremely high expression in the heat-stress group but a low expression in the heat-death group.

CONCLUSIONS

Our study found that acute heat stress caused multiple tissue injuries broadly and the lung was the main target tissue of acute heat stress in chicken. Acute heat stress caused a severe inflammatory response, emphysema, and pulmonary haemorrhage, The severe inflammatory response in the heat-death group was related to the up-regulation of pro-inflammatory genes and down-regulation of anti-inflammatory genes.

Chitosan Oligosaccharides Alleviate Heat-Stress-Induced Lipid Metabolism Disorders by Suppressing the Oxidative Stress and Inflammatory Response in the Liver of Broilers

Heat stress has been reported to induce hepatic oxidative stress and alter lipid metabolism and fat deposition in broilers. Chitosan oligosaccharides (COSs), a natural oligosaccharide, has anti-oxidant, anti-inflammatory, and lipid-lowering effects. This study is conducted to evaluate dietary COS supplementation on hepatic anti-oxidant capacity, inflammatory response, and lipid metabolism in heat-stressed broilers. The results indicate that heat-stress-induced poor (p < 0.05) growth performance and higher (p < 0.05) abdominal adiposity are alleviated by COS supplementation. Heat stress increases (p < 0.05) serum AST and ATL activity, serum and liver MDA, TG, TC, and LDL-C levels, and the expression of hepatic IL-1β, IL-6, SREBP-1c, ACC, and FAS, while it decreases (p < 0.05) serum SOD and CAT activity, liver GSH-Px and SOD activity, and the expression of hepatic Nrf2, GPX1, IL-10, MTTP, PPARα, and CPT1. Nevertheless, COS supplementation decreases (p < 0.05) serum AST and ATL activity, serum and liver MDA, TG, TC, and LDL-C levels, and the expression of hepatic IL-1β, IL-6, SREBP-1c, ACC, and FAS, while it increases (p < 0.05) serum SOD and CAT activity, liver GSH-Px activity, and the expression of hepatic Nrf2, CAT, IL-10, LPL, MTTP, PPARα, and CPT1. In conclusion, COS could alleviate heat-stress-induced lipid metabolism disorders by enhancing hepatic anti-oxidant and anti-inflammatory capacity.

Effect of individual or combination of dietary betaine and glycine on productive performance, stress response, liver health, and intestinal barrier function in broiler chickens raised under heat stress conditions

The current experiment was conducted to investigate the effect of individual or combination of dietary betaine (Bet) and glycine (Gly) on productive performance, stress response, liver health, and intestinal barrier function in broiler chickens raised under heat stress (HS) conditions. A total of four hundred twenty 21-d-old Ross 308 broiler chickens were randomly allotted to 1 of 5 dietary treatments with 7 replicates. Birds in treatment 1 were raised under the thermoneutral condition (TN; 23 ± 0.6°C). Birds in other 4 treatment groups were subjected to a cyclic HS by exposing them to 32 ± 0.9°C for 8 h/d (from 09:00 to 17:00 h) and 28 ± 1.2°C for the remaining time for 14 d. Birds were fed a basal diet in TN condition (TN-C) and one group in HS conditions (HS-C), whereas other birds raised under HS conditions were fed the basal diet supplemented with 0.20% Bet (HS-Bet), 0.79% Gly (HS-Gly), or their combination (0.20% Bet + 0.79% Gly; HS-Bet+Gly). Results indicated that birds in HS-Bet, HS-Gly, or HS-Bet+Gly treatment had higher (P < 0.05) final BW and BW gain, but lower (P < 0.05) feed conversion ratio (FCR) than those in HS-C treatment. However, values for improved final BW, BW gain, and FCR by dietary treatments were lower (P < 0.05) than those measured in TN-C treatment. Under HS conditions, birds in HS-Bet, HS-Gly, or HS-Bet+Gly treatment had lower (P < 0.05) heterophil to lymphocyte ratio than those in HS-C treatment. Birds in HS-Gly or HS-Bet+Gly treatment had higher (P < 0.05) villus height and goblet cell number than birds in HS-C treatment. Intestinal permeability was higher (P < 0.05) in all HS-treatment groups than in TN-C treatment, but it was not affected by dietary treatment. In conclusion, individual supplementation of 0.20% Bet or 0.79% Gly in diets alleviates the negative effect of HS in broiler chickens. However, the synergistic effect of the combination of 0.20% Bet and 0.79% Gly in broiler diets seems lower than expected.

