Chronic Heat Stress Research Articles

Antioxidant and anti-apoptotic potential of whole-pomegranate extract promoted growth performance, physiological homeostasis, and meat quality of V-line rabbits under hot summer conditions

The present research evaluated the antioxidant and anti-apoptotic potentialities of whole-pomegranate extract (WPE) on the performance, hemato-biochemical indices, carcass yield, and meat quality of male V-line rabbits under hot summer conditions. For this purpose, 48 weaned, 4-week-old male V-line rabbits were randomly divided into groups of 12 as: group 1 was fed a basal diet (control); and groups 2, 3, and 4 were fed a basal diet supplemented with 1,000 mg/kg (T1), 1,250 mg/kg (T2), and 1,500 mg/kg (T3) of WPE, respectively, for 60 days during the summer. Chromatographic analysis of WPE indicated that syringic acid (SA), vanillic acid and caffeic acid were the predominant flavonoids, while Eicosapentaenoic acid (EPA) was the major quantified fatty acid. Concerning growth performance, WPE supplementation increased the final rabbit weight gain compared with that of the control. Meat-quality traits that were significantly affected (P < 0.05) by dietary WPE supplementation were tenderness and yellowness. Physiologically, WPE induced high levels of dose-dependent hemoglobin, superoxide dismutase (SOD), total antioxidant capacity (TAC), and high-density lipoprotein cholesterol. In addition, WPE significantly restricted heat oxidative stress indicators, namely malondialdehyde, aspartate aminotransferase (AST), alanine aminotransferase (ALT), total cholesterol, triacylglycerol, and white blood cells, which were adversely affected by summer heat stress in the control rabbits (P < 0.05). However, there were no significant variations (P> 0.05) in the catalase and creatinine levels between the WPE-treated groups and the control. Genetically, WPE increased the expressions of the antioxidant glutathione peroxidase (GPX1) and anti-apoptotic B-cell lymphoma 2 (Bcl-2) genes and inhibited the expressions of Bcl-2 Associated X-protein (Bax) and caspase-3 genes. The LibDock ligand-protein modelling suggested that the three biological candidates most likely modulated by SA supplementation at the molecular level were catalase enzyme, glutathione peroxidase (GPX1), and caspase genes. Collectively, rabbit supplementation with 1,250 or 1,500 mg/kg WPE potentially protected V-line rabbits from adverse effects of chronic heat stress by improving endogenous and genetic expressions of antioxidant and anti-apoptotic enzymes and genes.

Antioxidant Statues, Growth and Some Physiological Performances of the Gimmizah Male Chickens Supplemented by Dietary Spirulina Platensis under Chronic Heat Stress.

The present study was carried out to study the effect of Spirulina supplementation on the growth and some physiological performances of the Gimmizah males exposed to heat stress (HS). A total number of 150 male 4 weeks old Gimmizah were randomly allocated in five groups (3 replicates, 10 chicks each). The first (positive control, PC) was reared under 22-24OC and PH 45-55% and fed unsupplied basal diet, B). Whereas, the other groups were reused under HS (38°C±1; 55-65 % RH) for three successive days /wk from 11.00 a.m until 15.00 p.m, through the experimental period (4 to 14 wks of age) in a battery brooders. The first HS group was used as a negative control (NC) and fed B. The 3rd and 4rd groups fed B plus 250 and 150 mg Spirulina /kg diet, respectively. The 5 group was fed the B plus 75 mg VE /kg diet. The feed consumption was significantly decreased for all groups under HS compared with PC group, while FCR for the groups under HS (supplied with Spirulina or VE) were significantly improved compared with NC. The differential of leukocytic count for the NC group recorded the significant increase on Lymphocyte, Heterophil and the ratio of H/L compared with other groups. The concentration of globulin and activity of GSH-PX were significantly improved for the groups supplied with both levels of Spirolina under HS compared with the NC group. The highest Infections Bronchitis titer was recorded for the group supplied with VE and PC group. In conclusion, addition of 150 and 250 mg Spirulina platensis /kg diet improved performance, immunity and can be decreased the adverse effect of heat stress for Gimmizah mail during growing period (4-14 wks of age).

