Water amino acid-chelated trace mineral supplementation decreases circulating and intestinal HSP70 and proinflammatory cytokine gene expression in heat-stressed broiler chickens

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

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

Effects of dietary tryptophan supplementation on rectal temperature, humoral immunity, and cecal microflora composition of heat-stressed broilers

This trial aimed to determine the effects of tryptophan (Trp) on the rectal temperature, hormone, humoral immunity, and cecal microflora composition in broiler chickens under heat stress (HS). One hundred and eighty 18 days-old female Arbor Acres broilers were randomly divided into three treatment groups, with six replicates of ten birds in each replicate. The broilers were either raised under thermoneutral conditions (TN, 23 ± 1°C) or subjected to heat stress (34 ± 1°C for 8 h daily). The TN group received a basal diet, and another two heat-stressed groups were fed the basal diet (HS) or the basal diet supplemented with 0.18% Trp (HS + 0.18% Trp) for 21 consecutive days. The basal diet contained 0.18% Trp. Results revealed that HS increased the rectal temperature, serum epinephrine (EPI), and corticotropin-releasing hormone (CRH) concentrations (p < 0.05), reduced the bursal index, the levels of serum immunoglobulin A (IgA), IgG, IgM, and serotonin (5-HT) as well as the relative abundance of Actinobacteria in cecum (p < 0.05) compared with the TN group. Dietary supplementation of Trp decreased the rectal temperature, serum dopamine (DA), EPI, and the levels of CRH and L-kynurenine (p < 0.05), increased the bursal index, the levels of serum IgA, IgM, and 5-HT as well as the relative abundance of Ruminococcus torques group in cecum of heat-stressed broilers (p < 0.05) compared to HS group. In conclusion, dietary Trp supplementation decreased rectal temperature, improved cecal microbiota community and Trp metabolism, and enhanced humoral immunity of heat-stressed broilers.

Growth performance and carcass characteristics of Koekoek chickens exposed to temperature variation with supplementary Coriander seed powder

The aim of the present study was to evaluate the effects of ambient temperature and coriander seeds supplementation on growth performance and carcass characteristics of Koekoek chickens. In the experiment, chickens were exposed to two temperature rooms with a heated room of 32 ± 1.2 °C from 11:00 to16:00 h and a normal room temperature with an average maximum and minimum of 23.8 ± 3 °C and 16.6 ± 1.6 °C, respectively, and a relative humidity between 34.5 ± 4 and 44.8 ± 3%. The chickens were supplemented with 0, 5, and 10 g/kg of coriander seed powder. The results showed that the group of Koekoek chickens placed in a heated room had significantly lower (P < 0.05) feed intake and weight gain and significantly higher (P < 0.05) feed conversion ratio than the groups placed at normal room temperature. Water intake was 1.8% higher in the groups placed in a heated room than those placed at normal room temperature. Supplementation with coriander seed powder enhanced growth performance and carcass traits. The carcass weight and breast percentage were higher (P < 0.05) in the groups that received 10 g/kg coriander seed powder. The growth performance of the Koekoek groups supplemented with 10 g/kg coriander seed powder in a heated room also improved significantly compared to groups in a heated room without supplementation. This suggests that the supplementation of coriander seed improves performance, and has a positive potential effect in alleviating the negative effects of heat stress on growth performance of chickens.