Dietary supplementation of solubles from shredded, steam-exploded pine particles modifies gut length and cecum microbiota in cyclic heat-stressed broilers

This study was conducted to investigate the effect of supplementing solubles from steam-exploded pine particles (SSPP) on mitigating the adverse effects of cyclic heat stress (CHS) in broilers which were distributed into 3 dietary treatment groups and 2 temperature conditions. Heat stress (HS) exposure for 6 h daily for 7 d adversely affected performance parameters and rectal temperature of chickens. The absolute and relative weights of the liver and bursa of Fabricius decreased in the CHS group while the relative lengths of the jejunum and ileum increased, which was rescued by dietary supplementation with SSPP. The expression of mucin2 (MUC2) and occludin (OCLN) genes was decreased in CHS birds. The expression of heat shock protein -70 and -90 increased in 0% HS compared to that in 0% NT. Birds supplemented with 0.4% SSPP had higher NADPH oxidase -1 expression than birds in the 0% and 0.1% SSPP treatments. Beta diversity of gut microbiota evaluated through unweighted UniFrac distances was significantly different among treatments. Bacteroidetes was among the 2 most abundant phyla in the cecum, which decreased with 0.1% NT and increased with 0.1% HS in comparison to 0% NT. A total of 13 genera were modified by HS, 5 were altered by dose, and nine showed an interaction effect. In conclusion, CHS adversely affects performance and gut health which can be mitigated with dietary SSPP supplementation that modifies the cecal microbiota in broilers.

Impact of resveratrol-loaded liposomal nanocarriers on heat-stressed broiler chickens: Effects on performance, sirtuin expression, oxidative stress regulators, and muscle building factors

Climate change is considered to be the primary cause of heat stress (HS) in broiler chickens. Owing to the unique properties of extracted polyphenols, resveratrol-loaded liposomal nanoparticles (Resv-Lipo NPs) were first explored to mitigate the harmful effects of HS. The dietary role of Resv-Lipo NPs in heat-stressed birds was investigated based on their growth performance, antioxidative potential, and the expression of heat shock proteins, sirtuins, antioxidant, immune, and muscle-building related genes. A total of 250 1-day-old Ross 308 broiler chickens were divided into five experimental groups (5 replicates/group, 10 birds/replicate) for 42 days as follows: the control group was fed a basal diet and reared in thermoneutral conditions, and the other four HS groups were fed a basal diet supplemented with Resv-Lipo NPsI, II, and III at the levels of 0, 50, 100, and 150 mg/kg diet, respectively. The results indicated that supplementation with Resv-Lipo NP improved the growth rate of the HS group. The Resv-Lipo NP group showed the most significant improvement in body weight gain (p &lt; 0.05) and FCR. Additionally, post-HS exposure, the groups that received Resv-Lipo NPs showed restored functions of the kidney and the liver as well as improvements in the lipid profile. The restoration occurred especially at higher levels in the Resv-Lipo NP group compared to the HS group. The elevated corticosterone and T3 and T4 hormone levels in the HS group returned to the normal range in the Resv-Lipo NPsIII group. Additionally, the HS groups supplemented with Resv-Lipo NPs showed an improvement in serum and muscle antioxidant biomarkers. The upregulation of the muscle and intestinal antioxidant-related genes (SOD, CAT, GSH-PX, NR-f2, and HO-1) and the muscle-building genes (myostatin, MyoD, and mTOR) was observed with increasing the level of Resv-Lipo NPs. Heat stress upregulated heat shock proteins (HSP) 70 and 90 gene expression, which was restored to normal levels in HS+Resv-Lipo NPsIII. Moreover, the expression of sirtuin 1, 3, and 7 (SIRT1, SIRT3, and SIRT7) genes was increased (p &lt; 0.05) in the liver of the HS groups that received Resv-Lipo NPs in a dose-dependent manner. Notably, the upregulation of proinflammatory cytokines in the HS group was restored in the HS groups that received Resv-Lipo NPs. Supplementation with Resv-Lipo NPs can mitigate the harmful impact of HS and consequently improve the performance of broiler chickens.

