Stress In Broiler Chickens Research Articles

Curcuma and Scutellaria baicalensis extracts reduced thermoregulatory behavior in chickens subjected to moderate heat stress

Using phytogenic additives represents a new trend in the poultry feed industry because of purported beneficial impacts. There is limited information about the effects on chicken behavior, but based on new studies, some plant-based active compounds influence animal cognitive function. Therefore, the primary objective of this experiment was to investigate the impact of a feed additive consisting of a mixture of Curcuma and Scutellaria baicalensis on behaviors associated with exposure to heat stress in broiler chickens. Chickens before 21 days of age were kept in 12 littered floor boxes according to guidelines for Cobb 500 hybrid. The Cobb 500 chickens of both sexes were fed identical diets until they reached 21 days of age. From this point onward, the experimental group received in the diet a 0.1% supplement containing Curcuma and Scutellaria baicalensis extracts. The control group received a feed mixture without phytogenic additives. Both groups had six replicates, and each group comprised 75 chickens. The pens of experimental and control group were randomly selected. The experimental period spanned from 28 to 35 days of age, during which the chickens were subjected to mild constant heat stress (28°C). Ethological observations were conducted at 31, 32, and 33 days of age, divided into three observation periods at the beginning, middle, and end of the daylight period (18h) using the visual scan sampling method. After the experimental period at 35 days of age, chickens from both groups exhibited nearly identical live body weights and daily feed intake. However, the experimental group demonstrated significantly higher daily weight gain (P < 0.05). Thermoregulatory behaviors such as panting and wing spreading were suppressed (P < 0.05) in the experimental group, while there was a simultaneous increase in the number of chickens that were feeding (P < 0.05). Similarly, age significantly influenced behavioral patterns (P < 0.05), whereas time of the day only affected the number of chickens engaged in feeding (P < 0.05). In conclusion, the feed mixture enriched with Curcuma and Scutellaria baicalensis extracts exhibited performance-enhancing and behavior-changing effects, providing significant insights into the potential of this feed additive in improving performance and reducing thermoregulatory behavior manifestations within a flock under heat-stress conditions, thereby informing the poultry feed industry of a promising new development.

Evaluating the efficacy of probiotics and ascorbic acid as anti-stress agents against heat stress in broiler chickens.

Heat stress poses a substantial challenge to poultry production worldwide, highlighting the urgent need for effective management strategies. This study investigated the efficacy of probiotics (Saccharomyces cerevisiae) and ascorbic acid as antistress agents using cloacal and body surface temperatures (CT and BST) as heat stress biomarkers in broiler chickens. A total of 56 broiler chicks were used for the experiment and were divided into four distinct groups: control, probiotics (1 g/kg of feed), ascorbic acid (200 mg/kg of feed) and the combination of probiotics and ascorbic acid (1 g/kg and 200 mg/kg of feed, respectively). The study lasted 35 days; measurements were taken for ambient temperature (AT), CT, and BST. The ambient temperature in the pens consistently exceeded the thermoneutral zone (TNZ) established for broiler chickens. The CT values for broiler chickens in the probiotic group were significantly lower (p < 0.05) compared to the control group. Additionally, the BST values in the probiotic and probiotic + ascorbic acid groups were significantly lower (p < 0.05) than those in the control group. The findings suggest that incorporating probiotics, with or without ascorbic acid, can effectively reduce CT and BST values in broiler chickens thereby, enhancing thermoregulation when compared to the control group. This implies that using probiotics in poultry diets may enhance health and growth performance, potentially leading to better feed efficiency and reduced reliance on antibiotics. Implementing these dietary strategies could improve the productivity and welfare of broiler chickens in commercial settings.