Impact of Phytase Supplementation on Meat Quality of Heat-Stressed Broilers

Heat stress (HS) is one of the most challenging stressors to poultry production sustainability. The adverse effects of HS range from feed intake and growth depression to alteration of meat quality and safety. As phytase supplementation is known to improve nutrient utilization and consequently growth, we undertook the present study to evaluate the effects of dietary phytase on growth and meat quality in heat-stressed broilers. A total of 720 day-old hatch Cobb 500 chicks were assigned to 24 pens within controlled environmental chambers and fed three diets: Negative Control (NC), Positive Control (PC), and NC diet supplemented with 2000 phytase units (FTU)/kg) of quantum blue (QB). On day 29, birds were exposed to two environmental conditions: thermoneutral (TN, 25 °C) or cyclic heat stress (HS, 35 °C, 8 h/d from 9 a.m. to 5 p.m.) in a 3 × 2 factorial design. Feed intake (FI), water consumption (WI), body weight (BW), and mortality were recorded. On day 42, birds were processed, carcass parts were weighed, and meat quality was assessed. Breast tissues were collected for determining the expression of target genes by real-time quantitative PCR using the 2^-ΔΔCt method. HS significantly increased core body temperature, reduced feed intake and BW, increased water intake (WI), elevated blood parameters (pH, SO₂, and iCa), and decreased blood pCO₂. HS reduced the incidence of woody breast (WB) and white striping (WS), significantly decreased drip loss, and increased both 4- and 24-h postmortem pH. Instrumental L* and b* values were reduced (p < 0.05) by the environmental temperature at both 4- and 24-h postmortem. QB supplementation reduced birds' core body temperature induced by HS and improved the FCR and water conversion ratio (WCR) by 1- and 0.5-point, respectively, compared to PC under HS. QB increased blood SO₂ and reduced the severity of WB and WS under TN conditions, but it increased it under an HS environment. The abovementioned effects were probably mediated through the modulation of monocarboxylate transporter 1, heat shock protein 70, mitogen-activated protein kinase, and/or glutathione peroxidase 1 gene expression, however, further mechanistic studies are warranted. In summary, QB supplementation improved growth performance and reduced muscle myopathy incidence under TN conditions. Under HS conditions, however, QB improved growth performance but increased the incidence of muscle myopathies. Therefore, further QB titration studies are needed.

The Interaction between Feed Bioactive Compounds and Chicken Genome

Consumer demand for high quality and safe foods that will have a positive impact on their health has increased in recent years. Today, it is possible to meet those demands by combining the genetic potential of domestic animals and applying different feeding strategies. Nutrigenomics is one of the "omics" sciences that studies the interaction between nutrients and the genome together with their influence on metabolic and physiological processes in the body. While nutrition of domestic animals is solely based on studying the influence of nutrients on animal health and production traits, nutrigenomics integrates the fields of nutrition, genomics, molecular genetics and bioinformatics. By understanding the molecular relationships between different forms and/or concentrations of nutrients in feed and genes, it is possible to answer the question of how small changes in the diet of farm animals can produce a quality product with positive effects on human health. The aim of this article is to describe how the manipulation of adding different nutrients in the feed affects the expression of different genes in chicken and consequently alters their phenotype.

Influence of water quality and pollution on broiler's performance, vaccine and antibiotic efficiencies

Good water quality for livestock is critical for preserving animal health, ensuring the quality of animal products, supplying safe food, and increasing food production economics. Higher water levels of toxic compounds than permitted can impair meat, fat, eggs, and milk production, lower fertility, and represent public health hazards. Water picks up pollutants from its surroundings and those caused by animal and human activities. Many physicochemical parameters were used to ensure water quality, including pH, salt, taste, color, alkalinity, odor, and hardness. Water quality, directly and indirectly, impacts livestock performance and, thus, the poultry industry. Employing drinking water as a carrier of drugs still faces substantial barriers. The effectiveness of vaccinations and drugs is affected by inadequate water quality. Furthermore, contaminated water and poor nutrition negatively affect broiler chicken immunity, survival, and production. Antibiotics are widely utilized in poultry production to preserve animal health and growth. They can eliminate harmful bacteria in the gut, reduce the load on the immune system, optimize the digestive system, and boost growth performance. However, the abuse of antibiotics in animal agriculture has resulted in antibiotic-resistant infections threatening people and animals. As a result of its positive impact on the metabolome and gut microbiome, the natural antimicrobial combination could be used as an alternative; improving broiler chicken growth performance without negatively affecting the environment is currently paramount.

Effect of methionine and trace minerals (zinc, copper and manganese) supplementation on growth performance of broilers subjected to Eimeria challenge