Genome-wide mapping of signatures of selection using a high-density array identified candidate genes for growth traits and local adaptation in chickens

BACKGROUND

Availability of single nucleotide polymorphism (SNP) genotyping arrays and progress in statistical analyses have allowed the identification of genomic regions and genes under selection in chicken. In this study, SNP data from the 600 K Affymetrix chicken array were used to detect signatures of selection in 23 local Italian chicken populations. The populations were categorized into four groups for comparative analysis based on live weight (heavy vs light) and geographical area (Northern vs Southern Italy). Putative signatures of selection were investigated by combining three extended haplotype homozygosity (EHH) statistical approaches to quantify excess of haplotype homozygosity within (iHS) and between (Rsb and XP-EHH) groups. Presence of runs of homozygosity (ROH) islands was also analysed for each group.

RESULTS

After editing, 541 animals and 313,508 SNPs were available for statistical analyses. In total, 15 candidate genomic regions that are potentially under selection were detected among the four groups: eight within a group by iHS and seven by combining the results of Rsb and XP-EHH, which revealed divergent selection between the groups. The largest overlap between genomic regions identified to be under selection by the three approaches was on chicken chromosome 8. Twenty-one genomic regions were identified with the ROH approach but none of these overlapped with regions identified with the three EHH-derived statistics. Some of the identified regions under selection contained candidate genes with biological functions related to environmental stress, immune responses, and disease resistance, which indicate local adaptation of these chicken populations.

CONCLUSIONS

Compared to commercial lines, local populations are predominantly reared as backyard chickens, and thus, may have developed stronger resistance to environmental challenges. Our results indicate that selection can play an important role in shaping signatures of selection in local chicken populations and can be a starting point to identify gene mutations that could have a useful role with respect to climate change.

Metabolomics analysis of the effects of different litter size on reproductive metabolism and oxidative stress in breeding pigeon (Columba livia)

The pigeon breeding industry employs a high-rearing pattern to achieve economic benefits. However, too many squabs consume more energy of the breeding pigeons causing adverse effects on their breeding performance. To determine the optimal rearing patterns and the effects of different numbers of squabs on reproductive performance, oxidative stress, and glucolipid metabolism of lactating breeding pigeons in winter, three rearing patterns consisting of "2 + 2″, "2 + 3″ and "2 + 4" (a pair of breeding pigeons feeding two, three and four squabs, respectively) were adopted using European Mimas white pigeons breed. The feed intake, bodyweight loss, feed-to-meat ratio, and squab mortality were linearly increased with the number of squabs during lactation, while the bodyweight recovery rate and squab growth performance were significantly slowed down after lactation. Similarly, the laying rate was linearly decreased on days 16, 17, and 18 of lactation, with a similar pattern on the re-laying rate on days 11, 12, and 13 after first laying. In addition, the number of non-laying pigeons in the second batch was significantly increased, implying that the number of squabs significantly affected the reproductive performance of female pigeons. The eggshell weight and thickness in the "2 + 3″ group were significantly increased. However, the number of squabs in the "2 + 3″ group had no significant effect on plasma calcium (Ca) and phosphorus (P) levels. Analysis of the glucolipid metabolism index and oxidative stress level of pigeons further revealed that the contents of triglyceride (TG), total cholesterol (T-CHO), and low-density lipoprotein cholesterol (LDL-C) in the plasma of male pigeons were significantly decreased with the increase in the number of squabs, but there was no obvious oxidative stress. On the contrary, glucose (GLU), TG, malondialdehyde (MDA) in the plasma of female pigeons were significantly increased, total antioxidant capacity (T-AOC) were significantly decreased, implying that the female pigeons suffered more oxidative stress and more dramatic changes in glucolipid metabolism. Metabolomics revealed that the differential metabolites in the plasma of female pigeons in "2 + 2″, "2 + 3″, and "2 + 4″ groups were significantly enriched in the fatty acid, phospholipid, sphingolipid metabolism, and the Krebs cycle pathways, especially under "2 + 4″ rearing pattern. Overall, in female pigeons, the available lipids were reduced; hence, their body turned to sugar dysplasia and protein utilization mode, increasing the oxidative stress level and decreasing their reproductive performance. Therefore, an increased number of squabs significantly affects the body condition and reproductive performance of breeding pigeons. The "2 + 3″ rearing pattern is the most suitable for winter breeding pigeon production under the current nutrition level.