Variáveis de incubação, desempenho e morfometria da mucosa duodenal de codornas japonesas (Coturnix coturnix japonica) submetidas a diferentes temperaturas de incubação e desafiadas termicamente após eclosão

ABSTRACT This study aimed to evaluate the effects of different temperatures on incubation variables, performance, and morphometry of the duodenal mucosa of Japanese quails (Coturnix coturnix japonica) submitted to chronic heat stress after hatching. We distributed 540 eggs in three incubators with a temperature of 37.8°C and 60% of humidity. From the 6th day of incubation until hatching, the temperatures were adjusted to (37.8°C, 38.5°C and 39.5°C). After hatching, quails were evaluated for the quality score, weighed, and distributed in a completely randomized design with three incubation temperatures (37.8, 38.5, and 39.5°C) and two ambient temperatures (stress and thermoneutral). At 10, 20, 30, and 40 days they were weighed to determine the live weight (g) and weight gain(g). To collect the duodenum and determine morphometric parameters, we euthanized four quails of each treatment. The data were analyzed, and the differences between the means determined by the Tukey test at 5%. The incubation temperature of 39.5°C provided lower hatching rate and the live weight at birth; however, from the 10th day of age, increased live weight, weight gain, and positively influenced the morphological parameters of the duodenal mucosa in situations of chronic stress.

Effects of Bile Acids on Growth Performance and Lipid Metabolism during Chronic Heat Stress in Broiler Chickens.

Simple SummaryThe negative impacts of heat stress (HS) on growth performance and lipid metabolism have been reported, but there are still no effective nutritional strategies to alleviate heat stress. Bile acids are new for their antioxidative properties and regulatory effect on lipid metabolism. This study was carried out to evaluate the growth performance and lipid metabolism in chickens under heat stress when fed with bile acid supplements in their diet. The results showed that mild heat stress (32 °C) induced hepatic lipogenic gene (hepatic SREBP-1c) expressions and lipid deposition, without obvious tissue damage in broilers. Dietary supplementation of bile acid could decrease hepatic lipid deposition without affecting endogenous bile acid biosynthesis. Therefore, bile acid supplements can benefit broiler chickens during high ambient temperatures, serving as a new nutritional strategy against heat stress.This study aimed to investigate whether dietary bile acid (BA) supplements can improve growth performance and lipid metabolism in heat-stressed broiler chickens. A total of 288 Arbor Acres broilers were blocked by BW and then randomly allocated into 4 treatments at 21 days of age. Birds reared under 32 °C had a higher cloacal temperature (p = 0.01), faster respiratory rate (p < 0.001), and a greatly reduced average daily feed intake (ADFI, p = 0.016), average daily gain (ADG, p = 0.006), final body weight (FBW, p = 0.008), and feed conversion rate (FCR, p = 0.004). In heat stress (HS) birds, the breast muscle rate (p = 0.006) and pH 24 h postmortem (p = 0.065) were lower, and the shear force was higher (p = 0.027). Dietary BA supplements tended to increase the breast muscle rate (p = 0.075) without affecting the growth performance and serum lipids (p > 0.05). Serum total bile acid (TBA) was roughly duplicated after BA supplements (p = 0.001). In the liver, total cholesterol was lower (p = 0.046), and triglycerides were higher (p = 0.04) in the HS birds, whereas the expression of SREBP-1c showed an increasing trend (p = 0.06). In contrast, dietary BA decreased triglycerides and the expressions of hepatic SREBP-1c and FAS in the liver (p < 0.05). In summary, mild HS causes hepatic lipid accumulation without obvious tissue damages, whereas BA has positive effects on relieving abnormal lipid metabolism, indicating that BA as a nutritional strategy has a certain potential in alleviating HS.

