Heat-stressed Broiler Chickens Research Articles

Protective Effects of 1,8-Cineole Microcapsules Against Inflammation and Gut Microbiota Imbalance Associated Weight Loss Induced by Heat Stress in Broiler Chicken.

Intestinal microbiota dysregulation is considered the primary trigger of low-grade inflammation responsible for weight loss due to heat stress. 1,8-Cineole is the major bacteriostatic agent in eucalypt and possesses remarkable anti-inflammatory properties. However, the mechanisms of its effect on intestinal microbiota remain unclear. In this study, 1,8-cineole was prepared into microcapsules prior to use as feed supplement in chickens. The microencapsulation efficiency and chemical stability of 1,8-cineole microcapsules were evaluated. The chicken treatment with 1,8-cineole microcapsules (1 or 3%) for 45 days, in the presence or absence of heat stress for fifteen days, commenced on Day 31, with or without an antibiotics mix (Abx) for three days on Day 27. Performance parameters were measured once a week from Day 30 through Day 45. Surface and entrapped concentration of 1,8-cineole was estimated as 7.89 g/100 g powder in the microcapsules. The time to maximal concentration (Tmax), terminal half-life (T1/2), and the area under plasma concentration-time curve (AUC0-t) of the encapsulated 1,8-cineole were higher than those of the nonencapsulated in treated chickens, although the maximal concentrations (Cmax) were similar. Chickens treated under higher temperatures with 1,8-cineole microcapsules exhibited lower levels of grade inflammation and higher body weight gain. Dietary 1,8-cineole microcapsules recovered the normal structure of upper ileum and altered the ratio of gut microbiota under heat stress and increased the ratio of Lactobacillus and Escherichia, whereas the proportion of Salmonella decreased based on 16S rRNA analysis of the upper ileum microbiota. In vitro, 1,8-cineole effectively inhibited the growth of Salmonella as demonstrated by inhibition zone assay. In summary, our findings elucidated the interaction between 1,8-cineole and intestinal microbiota as a new mechanism for the anti-heat stress effect of 1,8-cineole in preventing low-grade inflammation and weight loss. The results suggest that 1,8-cineole microcapsules may be a good feed supplement to protect against heat stress injury.

Effect of replacement different methionine levels and sources with betaine on blood metabolites, breast muscle morphology and immune response in heat-stressed broiler chickens

This study was performed to evaluate the effect of replacement different methionine (Met) levels and sources (DL or L) with betaine on blood metabolites, breast muscle morphology and immune response in heat-stressed broiler chickens. A total of 1200 unsexed day-old Ross-308 chicks were raised under the same condition in the first 10 days and then reared under normal or subnormal (32 °C) ambient temperatures for the 11 to 42 days of age. The experiment was designed as a split-plot factorial arrangement with 2 (temperatures) × 2 (Met sources) × 3 (Met levels) × 2 (betaine amounts). Met level in the basal diet was 30% lower than recommendation (Low-Met) and was increased to recommendation (Rec-Met) or 30% more than it (High-Met) by supplemental DL- or L-Met. Betaine was or was not substituted at the rate of 30% of the supplemental DL- or L-Met. From 11 to 24 d of age, broilers fed high-met diets showed better FCR than those received Low- and Rec-Met diet. High-Met diet under heat stress (HS) showed highest plasma uric acid and homocysteine concentration than two other diets, under normal or HS condition. Replacing 30% of the supplemental Met with betaine showed lower plasma homocysteine concentration compared to non-supplemented betaine diets. Birds fed Low- and Rec-Met diets under normal condition showed a significant decrease in heterophil/lymphocyte ratio compared to their counterparts under HS. Birds fed L-Met supplemented diet showed a greater myofibers diameter than birds fed DL-Met diet. In general, High-Met diet decreased heterophil/lymphocyte ratio and FCR of broilers. A total of 30% of dietary supplemental Met can be replaced by betaine. Highlights Heat stress increase methionine requirements of broiler chickens. L-methionine increases breast yield in compare with DL-methionine. Betaine in animal feed can be replaced by methionine without adverse effect on broiler chickens.