Coccidiosis is a major intestinal challenge that causes economic loss to the broiler industry. Two battery cage studies were conducted to evaluate the effect of trace minerals, source and dose of methionine on growth performance and gut health of broilers subjected to Eimeria challenge. Experiment #1 consisted of 9 treatments of 2 × 2 × 2 factorial design + 1 arrangement with main factors of methionine (Met) sources (DL-Met vs. 2-hydroxy-4-(methylthio)-butanoic acid (HMTBa)), total sulfur amino acid (TSAA) levels (high vs. low; ±5% of recommended level), and sources of trace minerals (TM) Zn:Cu:Mn in the form Inorganic trace minerals (ITM) in sulfates (80:20:100ppm) vs. mineral methionine hydroxy-analogue bis-chelate (MMHAC, 40:10:50ppm), each with 8 pens of 10 birds. Experiment #2 consisted of 2 treatments--ITM [ZnSO4:tribasic copper chloride (TBCC):MnSO4 110:125:120ppm] and MMHAC (Zn:Cu:Mn, 40:30:40ppm), each with 36 pens of 10 birds. All birds except for treatment 9 in experiment #1 were orally gavaged with 1x, 4x and 16x recommended dose of coccidiosis vaccine on d0, d7 and d14, respectively. Data were subjected to one-way and/or three-way ANOVA, and means were separated by Fisher's protected LSD test with significance at p ≤ 0.05. In experiment #1, factorial analysis revealed the main effects of TSAA level and TM, but not Met source. High TSAA level improved body weight and cumulative feed intake at 14, 20, and 27d. MMHAC improved body weight at 14, and 27d; feed intake at 14, 20, and 27d; and cumulative FCR at 27d vs. sulfates. One-way ANOVA analysis showed that birds fed MMHAC and high levels of TSAA regardless of Met source had similar body weight as unchallenged birds on d27. In experiment #2, MMHAC improved body weight and cumulative FCR, and reduced jejunal IL-17A gene expression on d28. In summary, in broilers subjected to Eimeria challenge, supplementation of the reduced levels of bis-chelated trace minerals MMHAC improved growth performance compared to high levels of ITM (sulfates or TBCC), which might partially result from better immune response, high levels of TSAA improved growth performance, Met source had no effect. Supplementation of both bis-chelated trace minerals MMHAC and high levels of TSAA could overcome the growth performance challenge issue due to coccidiosis.

Hypocholesterolemic, Antioxidative, and Anti-Inflammatory Effects of Dietary Spirulina platensisis Supplementation on Laying Hens Exposed to Cyclic Heat Stress

This study aimed to investigate the role of dietary Spirulina platensis (SP) supplementation in relieving the negative impacts of heat stress (HS) on the productive performance, cholesterol profile, redox status, and inflammatory cytokines of laying hens. A total of 288, 45-wk-old and 1550.7 ± 2.3 g initial body weight, HY-Line W-36 laying hens were housed in two environmental-controlled compartments. Layers were allotted to eight treatments of a two × four factorial design, with six replicates containing six birds per treatment. The temperature in one of the compartments was kept at a thermoneutral condition (24 °C group), while the temperature in the other compartment was raised to a cyclic heat stress of 35 °C from 9:00 a.m. to 5.00 p.m. (35 °C group). Layers in each compartment were fed on one of four experimental diets, containing 0%, 3%, 6%, or 9% SP (SP groups). The trial continued for five weeks. As a result of this study, exposure of laying hens to cyclic HS resulted in a significant (p < 0.05) increase in the total cholesterol (CH), low-density lipoprotein-CH, liver- and egg yolk-CH, ceruloplasmin, malondialdehyde, interleukins (IL-1β and IL-6), and tumor necrosis factor-α, and a significant (p < 0.05) decrease in the high-density lipoprotein-CH, total antioxidant capacity, and reduced glutathione levels. HS negatively (p < 0.05) affected the hen−day egg production (EP, 90.5% vs. 77.0%), egg weight (EW, 61.8 g vs. 56.8 g), feed intake (FI, 111.6 g vs. 101.5 g) and feed conversion ratio (FCR, 2.00 vs. 2.37). As SP levels increased in layer diets, a linear (p < 0.05) improvement response in most of the parameters was obtained in both HS and non-HS layers, recording the best results with 9% SP (e.g., 78.8% vs. 87.6% EP, 56.7 g vs. 61.9 g EW, 103.3 g vs. 110.2 g FI, and 2.38 vs. 2.04 FCR, in 0% vs. 9% SP, respectively). When incorporating SP into the diets of HS-layers, the negative impacts of HS were remarkably relieved (p < 0.05). Therefore, diets containing 9% SP could be used as a promising approach to improve the productive and physiological performance of laying hens, particularly under heat stress conditions.

Duodenal Metabolic Profile Changes in Heat-Stressed Broilers

Simple Summary

Heat stress (HS) represents an environmental and socio-economic burden to the poultry industry worldwide. However, the underpinning mechanisms for HS responses are still not well defined. Here, we used a high-throughput analysis to determine the metabolite profiles in acute and chronic heat-stressed broilers in comparison with thermoneutral and pair-fed birds. The results showed that HS altered several duodenal metabolites in a duration-dependent manner and identified potential metabolite signatures.