Arachidonic acid impairs the function of the blood-testis barrier via triggering mitochondrial complex-ROS-P38 MAPK axis in hyperthermal Sertoli cells

The death of Sertoli cells (SCs) under condition of heat stress (HS) affects spermatogenesis and is associated with impaired function of the blood-testis barrier (BTB). The fatty acid arachidonic acid (AA) is essential for the maintenance of cellular function. However, excessive release of AA during HS may adversely affect the reproductive function. The molecular mechanisms through which AA modulates the BTB in SCs are unclear. In this study, we found that 100 µM AA damaged testicular morphology and accelerated SC apoptosis during HS, reducing the stability of tight junction proteins (TJPs), shown by measurement of the levels of Claudin 11, 5, Occludin, and trans-epithelial electrical resistance (TEER). It was also found that AA adversely affected TJPs by increasing the accumulation of reactive oxygen species (ROS) and malondialdehyde (MDA), activating p38 mitogen-activated protein kinases (P38 MAPK) and reducing mitochondria DNA (mtDNA) and the expression of mitochondrial complexes I and III. In contrast, pretreatment with SB203508 (a P38 MAPK inhibitor), Rotenone (an inhibitor of complex I) and Antimycin A1 (an inhibitor of complex III) reversed TJPs degradation induced by AA. Interestingly, pretreatment of cells with 10 µM Baicalein, a 12/15 lipoxygenase (12/15-LOX) -dependent inhibitor of AA production, protected against AA-induced TJPs degradation, restored mitochondrial function, and reduced apoptosis. These results suggested an intriguing link between the induction of TJPs degradation induced by AA overload and mitochondrial antioxidant function during HS, which was found to be regulated by the mitochondrial complex-ROS-P38 MAPK axis.

Research Progress on Lycopene in Swine and Poultry Nutrition: An Update

Oxidative stress and in-feed antibiotics restrictions have accelerated the development of natural, green, safe feed additives for swine and poultry diets. Lycopene has the greatest antioxidant potential among the carotenoids, due to its specific chemical structure. In the past decade, increasing attention has been paid to lycopene as a functional additive for swine and poultry feed. In this review, we systematically summarized the latest research progress on lycopene in swine and poultry nutrition during the past ten years (2013-2022). We primarily focused on the effects of lycopene on productivity, meat and egg quality, antioxidant function, immune function, lipid metabolism, and intestinal physiological functions. The output of this review highlights the crucial foundation of lycopene as a functional feed supplement for animal nutrition.

Effects of Dietary Glutamine Supplementation on Heat-Induced Oxidative Stress in Broiler Chickens: A Systematic Review and Meta-Analysis

