Hepatic expression responses of DNA methyltransferases, heat shock proteins, antioxidant enzymes, and NADPH 4 to early life thermal conditioning in broiler chickens

Early life thermal conditioning alters heat-shock protein expression in response to an adult thermal stressor

Developmental environmental stressors can have instructive effects on an organism's phenotype. This developmental plasticity can prepare organisms for potentially stressful future environments, circumventing detrimental effects on fitness. However, the physiological mechanisms underlying such adaptive plasticity are understudied, especially in vertebrates. We hypothesized that captive male zebra finches (Taeniopygia castanotis) exposed to a mild heat conditioning during development would acquire a persisting thermotolerance, and exhibit increased heat-shock protein (HSP) levels associated with a decrease in oxidative damage when exposed to a high-intensity stressor in adulthood. To test this, we exposed male finches to a prolonged mild heat conditioning (38°C) or control (22°C) treatment as juveniles. Then in a 2 × 2 factorial manner, these finches were exposed to a high heat stressor (42°C) or control (22°C) treatment as adults. Following the adult treatment, we collected testes and liver tissue and measured HSP70, HSP90, and HSP60 protein levels. In the testes, finches exhibited lower levels of HSP90 and HSP60 when exposed to the high heat stressor in adulthood if they were exposed to the mild heat conditioning as juveniles. In the liver, finches exposed to the high heat stressor in adulthood had reduced HSP90 and HSP60 levels, regardless of whether they were conditioned as juveniles. In some cases, elevated testes HSP60 levels were associated with increased liver oxidative damage and diminishment of a condition-dependent trait, indicating potential stress-induced tradeoffs. Our results indicate that a mild conditioning during development can have persisting effects on HSP expression and acquired thermotolerance.

Synthetic and phytogenic antioxidants improve productive performance, antioxidant activity, gene expression, and offspring quality in breeder hens subjected to heat stress

This study aimed to investigate the efficacy of a synthetic source (a combination of vitamin E, vitamin C, selenium, and L-carnitine) and phytogenic sources (a combination of clove, green tea pomace, and Vietnamese coriander) in overcoming heat stress (HS) damage in female breeder hens on production, blood chemistry, sperm survival in the oviduct, antioxidant properties, gene expression, and quality of offspring. One hundred SUT female breeder hens were housed in individual cages and divided into 4 treatment groups: T1) basal diets in the thermoneutral (TN) zone; T2) basal diets under HS; 3) basal diets with synthetic antioxidants under HS; and T4) basal diets with phytochemical antioxidants under HS. The result revealed that HS condition had a negative effect on reducing final body weight, egg weight, and 1-day-old chick weight while increasing water intake and FCR and altered blood chemicals in breeder hens compared to TN breeder hens (P < 0.05). However, either synthetic or phytogenic antioxidants resulted in increased egg production and hatchability, while decreasing the number of late stages of embryo death during the incubation (P < 0.05). Furthermore, the synthetic antioxidants also improved the uniformity of chicks and reduced late-stage embryo death compared with phytogenic antioxidants (P < 0.05). HS breeder hens fed with either of the antioxidant sources exhibited higher antioxidant capacity in terms of DPPH and ABTS radical scavenging (in yolk, liver, and breast meat) and FRAP radical scavenging (in yolk and liver) and lower liver malondialdehyde than HS breeder hens fed with the control diet (P < 0.05). Additionally, the gene expression of antioxidant enzymes (superoxide dismutase, catalase, and glutathione peroxidase) in the liver was upregulated, whereas the expression of proinflammatory cytokines (nuclear factor-κB) and heat shock proteins (HSP70 and HSP90) was downregulated in breeder hens that received both antioxidant sources (P < 0.05). Future investigations should focus on the potential for combinations of synthetic and phytogenic antioxidants in diets for HS breeder hens.

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.

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.

Modulation of heat shock protein 70 (HSP70) gene expression ex vivo in response to heat stress in chicken

The present study was conducted to assess the effect of exposure to heat stress on the HSP70 gene expression pattern ex vivo in chickens. The adult healthy birds (n = 15) grouped into three replicates of n = 5 each were used to isolate peripheral blood mononuclear cells (PBMCs). The PBMCs were subjected to heat stress at 42 °C for 1 h, and cells without heat stress (NHS) were taken as control. The cells were seeded in 24 well plates and incubated in a humidified incubator at 37 °C under 5% CO2 for recovery. HSP70 expression kinetics were evaluated at 0, 2, 4, 6, and 8 h of the recovery period. Compared with NHS, the expression pattern of HSP70 was upregulated gradually from 0 to 4 h with peak (p < 0.05) expression recorded at 4 h of recovery time. mRNA expression of HSP70 escalated in a time-dependent manner from 0 to 4 h of heat exposure and thereafter exhibited a gradually decreasing pattern till 8 h of the recovery period. The findings from this study highlight the protective role of HSP70 against the deleterious effects of heat stress in chicken PBMCs. Further, the study demonstrates the possible use of PBMCs as a cellular system in assessing the heat stress effect in chickens ex vivo.