Effects of replacement different levels and sources of methionine with betaine on jejunal morphology, duodenal mitochondrial respiration, and lipid peroxidation in heat-stressed broiler chickens

This study aimed to investigate the effects of replacement different levels and sources of methionine (Met) with betaine on jejunal morphology, duodenal mitochondrial respiration, and lipid peroxidation in heat-stressed broiler chickens. A total of 1,200 one-day-old Ross 308 broilers were randomly assigned to two similar poultry houses. The experiment was designed as a 2 (ambient temperatures) × 2 (Met sources) × 3 (Met levels) × 2 (betaine amounts) split-plot factorial arrangement. Basal diets (Low-Met) were formulated with DL-or L-Met to meet Ross 308 nutrient recommendations except for Met which was 30% lower than the recommendation. Met level in basal diets was increased to the recommendation and/or 30% more than recommendation (High-Met) by supplemental DL-or L-Met. Betaine was or was not partially substituted at a 30% equivalent level of supplemental DL- or L-Met. HS was induced by increasing ambient temperature to 32 °C for 6 h daily in one house from 10 to 42 d. The highest feed conversion ratio (FCR) was observed in Low-Met diets. Low-L-Met diets showed greatest FCR than Low-DL-Met diets groups. Breast muscle malondialdehyde (MDA) concentration was decreased by increasing dietary Met level under HS. Duodenal MDA concentration and complex (Cox) III activity was lower and higher in L-Met diets than DL-Met diets, respectively. Cox II activity was increased in High-Met diets, and also was improved by betaine replacement. Villus height (VH) and Villus surface (VS) was increased in L-Met diets compared to DL-Met diets. Generally, L-Met was more effective than DL-Met in jejunal morphology, reducing duodenal MDA, and increasing Cox III activity. Betaine had the potential to be a partial replacement for Met. HIGHLIGHTS L-Met was more efficient than DL-Met in duodenal malondialdehyde concentration and complex III activity. Heat stress reduced the growth performance of broilers through its negative effects on intestinal development and duodenal activity of respiratory chain complexes. Betaine could have a protective effect on mitochondrial function in the tissues of broiler chickens.

Cloacal temperature responses of broiler chickens administered with fisetin and probiotic (Saccharomyces cerevisiae) and exposed to heat stress

Abstract There is dearth information on the role of fisetin as an antistress agent in ameliorating heat stress in broiler chickens. Here, we experimentally compared probiotic, an antioxidant and antistress agent, with fisetin, an antioxidant agent with little or no report on its antistress effect. Sixty-day-old broiler chickens (Arbo Acre breed) were allotted into 4 groups of 15 birds each as follows; control, fisetin, probiotic, and fisetin + probiotic groups, respectively. All administrations were performed orally through gavage for the treatment groups. The environmental and cloacal temperature (CT) parameters were measured bi-hourly at Days 21, 28, and 35 from 7:00 to 7:00 hr, during the period of study. The environmental parameters exceeded the thermoneutral zone for broiler chickens. The probiotic-supplemented group had the least overall mean CT values all through the experimental period. Based on our findings, fisetin was not a potent antistress agent in mitigating heat stress in birds.

Effect of dietary ascorbic acid supplementation on performance, behaviour and gene expression in heat-stressed broiler chickens

Effect of dietary ascorbic acid supplementation on performance, behaviour and gene expression in heat-stressed broiler chickens

Impact of both early-age acclimation and linseed dietary inclusion on fat deposition and fatty acids' meat traits in heat-stressed broiler chickens.

Objective:The purpose of this work was to investigate the combination of early-age acclimation and linseed dietary inclusion in enriching polyunsaturated fatty acids (PUFAs) in broilers’ meat as a strategy to mitigate heat stress.Materials and Methods:A total of 400 broiler chicks were assigned to four experimental groups with four duplicates (25 animals each): C: control (basal diet), AC: early-age acclimated (basal diet), Cl: fed 5% ground linseed, and Acl: early-age acclimated and fed 5% ground linseed. The lipid and fatty acid contents of different parts (breast, thigh, liver, subcutaneous, and abdominal fat) of broilers were determined.Results:Low levels of lipids and unsaturated fatty acids have been found in the meat of acclimated broilers. Higher levels of linolenic acids were noted in Cl thigh meat compared to C (6% vs. 2.68%, respectively). The results showed that oleic and linoleic acids constitute a large part of the PUFAs of different meats. The most elevated levels of monounsaturated fatty acids were recorded in the breast meat of AcL animals. The highest content of omega-3 was recorded in the liver of AcL animals compared to that of C (14.98% vs. 7.8%, respectively). Conclusion:We suggest that the combination of treatments during hot conditions has led to the reversion of the environment-affected variables to accepted values, and yields better thermoresistance, PUFA-enriched meat, and safeguard animal health which conferred to birds’ better solutions to reduce fatigue and hypoxic activities, which induces a considerable consumption of oxygen.