Omega-3 fatty acids mitigate histological changes and modulate the expression of ACACA, PFK1 and ET-1 genes in broiler chickens under environmental stress: a pulmonary artery, cardiomyocyte and liver study

The aim of this study was to investigate the effects of omega-3 fatty acids on blood biochemical parameters, histological changes in pulmonary artery, cardiomyocytes, and liver, as well as the expression of ACACA, PFK1, and ET-1 genes in broiler chickens under environmental stress (high stoking density). A total of 420 one-day-old male Ross broilers were used in a 2 × 2 factorial arrangements, with 2 levels of environmental stress (without and with stress; 9 and 17 birds/m2, respectively) and 2 levels of omega-3 fatty acids (low and high; 0.057 and 0.5% of the diet, respectively) in a completely randomized design comprising 4 treatments and 5 replicates per each. The body weight decreased at d 40 because of environmental stress (P ≤ 0.05). The ascites heart index (AHI) in broilers fed high omega-3 fatty acids diets was lower (P = 0.062) than broiler fed low omega-3 fatty acids diet (0.279 vs. 0.316). Stressed birds showed a higher neutrophil: lymphocyte ratio compared to non-stressed birds (P ≤ 0.05). Broiler chickens receiving high omega-3 fatty acids diets exhibited elevated levels of hematocrit (HCT), hemoglobin (HGB), and lymphocytes (P ≤ 0.05). The neutrophil: lymphocyte ratio, and serum concentration of alanine aminotransferase (ALT), and aspartate aminotransferase (AST) decreased in broilers fed high omega-3 fatty acids diets (P ≤ 0.05). In stressed broilers on a high omega-3 diet, pulmonary artery wall thickness decreased (P ≤ 0.05). Additionally, under stress, myocardial cell diameter, hepatocyte and cell nucleus diameter significantly increased (P ≤ 0.05). Stressed broilers showed an increased relative fold change in PFK1 enzyme activity but reduced ET-1 mRNA expression in the liver compared to stressed birds on a high omega-3 diet (P ≤0.05). In conclusion, the results indicate that dietary omega-3 fatty acids have the potential to alleviate the adverse histological changes in the pulmonary artery, cardiomyocytes, and liver, while also modulating the expression of genes ACACA, PFK1, and ET-1 that are influenced by environmental stress in broiler chickens.

The comparative effects of probiotics on growth, antioxidant indices and intestinal histomorphology of broilers under heat stress condition.

Heat stress adversely affects both the productivity and well-being of chickens. Probiotics offer beneficial impacts on the health and growth performance of broilers. The current study investigates the influence of administering of Bacillus (including B. subtilis, B. licheniformis, B. coagulans, and B. indicus) and Lactobacillus (consisting of L. acidophilus, L. plantarum, L. buchneri, and L. rhamnosus) probiotics via drinking water, either singular or combined, on various aspects including growth performance, oxidative stress markers, carcass characteristics, fecal microbial composition, intestinal structure, and intestinal pH in broilers exposed to chronic heat stress. A total of 150 one-day-old broiler chicks were divided into 5 groups: (1) NC, negative control; (2) HS, birds exposed to chronic heat stress; (3) HSpBacil, exposed to chronic heat stress and received Bacillus probiotic; (4) HSpLAB, subjected to chronic heat stress and provided with Lactobacillus probiotic; (5) HSpMix, subjected to chronic heat stress and administered a combined probiotic from Bacillus and Lactobacillus. The HS group exhibited significantly reduced levels of growth performance, carcass traits, and notably affected oxidative stress indices, as well as intestinal pH and histomorphology in the birds. Additionally, the administered probiotics led to increased weight of lymphoid organs, enhanced body weight gain, and improved intestinal histomorphology. Furthermore, the probiotics decreased malondialdehyde and increased total antioxidant capacity in broilers. In conclusion, Bacillus and Lactobacillus probiotics, as single or multi-species, particularly Lactobacillus and combined probiotic, demonstrated potential in alleviating the adverse effects of heat stress in broiler chickens. They could serve as beneficial feed additives and growth enhancers.

Mitigation of Heat Stress in Broiler Chickens during Hot Summer Seasons Through Betaine Hydrochloride Osmoprotectant Intervention

Mitigation of Heat Stress in Broiler Chickens during Hot Summer Seasons Through Betaine Hydrochloride Osmoprotectant Intervention

Oxidative stress and plasma ceramides in broiler chickens.