Abstract

Heat stress (HS) is devastating to poultry production sustainability worldwide. In addition to its adverse effects on growth, welfare, meat quality, and mortality, HS alters the gut integrity, leading to dysbiosis and leaky gut syndrome; however, the underlying mechanisms are not fully defined. Here, we used a high-throughput mass spectrometric metabolomics approach to probe the metabolite profile in the duodenum of modern broilers exposed to acute (AHS, 2 h) or chronic cyclic (CHS, 8 h/day for 2 weeks) HS in comparison with thermoneutral (TN) and pair-fed birds. Ultra high performance liquid chromatography coupled with high resolution mass spectrometry (UHPLC–HRMS) identified a total of 178 known metabolites. The trajectory analysis of the principal component analysis (PCA) score plots (both 2D and 3D maps) showed clear separation between TN and each treated group, indicating a unique duodenal metabolite profile in HS birds. Within the HS groups, partial least squares discriminant analysis (PLS-DA) displayed different clusters when comparing metabolite profiles from AHS and CHS birds, suggesting that the metabolite signatures were also dependent on HS duration. To gain biologically related molecule networks, the above identified duodenal metabolites were mapped into the Ingenuity Pathway Analysis (IPA) knowledge-base and analyzed to outline the most enriched biological functions. Several common and specific top canonical pathways were generated. Specifically, the adenosine nucleotide degradation and dopamine degradation pathways were specific for the AHS group; however, the UDP-D-xylose and UDP-D-glucuronate biosynthesis pathways were generated only for the CHS group. The top diseases enriched by the IPA core analysis for the DA metabolites, including cancer, organismal (GI) injury, hematological, cardiovascular, developmental, hereditary, and neurological disorders, were group-specific. The top altered molecular and cellular functions were amino acid metabolism, molecular transport, small molecule biochemistry, protein synthesis, cell death and survival, and DNA damage and repair. The IPA-causal network predicted that the upstream regulators (carnitine palmitoyltransferase 1B, CPT1B; histone deacetylase 11, HDAC11; carbonic anhydrase 9, CA9; interleukin 37, IL37; glycine N-methyl transferase, GNMT; GATA4) and the downstream mediators (mitogen-activated protein kinases, MAPKs; superoxide dismutase, SOD) were altered in the HS groups. Taken together, these data showed that, independently of feed intake depression, HS induced significant changes in the duodenal metabolite profile in a duration-dependent manner and identified a potential duodenal signature for HS.

Effect of a synbiotic supplement as an antibiotic alternative on broiler skeletal, physiological, and oxidative parameters under heat stress

The aim of this study was to examine if synbiotics can function as alternatives to antibiotics in broiler production under heat stress (HS). Day-old broiler chicks (528 birds) were randomly placed in floor pens within 2 identical temperature-controlled rooms (11 birds/pen and 24 pens/room). The pens of each room were evenly divided among 3 treatments (n = 8): basal diet (CON), the basal diet mixed with 50 ppm of bacitracin methylene disalicylate (BMD) or a synbiotic (50 ppm of PoultryStar me^US, SYN). From d 15, room 2 was under thermoneutral (TN) conditions (TN-CON, TN-BMD, and TN-SYN), while HS was applied to room 1 at 32^oC for 9 hrs/d (0800 to 1700) (HS-CON, HS-BMD, and HS-SYN). Treatment effects on footpad dermatitis and gait score were measured on 5 birds/pen, and latency to lie (LTL) test was measured on 2 birds/pen at d 27 and d 41; and 1 broiler/pen was sampled on d 28 and d 42, respectively. Body, liver, and spleen weight were determined. Plasma levels of interleukins (IL), heat shock protein 70, immunoglobulin (Ig)Y, liver superoxide dismutase (SOD) and glutathione peroxidase (GPx) enzyme activities were examined. Heat stress suppressed BW and IgY concentrations on both d 28 and d 42, while suppressed plasma IL-6 concentrations, SOD activities, and LTL duration on d 28 only (P < 0.05). Among all treatments, SYN birds had the best foot and skeletal health scores on both d 27 and d 41 (P < 0.05). On d 42, SYN increased BW, and TN-SYN birds had higher relative spleen weight than both TN-BMD and TN-CON birds (P < 0.05). Antibiotic BMD increased BW (P < 0.05) but decreased SOD activities (P < 0.05) on d 42. These results indicate that the SYN supplementation decreases HS negative effect on broilers by improving BW, foot, and skeletal health, while BMD improves BW but also increases oxidative stress in broilers. The data suggest that synbiotic supplement may function as an alternative to antibiotics in broiler production during summer seasons, especially in the tropical and subtropical regions.