Effects of free and dipeptide forms of methionine supplementation on oxidative metabolism of broilers under high temperature

Our previous studies have shown that methionine supplementation could help to attenuate the effects of heat stress on the metabolism of broiler chickens. Here we investigated for the first time the effects of methionine supplementation in the form of DL-methionyl-DL-methionine on broilers subjected to heat stress during the growth phase. Broilers were divided into two groups; one group was reared under thermoneutral conditions and the other under continuous heat stress (30 ± 1 °C, 60% relative humidity). Both groups were subdivided into three dietary treatments: a methionine-deficient (MD) diet, a diet supplemented with free methionine (DL-M), and a diet supplemented with methionine dipeptide (DL-MM). Broilers raised under chronic heat stress had lower feed intake and weight gain than broilers raised under thermoneutral conditions (P < 0.05). There were no differences in animal performance between methionine-supplemented diets (DL-M and DL-MM). Heat-stressed birds had significantly higher heterophil/lymphocyte (H/L) ratio than thermoneutral birds. Under heat stress, broilers fed DL-M and DL-MM diets had lower H/L ratio than birds fed the MD diet. Higher concentrations of carbonylated proteins and lower concentration of reduced glutathione were observed in broilers raised under heat stress. In comparing heat-stressed broilers, we found that birds fed the DL-M diet had lower concentrations of thiobarbituric acid-reactive substances and carbonylated proteins than those fed the MD diet (P < 0.05). Higher expression of glutathione peroxidase (GPX) and glutathione synthetase (GSS) genes was observed in heat-stressed broilers (P < 0.05). Under heat stress, the MD diet increased GPX expression compared with other diets. Under thermoneutral conditions, the DL-M diet resulted in the highest GSS expression. There was a negative correlation between DNA methylation and GPX and GSS expression. Our results showed that supplementation of broiler diets with free methionine or methionine dipeptide may help attenuate the effects of heat stress through enhanced activation of genes related to the glutathione antioxidant system. Methionine effects were found for gene regulation, gene expression, and post-translational processing.

Diffuse reflectance spectroscopy reveals heat stress-induced changes in hemoglobin concentration in chicken breast

Heat stress (HS) is devastating to the poultry industry due to its adverse effects on animal well-being and performance. The effects of heat stress are typically measured using a portable i-STAT blood analyzer that quantifies circulatory hemoglobin concentration and other blood chemistry parameters. Here, we used diffuse reflectance spectroscopy (DRS) as a novel non-invasive method to directly determine changes in hematological parameters in the breast tissues of live heat-stressed broilers. Three-week-old male broilers were randomly subjected to two environmental conditions (thermoneutral, TN, 24 °C vs. cyclic heat stress, HS, 35 °C, 12 h/day). Optical spectra were acquired using DRS to monitor breast hemoglobin (Hb) concentration and vascular oxygen saturation (sO2) at three time points: at baseline prior to heat stress, 2 days, and 21 days after initiation of HS. While i-STAT did not demonstrate a discernible change due to HS in circulatory hemoglobin, DRS found a significant decrease in breast Hb and sO2 after exposure to chronic HS. The decrease in sO2 was found to be due to a decrease in oxygenated hemoglobin concentration, indicating a large increase in oxygen consumption in heat-stressed broilers. Our results demonstrate that DRS could potentially be used to study the effects of HS directly in specific organs of interest, such as the breast and thigh, to improve meat quality.

Transcriptome profiling of olive flounder responses under acute and chronic heat stress.

The olive flounder (Paralichthys olivaceus) is a saltwater fish, which is valuable to the economy. The olive flounder strives to adapt to environmental stressors through physiological, biochemical, and transcriptional responses. The rise in water temperature threatens the growth, development, reproduction, and survival of olive flounder. Each organ in the olive flounder can differentially respond to heat stress. The purpose of this study is to investigate organ-specific transcriptional changes in olive flounder tissues during heat stress. In this study, transcriptome dynamics of the gill, liver, and muscle of olive flounder to acute or chronic heat stress were investigated. Principal component analysis plotting revealed that the transcriptome of each organ is quite separated. K-means clustering, gene ontology, and Kyoto Encyclopedia of Genes and Genomes pathway analysis showed the differential transcriptome responses of each organ to heat stress. Heat stress commonly affects the pathways involved in the correct protein folding, DNA repair, and cell cycle. Our results may provide a valuable molecular basis of heat acclimation in fishes.