Heat stress and poultry production: a comprehensive review

The impact of global warming on poultry production has gained significant attention over the years. However, our current knowledge and understanding of the mechanisms through which heat stress (HS) resulting from global warming affects the welfare, behavior, immune response, production performance, and even transgenerational effects in poultry are still incomplete. Further research is needed to delve deeper into these mechanisms to gain a comprehensive understanding. Numerous studies have investigated various biomarkers of stress in poultry, aiming to identify reliable markers that can accurately assess the physiological status and well-being of birds. However, there is a significant amount of variation and inconsistency in the results reported across different studies. This inconsistency highlights the need for more standardized methods and assays and a clearer understanding of the factors that influence these biomarkers in poultry. This review article specifically focuses on 3 main aspects: 1) the neuroendocrine and behavioral responses of poultry to HS, 2) the biomarkers of HS and 3) the impact of HS on poultry production that have been studied in poultry. By examining the neuroendocrine and behavioral changes exhibited by poultry under HS, we aim to gain insights into the physiological impact of elevated temperatures in poultry.

The role of different dietary Zn sources in modulating heat stress-related effects on some thermoregulatory parameters of New Zealand white rabbit bucks

The present work was conducted to assess the effect of diets supplementation to heat-stressed buck rabbits with different zinc (Zn) sources on the thermoregulatory and hematobiochemical parameters, and antioxidant status. A total of 24 mature buck rabbits (32-36 weeks of age) were randomly distributed into four groups (6 each). Group 1, non-heat-stressed control (NHSC), was reared in the absence of heat stress (HS) conditions and received the basal diet only. The other three groups (groups 2, 3 and 4) were kept in HS conditions. Group 2, heat-stressed control (HSC), received the basal diet only. The diet supplemented with 75 mg Zn/kg diet either in the inorganic form (Zn sulfate) or in the organic form (Zn picolinate) for groups 3 and 4, respectively. Zn supplementation to rabbits' diets lowered the heat stress-related increase of serum urea, alanine transaminase and malondialdehyde (MDA) concentration. These supplementations also increased the concentration of testosterone under HS conditions. Zn picolinate was more effective than Zn sulfate in restoring serum concentrations of urea, testosterone, and MDA. In conclusion, Zn addition to rabbits' diets from different sources, especially Zn picolinate, exhibits an ameliorative effect against the harmful impact of HS on hematobiochemical parameters and antioxidant status.

Hepatic heat shock proteins, antioxidant-related genes, and immunocompetence of heat-stressed broilers in response to short periods of incubation during egg storage and thermal conditioning

Short Periods of Incubation During Egg Storage (SPIDES) approach improves chick quality and hatching rates. Also, embryonic thermal conditioning (TC) is a strategy for enhancing thermotolerance in avian species. Until now, evaluating the effect of either SPIDES or embryonic TC effects has only been separately conducted, so we hypothesized that combining TC and SPIDES may enhance the response of broilers to thermal stress. Eight hundred Ross broiler eggs were divided into two groups; the first one was kept under appropriate storage room conditions, S0 (control) The 2nd was subjected to SPIDES for 5 h at 37.8 ○C ± 0.1 three times at days 5, 10, and 15 (S1) after egg collection respectively. On the 14th day of incubation (DOI) each of the two main groups was randomly divided into two equal subgroups; the control one was left under the appropriate incubation settings (TC0) whereas the other received prenatal heat conditioning (TC1) at 39.5 ○C ± 0.1 for 6 h/d from the 14th to the 18th embryonic day (E), resulting finally in four experimental subgroups (S0TC0, S1TC0, S0TC1 & S1TC1). RESULTS: showed that SPIDES treatment improved the hatchability of the stored eggs by almost 20% compared to untreated eggs. A combination of SPIDES and TC (S1TC1) increased significantly the levels of Immunoglobulin (IgG and IgM) production at hatch and heat-stressed birds. Our findings revealed that the hepatic heat shock proteins (hsp70, 90 A,90 B, 60 and hspA9), antioxidants-related genes (CAT, and SOD2), and NADPH4 were significantly downregulated in the thermally conditioned group that challenged with thermal stress conditions. As opposed to that, the SPIDES group showed a significant increase in hepatic heat shock proteins, antioxidants-related genes, and NADPH4 when subjected to thermal-stress conditions. In conclusion, the combination of SPIDES and TC has a positive effect on some pre and post-hatch traits of broiler chicks. Under heat stress challenge, thermal conditioning can modify the expression of antioxidant-related genes and Hsps, leading to the enhanced acquisition of thermotolerance as evidenced by lower expression of Hsps and NADPH4. While SPIDES does not have a significant role in thermotolerance acquisition.