The selection for rapid growth in chickens has rendered meat-type (broiler) chickens susceptible to develop metabolic syndrome and thus inflammation. The sphingolipid ceramide has been linked as a marker of oxidative stress in mammals, however, the relationship between sphingolipid ceramide supply and oxidative stress in broiler chickens has not been investigated. Therefore, we employed a lipidomic approach to investigate the changes in circulating sphingolipid ceramides in context of allopurinol-induced oxidative stress in birds. Day zero hatched chicks (n = 60) were equally divided into six groups; an unsupplemented control, an allopurinol group (25mg/kg body weight), a conjugated linoleic acid (CLA) group where half of the oil used in the control diet was substituted for a CLA oil mixture, a CLA and an allopurinol group utilizing the same dose of CLA and allopurinol, a berberine (BRB) group consisting of berberine supplementation (200mg/kg feed), and a BRB and allopurinol group, utilizing the same dose of BRB and allopurinol. Conjugated linoleic acid and berberine were utilized to potentially enhance antioxidant activity and suppress the oxidative stress induced by allopurinol treatment. Body weight, plasma uric acid, nonesterified fatty acids (NEFA) and sphingolipid ceramides were quantified. Allopurinol induced an inflammatory state as measured by a significant reduction in plasma uric acid - an antioxidant in birds as well as a metabolic waste product. Results showed that both total and saturated sphingolipid ceramides declined (p < 0.05) with age in unsupplemented chicks, although plasma ceramides C16:0 and 18:0 increased in concentration over the study period. Simple total and saturated sphingolipid ceremide's were further decreased (p < 0.05) with allopurinol supplementation, however, this may be an indirect consequence of inducing an inflammatory state. Neither CLA or BRB were able to significantly attenuate the decline. The administration of allopurinol specifically targets the liver which in birds, is the primary organ for fatty acids synthesis. For this reason, sphingolipid ceramide production might have been unwittingly affected by the addition of allopurinol.

Prenatal auditory stimulation and impacts on physiological response to feed restriction in broiler chickens at market age

Feed restriction could induce physiological stress in broiler chickens, leading to welfare issues. Prenatal stimulation could improve stress-coping mechanisms in poultry. The present study aimed to elucidate the effects of subjecting developing embryos to auditory stimulation on physiological stress response to feed restriction in broiler chickens at market age. A total of 423 hatching eggs of Cobb 500 (Gallus domesticus) were subjected to the following auditory treatments: 1) no additional sound treatment other than the background sound of the incubator's compressors at 40 dB (CONTROL), 2) exposure to pre-recorded traffic noise at 90 dB (NOISE), and 3) exposure to Mozart's Sonata for Two Pianos in D Major, K 488 at 90 dB) (MUSIC). The NOISE and MUSIC treatments were for 20 min/h for 24 h (a total of 8 h/d), starting from embryonic days (ED) 12 to hatching. On d 42, an equal number of birds from each prenatal auditory stimulation (PAS) group were subjected to either ad libitum feeding (AL) or 30-h of feed restriction (FR) in a completely randomised design. The FR chickens exhibited significantly higher serum levels of corticosterone (CORT), and heat shock protein (HSP) 70 compared to those of AL. Prenatal auditory stimulation, particularly NOISE, led to lower serum levels of CORT and alpha-1-acid glycoprotein (AGP) levels compared to the CONTROL group. Additionally, NOISE significantly increased brain mRNA glucocorticoid receptor and HSP70 gene expression. The cecal population of E. coli and Lactobacillus spp. was not significantly affected by prenatal auditory stimulation. In conclusion, our findings suggest that prenatal auditory stimulation, particularly NOISE, positively impacts broiler chickens' ability to cope with feed restriction.

Effect of Moringa Oleifera Leaves Meal (MOLM) Supplement in Combating Heat Stress in Broiler Chickens Fed Maize Soya Bean Diet

Effect of Moringa Oleifera Leaves Meal (MOLM) Supplement in Combating Heat Stress in Broiler Chickens Fed Maize Soya Bean Diet

An Algoclay-Based Decontaminant Decreases Exposure to Aflatoxin B1, Ochratoxin A, and Deoxynivalenol in a Toxicokinetic Model, as well as Supports Intestinal Morphology, and Decreases Liver Oxidative Stress in Broiler Chickens Fed a Diet Naturally Contaminated with Deoxynivalenol.