THE PROTECTIVE ROLE OF GINGER (ZINGIBER OFFICINALE) ON ALLEVIATION OF HEAT STRESS IN BROILER CHICKEN

Heat stress is one of the most crucial issues in broiler production, particularly in tropical regions. Ginger can serve as an antioxidant. Being part of the nutritional interventions, treatment using ginger has been documented to alleviate the negative impact of heat stress on broiler chickens, in terms of production, physiology, immunology, and antioxidant status of broilers. The present review elucidates the alleviation of heat stress in broiler chicken using ginger based on the most recent literature in order to provide complete information on the impact of ginger powder (GP) on haematology, biochemistry and thyroid hormones of broilers under heat stress (HS) (34 ± 2° C) and thermoneutral temperature (TN) (22 ± 4 °C). An 80 of one-day-old broiler chicks (cobb-500), 20 birds in each group either control (basal diet) or 0.75% ginger. Chronic HS at 42 d of age resulted in significant decrease in PCV, RBCs, total protein, Albumin, serum T3 and T4, whereas increased H/L, triglycerides, cholesterol, LDL-cholesterol, uric acid, AST, ALP, ALT, DBIL, TBIL, and creatinine significantly. Supplementation of GP significantly increased PCV, RBCs, total protein, albumin while significant decrease in AST, uric acid and improvements in lipid profile parameters. Findings of the research study indicated that ginger has improved birds health.

THE PROTECTIVE ROLE OF TURMERIC (CURCUMA LONGA) ON BROILERS EXPOSED TO CHRONIC HEAT STRESS

Heat stress (HS) is one of the most significant stressors in the broiler industry in hot regions. In order to provide complete information on the impact of turmeric powder (TP) on hamartiology, biochemistry and thyroid hormones of broilers under thermoneutral conditions (TN) (22 ± 4 °C) and heat stress (HS) (34 ± 2° C), the present research was carried out. A 60 of one-day-old (Cobb) broiler chicks, 15 birds in each replicate either control (basal diet) or 0.5% turmeric. Chronic HS at 42 d of age resulted in significant decrease in HGB, PCV, RBCs, total protein, Albumin, serum T3 and T4, whereas increased H/L, triglycerides, cholesterol, LDL-cholesterol, uric acid, AST, ALT, ALP, TBIL, DBIL and creatinine significantly. Supplementation of 0.5% TP significantly increased HGB, PCV, total protein, while significant decrease in AST, ALT, ALP, uric acid, total cholesterol and triglycerides. Results indicated that groups receiving turmeric have improved lipid profile.

Effects of methionine as free amino acid and dipeptide on productive efficiency and meat quality of broilers under acute and chronic heat stress

Context Methionine in the form of free amino acid has been widely studied in broilers challenged by heat stress (HS). However, the effects of methionine dipeptide in broilers subjected to HS are not known. Aims To evaluate the effects of methionine as free amino acid and dipeptide on the performance, oxidative status, plasma parameters and meat quality of broilers subjected to acute and chronic HS. Methods Broilers were evaluated at the following three experimental periods: 24 h of evaluation (21–22 days of age); 10 days of evaluation (22–32 days of age); and 20 days of evaluation (22–42 days of age). Broilers were divided into two groups; one group was raised in thermal comfort, and the other group was raised in continuous HS of 30°C. In both groups, animals received a diet without methionine supplementation (MD), with supplementation of methionine as free amino acid (dl-M), and with supplementation of methionine as dipeptide (dl-MM). Key results HS reduced body weight gain after 10 and 20 days of evaluation. Broilers under HS condition fed the MD diet had the highest concentrations of thiobarbituric acid reactive substances (TBARS) at 22 days of age and carbonylated proteins (CP) at 32 days of age. At 42 days of age, broilers fed the MD diet had higher concentrations of TBARS and CP. At 32 days of age, broilers under HS had lower high-density lipoprotein and higher low-density lipoprotein concentrations. In breast meat, broilers in thermal comfort fed the dl-M or dl-MM diets had a lower cooking loss. Broilers in HS fed the dl-M diet had the lowest cooking loss. HS reduced the pH of the meat of legs. Conclusions The acute and chronic HS affect the broiler performance in different ways. Methionine supplementation contributes to reduce the effects of HS. There were no notable differences between the supplementation of dl-M or dl-MM. Implications Productivity and the quality of the chicken meat are the most important attributes of the production. The ambient temperature can influence these parameters. The methionine in its most varied forms, due to its direct and indirect antioxidant function, has been shown to be an effective source of protection for the animal in adverse conditions such as during HS.

