The probiotic Bacillus licheniformis ameliorates heat stress-induced impairment of egg production, gut morphology, and intestinal mucosal immunity in laying hens

Sex differences in intestinal morphology and increase in diencephalic neuropeptide Y gene expression in female but not male Pekin ducks exposed to chronic heat stress

The impact of heat stress (HS) on production is intricately linked with feed intake. We investigated the effects of HS on intestines and diencephalic genes in Pekin ducks. One hundred and sixty adult ducks were allocated to two treatment rooms. The control room was maintained at 22°C and the HS room at 35°C for the first 10 h of the day then reduced to 29.5°C. After 3 weeks, 10 hens and 5 drakes were euthanized from each room and jejunum and ileum collected for histology. Brains were collected for gene expression analysis using qRT-PCR. Intestinal morphology data were analyzed with two-way ANOVA and diencephalic gene data were analyzed with Kruskal-Wallis test. There was an increase in villi width in the ileum (p = .0136) and jejunum (p = .0019) of HS hens compared to controls. HS drakes showed a higher crypt depth (CD) in the jejunum (p = .0198) compared to controls. There was an increase in crypt goblet cells (GC) count in the ileum (p = .0169) of HS drakes compared to HS hens. There was higher villi GC count (p = .07) in the jejunum of HS drakes compared to controls. There was an increase in the crypt GC density (p = .0054) in the ileum, not jejunum, of HS drakes compared to HS hens. Further, there were no differences in the proopiomelanocortin gene expression in either sex but there was an increase in the expression of neuropeptide Y (NPY) gene in HS hens (p = .031) only and a decrease in the corticotropin releasing hormone gene in the HS drakes (p = .037) compared to controls. These data show that there are sex differences in the effect of HS on gut morphology while the upregulation in NPY gene may suggest a role in mediating response to chronic HS.

Phenomenological and mechanistic insights into potential dietary nucleotide - probiotic synergies in layer chickens: A review

Despite their growing popularity as alternatives to antibiotic growth promoters (AGPs), the individual effects of nucleotides and probiotics on poultry gut functionality remain poorly understood. In addition, inconsistent outcomes are quite common in studies where these two additives have been used separately to modify gut function and related parameters in birds. These inconsistencies, which have limited the potential of probiotics and nucleotides as AGP replacements, stem from various factors and need to be addressed. Combining probiotics and nucleotides could potentially enhance their effectiveness and lead to more consistent outcomes in layer chickens. Since their mechanisms of action complement each other, some level of synergy is expected when used together. Both additives have been shown to support gut health, boost immune function, and improve performance in chickens when used individually. However, no studies have investigated the possible synergistic effects of nucleotides and probiotics in poultry. This review makes the case for combined use of probiotics and nucleotides in layer chickens by providing phenomenological and mechanistic insights into hypothetical synergistic effects. This paper highlights the need for AGP alternatives and reviews studies on the effects and mechanisms of probiotics and nucleotides in layer chickens when used individually. We then propose potential mechanisms for their synergistic effects on gut health, performance, and egg quality based on logical deductions from observed biological responses. These proposed mechanisms are hypothetical and require experimental validation. Finally, the review explores how this synergy could lead to more consistent outcomes and enhance the feasibility of AGP-free egg production.

Effects of Lactiplantibacillus plantarum and Galactooligosaccharide Administered In Ovo on Hatchability, Chick Quality, Performance, Caecal Histomorphology and Meat Quality Traits of Broiler Chickens

The presented study explored the promising alternatives of in ovo injection with Lactiplantibacillus plantarum (LP) and galactooligosaccharide (GOS) in the poultry industry. The study aimed to assess the effects of probiotic and prebiotic on various aspects of poultry production. The study involved 300 Ross broiler eggs, individually candled on Day 7 of embryonic development. The eggs were sorted into four groups: negative control (no injection), positive control (0.9% physiological saline injection), GOS 3.5 mg/egg and LP 1 × 106 CFU/egg. The groups used during the incubation period were the same for the animal trial; each pen/group had 25 chickens. At the end of the experiment, 8 chickens from each group were slaughtered for tissue sample collection and 12 chickens were slaughtered to determine slaughter yield, carcass and meat quality. All data were analysed by one-way ANOVA or repeated measured ANOVA except for the parameters that did not meet the assumption of normality, the Kruskal-Wallis test (Dunn's test) was used. Key findings revealed that hatchability remained unaffected across groups, indicating the safety of the in ovo injections. Both LP and GOS enhanced chick quality, as evidenced by improved body weight, Pasgar score and chick length. The in ovo administration of LP increased the body weight of the chickens during the first-week post-hatch (7 days of age) without impacting feed intake and feed conversion ratio in the later stages. The study demonstrated no adverse effects on meat quality due to the in ovo injection of LP and GOS. Additionally, a positive impact on caecal histomorphology was observed and early gut colonization of beneficial bacteria (Lactobacillus spp. and Bifidobacteria spp.) indicated potential benefits for intestinal health in broilers. In conclusion, the in ovo inoculation of 1 × 106 LP and 3.5 mg of GOS per egg increased the relative abundance of Lactobacillus spp. and Bifidobacterium spp. and showcased promising enhancements in chick quality without compromising growth performance, meat quality and caecal histomorphology. These findings suggest a positive outlook for these substances as a viable alternative for improving poultry health and productivity.