Effect of dietary saffron (Crocus sativus) petal extract on growth performance, blood biochemical indices, antioxidant balance, and immune responses of broiler chickens reared under heat stress conditions

To evaluate the alleviative effects of saffron (Crocus sativus) petal extract (SPE) on growth performance, blood biochemical indices, antioxidant status, and immunity of heat-stressed broilers, 250 newly hatched male broiler chickens were randomly allocated to control diet (basal diet, two groups), or control diet supplemented with 300, 500, or 700 mg SPE/kg diet, with five replicates and 10 birds each. The broiler chickens, except one of the control groups, were exposed to heat stress (HS, 37 ± 1 °C, 55% relative humidity) for 6 h/day from day 25 to 42. Heat stress reduced body weight gain (BWG), feed intake (FI), and abdominal fat percentage, and increased feed conversion ratio (FCR, p < .05). It also caused decreases in the antibody production against sheep red blood cells (SRBC) and Newcastle disease virus (NDV) and an increase in the heterophil: lymphocyte (H: L) ratio. However, SPE linearly increased the FI during the entire experimental period (p = .024) and linearly improved the BWG and FCR during the finisher and entire experimental periods (p < .05). The abdominal fat percentage decreased linearly with increasing dietary SPE levels (p < .005). Dietary SPE also caused significant reductions in the plasma concentration of cholesterol (L, p < .001), uric acid (L, p < .001), and MDA (L, p < .001; Q, p < .001) and enzyme activity of LDH (L, p = .002; Q, p = .015) and AST (L, p = .002; Q, p = .019), whereas enhanced the total protein concentration (L, p = .006), SOD and GPx (L, p < .001; Q, p = .028) activities, and TAC content (L, p < .001). Meanwhile, supplementation with dietary SPE enhanced the bursa percentage (p = .05) and improved the primary and secondary antibody production titres against SRBC and antibody response to NDV at 24 and 24 days (p < .01). The results indicate that SPE is an effective additive for broiler chickens under heat stress conditions. According to estimates of regression models, the optimum amount of extract recommended is 689.5 mg/kg. HIGHLIGHTS Saffron petal extract (SPE) enhanced the growth performance of heat-stressed broiler chickens. Dietary SPE improved the liver function in broilers reared in heat stress conditions. Supplementation of SPE improved the antioxidant status and immune responses in heat-stressed broiler chickens.

Mitigation of Heat Stress in Broiler Chickens with Heat Shock Protein 70 Gene Expression as its Indicator

&lt;p class="awabstrak2"&gt;&lt;span lang="EN-US"&gt;Heat stress is an important issue in broiler chicken farms in tropical countries, such as Indonesia. Heat stress is very detrimental to broiler chickens because reducing production performance, health, and causing mortality. In the condition of heat stress, broilers synthesize Heat Shock Protein (HSP) quickly as the body's response to heat stress. HSP 70 is the most studied HSP group related to heat stress. The objective of this study was to review the nutritional approach that has been done to mitigate heat stress in broiler chickens with the HSP70 gene expression as its indicator. Based on some studies, nutritional approaches that can be taken are through the management of feed availability, supplementation of vitamin C, vitamin E, plant bioactives, amino acids (taurine and glutamine), probiotics, prebiotics, synbiotics, manan oligo saccharide (MOS) and minerals (selenium, zinc, manganese, chromium). By these approaches, HSP70 gene expression decreased indicating that the heat stress level of broiler chicken also reduced. It can be concluded that the nutritional approach can be used as a method for heat stress mitigation in broilers with the HSP70 gene expression indicator. &lt;/span&gt;&lt;/p&gt;

Ameliorative effects of Citrullus lanatus (watermelon) juice on survival, performance and lipid peroxidation status of heat-stressed broiler chickens

Heat stress is highly detrimental to the wellbeing of broiler chickens especially at the finisher stage (4-8 weeks) of production. Ameliorative effects of watermelon juice (WJ) supplement were investigated over three weeks period to monitor survival, performance and lipid peroxidation of finisher broiler chickens raised during hot season. Proximate and phytochemical analyses of the WJ were conducted. Then, one hundred five-week-old broiler chickens of 0.9kg average body weight were allotted into 4 groups- (Control, Test 1, Test 2 and Reference) each in 3 replicates in a completely randomised design. The control group received non-supplemented water, the test groups (T1 and T2) received 20% and 40% WJ respectively, and the reference group (RG) received 200mg of ascorbic acid (AA) /litre of water. Data were analysed using one way ANOVA. The results showed that relatively high survival rates were recorded in the test (T1: 84.0%, T2:100.0%) and reference (RG: 80.0%) groups compared to the control group (CG: 36.0%). Feed intake and weight gain improved significantly (p&lt;0.05) in all the supplemented groups. The best ameliorative effects of the WJ on weight gain (1.60kg/b), Feed Conversion Ratio (0.90), survival rate (100%) and malodialdehyde (MDA) concentration (3.25) were obtained at 40% supplementation level (T2) compared to other treatments. In conclusion, WJ effectively alleviated negative impacts of heat stress in the finisher broilers at 40% supplementation level. Its supplementation is therefore recommended for broiler chickens to minimise economic loss commonly encountered in the tropical regions where extreme ambient temperature is a major constraint to poultry production.