Heat Stress and Feed Restriction Distinctly Affect Performance, Carcass and Meat Yield, Intestinal Integrity, and Inflammatory (Chemo)Cytokines in Broiler Chickens

This study was conducted to distinguish the effects of heat stress (HS) and feed intake (FI) on broiler chicken’s physiological responses. Day-old male Cobb 500 broilers (n = 672) were allocated to three treatments: (1) control (CTL): birds raised under normal temperature (23°C) from day 29 to 42; (2) cyclic heat stress (CHS): birds exposed to high temperatures (8 h/day at 35°C; from 9:30 am to 5:30 pm) from day 29 to 42; (3) pair-fed (PF): birds raised under thermoneutral condition but fed the same amount of feed as CHS from day 29 to 42. On day 42, 15 birds/pen were processed, to measure carcass and meat yields. To measure blood parameters and gut integrity (using fluorescein isothiocyanate-dextran), on day 42, CHS birds were sampled before (Pre-CHS) and 2 h after (Post-CHS) the temperature increased. Furthermore, after sampling CTL birds, they were exposed to 2h heat and sampled (acute heat stress, AHS). Data were analyzed using one-way ANOVA (JMP Pro15) and significance between treatments identified by LSD (P < 0.05). BW and relative carcass yield were significantly higher in CTL compared to CHS and PF. Compared to CHS, PF had significantly higher BW and lower relative carcass yield. Breast yield was significantly higher for CTL and PF, while leg quarters and wings yield were significantly lower compared to CHS. Gut barrier integrity was significantly altered in Post-CHS and AHS compared to CTL. mRNA abundances of tumor necrosis factor-α, C-C motif chemokine ligand-20, heat shock protein (HSP)-27, and HSP70 were significantly higher in Post-CHS and AHS compared to CTL. AHS had significantly higher mRNA abundances of CARD domain containing (NLRC)-3 and NLRC5 inflammasomes, and lower superoxide dismutase (SOD)-1 and SOD2 abundance compared with CTL. PF had significantly higher liver weight (% BW) compared to all other groups; while abdominal fat was significantly higher in Pre-CHS compared to CTL, PF, and AHS. Together, these data indicate that the negative effects of HS are partially due to reduced FI. However, the negative effect of HS on gut integrity, average daily gain, feed conversion ratio, and meat yield are direct and independent of the reduced FI during the HS. Thus, warrant investigating the underlying mechanisms in future research.

Oral administration of L-citrulline changes the concentrations of plasma hormones and biochemical profile in heat-exposed broilers

We examined the effects of oral administration of L-citrulline (L-Cit) on plasma metabolic hormones and biochemical profile in broilers. Food intake, water intake, and body temperature were also analyzed. After dual oral administration (20 mmol/head/administration) of L-Cit, broilers were exposed to a high ambient temperature (HT; 30 ± 1°C) chamber for 120 min. Oral administration of L-Cit reduced (p < .001) rectal temperature in broilers. Food intake was increased (p < .05) by heat stress, but it was reduced (p < .05) by L-Cit. Plasma levels of 3,5,3'-triiodothyronine, which initially increased (p < .0001) due to heat stress, were reduced (p < .01) by oral administration of L-Cit. Plasma insulin levels were increased by heat exposure (p < .01) and oral L-Cit (p < .05). Heat stress caused a decline (p < .05) in plasma thyroxine. Plasma lactic acid (p < .05) and non-esterified fatty acids (p < .01) were increased in L-Cit-treated heat-exposed broilers. In conclusion, our results suggest that oral L-Cit can modulate plasma concentrations of major metabolic hormones and reduces food intake in broilers.