An Ethylene Over-Producing Mutant of Tomato (&amp;lt;i&amp;gt;Solanum lycopersicum&amp;lt;/i&amp;gt;), Epinastic, Exhibits Tolerance to High Temperature Conditions

Above-optimal temperatures reduce yield in many crops, including tomato, largely because of the heat-sensitivity of their reproduction process. A full understanding of heat-stress (HS) response and thermotolerance of tomato reproduction is still lacking. Recently, using external application of the plant hormone ethylene, it was demonstrated that ethylene plays a role in heat-tolerance of tomato pollen (the male reproductive cells). In order to expand our understanding on involvement of ethylene in tomato pollen thermotolerance, we analyzed the response of wild type and ethylene-related tomato mutant plants to HS, at physiological and molecular levels. We report that mild chronic HS conditions highly reduce the number of viable and germinating pollen grains as well as the production of seeded fruits in wild type tomato plants, while no significant reduction was detected/observed in pollen quality, number of seeded fruits and seeds per fruit in plants of the ethylene over-producer mutant epinastic. Our findings suggest that ethylene is involved in thermotolerance of tomato reproduction, pointing to an effect on pollen viability and germination potential, highlighting candidate genes involved in pollen response to HS (like SlHSP17, SlHSP101, SlMBF1) and suggesting directions for further studies.

Proteome analysis of rainbow trout (Oncorhynchus mykiss) liver responses to chronic heat stress using DIA/SWATH

Aquaculture of rainbow trout (Oncorhynchus mykiss) is severely hampered by high temperatures in summer, and understanding the regulatory mechanisms controlling responses to chronic heat stress may assist the development of measures to relieve heat stress. In the present study, biochemical parameters revealed a strong stress response in rainbow trout at 24 °C, including activation of stress defence and immune systems. Liver proteome analysis under heat stress (24 °C) and control (18 °C) conditions using DIA/SWATH identified precursors (90,827), peptides (67,028), proteins (6770) and protein groups (5124), among which 460 differentially abundant proteins (DAPs; q-value < 0.05, fold change >1.5), 201 and 259 were up- and down-regulated, respectively. Many were related to heat shock proteins (HSPs), metabolism and immunity. Gene Ontology (GO) analysis showed that some DAPs induced at high temperature were involved in regulating cell homeostasis, metabolism, adaptive stress and stimulation. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis identified metabolic pathways, protein processing in endoplasmic reticulum, PPAR signalling, and complement and coagulation cascades. Protein-protein interaction (PPI) network analysis indicated that HSP90b1 and C3 may cooperative to affect cell membrane integrity under heat stress. Our findings assist the development of strategies to relieve heat stress in rainbow trout.

Proteomic Analysis of the Protective Effect of Early Heat Exposure against Chronic Heat Stress in Broilers.

Simple SummaryHeat stress affects the livestock industry, especially in poultry. Screening for metabolic changes after early and chronic heat exposure in poultry would be beneficial in resolving the production issues. In this study, we identified differentially expressed proteins that affected early heat exposure during chronic heat stress. Chronic heat stress affected 277 proteins, of which 95 differed in expression by early heat exposure. Differentially expressed proteins were related to actin metabolism and also involved in carbohydrate and carbon metabolism. According to our results, early heat exposed liver of broilers activates the different physiological mechanisms for protection from later heat stress.The increasing trend of global warming has affected the livestock industry through the heat stress, especially in poultry. Therefore, a better understanding of the mechanisms of heat stress in poultry would be helpful for maintaining the poultry production. Three groups were designed to determine early heat stress effects during chronic heat stress: CC, raised at a comfortable temperature; CH, chronic heat exposure at 35 °C for 21–35 days continuously; and HH, early heat exposure at 40 °C for 24 h at 5 days old with 35 °C temperature for 21–35 days continuously. In this study, proteome analysis was carried out to identify differentially expressed proteins in the liver tissue of broilers under chronic and early heat exposure. There were eight differentially expressed proteins from early heat stress during chronic heat exposure, which were related to actin metabolism. According to KEGG (Kyoto encyclopedia of genes and genomes) analysis, the proteins involved in carbohydrate metabolism were expressed to promote the metabolism of carbohydrates under chronic heat stress. Early heat reduced the heat stress-induced expression changes of select proteins. Our study has shown that early heat exposure suggests that the liver of broilers has various physiological mechanisms for regulating homeostasis to aid heat resistance.