The Mediation of miR-34a/miR-449c for Immune Cytokines in Acute Cold/Heat-Stressed Broiler Chicken.

Simple SummaryIn the intensive and scale poultry industry, the level of heat stress (HS) directly affects the growth, development, and production performance of poultry. To alleviate the adverse effects of stress in broilers, microRNA (miRNA) was regarded as a potential regulator of immune cytokines. In this study, through the sequencing analysis of spleens after cold/heat stress, we found that 33 and 37 miRNA were differentially expressed in the heat stress group compared with the normal (NS) group and cold stress (CS) group, respectively. The differential miRNA were mainly involved in biological processes such as the cytokine–cytokine receptor interaction. To further understand the miRNA-mediated effect of heat stress on the immune level of chickens, we selected miR-34a and miR-449c as the research objects, predicted and verified that interleukin 2 (IL-2) and interleukin 12α (IL-12α) were the target genes of miR-34a and miR-449c. Coupled with the analysis of the expression of other cytokines, we found that miRNA could change the expression of immune cytokines directly or indirectly. This discovery provides a new insight into the mediation of miRNA for immune cytokines in acute cold/heat stressed broiler chicken.An increasing amount of evidence has revealed that microRNAs (miRNAs) participated in immune regulation and reaction to acute cold and heat stresses. As a new type of post-transcriptional regulatory factor, miRNA has received widespread attention; However, the specific mechanism used for this regulation still needs to be determined. In this study, thirty broilers at the same growth period were divided into three groups and treated with different temperature and humidity of CS (10–15 °C and 90% Relative Humidity (RH)), HS (39 °C and 90% RH), and NS (26 °C and 50–60% RH) respectively. After 6 h, splenic tissues were collected from all study groups. miRNA sequencing was performed to identify the differentially expressed miRNAs (DEMs) between HS, CS, and NS. We found 33, 37, and 7 DEMs in the HS-NS, HS-CS, CS-NS group. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that DEMs were significantly enriched in cytokine–cytokine receptor interaction and functioned as the cellular responders to stress. We chose two miRNA, miR-34a and miR-449c, from the same family and differential expressed in HS-CS and HS-NS group, as the research objects to predict and verify the target genes. The dual-luciferase reporter assay and quantitative real-time PCR (qRT-PCR) confirmed that two cytokines, IL-2 and IL-12α, were the direct target genes of miR-34a and miR-449c. To further understand the mediation mechanism of miRNAs in acute cold/heat-stressed broiler chicken, a splenic cytokines profile was constructed. The results showed that IL-1β was strongly related to acute heat stress in broiler chicken, and from this we predicted that the increased expression of IL-1β might promote the expression of miR-34a, inducing the upregulation of interferon-γ (INF-γ) and IL-17. Our finds have laid a theoretical foundation for the breeding of poultry resistance and alleviation of the adverse effects of stress.

Effects of zinc oxide nanoparticles on regulatory appetite and heat stress protein genes in broiler chickens subjected to heat stress.

This study was conducted to explore the effect of the zinc oxide nanoparticles (ZnONPs) supplement on the regulatory appetite and heat stress (HS) genes in broiler chickens raised under high or normal ambient temperatures. In this study, 240 one-day-old male broiler chicks (Cobb 500) were randomly assigned to 48 battery cages. From day 1, these 48 cages were randomly subjected to four different treatment strategies: Control (wherein, their basal diet included 60 mg/kg of ZnO), ZNONPs 40 (wherein basal diet included 40 mg/kg of ZnONPs), ZnONPs 60 (basal diet included 60 mg/kg of ZnONPs), and ZnONPs 100 (basal diet included 100 mg/kg of ZnONPs). Thereafter, from day 22 to 42, the chickens from each dietary treatment group were subjected to different temperature stresses either normal (23 ± 1 °C constant) or HS (34 ± 1 °C for 6 h/d), which divided them into eight different treatment groups. Our findings revealed that dietary ZnONPs altered the gene expression of cholecystokinin (ileum), heat stress proteins (HSP) 70 (jejunum and ileum), and HSP 90 (duodenum, jejunum, and ileum). The gene expression of ghrelin was affected by the interaction between the ZnONPs concentration and temperature in the duodenum and stomach. More studies are required to elucidate its complex physiological and biochemical functions of the regulation of gene expression within the intestine in heat-stressed broiler chickens.