Anti-Nutritional Factors of Plant Protein Feeds for Ruminants and Methods for Their Elimination

In recent years, the rapid development of the ruminant feeding industry and the limited availability and rising prices of traditional protein feed ingredients have renewed the focus on protein feeds in ruminant diets. Plant protein feeds are a core component of protein feeds for ruminants; however, the utilisation of both conventional and non-conventional plant protein feeds is limited by the presence of anti-nutritional factors (ANFs). In order to maximise the use of plant protein feeds and to promote their application in ruminant production, it is important to have a comprehensive understanding of the types and nature of their ANFs, their anti-nutritional mechanisms, and current effective methods of eliminating ANFs. Therefore, the types, anti-nutritional mechanisms, and elimination methods of ANFs in major plant protein feeds for ruminants are initially summarised in this review, which provides a reference for anti-nutritional factor elimination and the production of full-price compound feeds for ruminants.

Fish oil a source of omega-3 fatty acids affects hypothalamus heat resistance genes expressions and fatty acid composition in heat-stressed chicks

This study investigated the effects of fish oil (FO) supplementation on the hypothalamus heat resistance gene expressions and fatty acid composition of chicks under acute high-temperature stress, for treating Cholestasis. A total of 48 chicks (Ross 308) at age of 14 days were acclimatized to corn oil or FO (n = 24 for each) by oral gavaging for 10 days, and then subjected to heat stress (35 ± 1 °C, HT) for 3 h or maintained at the normal temperature (26 ± 1 °C, NT) as grouped as NT and FO-NT control and HT and FO-HT (n = 12 for each).. The results showed that FO supplementation had no significant (P > 0.05) effect on feed intake or body weight. The FO-HT group exhibited (P<0.05) a lower rectal temperature, and plasma interleukin-6 (IL-6), triglyceride and corticosterone levels, in accompany with lower expressions of hypothalamic adenine nucleotide translocators (ANT) and uncoupling protein (UCP) but increased (P<0.05) plasma superoxide dismutase activity and hypothalamic neuropeptide-Y (NPY) and heat shock protein-70 (HSP-70) expressions.. Additionally, the FO-HT group (P < 0.05) demonstrated a higher unsaturated fatty acid/saturated fatty acid (UFA/SFA) ratio in the breast muscle. These findings suggest that FO supplementation can enhance the heat resistance of broiler chicks under acute heat stress and alter the fatty acid composition of their breast muscle. However, further studies are needed to determine whether desirable fatty acids can cross the blood-brain barrier and their implications for human health.

Effects of β-glucan on the performance and gut integrity of broilers under acute heat stress conditions

Heat stress (HS) has negative impacts on farm animals. Many studies have been conducted to ameliorate the effects of HS in farm animals. The current project investigated the effects of β-glucan (BG) supplementation under thermo-neutral and HS conditions on the production, physiological, and histological parameters in broiler chickens. Three-hundred and twenty chicks were randomly assigned into four treatments (10 replicates/treatment; 8 chicks/replicate). The treatments were: 1) a basal diet (Ctrl); 2) a diet containing 1 g/kg of β-glucan (BG1); 3) a diet containing 2 g/kg of β-glucan (BG2); 4) a diet containing 3 g/kg of β-glucan (BG3). All treatments were reared under thermo-neutral (TN) conditions from day 0-30 days of age then exposed to cyclical HS at the age of 31 days for 3 consecutive days (4 hours/day). During HS conditions, BG3 has increased feed intake (FI; 23 %; P < 0.01), and decreased rectal temperature (Tr) relative to the control treatment (0.5 °C; P <0.01). Besides, supplementing BG has improved average daily gain under HS conditions. In addition, BG supplementation had a positive effect on intestinal morphometric parameters (villous height, width, depth, and surface area) under HS conditions. In conclusion, feeding BG improved FI, average daily gain (ADG), and intestinal health in heat-stressed broiler chickens.