423 WS Young Scholar Talk MS II: Heat stress-induced deficits in growth, metabolic efficiency, and cardiovascular function coincided with chronic systemic inflammation and hypercatecholaminemia in ractopamine-supplemented feedlot lambs

Abstract Our 1st study evaluated the effects of □-adrenergic agonist (ractopamine) supplementation on growth, health, and wellbeing in heat-stressed feedlot wethers. Chronic heat stress impaired growth, metabolism, and wellbeing even when the impact of reduced feed intake was eliminated by pair-feeding. We observed systemic inflammation and hypercatecholaminemia that were likely mediators of these deficits. Moreover, ractopamine did not diminish any wellbeing indicators and improved muscle growth without worsening the effects of heat stress. Our 2nd study assessed the effects of pubertal cyclicity (weaning to 1st breeding) in cows on myoblast-mediated muscle growth, metabolism, and growth efficiency of their offspring. Maternal fertility and postnatal growth efficiency of offspring are imperative to successful beef cattle production. A maternal condition was previously identified in which cows exhibited irregular cyclicity patterns or were non-cyclic between weaning and 1st breeding. This condition is thought to be associated with high concentrations of androstenedione in their follicular fluid, which causes cows to be sub-fertile but also wean heavier calves when they do become pregnant. We hypothesized that calves from cows exhibiting irregular pubertal cyclicity would have enhanced growth efficiency compared to calves from cows with normal pubertal cyclicity. To test this hypothesis, we evaluated myoblast function, growth, and metabolism pre-weaning, as well as growth efficiency in the feedlot and carcass characteristics at harvest in calves from cows that were previously identified as having typical, start-stop, or non-cycling pubertal cyclicity patterns. Calves from irregular cycling cows had reductions in insulin sensitivity, plasma proteins and lipids paired with increased myoblast function and reduced myoblast glycolytic capacity. Data independently and combined suggest calves from cows with irregular cyclicity from weaning to 1st breeding have chronic inflammation. While the specific mechanism of inflammation is unknown, further research may allow mediators of abnormal cyclicity and offspring inflammation-induced dysfunction to be elucidated.

Cellular antioxidant mechanism of selenium-enriched yeast diets in the protection of meat quality of heat-stressed hens

The effects and mechanisms of dietary selenium-enriched yeast (SeY, at Se 0, 0.25, and 0.50 mg/kg) on breast meat quality and oxidative stability of heat-stressed laying hens were studied. Two hundred and forty healthy Jingbai cross-bred hens at late laying period were randomly assigned to 4 experimental groups: one control group reared in a controlled thermal environment, and three treatment groups reared with heat stress (HS). The birds assigned to the controlled thermal environment were fed the basal diet, and the birds in the HS groups were fed the basal diet supplemented with 0, 0.25, or 0.50 mg Se (as SeY)/kg diet for 28 days. Chronic HS decreased pH45min, increased lightness and drip loss, and impaired postmortem oxidative stability of breast muscle. The inclusion of SeY effectively reduced these stress-induced negative impacts, particularly on paleness, drip loss, and pH45min decline. The SeY significantly enhanced the cellular antioxidant defense system, suppressed the reactive oxygen species (ROS) overproduction, and mitigated the mitochondrial damage and apoptosis of stressed muscle. In conclusion, dietary modification with SeY reduced quality loss and oxidative instability of meat from heat-stressed hens by maintaining a balanced mitochondrial redox status and inhibiting ROS induced myocyte apoptosis.

Heat Stress Increases In Vitro Hindgut Fermentation of Distinct Substrates in Iberian Pigs.