Spirulina platensis Inclusion Reverses Circulating Pro-inflammatory (Chemo)cytokine Profiles in Broilers Fed Low-Protein Diets

Proteins are considered the most expensive nutrients in commercial modern broiler production, and their dietary inclusion at low levels is pivotal to minimize feed costs and reduce nitrogen waste. The quest for an environmentally friendly source of proteins that favor the formulation of low protein diets without compromising broiler health, welfare, and growth performance has become a hotspot in nutrition research. Due to its high protein content, the naturally growing Spirulina microalgae is considered a promising nutrient source. The purpose of the present study was, therefore, to determine the effects of Spirulina supplementation on liver bacterial translocation, hematological profile, and circulating inflammatory and redox markers in broilers fed a low-protein diet. One-day-old Ross 708 male broilers (n = 180) were randomly assigned into one of three experimental treatments: standard diet as a control, low protein diet, and low protein diet supplemented with 100 g/kg of Spirulina. Target molecular markers were measured in the peripheral blood circulation using real-time quantitative PCR. Reducing dietary proteins increased bacterial translocation and systemic inflammation as indicated by proportions of basophils among blood leukocytes. The expression levels of circulating pro-inflammatory cytokines [interleukin (IL)-3, IL-6, IL-4, IL-18, and tumor necrosis factor-α], chemokines (CCL-20), and NOD-like receptor family pyrin domain containing 3 inflammasome were significantly upregulated in birds fed the low protein diet compared with the control. The inclusion of Spirulina reversed these effects, which indicates that Spirulina reduces systemic inflammation- and bacterial translocation-induced by a low protein diet and could be a promising alternative protein source in poultry diets.

Nutritional manipulation to combat heat stress in poultry - A comprehensive review

Global warming and climate change adversely affect livestock and poultry production sectors under tropical and subtropical conditions. Heat stress is amongst the most significant stressors influencing poultry productivity in hot climate regions, causing substantial economic losses in poultry industry. These economic losses are speculated to increase in the coming years with the rise of global temperature. Moreover, modern poultry strains are more susceptible to high ambient temperature. Heat stress has negative effects on physiological response, growth performance and laying performance, which appeared in the form of reducing feed consumption, body weight gain, egg production, feed efficiency, meat quality, egg quality and immune response. Numerous practical procedures were used to ameliorate the negative impacts of increased temperature; among them the dietary manipulation, which gains a great concern in different regions around the world. These nutritional manipulations are feed additives (natural antioxidants, minerals, electrolytes, phytobiotics, probiotics, fat, and protein), feed restriction, feed form, drinking cold water and others. However, in the large scale of poultry industry, only a few of these strategies are commonly used. The current review article deliberates the different practical applications of useful nutritional manipulations to mitigate the heat load in poultry. The documented information will be useful to poultry producers to improve the general health status and productivity of heat-stressed birds via enhancing stress tolerance, oxidative status and immune response, and thereby provide recommendations to minimize production losses due to heat stress in particular under the growing global warming crisis.

Protective effects of dietary betaine on intestinal barrier function and cecal microbial community in indigenous broiler chickens exposed to high temperature environment

High temperature environment causes reduction in productivity in broilers by disrupting the intestinal barrier function. This study aimed to investigate the protective effects of dietary betaine on intestinal barrier function and cecal microbial community in indigenous broilers (Huaixiang chickens) exposed to high temperature environment. A total of 144 5-week-old male broilers (average initial body weight of 401.62 ± 9.51 g) were randomly allocated to three treatments for 10 weeks feeding trial; each treatment contained six replicates with eight birds per replicate. The three treatments included normal temperature control group (NT, fed basal diet, 26 ± 1 °C), high temperature control group (HT, fed basal diet, 32 ± 1 °C for 8 h/day), and HT group supplemented 1000 mg/kg betaine (HTB). The results showed that high temperature environment reduced the Occludin, Claudin-4, and ZO-1 expressions in duodenal mucosa (P < 0.05). Dietary betaine improved the Claudin-4 and ZO-1 expressions of duodenal mucosa (P < 0.05). In jejunal mucosa, HT group had lower Occludin, Claudin-1, Claudin-4, and ZO-1 expressions than NT group (P < 0.05). Compared with HT group, HTB group had higher Occludin and ZO-1 expression (P < 0.05). In ileal mucosa, the relative mRNA expression of ZO-1 in HT group was lower than those in NT group (P < 0.01), and dietary betaine (HTB group) improved ZO-1 expression compared with HT group (P < 0.05). Based on the results of 16S rRNA sequencing, the enriched and dominant microbials in NT group are Epsilonbacteraeota, Bacteroidetes, and Gammaproteobacterial, the enriched and dominant microbial in HT group is Muribaculaceae, and Firmicutes is the enriched and dominant microbial in HTB group. Taken together, the findings revealed that dietary betaine improved the intestinal barrier function and cecal microbial community in indigenous broilers under high ambient temperature.