The aims of this study were (i) to determine the effect of an algoclay-based decontaminant on the oral availability of three mycotoxins (deoxynivalenol; DON, ochratoxin A; OTA, and aflatoxin B1; AFB1) using an oral bolus model and (ii) to determine the effect of this decontaminant on the performance, intestinal morphology, liver oxidative stress, and metabolism, in broiler chickens fed a diet naturally contaminated with DON. In experiment 1, sixteen 27-day-old male chickens (approximately 1.6 kg body weight; BW) were fasted for 12 h and then given a bolus containing either the mycotoxins (0.5 mg DON/kg BW, 0.25 mg OTA/kg BW, and 2.0 mg AFB1/kg BW) alone (n = 8) or combined with the decontaminant (2.5 g decontaminant/kg feed; circa 240 mg/kg BW) (n = 8). Blood samples were taken between 0 h (before bolus administration) and 24 h post-administration for DON-3-sulphate, OTA, and AFB1 quantification in plasma. The algoclay decontaminant decreased the relative oral bioavailability of DON (39.9%), OTA (44.3%), and AFB1 (64.1%). In experiment 2, one-day-old male Ross broilers (n = 600) were divided into three treatments with ten replicates. Each replicate was a pen with 20 birds. The broiler chickens were fed a control diet with negligible levels of DON (0.19-0.25 mg/kg) or diets naturally contaminated with moderate levels of DON (2.60-2.91 mg/kg), either supplemented or not with an algoclay-based decontaminant (2 g/kg diet). Jejunum villus damage was observed on day 28, followed by villus shortening on d37 in broiler chickens fed the DON-contaminated diet. This negative effect was not observed when the DON-contaminated diet was supplemented with the algoclay-based decontaminant. On d37, the mRNA expression of glutathione synthetase was significantly increased in the liver of broiler chickens fed the DON-contaminated diet. However, its expression was similar to the control when the birds were fed the DON-contaminated diet supplemented with the algoclay-based decontaminant. In conclusion, the algoclay-based decontaminant reduced the systemic exposure of broiler chickens to DON, OTA, and AFB1 in a single oral bolus model. This can be attributed to the binding of the mycotoxins in the gastrointestinal tract. Moreover, dietary contamination with DON at levels between 2.69 and 2.91 mg/kg did not impair production performance but had a negative impact on broiler chicken intestinal morphology and the liver redox system. When the algoclay-based decontaminant was added to the diet, the harm caused by DON was no longer observed. This correlates with the results obtained in the toxicokinetic assay and can be attributed to a decreased absorption of DON.

Influence of Betaine Hydrochloride on Glucocorticoid-induced Stressed Broiler Chickens

Influence of Betaine Hydrochloride on Glucocorticoid-induced Stressed Broiler Chickens

Pre-hatch thermal manipulation of embryos and post-hatch baicalein supplementation mitigated heat stress in broiler chickens