Climate-smart livestock nutrition in semi-arid Southern African agricultural systems

Climate change is disrupting the semi-arid agricultural systems in Southern Africa, where livestock is crucial to food security and livelihoods. This review evaluates the bioenergetic and agroecological scope for climate-adaptive livestock nutrition in the region. An analysis of the literature on climate change implications on livestock nutrition and thermal welfare in the regional agroecological context was conducted. The information gathered was systematically synthesized into tabular summaries of the fundamentals of climate-smart bioenergetics, thermoregulation, livestock heat stress defence mechanisms, the thermo-bioactive feed components, and potentially climate-smart feed resources in the region. The analysis supports the adoption of climate-smart livestock nutrition when conceptualized as precision feeding combined with dietary strategies that enhance thermal resilience in livestock, and the adaptation of production systems to the decline in availability of conventional feedstuffs by incorporating climate-smart alternatives. The keystone potential climate-smart alternative feedstuffs are identified to be the small cereal grains, such as sorghum (Sorghum bicolor) and pearl millet (Pennisetum glaucum) as dietary energy sources, the native legumes, such as the cowpea (Vigna unguiculata) and the marama bean (Tylosema esculentum) as protein sources, wild browse Fabaceae trees such as Vachellia spp. and Colophospermum mopane, which provide dry season and drought supplementary protein, minerals, and antioxidants, the non-fabaceous tree species such as the marula tree (Sclerocarya birrea), from which animals consume the energy and electrolyte-rich fresh fruit or processed pulp. Feedstuffs for potential circular feeding systems include the oilseed cakes from the macadamia (Macadamia integrifolia) nut, the castor (Ricinus communis), and Jatropha (Jatropha curcas) beans, which are rich in protein and energy, insect feed protein and energy, primarily the black soldier fly larvae (Hermetia illucens), and microbial protein from phototrophic algae (Spirulina, Chlorella), and yeasts (Saccharomyces cerevisiae). Additives for thermo-functionally enhanced diets include synthetic and natural anti-oxidants, phytogenics, biotic agents (prebiotics, probiotics, synbiotics, postbiotics), and electrolytes. The review presents a conceptual framework for climate-smart feeding strategies that enhance system resilience across the livestock-energy-water-food nexus, to inform broader, in-depth research, promote climate-smart farm practices and support governmental policies which are tailored to the agroecology of the region.

Clinical and mechanistic insights into biomedical application of Se-enriched probiotics and biogenic selenium nanoparticles

Selenium is an essential element with various industrial and medical applications, hence the current considerable attention towards the genesis and utilization of SeNPs. SeNPs and other nanoparticles could be achieved via physical and chemical methods, but these methods would not only require expensive equipment and specific reagents but are also not always environment friendly. Biogenesis of SeNPs could therefore be considered as a less troublesome alternative, which opens an excellent window to the selenium and nanoparticles' world. bSeNPs have proved to exert higher bioavailability, lower toxicity, and broader utility as compared to their non-bio counterparts. Many researchers have reported promising features of bSeNP such as anti-oxidant and anti-inflammatory, in vitro and in vivo. Considering this, bSeNPs have been tried as effective agents for health disorders, especially as constituents of probiotics. This article briefly reviews selenium, selenium nanoparticles, Se-enriched probiotics, and bSeNPs' usage in an array of health disorders. Obviously, there are very many articles on bSeNPs, but we wanted to summarize studies on prominent bSeNPs features published in the twenty-first century. This review is hoped to give an outlook to researchers for their future investigations, ultimately serving better care of health disorders.

Heat Stress in Japanese Quails (Coturnix japonica): Benefits of Phytase Supplementation

In tropical and subtropical climate regions, heat stress is one of the main causes of production losses in laying quails, aggravated by the antinutritional effects of the phytate in diet ingredients, which negatively affect the bioavailability of minerals, especially calcium and phosphorus. This situation results in a reduction in production and the quality of eggs from commercial laying quails. Several nutritional strategies are utilized to reduce the adverse effects of high temperatures and antinutritional factors such as phytate. Among these strategies, the use of exogenous enzymes, such as phytase, stands out as a viable alternative. Phytase breaks down phytate molecules, optimizing the absorption of essential minerals and improving productive performance and egg quality under unfavorable conditions. Specifically, it is recommended to use 1500 FTU of phytase, as it not only reduces the effects of thermal stress but also enhances eggshell thickness and calcium absorption. In this context, this bibliographic review sought to produce a document demonstrating the beneficial effects of the phytase enzyme on the hydrolysis of the phytate molecule, the availability of calcium for Japanese quails (Coturnix japonica), and its implications in thermal stress due to heat.