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

Lipid metabolism in avian species places unique demands on the liver in comparison to most mammals. The avian liver synthesizes the vast majority of fatty acids that provide energy and support cell membrane synthesis throughout the bird. Egg production intensifies demands to the liver as hepatic lipids are needed to create the yolk. The enzymatic reactions that underlie de novo lipogenesis are energetically demanding and require a precise balance of vitamins and cofactors to proceed efficiently. External stressors such as overnutrition or nutrient deficiency can disrupt this balance and compromise the liver’s ability to support metabolic needs. Heat stress is an increasingly prevalent environmental factor that impairs lipid metabolism in the avian liver. The effects of heat stress-induced oxidative stress on hepatic lipid metabolism are of particular concern in modern commercial chickens due to the threat to global poultry production. Chickens are highly vulnerable to heat stress because of their limited capacity to dissipate heat, high metabolic activity, high internal body temperature, and narrow zone of thermal tolerance. Modern lines of both broiler (meat-type) and layer (egg-type) chickens are especially sensitive to heat stress because of the high rates of mitochondrial metabolism. While this oxidative metabolism supports growth and egg production, it also yields oxidative stress that can damage mitochondria, cellular membranes and proteins, making the birds more vulnerable to other stressors in the environment. Studies to date indicate that oxidative and heat stress interact to disrupt hepatic lipid metabolism and compromise performance and well-being in both broilers and layers. The purpose of this review is to summarize the impact of heat stress-induced oxidative stress on lipid metabolism in the avian liver. Recent advances that shed light on molecular mechanisms and potential nutritional/managerial strategies to counteract the negative effects of heat stress-induced oxidative stress to the avian liver are also integrated.

Nutritional significance of amino acids, vitamins and minerals as nutraceuticals in poultry production and health - a comprehensive review

Nutraceuticals have gained immense importance in poultry science recently considering the nutritional and beneficial health effects of their constituents. Besides providing nutritional requirements to birds, nutraceuticals have beneficial pharmacological effects, for example, they help in establishing normal physiological health status, prevent diseases and thereby improve production performance. Nutraceuticals include amino acids, vitamins, minerals, enzymes, etc. which are important for preventing oxidative stress, regulating the immune response and maintaining normal physiological, biochemical and homeostatic mechanisms. Nutraceuticals help in supplying nutrients in balanced amounts for supporting the optimal growth performance in modern poultry flocks, and as a dietary supplement can reduce the use of antibiotics. The application of antibiotic growth enhancers in poultry leads to the propagation of antibiotic-resistant microbes and drug residues; therefore, they have been restricted in many countries. Thus, there is a demand for natural feed additives that lead to the same growth enhancement without affecting the health. Nutraceuticals substances have an essential role in the development of the animals' normal physiological functions and in protecting them against infectious diseases. In this review, the uses of amino acids, vitamins and minerals as well as their mode of action in growth promotion and elevation of immune system are discussed.

Sprinkler Technology Improves Broiler Production Sustainability: From Stress Alleviation to Water Usage Conservation: A Mini Review

Global poultry production is facing several challenges including a projected increase in global demand for high quality animal proteins and the need to adapt to environmental contrasts including heat stress and the increasing pressure on natural resource (water, land, and energy) availability. Heat stress is one of the most challenging stressor to poultry production because of its strong adverse effects on welfare, production, mortality, and water usage. Most commercial poultry houses worldwide are equipped with a combination of tunnel ventilation and evaporative cooling system (pads, fogging, or low-pressure misting systems) as the status quo to overcome heat stress. Despite prior investments in these systems, critical problems continue to impede poultry production efficiency, which still declines during hot seasons. In fact, these systems tend to saturate the barn air with moisture (>70% relative humidity) which is counterproductive to the bird's own physiological ability to cool itself by hyperventilation (evaporative heat loss). The second challenge with these systems is the significant amount of water usage. This review will summarize some of the benefits of surface wetting of birds through sprinkler technology (SPRINK) that has higher efficiency to maintain birds' comfort with significantly less use of cooling water. Despite higher air temperature and lower relative humidity in the sprinkler house, the SPRINK decreased broiler body core temperature, reduced systemic and intracellular stress, preserved intracellular energy, and averaged six points better FCR compared to evaporative cooling system.