Simple SummaryHeat stress is a major concern in pig production in summer, as pigs have a limited number of functional sweat glands to transfer body heat. Above 25 °C pigs are out of their comfort zone and mechanisms such as decreasing feed intake or diverting blood from the internal organs to the skin are triggered. Intestinal microbiota is also affected by high ambient temperature but the consequences on fermentation capacity are poorly known. Short-chain fatty acids are the end-products of bacterial metabolism of carbohydrates and protein mainly in the hindgut and, in addition to being a source of energy, they have beneficial effects on immune status and health. An understanding of the effects of heat stress on intestinal fermentation could help to develop strategies mitigating intestinal disorders. We used an in vitro method to assess gas and short-chain fatty acid production, utilizing as inoculum feces from Iberian pigs fed a commercial diet for 28 days under neutral (20 °C) or heat stress (30 °C) conditions. Four substrates with dissimilar fermentation characteristics were incubated in vitro with fecal inoculum for 24 h. Chronic heat stress increased in vitro production of short-chain fatty acids, suggesting a modification of intestinal microbiota activity.Heat stress reduces the feed intake and growth of pigs. We hypothesized that heat stress affects the intestinal fermentation capacity of pigs. Sixteen Iberian pigs (44 ± 1.0 kg) were randomly assigned to one of two treatments (eight pigs/treatment) for 4 weeks—heat stress (HS; 30 °C) ad libitum or thermoneutral (TN; 20 °C) pair feeding. Frozen rectum contents were used as inocula for 24 h in vitro incubations in which a mixture of starches, citrus pectin, inulin from chicory, and cellulose were the substrates. Cellulose was poorly degraded, whereas pectin and the mixture of starches were the most fermentable substrates according to total short-chain fatty acid (SCFA) production. The mixture of starches and inulin produced the greatest amount of gas. For all substrates, heat stress enhanced gas production (8%, p = 0.001), total SCFA production (16%, p = 0.001), and the production of acetate and propionate (12% and 42%, respectively; p = 0.001). The increased isoacid production (33%, p = 0.001) and ammonia concentration (12%, p = 0.001) may indicate protein fermentation under heat stress. In conclusion, the in vitro intestinal fermentation capacity of pigs under heat stress was increased compared to thermoneutral conditions, which may indicate an adaptive response to heat stress.

Chronic heat stress regulates the relation between heat shock protein and immunity in broiler small intestine

Chronic heat stress is considered to decrease the immune functions which makes negative effect on broiler growth performance. Here, we investigated the relationship between chronic heat stress, growth performance, and immunity in the small intestine of broilers. The study included two groups (control and heat stressed group) with eight replications per group. Ten broilers of 20-day aged were allocated in each replication. On day 35, the treatment group was subdivided into two groups based on their body weights (heavy and low body weight). Although, there was only the control and treatment group on day 28. The growth performance decreased and expression of heat shock protein 70 (HSP70), HSP60, and HSP47 increased on days 28 and 35 in the chronic heat stress group as compared with those in the control group. The expression levels of HSPs were significantly higher in the low body weight group than in the control group. The genes HSP70 and HSP60 were significantly associated with pro- and anti-inflammatory cytokines in the small intestine of the broilers of the treatment group. Thus, HSP70 and HSP60 activated the adaptive immunity in the small intestines of the broilers from the treatment group to allow adaptation to chronic heat stress environment.

Effect of quercetin (flavonoid) supplementation on growth performance, meat stability, and immunological response in broiler chickens