Effects of dietary pretreated Chinese herbal medicine supplementation on production performance, egg quality, uterine histopathological changes, and antioxidant capacity in late-phase laying hens

Aims: The study aimed to evaluate the effects of pretreated Chinese herbal medicine (PCHM) on egg quality, production performance, histopathological changes in the uterus, antiox idant capacity, and antioxidant gene expression in late-phase layers. Methods: Jinghong No.1 layers (n = 360, 68 weeks old) were assigned randomly to one of f our dietary interventions. Each treatment was replicated six times. Repeat 15 chickens per g roup. All birds were fed a diet composed of a corn-soybean meal-based diet supplemented with 0, 0.2, 0.4, or 0.8% PCHM for 6 weeks. Results: Dietary PCHM supplementation had no significant effects on laying rate, feed con sumption, yolk color, and shape index. With increasing PCHM level the Haugh unit linearly increased (P < 0.05). Supplementation of 0.8% PCHM increased egg weight, compared with the control (P < 0.05). PCHM can effectively alleviated the pathological changes caused by aging in the uterus including hemorrhage, and many inflammatory cell infiltrations. Supplementation of 0.4% PCHM increased glutathione peroxidase (GSHPx) in liver, magnum, and plasm considerably, compared with the control (P < 0.05). Supplementation of PCHM decr ease in the liver, magnum, and uterus on malondialdehyde (MDA) content, compared with the control (P < 0.05). Compared with the control group, mRNA expressions of glutathione peroxidase 1 (GPX1), peroxidase 4 (GPX4), catalase (CAT), and nuclear factor E2-related factor 2 (Nrf2) in the magnum, liver, and uterus were dramatically rose in the 0.4% PCHM supplementation group (P < 0.05). In summary, dietary supplementation after PCHM increased egg weight and quality in late-phase laying hens. Conclusion: Dietary PCHM increased the antioxidative capacity of late-phase laying hens, which could be associated with increased mRNA expression of antioxidant enzymes and Nrf2. These findings provide potential for using PCHM to increase the production performance in late-phase laying hens.

Antioxidants status and physiological responses to early and late heat stress in two rabbit breeds

Early life heat stress negatively affects rabbit production and well-being. However, the physiological response to acute heat stress in later life is not clearly defined. The present study aims to investigate the effects of early and late heat stress at 36°C on some blood constituents, antioxidant enzymes activity in the blood, and muscle in New Zealand white and Baladi Black rabbits. A total of sixty post-weaning rabbits of each breed were randomly divided into two groups; control groups (NZWC and BBC) and early heat-stressed groups for six hours at 36 ± 1°C and 62% relative humidity (RH) (NZWT and BBT groups). After heat stress, six rabbits from each group were slaughtered for blood and muscle tissue collection. The surviving rabbits were kept at 28 ± 1°C and 40% RH till 13 weeks of age. At the end of 13 weeks, all rabbits were exposed to late heat stress as precious described to perform four groups: single late stressed groups; NZWC2, BBC2, and double stressed groups; NZWT2 and BBT2. After late heat stress, six rabbits from each group were slaughtered for blood and muscle tissue collection. The early and late heat stress caused a significant reduction in the blood creatine kinase, lactate dehydrogenase, and high-density lipoprotein and antioxidant enzymes' activity in blood and muscle of both NZW and BB rabbits compared with the control groups. While, the blood total cholesterol, triglycerides, total lipids levels, and lipid peroxidation activity in blood and muscle were significantly increased due to the early and late heat-stressed both breeds compared with the control groups. It could be concluded that the early heat stress at 36°C has negative effects on several physiological indicators and antioxidant activities in the blood and muscle of NZW and BB rabbits.