Research Note: Responses of growth performance, immune traits, and small intestinal morphology to dietary supplementation of chromium propionate in heat-stressed broilers

This study was conducted to investigate the dose responses of growth performance, immune traits, and small intestinal morphology to dietary supplementation of chromium propionate (CrPro) in heat-stressed broilers. A total of 252 1-day-old Cobb 500 male broilers were randomly assigned to 6 treatments with 7 replicate cages of 6 birds per cage. The dietary treatments consisted of a basal diet supplemented with 0, 0.2, 0.4, 0.8, 1.6, and 3.2 mg/kg Cr in the form of CrPro. The birds had ad libitum access to feed and tap water for an experimental period of 42 D. For induction of heat stress, the house temperature was set at 35°C ± 2°C from 22 to 42 D of age. No differences were detected among treatments in growth performance during the experimental period (P > 0.05). Serum IgA concentrations were not affected by treatment (P > 0.05). However, a quadratic response was detected for serum IgG (P < 0.01) and IgM (P < 0.01) concentration as dietary Cr supplementation was increased. The highest response of IgG and IgM in serum was observed for broilers fed a diet supplemented with 0.2 mg of Cr/kg. Dietary supplementation of Cr had no impacts on villus height, crypt depth, or the ratio of villus height to crypt depth in the jejunum and ileum. A quadratic response of villus height and the ratio of villus height to crypt depth and a linear response of crypt depth to increased dietary Cr supplementation were observed in the duodenum (P < 0.01). The results indicate that CrPro supplementation could modify the intestinal morphology of the duodenum and influence serum IgG and IgM concentrations in heat-stressed broiler chickens. Based on the results of this experiment, the 0.2-mg Cr/kg diet from CrPro increases immune response and intestinal health in heat-stressed broilers.

Impact of Heat Stress on Poultry Health and Performances, and Potential Mitigation Strategies.

Simple SummaryHigh environmental temperature alters the poultry health and performances by causing heat stress. Heat stress elicits physiological, behavioral, and production changes in poultry. This review article summarizes these changes along with the strategies that have been used in the poultry industry to ameliorate the adverse effects of heat stress in poultry.Heat stress is one of the major environmental stressors in the poultry industry resulting in substantial economic loss. Heat stress causes several physiological changes, such as oxidative stress, acid-base imbalance, and suppressed immunocompetence, which leads to increased mortality and reduced feed efficiency, body weight, feed intake, and egg production, and also affects meat and egg quality. Several strategies, with a variable degree of effectiveness, have been implemented to attenuate heat stress in poultry. Nutritional strategies, such as restricting the feed, wet or dual feeding, adding fat in diets, supplementing vitamins, minerals, osmolytes, and phytochemicals, have been widely studied and found to reduce the deleterious effects of heat stress. Furthermore, the use of naked neck (Na) and frizzle (F) genes in certain breed lines have also gained massive attention in recent times. However, only a few of these strategies have been widely used in the poultry industry. Therefore, developing heat-tolerant breed lines along with proper management and nutritional approach needs to be considered for solving this problem. Thus, this review highlights the scientific evidence regarding the effects of heat stress on poultry health and performances, and potential mitigation strategies against heat stress in broiler chickens and laying hens.

Probiotic bacteria maintain normal growth mechanisms of heat stressed broiler chickens.