BackgroundHigh environmental temperatures induce heat stress in broiler chickens, affecting their health and production performance. Several dietary, managerial, and genetics strategies have been tested with some success in mitigating heat stress (HS) in broilers. Developing novel HS mitigation strategies for sustaining broiler production is critically needed. This study investigated the effects of pre-hatch thermal manipulation (TM) and post-hatch baicalein supplementation on growth performance and health parameters in heat-stressed broilers.ResultsSix hundred fertile Cobb 500 eggs were incubated for 21 d. After candling on embryonic day (ED) 10, 238 eggs were thermally manipulated at 38.5 °C with 55% relative humidity (RH) from ED 12 to 18, then transferred to the hatcher (ED 19 to 21, standard temperature) and 236 eggs were incubated at a controlled temperature (37.5 °C) till hatch. After hatch, 180-day-old chicks from both groups were raised in 36 pens (n = 10 birds/pen, 6 replicates per treatment). The treatments were: 1) Control, 2) TM, 3) control heat stress (CHS), 4) thermal manipulation heat stress (TMHS), 5) control heat stress supplement (CHSS), and 6) thermal manipulation heat stress supplement (TMHSS). All birds were raised under the standard environment for 21 d, followed by chronic heat stress from d 22 to 35 (32–33 °C for 8 h) in the CHS, TMHS, CHSS, and TMHSS groups. A thermoneutral (22–24 °C) environment was maintained in the Control and TM groups. RH was constant (50% ± 5%) throughout the trial. All the data were analyzed using one-way ANOVA in R and GraphPad software at P < 0.05 and are presented as mean ± SEM. Heat stress significantly decreased (P < 0.05) the final body weight and ADG in CHS and TMHS groups compared to the other groups. Embryonic TM significantly increased (P < 0.05) the expression of heat shock protein-related genes (HSP70, HSP90, and HSPH1) and antioxidant-related genes (GPX1 and TXN). TMHS birds showed a significant increment (P < 0.05) in total cecal volatile fatty acid (VFA) concentration compared to the CHS birds. The cecal microbial analysis showed significant enrichment (P < 0.05) in alpha and beta diversity and Coprococcus in the TMHSS group.ConclusionsPre-hatch TM and post-hatch baicalein supplementation in heat-stressed birds mitigate the detrimental effects of heat stress on chickens' growth performance, upregulate favorable gene expression, increase VFA production, and promote gut health by increasing beneficial microbial communities.

The Immuno-Suppressive Effects of Cyclic, Environmental Heat Stress in Broiler Chickens: Local and Systemic Inflammatory Responses to an Intradermal Injection of Lipopolysaccharide.

To assess effects of environmental heat stress (HS) on the local and systemic inflammatory responses to lipopolysaccharide (LPS), broilers were reared under thermoneutral (TN) or cyclic HS conditions. Thermoneutral temperatures followed commercial production settings, with HS broilers exposed to 35 °C for 14 h/day from 4 days onward. At 37 days, HS- and TN-broilers were assigned to either LPS (100 μg/mL) or endotoxin-free phosphate-buffered saline (PBS; vehicle) treatments, eight each to HS- and TN-LPS, four each to HS- and TN-PBS. Treatments were administered by intradermal injection of growing feather (GF) pulps; 10 μL/GF; 12 GF/broiler. Blood and GF were collected before and at 6 and 24 h post-injection to assess leukocyte population changes in GF-pulps and blood, reactive oxygen species (ROS) generation and cytokine expression in GF-pulps, and plasma concentrations of alpha-1 acid glycoprotein (AGP-1). HS-LPS broilers had lower (p ≤ 0.05) infiltration of heterophils and macrophages, ROS generation, and inflammatory cytokine expression in GF-pulps, and lacked the increases in heterophil, monocyte, and plasma AGP-1 concentrations observed in TN-LPS broilers. HS-broilers had similar or greater drops in blood lymphocytes 6 h post-LPS or -PBS injection, respectively, and lower baseline levels (p ≤ 0.05) of circulating T- and B-lymphocytes than TN-broilers. Results indicated that cyclic HS reduced the local and systemic acute inflammatory responses to LPS in broilers, likely impairing their innate defense against microbial infection.

Effect of Moringa Oleifera Leaves Meal (MOLM) Supplement in Combating Heat Stress in Broiler Chickens Fed Maize Soya Bean Diet

A growth experiment was conducted for 56 days to study productive performance, carcass characteristics and some blood parameters of broiler chicks fed corn-soybean meal diets supplemented with Moringa Oleifera leaves meals (MOLM) under heat stress condition. Three hundred a day old chicks were randomly assigned to five treatments designated as T1, T2, T3, T4 and T5 supplemented with MOLM (0, 5, 7.5, 10 and 12.5%) respectively. The results did not show body weight gain, feed intake and final weight increased with increased inclusion levels of MOLM, so also was the feed conversion ratio. The cumulative feed conversion ratio was better in T2. The levels of MOLM had no significant effect on carcass relative weight, Haemoglobin (HB), white blood cells (WBC), albumin and total plasma protein increased with increasing levels of MOLM. Mortality rates decreased with increasing levels of MOLM. The best result however, was obtained in T2 (5%) inclusion level. It could be concluded that addition of Moringa Oleifera leaves improved broiler performance, physiological parameters and enhanced the ability to resist heat stress conditions of broilers fed corn-soybean meal diet