Growth performance and hepatic antioxidants responses to early thermal conditioning in broiler chickens

There are little data about antioxidants' status responses to early thermal conditioning (TC) on broiler chickens. Therefore, the present study was conducted to investigate the different time ages of thermal conditioning on antioxidants responses and the growth rate of broiler chicks. A total of two hundred forty-one-day-old male broiler chicks (Cobb 500) weighed on average 51.5 ± 0.5g were randomly distributed into four equal groups (60 chicks each), and chicks of each group were ranked in five replicates. The first group reared under the ambient temperature, while the second, third and fourth groups (TC3, TC5 and TC7) were subjected to early-age thermal conditioning at 39°C for 6 h on the third, fifth and seventh day of age respectively. Broilers were fed ad-libitum, and drinking water was a free choice during the experimental period. At the end of the experimental period that lasted 5 weeks, all experimental groups were exposed to heat challenge at 36°C for 6 h. Early-age thermal conditioning did not affect growth performance. Plasma corticosterone elevation in TC5 (as a post-challenge response) was the lowest among the experimental groups. Hepatic malondialdehyde significantly increased in TC5 and TC7 groups both at the post-conditioning stage and at the end of the experimental period. Hepatic glutathione, glutathione S-transferases, catalase and superoxide dismutase significantly decreased by early-age thermal conditioning compared with non-conditioned broilers. Microscopic examination of the liver sections from broilers chickens in TC5 and TC7 groups showed all the basic features of normal liver tissue, while the control and TC3 groups showed few necrotic areas. It could be concluded that early-age thermal conditioning at 39°C for 6 h on the fifth day of age could improve the antioxidant defence system of broilers without any adverse effects on growth performance.

Effects of Alhagi Honey Polysaccharides as Feed Supplement on Intestine Function and Microbiome, Immune Function, and Growth Performance in Chicken

Hy-Line Brown chickens’ health is closely related to poultry productivity and it is mainly maintained by the immune system, healthy intestinal function, and microflora of chicken. Polysaccharides are biological macromolecules with a variety of activities that can be used as a potential prebiotic to improve poultry health. In this experiment, the function of Alhagi honey polysaccharides (AH) as an immunomodulator on the chicken was investigated. All chicken (120) were randomly distributed to four groups (five replicas/group, six hens/replica). A total of 0.5 mL water was taken orally by the chicken in control group. AH (0.5 mL) in different concentrations (three dosages, 0.3 g/kg, 0.6 g/k, and 1.2 g/kg) were used for the AH-0.3 g/kg, AH-0.6 g/k, and AH-1.2 g/kg group, respectively. The results showed that the growth performance of the chickens and the index of immune organs (the weight of immune organs/the body weight) were enhanced significantly after being AH-treated (p < 0.05). The content of sIgA and cytokines was upregulated remarkably in the intestine after being AH-treated (p < 0.05). The AH treatment significantly enhanced the intestinal epithelial barrier (p < 0.05). Moreover, the percentage of CD4+ and CD8+ T cells in the ileum, spleen, and serum were obviously upscaled (p < 0.05). In addition, the AH treatment significantly enhanced the production of short chain fatty acids (SCFAs) and improved the structure of gut microbiota (p < 0.05). In conclusion, we found that AH-1.2g/kg was the best dosage to improve the chicken’s health, and these data demonstrated that AH could be used as a potential tool to enhance growth performance through improving intestine function, immunity, and gut microbiome in chicken.

Dietary L-citrulline modulates the growth performance, amino acid profile, and the growth hormone/insulin-like growth factor axis in broilers exposed to high temperature

Heat stress adversely affects the growth performance, muscle development, and protein metabolism in poultry. l-Citrulline (L-Cit), is a non-essential amino acid that is known to stimulate muscle protein synthesis under stress conditions. This study investigated whether L-Cit could influence the growth performance, amino acid profile, and protein metabolism in broilers exposed to high ambient temperature. In a 2 × 2 factorial arrangement, Arbor acre broilers (288 chickens) were fed with basal diet (CON) or 1% L-Cit supplemented diet and later subjected to either thermoneutral (TNZ: 24°C, 24 h/d) or heat stress (HS: 35°C for 8 h/d) environment for 21 days. The results showed that L-Cit diet promoted the body weight and body weight gain of broilers higher than the CON diet, and it further alleviated HS suppression of body weight and feed intake at certain periods (p < 0.05). Plasma urea, uric acid, glucose, and total cholesterol were elevated during HS, whereas, the triglyceride content was decreased (p < 0.05). Serum amino acids including citrulline, alanine, aspartate, and taurine were decreased by HS. L-Cit supplementation restored the citrulline level and alleviated HS induction of 3-methylhistidine (p < 0.05). L-Cit supplementation increased the plasma growth hormone (GH) and insulin-like growth factor-1 (IGF-1) concentration, as well as the GH concentration in the breast muscle (p < 0.05). The mRNA expression showed that HS elicited tissue-specific responses by upregulating some growth factors in the breast muscle, but downregulated the GH receptor, GH binding protein, and IGF-1 expression in the hypothalamus. L-Cit supplementation upregulated the GHRH and IGFBP2 expression in the hypothalamus. L-Cit also upregulated the expression of IGF-1R and IGFBP2 in the breast muscle of HS broilers. The total mTOR protein level in the breast muscle of HS broilers was also increased by L-Cit diet (p < 0.05). Therefore, this study demonstrated that HS negatively affected the growth performance of broilers and dysregulated the expression of growth factors related to protein metabolism. Contrarily, L-Cit promoted the growth responses of broilers via its stimulation of circulating GH/IGF-1 concentration. To certain extents, L-Cit supplementation elicited protective effects on the growth performance of HS broilers by diminishing protein catabolism.