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.

Effect of a probiotic supplement (Bacillus subtilis) on struggling behavior, immune response, and meat quality of shackled broiler chickens exposed to preslaughter stress

This study aimed to investigate the impact of a dietary probiotic supplement on struggling behavior, immune response, and meat quality of shackled broiler chickens exposed to preslaughter stress. Two hundred and ten 1-day-old male Ross 708 broiler chicks were divided among 21 floor pens (10 chicks per pen). The pens were randomly distributed to 1 of 3 dietary treatments containing a probiotic, Bacillus subtilis, at 0 (control), 0.25 (0.25×), and 0.5 (0.5×) g/kg (n = 7). At the end of the experiment (d 35), birds were transported for a journey of 80 km to the abattoir, each crate contained 5 pen mates, 2 birds of them (2 bird per crate, total 14 birds per treatment) were randomly selected for testing. Struggling behavior measurements began after the birds had arrived at the abattoir. Serum and muscle samples (right leg and breast) were collected for immune response and meat quality parameters. The results indicated that probiotic supplemented broilers had lower breast muscle protein carbonyls and serum levels of IgM but higher breast muscle total antioxidant capacity (TAC) compared to those of controls. In addition, probiotic supplemented broilers' leg and breast muscle had higher color lightness and greater water holding capacity (WHC%) with lower cooking loss (CL) and lower pH values (P < 0.05). Probiotic supplemented broilers' breast and leg meat was also tastier (P < 0.05) compared to controls. There were no treatment effects on other measured parameters including struggling behavior, serum IgA and IgG concentrations, and breast muscle malondialdehyde (MDA) (P > 0.05). These results suggest that the probiotic supplement could be an alternative management tool for promoting broiler health and welfare by modifying immune response and meat quality.

Marine red yeast supplementation improves laying performance by regulating small intestinal homeostasis in aging chickens

Recent studies have shown that age-related aging evolution is accompanied by imbalances in intestinal homeostasis. Marine red yeast (MRY) is a functional probiotic that has been shown to have antioxidant, immune and other properties. Therefore, we chose 900 healthy Hy-Line Brown hens at 433 d old as the research subjects and evaluated the correlation between intestinal health, laying performance, and egg quality in aged hens through the supplementation of MRY. These laying hens were assigned into 5 groups and received diet supplementation with 0%, 0.5%, 1.0%, 1.5%, and 2% MRY for 12 weeks. The results showed that MRY supplementation increased egg production rate, average egg weight, and egg quality, and decreased feed conversion ratio and daily feed intake (P < 0.05). The MRY supplement improved antioxidant indicators such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), stimulated villus height, and increased the villus height to crypt depth ratio (V/C ratio) in the intestine (P < 0.05). It also regulated the expression of intestinal inflammatory factors (transforming growth factor-β [TGF-β], interleukin [IL]-1β, IL-8, tumor necrosis factor-α [TNF-α]) while increasing serum immunoglobulin G (IgG) levels (P < 0.05). Furthermore, MRY supplementation upregulated the mRNA expression of tight junction proteins (occludin and zonula occludens-1 [ZO-1]), anti-apoptotic gene (Bcl-2), and autophagy-related proteins (beclin-1 and light chain 3I [LC3I]) in the intestine (P < 0.05). The MRY supplement also led to an increase in the concentration of short-chain fatty acids in the cecum, and the relative abundance of the phylum Bacteroidetes, and genera Bacteroides and Rikenellaceae_RC9_gut_group. The LEfSe analysis revealed an enrichment of Sutterella and Akkermansia muciniphila. In conclusion, the results of this experiment indicated that the additional supplementation of MRY can improve the production performance of laying hens and may contribute to the restoration and balance of intestinal homeostasis, which supports the application potential of MRY as a green and efficient feed additive for improving the laying performance in chickens.

Translucent eggs of laying hens: a review

Eggshell quality is a significant characteristic that influences consumer preferences. Eggshell translucency is a common defect in the appearance of eggshells, which are characterized by gray spots that are visible to the naked eye under natural light. The presence of various defects resulting from eggshell translucency has caused a decrease in consumer willingness to purchase eggs, leading to considerable economic losses in the egg industry. Although the impact of eggshell translucency on food safety, egg quality, and hatchability has been extensively investigated, the classification and causes of eggshell translucency remain unclear and lack a systematic summary. In recent studies, new interpretations of evaluation methods and causes of eggshell translucency have been proposed, along with numerous innovative solutions. Therefore, this paper aims to provide a comprehensive review of the evaluation methods, classification, causes, effects, and influencing factors of eggshell translucency and to summarize the treatments for translucent eggs. We believe that this review will serve as a valuable reference for researchers involved in the study of translucent eggs.