In avian species, heat stress (HS) is usually the result of being exposed to high ambient temperatures, whereas oxidative stress (OS) results from the overproduction of reactive oxygen species. The current literature suggests that HS often leads to OS. Therefore, this systematic review and meta-analysis was conducted to assess the effects of dietary supplementation of glutamine on the antioxidant status and growth performances in heat-stressed broilers. A total of 13 studies were deemed eligible after an exhaustive search of the literature from Google Scholar, PubMed, and Scopus. Briefly, the following criteria were used to select the studies: trials performed on broilers; publication in peer-review journals using English as the text language; and sufficient details about the design and inclusion of dietary glutamine as a treatment for HS. Two main categories of outcomes were extracted from the studies included in the review: growth parameters and OS markers. For the meta-analysis, a random effect model was used when the heterogeneity was higher than 50%, and a fixed effect model was applied otherwise. Pooled standardized mean differences (SMD), and mean differences (MD) with their confidence intervals (CI) from the studies revealed that dietary glutamine could increase body weight gain (SMD = 0.70, CI = 0.50 to 0.90, p < 0.05), and feed intake (FI) (SMD = 0.64, CI = 0.43 to 0.86, p < 0.05), and reduce the feed conversion ratio (MD = -0.05, CI = -0.07 to -0.02, p < 0.05) in heat-exposed birds. Additionally, higher glutamine (SMD = 1.21, CI = 1.00 to 1.43, p < 0.05), glutathione (SMD = 1.25, CI = 0.88 to 1.62, p < 0.05), superoxide dismutase (SOD) (SMD = 0.97, CI = 0.58 to 1.36, p < 0.05), and catalase (SMD = 0.94, CI = 0.72 to 1.16, p < 0.05) levels were recorded in the serum, breast, and thigh muscle after supplementation of glutamine. Furthermore, the subgroup analysis revealed that malondialdehydes levels were decreased only in the serum (SMD = -0.83, CI = -1.25 to -0.41, p < 0.001) and thigh muscle (SMD = -1.30, CI = -1.86 to -0.35, p < 0.001) while glutathione peroxidase (GPX) activity was increased in the breast (SMD = 1.32, CI = 0.95 to 1.68, p < 0.05) and thigh muscle (SMD = 1.53, CI = 1.06 to 1.99, p < 0.05). Meta-regression models indicated that longer periods of heat exposure were inversely associated with the effectiveness of dietary glutamine in increasing FI, GPX, and SOD (p < 0.05). Besides, increasing the dietary concentration of glutamine led to higher GPX and SOD levels (p < 0.05). Taken together, results suggest that dietary supplementation of glutamine can effectively mitigate the deleterious effects of HS by enhancing the antioxidant status and increasing growth performances in broilers.

Effect of Glutamine on the Growth Performance, Oxidative Stress, and Nrf2/p38 MAPK Expression in the Livers of Heat-Stressed Broilers

The purpose of this work was to study the effects of glutamine (Gln) on the growth performance, oxidative stress, Nrf2, and p38 MAPK pathway in the livers of heat-stressed broilers. In total, 300 broilers were divided into five groups, including a normal temperature (NT, without dietary Gln) group and four cyclic high temperature groups (HT, GHT1, GHT2, and GHT3) fed with 0%, 0.5%, 1.0%, and 1.5% Gln, respectively. High temperature conditions increased (p < 0.05) liver malonaldehyde (MDA) concentration, but decreased (p < 0.05), body weight gain (BWG), feed intake (FI), liver superoxide dismutase (SOD), total antioxidant capacity (T-AOC), glutathione peroxidase (GSH-Px), glutathione S-transferase (GST), and glutathione (GSH) levels in broilers. Nrf2 and p38 MAPK protein and mRNA expression levels were lower (p < 0.05) in the NT group than that in the HT group. However, dietary 1.5% Gln decreased (p < 0.05) liver MDA concentration, but increased (p < 0.05) BWG, FI, liver SOD, T-AOC, GSH-Px, GST, and GSH levels in heat-stressed broilers. Nrf2 and p38 MAPK protein and mRNA expression levels were higher (p < 0.05) in the GHT3 group than that in the HT group. In summary, Gln improved oxidative damage through the activation of Nrf2 and p38 MAPK expression in the livers of heat-stressed broilers.

Effects and potential mechanism of dietary vitamin C supplementation on hepatic lipid metabolism in growing laying hens under chronic heat stress

The adverse effects of chronic heat stress (CHS)-induced fatty liver syndrome on laying hens during the egg-producing stages have been wildly documented. However, until nowadays, the CHS responses of growing laying hens as well as its alleviating effects of vitamin C are rarely reported. In this study, 12-wk-old laying hens were subjected to CHS at 36 °C for 10 h/d for 3 wk with or without dietary supplementation of 300 mg/kg vitamin C. Results showed that CHS significantly impaired the growth performances and the liver functions of birds, as characterized by reduced feed intake and body weight, increased hepatic lipid accumulation and serum concentrations of TG, ALT, and AST, as well as the abnormal expression patterns of the lipid metabolism-related genes. Vitamin C supplementation successfully mitigated the lipid accumulation, while showing no alleviating effect on the serum contents of ALT or AST, which are two key indicators of liver functions. Metabolomic analysis based on UPLC-Q-TOF/MS identified 173 differential metabolites from the HS and HSV group samples, and they are mainly enriched in the pathways related to the cellular components, vitamin and amino acid metabolism and energy substance metabolism. The results indicate that CHS-induced hepatic lipid deposition in growing laying hens is effectively alleviated by dietary supplementation of vitamin C, which is probably resulted from the alterations of hepatocellular metabolic patterns.