Supplementation of Amla (Emblica officinalis) Fruit Powder Modulate Growth and Reduce Heat Stress in Broiler Chickens

Heat stress is a significant environmental challenge that impairs broiler production, negatively impacting growth, feed intake, nutrient absorption, and gut ecology. Various methods exist to mitigate heat stress such as genetic and nutritional approaches, air conditioning, ventilation, and antibiotic growth promoters but they are often expensive and not always adequate. Keeping this view in mind, research has been focused on medicinal herbs which are available, cheap and safer to use. Amla fruit possesses antioxidant, antimicrobial, and anti-stress properties that could mitigate heat stress’s harmful effects on broilers. Therefore, this study was conducted to evaluate the impact of amla fruit powder on growth performance, gut microbiota and blood lipid profile of broilers under ambient temperature and heat stressed condition. A total of 126 broiler chicks were divided into two major groups, one group kept under ambient temperature and another group exposed to heat stress. Each major group was split into 3 subgroups with 3 replications having 7 chicks per replication. In case of each major groups, first sub groups were kept as a control and latter two groups were supplemented with 0.5% and 1.0% amla fruit powder, respectively. Total duration of the experiment was 35 days, where treatments were given with basal diet from 12 days. All the experiment birds were maintained with the similar management except the experimental diets. The results showed that body weight and body weight gain at the end of the experiment were higher in amla treated group than in the control group at both temperatures. Supplementation of amla fruit powder also improved feed conversion ratio (FCR) and dressing percentage than the control groups. Additionally, amla powder reduced TC, TAG and LDL levels and slightly increased HDL content. Amla fruit powder decreased pathogenic bacterial population such as Escherichia coli and Salmonella spp. concentration in the gut and increased probiotic bacterial concentration such as Lactobacillus spp. under both rearing temperatures. Taken together, it can be concluded that, amla fruit powder could be used as an alternative tool to improve broiler performance and mitigate the deleterious effects of heat stress on broiler chickens.

Optimal Supplemental Chromium Concentration for Alleviating Heat Stress in Broiler Chickens: A Meta-analysis

Optimal Supplemental Chromium Concentration for Alleviating Heat Stress in Broiler Chickens: A Meta-analysis

Effect of melatonin on oxidative stress, inflammation cytokines, biochemical parameters and growth performance in broiler chicken under induced stress by dexamethasone

ABSTRACT A multitude of stressors exists in broiler chickens including oxidative stress and inflammation response. Both oxidative stress and inflammation response can activate apoptosis. Melatonin (ML) is a potent antioxidant and inflammatory agent. This study evaluated the effect of melatonin on oxidative stress, inflammation cytokines, biochemical parameters and growth performance in broiler chicken under induced stress by dexamethasone. Three hundred 1-day old broiler chicks were randomly distributed to four treatments as follows: positive control (without DEX), negative control (NC, with DEX) and NC + 30 and 60 mg/kg ML. Melatonin supplementation at the level of 60 mg improved the growth performance, and antioxidant status of stressed birds. The DEX-induced effect on IL-6 and IL-10 was ameliorated by ML supplementation. The heterophil, and activities of AST, ALT and ALP were decreased by ML supplementation. This implies that dietary ML may be useful for ameliorating the negative effect of stress in broiler chickens.