Effect of acute heat shock on stress gene expression and DNA methylation in zebu (Bos indicus) and crossbred (Bos indicus × Bos taurus) dairy cattle

Environmental temperature is one of the major factors to affect health and productivity of dairy cattle. Gene expression networks within the cells and tissues coordinate stress response, metabolism, and milk production in dairy cattle. Epigenetic DNA methylations were found to mediate the effect of environment by regulating gene expression patterns. In the present study, we compared three Indian native zebu cattle, Bos indicus (Sahiwal, Tharparkar, and Hariana) and one crossbred Bos indicus × Bos taurus (Vrindavani) for stress gene expression and differences in the DNA methylation patterns. The results indicated acute heat shock to cultured PBMC affected their proliferation, stress gene expression, and DNA methylation. Interestingly, expressions of HSP70, HSP90, and STIP1 were found more pronounced in zebu cattle than the crossbred cattle. However, no significant changes were observed in global DNA methylation due to acute heat shock, even though variations were observed in the expression patterns of DNA methyltransferases (DNMT1, DNMT3a) and demethylases (TET1, TET2, and TET3) genes. The treatment 5-AzaC (5-azacitidine) that inhibit DNA methylation in proliferating PBMC caused significant increase in heat shock-induced HSP70 and STIP1 expression indicating that hypomethylation facilitated stress gene expression. Further targeted analysis DNA methylation in the promoter regions revealed no significant differences for HSP70, HSP90, and STIP1. However, there was a significant hypomethylation for BDNF in both zebu and crossbred cattle. Similarly, NR3C1 promoter region showed hypomethylation alone in crossbred cattle. Overall, the results indicated that tropically adapted zebu cattle had comparatively higher expression of stress genes than the crossbred cattle. Furthermore, DNA methylation may play a role in regulating expression of certain genes involved in stress response pathways.

Synergy Between Dietary Quercetin and Vitamin E Supplementation in Aged Hen’s Diet Improves Hatching Traits, Embryo Quality, and Antioxidant Capacity of Chicks Hatched From Eggs Subjected to Prolonged Storage

The current study aims to investigate the effects of the synergy between quercetin and vitamin E in aged hen’s diet on hatchability and antioxidant levels of the embryo and newly hatched chicks from prolonged storage eggs. A total of 400 breeder laying hens of 65 weeks of age were selected and randomly divided into 4 groups. Birds were fed a basal diet alone (Control), and basal diets supplemented with quercetin (Q) (0.4 g/kg) and vitamin E (VE) (0.2 g/kg) alone and their combination (0.4 g/kg Q + 0.2 g/kg VE) for 14 weeks, respectively, to determine their effects on yolk antioxidant status, fertility, embryonic mortality, hatchability, antioxidant status of embryonic tissues, as well as the antioxidant status of the newly hatched chicks. The results showed that the hen’s dietary Q + VE increased the yolk weight, as well as increased the antioxidant status of the egg yolk (p < 0.05). Compared with the control group, the supplementation of Q + VE significantly increased the hatchability of set-fertile eggs and decreased early embryonic mortality in eggs stored for 7 and 14 days, respectively (p < 0.05), and also improved the antioxidant capacity of the embryos obtained from eggs stored for 14 days (before incubation) (p < 0.05). Moreover, Q + VE increased the levels of SOD, GSH-Px, T-AOC, T-SOD, and CAT in the liver, heart, and pectoral muscle of the embryo, 1-day-old and 14-day-old chicks (p < 0.05), as well as upregulated the antioxidant related genes (GPx-1, GPx-2, GPx-4, DIO-1, and SOD-1) in the liver of the embryo, 1-day-old and 14-day-old chicks hatched from 14-days storage eggs (p < 0.05). Meanwhile, the MDA levels were decreased by the Q + VE in the embryo and post-hatched chicks (p < 0.05). In conclusion, these findings suggested that maternal dietary Q + VE exerts beneficial synergistic effects on the antioxidant capacity of the egg yolk, embryo, and chicks during prolong egg storage, therefore, Q + VE could be used as a dietary measure to enhance hatchability and chick quality in poultry production.