Probiotics have growth promoting effects even under periods of heat stress challenge. More information is needed to understand the mechanisms by which probiotics maintain the growth performance. The aim of this study was to evaluate the effect of a probiotic based on Bacillus subtilis bacteria on growth related mechanisms of broilers under heat stress conditions. Specifically, growth performance, skeletal bone characteristics, skeletal muscles size, intestinal villus-crypt structure, intestinal bacteria, growth hormone (GH), insulin-like growth factor-1 (IGF-1), cholesterol, and glucose. A total of 1200 one day old Ross 308 male broilers were randomly distributed into 4 treatments, with 12 replicates per treatment and 25 birds per replicate. A 2×2 factorial arrangement was used; the main factors were environmental temperature (thermoneutral or heat stress) and diet (control or control+B. subtilis; 3×107cfu/kg of feed). From d 22 to 35 of age, birds were either exposed to thermoneutral conditions (21°C) or chronic heat stress (30°C). During the same period, each group was divided into 2 subgroups and fed either the control diet or the B. subtilis supplemented diet. The results demonstrated that B. subtilis had positive effects (P<0.05) on the body weight gain, feed conversion ratio, villus height, crypt depth, villus surface area, absorptive epithelial cell area and viable counts of intestinal beneficial bacteria. B. subtilis increased (P<0.05) serum GH, IGF-1 and maintain normal levels of cholesterol and glucose under heat stress conditions. In addition, broilers fed B. subtilis under heat stress conditions exhibited higher (P<0.05) skeletal muscles size and improved (P<0.05) tibia traits and lower (P<0.05) abdominal fat pads deposition compared with the controls. B. subtilis had no effect on rectal temperature under thermoneutral or heat stress conditions. It is concluded that B. subtilis can be used as growth promoters in broilers, particularly during the periods of heat stress conditions.

The influence of diets with dry corn barda and intermittent feeding mode on the productive and biological traits of broiler chickens

The inclusion of dry corn barda in diets helps to solve the problem of obtaining inexpensive feed protein for broilers, but the effectiveness of its use in different doses has not been studied good enough. The use of different intermittent feeding programs, as of a intermittent feeding mode can reduce the severity of heat stress in broiler chickens. However, the optimal duration of the break in feeding broiler chickens in the hottest daytime hours is not established in detail. The purpose of the researches was to determine the effect of diets with dry corn barda and intermittent feeding mode with the addition of the complex of trace elements (chromium, zinc) and vitamins (ascorbic acid, antisterility vitamin) on the productive and biological characteristics of broiler chickens at high air temperature in the hot arid climate. The productive and biological trats of broiler chickens have been determined when using 5, 10, 15 % dry corn barda in diets. Data on the productive and biological parameters of broiler chickens of the cross Ross-308 have been obtained when using intermittent feeding mode of different duration (2, 3, 4 hours). New data have been obtained on the productive and biological parameters of broiler chickens cross Ross-308 when using additives in feed of different doses of trace elements (Cr, Zn) and vitamins (C, E). The optimal parameters of the duration of intermittent feeding mode and the dose of trace elements (Cr, Zn) and vitamins (C, E) added to the feed have been revealed. It has been found that the inclusion of dry corn barda in the diet of broiler chickens and the influence of intermittent feeding mode with the addition of the complex of trace elements (Cr, Zn) and vitamins (C, E) in the feed improves the functional state of the body and increases the productivity of broiler chickens at elevated air temperature in the hot arid climate.

Strategies to Combat Heat Stress in Broiler Chickens: Unveiling the Roles of Selenium, Vitamin E and Vitamin C

Heat stress compromises efficient poultry production by impairing growth performance and increasing mortality. Mechanisms to dissipate excess heat divert energy from efficient production. This includes increased energy expenditure for respiration, oxidative stress and micronutrient absorption. The fortification of diets with particular feed additives has been known as one of the most important approaches to minimize the negative impacts of heat stress on broiler production. In this context, the promising functional feed additives appeared to be selenium and vitamins E and C. The fortification of broiler diets with these feed additives has been proven to enhance the function of vital organs, immune system response and growth performance of broilers under heat stress. The current review highlights recent successful experiences in the alleviation of heat stress symptoms in broilers using the above-mentioned additives. Selenium and vitamins E and C enhanced production performance in broiler chickens challenged with acute heat stress. The combination of these additives, by employing multiple mechanisms and through synergistic effects, improves heat stress symptoms more efficiently than their individual forms. Emerging literature reveals that selenium and vitamins E and C are involved in close interactions to protect proteins and lipids from oxidative damage and boost immune system function.