Measuring Chronic Stress in Broiler Chickens: Effects of Environmental Complexity and Stocking Density on Immunoglobulin-A Levels

Commercial housing conditions may contribute to chronic negative stress in broiler chickens, reducing their animal welfare. The objective of this study was to determine how secretory (fecal) and plasma immunoglobulin-A (IgA) levels in fast-growing broilers respond to positive and negative housing conditions. In three replicated experiments, male Ross 708 broilers (n = 1650/experiment) were housed in a 2 × 2 factorial study of high or low environmental complexity and high or low stocking density. In experiments 1 and 3 but not in experiment 2, high complexity tended to positively impact day 48 plasma IgA concentrations. When three experiments were combined, high complexity positively impacted day 48 plasma IgA concentrations. Stocking density and the complexity × density interaction did not impact day 48 plasma IgA concentrations. Environmental complexity and the complexity × density interaction did not impact day 48 secretory IgA concentrations. A high stocking density negatively impacted day 48 secretory IgA concentrations overall but not in individual experiments. These results suggest that environmental complexity decreased chronic stress, while a high stocking density increased chronic stress. Thus, plasma IgA levels increased under high-complexity housing conditions (at day 48), and secretory IgA levels (at day 48) decreased under high-density conditions, suggesting that chronic stress differed among treatments. Therefore, these measures may be useful for quantifying chronic stress but only if the statistical power is high. Future research should replicate these findings under similar and different housing conditions to confirm the suitability of IgA as a measure of chronic stress in broiler chickens.

Pequi Oil (Caryocar brasiliense Camb.) Attenuates the Adverse Effects of Cyclical Heat Stress and Modulates the Oxidative Stress-Related Genes in Broiler Chickens.

The present study was conducted to determine the possible antioxidant protection of pequi oil (PO) against cyclic heat stress in broiler chickens and to highlight the application of PO as a promising additive in broiler feed. A total of 400 one-day-old male broiler chicks (Cobb 500) were randomly assigned to 2 × 5 factorially arranged treatments: two temperature-controlled rooms (thermoneutral-TN or heat stress-HS for 8 h/day) and five dietary PO levels (0, 1.5, 3.0, 4.5, or 6.0 g/kg diet) for 42 days. Each treatment consisted of eight replicates of five birds. The results showed that HS increased glucose (p = 0.006), triglycerides (p < 0.001), and HDL (p = 0.042) at 21 days and reduced (p = 0.005) serum total cholesterol at 42 days. The results also showed that HS increased the contents of alanine aminotransferase (ALT) and aspartate aminotransferase (AST). In contrast, PO linearly decreased AST (p = 0.048) and ALT (p = 0.020) at 21 and 42 days, respectively. The heterophil-to-lymphocyte ratio in the birds under HS was higher than in those in the TN environment (p = 0.046). Heat stress decreased (p = 0.032) the relative weight of their livers at 21 days. The superoxide dismutase activity increased (p = 0.010) in the HS treatments in comparison to the TN treatments, while the glutathione peroxidase activity in the liver decreased (p < 0.001) at 42 days; however, the activity of catalase had no significant effects. Meanwhile, increasing the dietary PO levels linearly decreased plasma malondialdehyde (p < 0.001) in the birds in the HS environment. In addition, PO reduced (p = 0.027) the expression of Hsp 70 in the liver by 92% when compared to the TN treatment without PO, mainly at the 6.0 g/kg diet level. The expression of Nrf2 was upregulated by 37% (p = 0.049) in response to PO with the 6.0 g/kg diet compared to the HS treatment without PO. In conclusion, PO supplementation alleviated the adverse effects of HS on broilers due to its antioxidant action and modulation of the genes related to oxidative stress, providing insights into its application as a potential feed additive in broiler production.

Lipopolysaccharide-induced immune stress negatively regulates broiler chicken growth via the COX-2-PGE2-EP4 signaling pathway.