Exogenous Linoleic Acid Intervention Alters Hepatic Glucose Metabolism in an Avian Embryo Model

In the present study, developmental changes of gluconeogenesis and glycolysis in an avian model were measured, and then the intervention effects of in ovo feeding (IOF) linoleic acid (LA) on hepatic glucose metabolism were evaluated. In Experiment 1, thirty fertilized eggs were sampled on embryonic days (E) of 16, 19, 22, 25, 28, 31, and thirty newly-hatched ducklings at hatch (E34 and E35). In Experiment 2, a total of 120 fertilized eggs (60 eggs for each group) were injected into the yolk sac with PBS as the control group and LA as the IOF LA group on E25. Twelve eggs were selected for sample collection on E28 and E31. Serum contents of glucose, pyruvate, and lactate increased ( p < 0.05) linearly or quadratically from E16 to hatch, as well as hepatic glycogen and pyruvate contents. Hepatic mRNA expression related to energy homeostasis, gluconeogenesis, and glycolysis increased ( p < 0.05) in embryogenesis, and the plateau period was presented on E25–E31. IOF LA decreased ( p < 0.05) serum contents of glucose, triacylglycerol, cholesterol, and hepatic oleic acid, unsaturated fatty acids on E28, as well as the gene expression relative to gluconeogenesis. IOF LA increased ( p < 0.05) pyruvate content in serum and liver, and hepatic gene expression relative to glycolysis on E31. In summary, hepatic gluconeogenesis and glycolysis were enhanced to meet the increasing energy demands of embryonic development during E25 – hatch. Exogenous LA intervention on E25 could inhibit hepatic gluconeogenesis and enhance glycolysis during the later developmental period, disrupting glucose embryonic homeostasis and energy status.

Analysis of Genomic Alternative Splicing Patterns in Rat under Heat Stress Based on RNA-Seq Data

Heat stress is one of the most severe challenges faced in livestock production in summer. Alternative splicing as an important post-transcriptional regulation is rarely studied in heat-stressed animals. Here, we performed and analyzed RNA-sequencing assays on the liver of Sprague-Dawley rats in control (22 °C, n = 5) and heat stress (4 °C for 120 min, H120; n = 5) groups, resulting in the identification of 636 differentially expressed genes. Identification analysis of the alternative splicing events revealed that heat stress-induced alternative splicing events increased by 20.18%. Compared with other types of alternative splicing events, the alternative start increased the most (43.40%) after heat stress. Twenty-eight genes were differentially alternatively spliced (DAS) between the control and H120 groups, among which Acly, Hnrnpd and mir3064 were also differentially expressed. For DAS genes, Srebf1, Shc1, Srsf5 and Ensa were associated with insulin, while Cast, Srebf1, Tmem33, Tor1aip2, Slc39a7 and Sqstm1 were enriched in the composition of the endoplasmic reticulum. In summary, our study conducts a comprehensive profile of alternative splicing in heat-stressed rats, indicating that alternative splicing is one of the molecular mechanisms of heat stress response in mammals and providing reference data for research on heat tolerance in mammalian livestock.

Mitigating the detrimental effects of heat stress in poultry through thermal conditioning and nutritional manipulation

The poultry industry faces several obstacles and challenges, including the changes in global temperature, increase in the per capita demand for meat and eggs, and the emergence and spread of various diseases. Among these, environmental challenges are one of the most severe hurdles impacting the growth and productivity of poultry. In particular, the increasing frequency and severity of heat waves over the past few years represent a major challenge, and this is expected to worsen in the coming decades. Chickens are highly susceptible to high ambient temperatures (thermal stress), which negatively affect their growth and productivity, leading to enormous economic losses. In the light of global warming, these losses are expected to increase in the near future. Specifically, the worsening of climate change and the rise in global temperatures have augmented the adverse effects of heat on poultry production worldwide. At present, the world population is approximately 7.9 billion, and it has been predicted to reach 9.3 billion by 2050 and approximately 11 billion by 2100, implying a great demand for protein supply; therefore, strategies to mitigate future poultry challenges must be urgently devised. To date, several mitigation measures have been adopted to minimize the negative effects of heat stress in poultry. Of these, thermal acclimation at the postnatal stage or throughout the embryonic stages has been explored as a promising approach; however, for large-scale application, this approach warrants further investigation to determine the suitable temperature and poultry age. Moreover, molecular mechanisms governing thermal conditioning are poorly understood. To this end, we sought to expand our knowledge of thermal conditioning in poultry, which may serve as a valuable reference to improve the thermotolerance of chickens via nutritional management and vitagene regulation. Vitagenes regulate the responses of poultry to diverse stresses. In recent years, nutritionists have paid close attention to bioactive compounds such as resveratrol, curcumin, and quercetin administered alone or in combination. These compounds activate vitagenes and other regulators of the antioxidant defense system, such as nuclear factor-erythroid 2-related factor 2. Overall, thermal conditioning may be an effective strategy to mitigate the negative effects of heat stress. In this context, the present review synthesizes information on the adverse impacts of thermal stress, elucidating the molecular mechanisms underlying thermal conditioning and its effects on the acquisition of tolerance to acute heat stress in later life. Finally, the role of some polyphenolic compounds, such as resveratrol, curcumin, and quercetin, in attenuating heat stress through the activation of the antioxidant defense system in poultry are discussed.