This study was conducted to determine the effect of quercetin supplementation on growth performance, meat stability, excreta gas emission, and immunological response in broiler chickens. A total of 640 broiler chickens were randomly assigned to 1 of the 4 treatments (10 replicates per treatment with 18 chickens per pen). Dietary treatments: basal diet contained 0, 250, 500, and 1,000 mg quercetin/kg. The chronic heat stress condition was maintained (32 °C) for 24 h from the fourth day of the study. Growth performance was assessed on d 0, 7, 21, and 35, whereas all other response criteria were determined on d 35. Overall, a quadratic effect of quercetin supplementation on body weight gain (BWG) was observed when quercetin supplementation was increased (P < 0.05). And these responses were maximized in the broiler chickens fed diet with 250 mg quercetin/kg. There was a linear and quadratic effect of quercetin supplementation on Lactobacillus counts (P < 0.05). As the dietary supplementation of quercetin increased, the content of total superoxide dismutase (T-SOD) and total antioxidant capacity (T-AOC) linearly increased (P < 0.05), while the malondialdehyde (MDA) concentration linearly reduced in breast muscle (P < 0.05). There was a linear decrease in abdominal fat content when quercetin supplementation was increased (P < 0.05). The concentration of tumor necrosis factor-α (TNF-α) linearly increased by adding an increasing dosage of quercetin in the diet (P < 0.05). In conclusion, the addition of quercetin in the diet could improve BWG which reflected a beneficial effect of quercetin for growth performance. Increasing dose range from 0 to 1,000 mg quercetin/kg could linearly increase the content of T-AOC and T-SOD, and reduce the concentration of MDA, which reflected that the increased quercetin supplementation can enhance meat stability. Furthermore, supplementation of quercetin could increase the level of TNF-α, which indicated the ability of quercetin to enhance the immune capacity of broiler chickens.

Wet bulb globe temperatures and risk of acute kidney injury among Central American workers

Background/Aim: There is an epidemic in Central America of chronic kidney disease of unknown etiology (CKDu), also referred to as Mesoamerican Nephropathy (MeN). MeN prevalence is high among agricultural workers and other occupations involving physical labor in hot working environments, such as brickmaking. Chronic heat stress and volume depletion are hypothesized to be important risk factors. Methods: The MesoAmerican Nephropathy Occupational Study (MANOS) is a prospective cohort study of 569 Salvadoran and Nicaraguan workers designed to investigate environmental and occupational risk factors for MeN. MANOS participants represent five industries: sugarcane, corn, plantain, brick manufacturing, and construction. At baseline, workers were monitored for three consecutive work days. Wet bulb globe temperature (WBGT) was collected every minute during these work shifts using wet bulb globe thermometers. Participants provided serum samples pre- and post-shift on the third day of baseline monitoring. Results: At baseline, the mean estimated glomerular filtration rate (eGFR) of MANOS participants was 106.7 mL/min/1.73 m2. Fifty three (9.3%) had an eGFR &lt; 60 mL/min/1.73 m2. Fourteen participants met serum creatinine-based criteria for cross-shift acute kidney injury (AKI) during baseline monitoring. The mean percent increase in serum creatinine across work shifts was 5.3%. In El Salvador, WBGT was measured on forty-six separate days of workplace monitoring. On these days, an average of 54.7% of the work shift temperatures monitored after 6am were above 28°C, the American Conference of Governmental Industrial Hygienists Threshold Limit Value for moderate work at a continuous work rate. In unadjusted analyses, mean WBGT temperature on the third day of monitoring was positively associated with percent increase in serum creatinine (1.3% increase per 1°C) among Salvadoran workers. Conclusions: MANOS participants experience workplace temperatures that regularly exceed health-protective guidelines. Exposures to these high temperatures may increase the risk of AKI among these workers.

Immediate and transgenerational effects of thymol supplementation, inactivated Salmonella and chronic heat stress on representative immune variables of Japanese quail

Environmental challenges are integrated in the inmunoneuroendocrine interplay, impacting the immune system of the challenged individuals, and potentially implying transgenerational effects on their offspring. This study addressed whether dietary supplementation with thymol can modulate the immune response of adult Japanese quail when simultaneously exposed to an inoculum of inactivated Salmonella Enteritidis and a chronic heat stress (CHS). We also evaluated whether the experienced situations by adults can affect the immune response of their undisturbed offspring. In the parental generation, supplemented quail exposed to CHS had a higher inflammatory response and similar values of the heterophil/lymphocyte (H/L) ratio than those that were not supplemented. In their offspring, those chicks whose parents were exposed to CHS showed higher inflammatory response and lower antibody production. Regarding the H/L ratio, chicks whose parents were supplemented showed lower H/L ratio values. Dietary supplementation with thymol partially and positively modulated the inflammatory response and avoided H/L ratio alteration in the parental generation exposed to high environmental temperatures, suggesting these adults were better at dealing with the challenge. The lower H/L ratio values in the offspring suggests that chicks are more capable to deal with potential stressful situations associated with conventional breeding conditions.