Immune stress in broiler chickens is characterized by the development of persistent pro-inflammatory responses that contribute to degradation of production performance. However, the underlying mechanisms that cause growth inhibition of broilers with immune stress are not well defined. A total of 252 1-day-old Arbor Acres(AA) broilers were randomly allocated to three groups with six replicates per group and 14 broilers per replicate. The three groups comprised a saline control group, an Lipopolysaccharide (LPS) (immune stress) group, and an LPS and celecoxib group corresponding to an immune stress group treated with a selective COX-2 inhibitor. Birds in LPS group and saline group were intraperitoneally injected with the same amount of LPS or saline from 14d of age for 3 consecutive days. And birds in the LPS and celecoxib group were given a single intraperitoneal injection of celecoxib 15 min prior to LPS injection at 14 d of age. The feed intake and body weight gain of broilers were suppressed in response to immune stress induced by LPS which is an intrinsic component of the outer membrane of Gram-negative bacteria. Cyclooxygenase-2 (COX-2), a key enzyme that mediates prostaglandin synthesis, was up-regulated through MAPK-NF-κB pathways in activated microglia cells in broilers exposed to LPS. Subsequently, the binding of prostaglandin E2 (PGE2) to the EP4 receptor maintained the activation of microglia and promoted the secretion of cytokines interleukin-1β and interleukin-8, and chemokines CX3CL1 and CCL4. In addition, the expression of appetite suppressor proopiomelanocortin protein was increased and the levels of growth hormone-releasing hormone were reduced in the hypothalamus. These effects resulted in decreased expression of insulin-like growth factor in the serum of stressed broilers. In contrast, inhibition of COX-2 normalized pro-inflammatory cytokine levels and promoted the expression of Neuropeptide Y and growth hormone-releasing hormone in the hypothalamus which improved the growth performance of stressed broilers. Transcriptomic analysis of the hypothalamus of stressed broilers showed that inhibition of COX-2 activity significantly down-regulated the expression of the TLR1B, IRF7, LY96, MAP3K8, CX3CL1, and CCL4 genes in the MAPK-NF-κB signaling pathway. This study provides new evidence that immune stress mediates growth suppression in broilers by activating the COX-2-PGE2-EP4 signaling axis. Moreover, growth inhibition is reversed by inhibiting the activity of COX-2 under stressed conditions. These observations suggest new approaches for promoting the health of broiler chickens reared in intensive conditions.

Metabolic and microbiota response to arginine supplementation and cyclic heat stress in broiler chickens.

Little attention has been paid to the biological role of arginine and its dietary supplementation in broilers under heat stress (HS) conditions. Therefore, the main aim of this study was to assess the response of broilers to arginine supplementation and cyclic HS, with a focus on liver, pectoral muscle, and blood metabolic profiles and the cecal microbiota. Day-old male Ross 308 broilers (n = 240) were placed in 2 rooms with 12 pens each for a 44-day trial. Pens were assigned to one of two groups (6 pens/group/room): the control group (CON) was given a basal diet in mash form and the treated group (ARG) was fed CON diet supplemented with crystalline L-arginine. The total arginine:lysine ratio of CON diet ranged between 1.02 and 1.07, while that of ARG diet was 1.20. One room was constantly kept at thermoneutral (TN) conditions, while the birds in the other room were kept at TN conditions until D34 and subjected to cyclic HS from D35 onwards (∼34°C; 9:00 A.M.-6:00 P.M.). Blood, liver, Pectoralis major muscle, and cecal content were taken from 2 birds per pen (12 birds/group/room) for metabolomics and microbiota analysis. Growth performance data were also collected on a pen basis. Arginine supplementation failed to reduce the adverse effects of HS on growth performance. Supplemented birds showed increased levels of arginine and creatine in plasma, liver, and P. major and methionine in liver, and reduced levels of glutamine in plasma, liver, and P. major. HS altered bioenergetic processes (increased levels of AMP and reduced levels of fumarate, succinate, and UDP), protein metabolism (increased protein breakdown to supply the liver with amino acids for energy production), and promoted the accumulation of antioxidant and protective molecules (histidine-containing dipeptides, beta-alanine, and choline), especially in P. major. Arginine supplementation may have partially counterbalanced the effects of HS on energy homeostasis by increasing creatine levels and attenuating the increase in AMP levels, particularly in P. major. It also significantly reduced cecal observed diversity, while HS increased alpha diversity indices and affected beta diversity. Results of taxonomic analysis at the phylum and family level are also provided.