Tomato pomace as a nontraditional feedstuff: productive and reproductive performance, digestive enzymes, blood metabolites, and the deposition of carotenoids into egg yolk in quail breeders

This study aimed to evaluate the inclusion of tomato pomace (TP) into Japanese quail breeders' diet by investigating its effects on digestive enzymes, immune response, antioxidant status, blood biomarkers, productive performance, and the deposition of carotenoids into the egg yolk. A total of 150 mature 8-wk of age Japanese quails (100 females and 50 males) were allocated into 5 treatment groups, with 5 replicates, each of 6 quails (4 females and 2 males). The experimental diets were isoenergetic and isonitrogenous, based on corn and soybean meal, and included 0, 3, 6, 9, and 12% of tomato pomace, respectively. The results showed that dietary supplementation of tomato pomace up to 12% significantly improved the immune response, antioxidant response, and digestive enzymes of Japanese quail breeders, significantly decreased cholesterol, low-density lipoprotein (LDL), and increased high-density lipoprotein (HDL). Also, TP increased egg weight, egg mass and hatchability , where TP 6% had the greatest egg weight, egg mass and hatchability among other groups. Moreover, tomato pomace inclusion significantly had a positive effect on the deposition of lycopene into the egg yolk and it can be used as a good delivery system to improve human health. Tomato pomace up to 12% could be used as an alternative feedstuff in quail breeders' diets.

Impacts of Embryonic Thermal Programming on the Expression of Genes Involved in Foie gras Production in Mule Ducks

Embryonic thermal programming has been shown to improve foie gras production in overfed mule ducks. However, the mechanisms at the origin of this programming have not yet been characterized. In this study, we investigated the effect of embryonic thermal manipulation (+1°C, 16 h/24 h from embryonic (E) day 13 to E27) on the hepatic expression of genes involved in lipid and carbohydrate metabolisms, stress, cell proliferation and thyroid hormone pathways at the end of thermal manipulation and before and after overfeeding (OF) in mule ducks. Gene expression analyses were performed by classic or high throughput real-time qPCR. First, we confirmed well-known results with strong impact of OF on the expression of genes involved in lipid and carbohydrates metabolisms. Then we observed an impact of OF on the hepatic expression of genes involved in the thyroid pathway, stress and cell proliferation. Only a small number of genes showed modulation of expression related to thermal programming at the time of OF, and only one was also impacted at the end of the thermal manipulation. For the first time, we explored the molecular mechanisms of embryonic thermal programming from the end of heat treatment to the programmed adult phenotype with optimized liver metabolism.

The Full-Length Transcriptome Provides New Insights Into the Transcript Complexity of Abdominal Adipose and Subcutaneous Adipose in Pekin Ducks

Adipose tissues have a central role in organisms, and adipose content is a crucial economic trait of poultry. Pekin duck is an ideal model to study the mechanism of abdominal and subcutaneous adipose deposition for its high ability of adipose synthesis and deposition. Alternative splicing contributes to functional diversity in abdominal and subcutaneous adipose. However, there has been no systematic analysis of the dynamics of differential alternative splicing of abdominal and subcutaneous adipose in Pekin duck. In our study, the Pacific Biosciences (PacBio) Iso-Seq technology was applied to explore the transcriptional complexity of abdominal and subcutaneous adipose in Pekin ducks. In total, 143,931 and 111,337 full-length non-chimeric transcriptome sequences of abdominal and subcutaneous adipocytes were obtained from 41.78 GB raw data, respectively. These data led us to identify 19,212 long non-coding RNAs (lncRNAs) and 74,571 alternative splicing events. In addition, combined with the next-generation sequencing technology, we correlated the structure and function annotation with the differential expression profiles of abdominal and subcutaneous adipose transcripts. This study identified lots of novel alternative splicing events and major transcripts of transcription factors related to adipose synthesis. STAT3 was reported as a vital gene for adipogenesis, and we found that its major transcript is STAT3-1, which may play a considerable role in the process of adipose synthesis in Pekin duck. This study greatly increases our understanding of the gene models, genome annotations, genome structures, and the complexity and diversity of abdominal and subcutaneous adipose in Pekin duck. These data provide insights into the regulation of alternative splicing events, which form an essential part of transcript diversity during adipogenesis in poultry. The results of this study provide an invaluable resource for studying alternative splicing and tissue-specific expression.