Resveratrol relieves chronic heat stress-induced liver oxidative damage in broilers by activating the Nrf2-Keap1 signaling pathway

Heat stress (HS) affects poultry production and welfare, causing enormous damage to poultry. Resveratrol, an antioxidant and anti-inflammatory natural plant polyphenol, is widely used in agriculture for the prevention of oxidative stress-related diseases. This study aimed to explore the effects and potential mechanism of resveratrol on liver oxidative damage in heat-stressed broilers. Sixty SPF chickens were randomly divided into control, heat stress (HS) and HS+ resveratrol (resveratrol) groups. Broilers were exposed to 35 ± 2 ℃ (8 h/d) for 7 consecutive days to induce HS, and the other 16 h/d were kept at 23 ± 2 ℃, similar to the control group. Broilers received 400 mg/kg resveratrol in the basic diet 2 days before exposure to HS and for the following 7 days. The results showed that resveratrol improved growth performance by increasing the average daily gain (ADG) and reducing the feed conversion ratio (FCR), compared with the HS group. Heat stress reduced liver weight and index, increased inflammatory cell infiltration in the liver, enhanced serum AST levels, and decreased TP and ALB II levels, which resulted in liver injury in broilers, and resveratrol effectively alleviated liver injury. Moreover, supplementation with resveratrol enhanced the activities of liver antioxidant enzymes resulting in higher GPX and SOD levels than those in the heat-stressed broilers, and decreased MDA levels. Furthermore, resveratrol alleviated liver oxidative stress by activating the gene and protein levels of Nrf2 and HO-1, enhancing NQO1 and SOD1 gene levels, and decreasing protein levels of HSP70, p62, and Keap1, and thereby alleviated the liver injury of heat-stressed broilers. Compared with the HS group, Nrf2 immunofluorescence was significantly up-regulated in the livers of resveratrol group. These results suggest that resveratrol can enhance the liver antioxidant function by activating the Nrf2-Keap1 signaling pathway to promote growth performance in broilers under HS.

Seascape genomics of common dolphins (Delphinus delphis) reveals adaptive diversity linked to regional and local oceanography

Background

High levels of standing genomic variation in wide-ranging marine species may enhance prospects for their long-term persistence. Patterns of connectivity and adaptation in such species are often thought to be influenced by spatial factors, environmental heterogeneity, and oceanographic and geomorphological features. Population-level studies that analytically integrate genome-wide data with environmental information (i.e., seascape genomics) have the potential to inform the spatial distribution of adaptive diversity in wide-ranging marine species, such as many marine mammals. We assessed genotype-environment associations (GEAs) in 214 common dolphins (Delphinus delphis) along > 3000 km of the southern coast of Australia.

Results

We identified 747 candidate adaptive SNPs out of a filtered panel of 17,327 SNPs, and five putatively locally-adapted populations with high levels of standing genomic variation were disclosed along environmentally heterogeneous coasts. Current velocity, sea surface temperature, salinity, and primary productivity were the key environmental variables associated with genomic variation. These environmental variables are in turn related to three main oceanographic phenomena that are likely affecting the dispersal of common dolphins: (1) regional oceanographic circulation, (2) localised and seasonal upwellings, and (3) seasonal on-shelf circulation in protected coastal habitats. Signals of selection at exonic gene regions suggest that adaptive divergence is related to important metabolic traits.

Conclusion

To the best of our knowledge, this represents the first seascape genomics study for common dolphins (genus Delphinus). Information from the associations between populations and their environment can assist population management in forecasting the adaptive capacity of common dolphins to climate change and other anthropogenic impacts.