Growth performance, carcass and blood traits, immunity, jejunal morphology and meat quality of heat-stressed broiler chickens fed urea-treated pomegranate (Punica granatum L.) peel

The aim of this study was to evaluate the effects of dietary urea-treated pomegranate (Punica granatum L.) peel (UTPP) on growth performance, carcass attributes, blood biochemical indices, immunity, intestinal morphology, and meat quality of broiler chickens subjected to heat stress. The treatment with urea increased the gross energy and crude protein contents, while decreased the ash, calcium, phosphorous, neutral detergent fiber, acid detergent fiber, extractable polyphenols, total anthocyanins, condensed tannins, and hydrolyzable polyphenols contents of pomegranate peel. A total of 200 1-day-old male broiler chickens were randomly allocated to four groups; each group had 5 floor pens with 10 birds each. The broiler chickens were fed with the basal diet containing 0, 15, 30 or 50 g UTPP / kg diet from day 1, and exposed to a cyclic high temperature (37 ± 1 °C, 55 % relative humidity) for 6 h / day from day 29–42. Dietary UTPP increased body weight gain during the starter (linear (L), P = 0.001; quadratic (Q), P < 0.001) and overall experimental (L, P = 0.019; Q, P = 0.004) periods. However, it reduced feed intake during the starter (Q, P = 0.004) and grower (L, P = 0.019; Q, P = 0.007) periods. Dietary UTPP improved the feed conversion ratio during the starter (L, P < 0.001; Q, P < 0.001), grower (L, P = 0.018), finisher (L, P = 0.004), and overall experimental (L, P = 0.001) periods. The breast yield quadratically increased as UTPP level increased (P = 0.002), while the liver (L, P = 0.002) and abdominal fat (L, P < 0.001) percentages decreased. The concentration of blood glucose (P < 0.001), high density lipoprotein (P = 0.01), and globulin (P = 0.001) linearly increased with UTPP inclusion, but the plasma albumin (L, P < 0.001), alkaline phosphatase (L, P < 0.001), alanine aminotransferase (L, P < 0.001; Q, P < 0.001), lactate dehydrogenase (L, P < 0.001), cholesterol (L, P < 0.001; Q, P < 0.001), low-density lipoprotein (L, P < 0.001; Q, P < 0.001), and malondialdehyde (L, P < 0.001) concentrations decreased at day 42. The bursa percentage increased (L, P = 0.011; Q, P = 0.006) as UTPP level increased. Dietary UTPP also improved the primary total (L, P < 0.001), IgM (L, P < 0.001; Q, P = 0.003), and IgG (Q, P = 0.015) responses and the secondary total (L, P < 0.001; Q, P = 0.024) and IgG (L, P < 0.001) responses against sheep red blood cells. It increased the villus height (L, P < 0.001; Q, P = 0.003), crypt depth (L, P < 0.001; Q, P < 0.001), and villus height / crypt depth ratio (L, P < 0.001; Q, P = 0.001), while decreased the villus width (L, P < 0.001; Q, P = 0.038). Dietary UTPP improved the oxidative stability and water holding capacity of breast meat prior to and during frozen storage. Overall, based on the estimates from the regression models, UTPP (at a level of 26.1–50 g / kg) can be included as a cheap and valuable feed ingredient in heat-stressed broiler chickens diets.

Protective effects of the phytogenic feed additive “comfort” on growth performance via modulation of hypothalamic feeding- and drinking-related neuropeptides in cyclic heat-stressed broilers

Identification of alternatives to antibiotics in livestock and poultry is necessary. Fueled by consumer preferences, phytogenic feed additives are increasingly used in the food system; however, their mode of action is not well defined. Here, we used broiler chickens, in which appetite and feeding behavior regulation are controlled by complex mechanisms, to determine the effect of the phytogenic feed additive “comfort” (PFA-C) as well as its underlying molecular mechanisms on growth performance in heat-stressed broiler chickens. Heat stress significantly increased birds' core body temperature, water intake, and the hypothalamic expression of heat shock protein (HSP) 70, whereas it decreased feed intake, BW, and woody breast incidence. Phytogenic feed additive “comfort” supplementation downregulated the hypothalamic expression of HSP70, reduced core body temperature, increased feed and water intake, and improved BW in HS broilers. At molecular levels, the effect of PFA-C on growth performance seemed to be mediated by modulation of hypothalamic expression of melanocortin receptor 2, arginine vasopressin, aquaporin 2, and sodium and potassium-transporting ATPase subunit beta 1 polypeptides. In summary, PFA-C supplementation ameliorates heat stress productivity losses via a potential cytoprotective effect, reduction of hypothalamic intracellular stress, and modulation of hypothalamic feeding- and drinking-related polypeptide expression.

Splenic Gene Expression Signatures in Slow-Growing Chickens Stimulated in Ovo with Galactooligosaccharides and Challenged with Heat.