Thermal stress and high stocking densities in poultry farms: Potential effects and mitigation strategies

Environmental changes pose significant threats to agricultural activities particularly animal production. These changes have induced major concerns which will negatively affect the poultry health and productivity under the current climate changes. Moreover, they also alter the immunological status of the exposed birds and make them susceptible to different diseases. The adverse effects of environmental stress also include poor performance of birds (reduced feed intake, growth, feed efficiency, immunity, and egg production) and inferior product quality. The adverse effect of heat stress on different quail breeds like Japanese quail, bobwhite quail, scaled quail, and Gambel's quail ranged from decreased growth rates (11.0-14.5%), body weight (7.7-13.2%), feed intake (6.1-21.6%), feed efficiency (4.3-8.6%), and egg production (6.6-23.3%). Also, birds reared under heat stress (34 °C) had significantly decreased Haugh units by 10.8% and egg weight by 14.3% in comparison with the control group (reared at 22 °C). On the other hand, increasing stoking density from 30 to 45 kg/m² also negatively affected the feed intake and body weight. Recent studies have focused on evaluating the potential adverse effects of different environmental stresses on poultry performance, behavior, welfare, and reproduction. It is imperative to understand better the interaction of different environmental factors and their subsequent effects on avian physiology, to spotlights on the effective management and nutritional strategies to alleviate the adverse effects of different stresses in poultry. This review aims to present a comprehensive overview of physiological manifestations of major environmental stresses including thermal stress (heat and cold stress) and high stocking densities on poultry health and production. Moreover, we have also critically evaluated the scope and efficacy of some potential strategies to mitigate the influences of these environmental stressors in different poultry species.

L-Citrulline Influences the Body Temperature, Heat Shock Response and Nitric Oxide Regeneration of Broilers Under Thermoneutral and Heat Stress Condition

Heat stress (HS) adversely affects several physiological responses in organisms, but the underlying molecular mechanisms involved are yet to be fully understood. L-Citrulline (L-Cit) is a nutraceutical amino acid that is gaining research interest for its role in body temperature regulation and nitric oxide synthesis. This study investigated whether dietary supplementation with L-Cit (1% of basal diet) could ameliorate the effects of acute HS on thermotolerance, redox balance, and inflammatory responses of broilers. Ross 308 broilers (288 chicks) were subjected to two environments; thermoneutral at 24°C (TNZ) or HS at 35°C for 5 h, and fed two diets; control or L-Cit. The results showed that HS increased the ear, rectal (RT), and core body (CBT) temperatures of broilers, along with higher respiratory rate. The RT and CBT readings were intermittently affected with time effect, whereas, L-Cit supplementation lowered the mean CBT than the control diet. Antioxidant assays showed that superoxide dismutase was increased during HS, while, catalase was promoted by L-Cit supplementation. In addition, L-Cit induced glutathione peroxidase activity compared to the control diet during HS. Hypothalamic heat shock protein (HSP)-90 was upregulated by HS, but L-Cit downregulated heat shock factor (HSF)-1, and HSP 60 mRNA expressions. HSF 3 mRNA expression was downregulated by L-Cit under TNZ condition. More so, HS increased the plasma nitric oxide (NO) concentration but lowered the total NO synthase (tNOS) activity. In contrast, L-Cit supplementation limited NO production but increased the tNOS activity. Arginase activity was increased in the control fed group during HS but L-Cit supplementation lowered this effect. The NOS-COX pathway was significantly affected under TNZ condition, since L-Cit supplementation downregulated the mRNA expression of iNOS-COX2 in the hypothalamus, and further reduced the serum PGE2 concentration. Together, these data indicates that L-Cit influenced the antioxidant defense, heat shock response and nitric oxide regeneration both under thermoneutral and HS conditions; and that L-Cit may be directly and/or indirectly involved in the central regulation of body temperature.