Simple SummaryThe exposure of animals to excessive heat leads to heat stress, heat stroke, or even death. The first negative effects of heat exposure occur in the gut. The elevated temperature leads to damage in intestinal walls and shifts in the composition of intestinal microbiota. In effect, the gut content (mainly intestinal microbiota and their metabolites) leaks through compromised intestinal walls into milieu of the body. Prebiotics (e.g., GOS—galactooligosaccharides) can be used to mitigate the negative effects of the heat stress in poultry. GOS that are delivered in ovo on day 12 of egg incubation stimulates the development of healthy intestinal microbiota in a chicken embryo. Healthy intestinal microbiota enhances the barrier function of the gut and the immune system. Chickens were originally domesticated in southeast Asia and are therefore genetically adapted to handle high temperatures. However, genetic selection towards performance leads to sensitization to high ambient temperature. In this paper, we studied slow-growing chickens with a reputation for heat resistance. We used in ovo stimulation with the GOS prebiotic that was delivered in ovo to promote healthy gut microbiota. In this manner, we combine genetics and environment to describe a model of heat resistance in poultry.Galactooligosaccharides (GOS) that are delivered in ovo improve intestinal microbiota composition and mitigate the negative effects of heat stress in broiler chickens. Hubbard hybrids are slow-growing chickens with a high resistance to heat. In this paper, we determined the impact of GOS delivered in ovo on slow-growing chickens that are challenged with heat. The experiment was a 2 × 2 × 2 factorial design. On day 12 of incubation, GOS (3.5 mg/egg) was delivered into the egg (n = 300). Controls (C) were mock-injected with physiological saline (n = 300). After hatching, the GOS and C groups were split into thermal groups: thermoneutral (TN) and heat stress (HS). HS (30 °C) lasted for 14 days (days 36–50 post-hatching). The spleen (n = 8) was sampled after acute (8.5 h) and chronic (14 days) HS. The gene expression of immune-related (IL-2, IL-4, IL-6, IL-10, IL-12p40, and IL-17) and stress-related genes (HSP25, HSP90AA1, BAG3, CAT, and SOD) was detected with RT-qPCR. Chronic HS up-regulated the expression of the genes: IL-10, IL-12p40, SOD (p < 0.05), and CAT (p < 0.01). GOS delivered in ovo down-regulated IL-4 (acute p < 0.001; chronic p < 0.01), IL-12p40, CAT and SOD (chronic p < 0.05). The obtained results suggest that slow-growing hybrids are resistant to acute heat and tolerant to chronic heat, which can be supported with in ovo GOS administration.

Effects of thermal manipulation of eggs on the response of jejunal mucosae to posthatch chronic heat stress in broiler chickens

In this study, the aim was to investigate effects of chronic heat stress (CHS) on the mRNA levels of proinflammatory cytokines (interleukin [IL]-6, IL-8, IL-1β, and tumor necrosis factor alpha [TNF-α]), toll-like receptors (TLR2 and TLR4), heat shock proteins (Hsp70, heat shock transcription factor [HSF]-1, and HSF3) and antioxidant enzymes (catalase, glutathione peroxidase, NADPH oxidase, and superoxide-dismutase) in the jejunal mucosae of broiler chickens subjected to thermal manipulation (TM) during embryogenesis. TM was carried out at 39°C and 65% relative humidity (RH) for 18 h daily from embryonic days 10 to 18. Control group was incubated at 37.8°C and 56% RH. CHS was induced by raising the temperature to 35°C for 7 D throughout posthatch days 28 to 35. On post-hatch-day 28 (day zero of CHS) and after 1, 3, 5, and 7 D of CHS, the jejunal mucosae were collected from both groups to evaluate the mRNA levels by real-time reverse transcription-PCR analysis. On day zero of CHS, the mRNA levels of antioxidant enzymes, TLRs, HSF3, IL-1β, and TNF-α were not significantly different between TM and control groups, while the levels of IL-6, IL-8, and HSF1 were lower and the level of Hsp70 was higher in TM. However, during CHS, the mRNA levels of antioxidant enzymes, IL-1β, TNF-α, TLR4, and HSF1 were significantly lower in TM than in controls, while the levels of TLR2 and IL-8 were significantly higher in TM than in controls. In addition, TM led to significant increase of mRNA levels of IL-6 and HSF3 after 1 D and Hsp70 after 3 D of CHS and to significant decrease of mRNA levels of IL-6 after 3 and 5 D, HSF3 after 7 D, and Hsp70 after 5 D of CHS. Results of this study suggest that TM led to altered posthatch antioxidant, immunological, and Hsp response to CHS in the jejunal mucosae of broiler chickens, probably indicating that TM may mitigate the adverse effects of CHS.