Dynamic responses of systemic immunity and splenic inflammation to long-term cyclic high-temperature exposure in growing pullets and laying hens

Two trials were conducted to draw the phase-response curve of productive and immunological variables in heat-exposed layer chickens at different ages (71 to 130 d, and 211 to 270 d). Birds were acclimated to the following conditions for 60 d: constant optimal ambient temperature at 24°C and high ambient temperature at 34°C for 8 h/d (10:00-18:00). Data collection and biochemical measurements were performed every 10 d. In both age ranges, high temperature favored the innate immunity (P < 0.01) at the cost of performance (P < 0.05) during a given period, including the relative abundance of B and T-helper lymphocytes, lymphocyte proliferation ratio (B and T lymphocytes), and serum immunoglobulin contents (IgG and IgM) in the peripheral blood, as well as splenic expression of inflammation-related genes (iNOS, TLR-4, TNF-α, IL-6, and INF-γ). Compared with laying hens, growing pullets showed a time-delayed activation of immune response following heat challenge, and had no immunosuppression up to the end of exposure. Overall, the immune system of layer birds has a trade-off with production tissues in a hot environment, and exhibits distinct age-range-specific responses of acclimatization.

Effects of combined treatment with hydrogen-rich electrolyzed water and tea polyphenols on oxidative stress, intestinal injury and intestinal flora disruption in heat-stressed mice

Heat stress (HS) can cause damage to the organism, especially the intestinal tract. In this paper, we investigated the effects of the combined action of tea polyphenols (TP) and hydrogen-rich electrolyzed water (HRW) on HS in mice. The combination of HRW feeding and TP of intraperitoneal injection was screened by in vitro antioxidant activity assay. The results revealed that the combined treatment was more helpful in alleviating the effects of HS on the behavior, growth performance, oxidative damage, and intestinal tract of mice compared with the respective treatments of TP and HRW (P < 0.05). Additionally, the combined treatment could repair HS-induced intestinal dysbiosis in mice, augmenting the number and abundance of bacteria, increasing the number of beneficial genera (Lachnospiraceae_NK4A136_group and Lactobacillus), and decreasing the number of harmful genera (Desulfovibrio and Enterorhabdus), and the effect was significantly better than that of individual treatment (P < 0.05). In conclusion, the combined treatment of TP and HRW effectively mitigates the adverse effects of HS on mouse behavior, growth performance, oxidative damage, and intestinal dysbiosis, surpassing the efficacy of individual treatments with TP or HRW alone.

Effects of dietary curcumin nano-micelles on performance, biological responses, and thermal stress resilience in heat-stressed fattening lambs across varying temperature-humidity index conditions: Implications for climate change

Heat stress poses a significant challenge to sheep farming in arid and semi-arid regions, impacting growth performance, health, and physiological responses. While sheep have innate mechanisms to manage heat stress, prolonged exposure impairs their performance and health. This study evaluated the influence of varying doses of Curcumin Nano-Micelle (CNM) on heat-stressed fattening lambs in northeastern Iran over three months, examining the relationship between CNM doses and growth performance, feeding behavior, physiological responses, immune function, and antioxidant status. Thirty-two crossbred male lambs were included in a completely randomized design with four treatments and eight replications. The experimental treatments were as follows: 1) CTRL: No dietary inclusion of CNM, (control group); 2) T20: Dietary inclusion of 20 mg of CNM per head per day; 3) T40: Dietary inclusion of 40 mg of CNM per head per day; and 4) T80: Dietary inclusion of 80 mg of CNM per head per day. The results revealed that dietary supplementation with 20 and 40 mg of CNM significantly improved live body weight, weight gain, average daily gain (ADG), and feed conversion ratio (FCR) compared to the control treatment. Regression analysis demonstrated quadratic models between growth performance parameters and the Temperature-Humidity Index (THI), indicating a correlation between CNM doses and the animals' responses to heat stress. Regarding eating behavior, CNM doses of 40 and 80 mg/day significantly reduced eating time while increasing ruminating time. Blood analysis indicated significant reductions in glucose levels across all treatments, with T40 significantly reducing both cholesterol and triglyceride (TG) levels. Additionally, CNM supplementation decreased serum malondialdehyde (MDA) levels and increased superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities, indicating enhanced antioxidant status. Physiological responses were influenced by CNM, notably reducing rectal temperature (RT), skin temperature (ST), respiration rate (RR), while pulse rate (PR) increased across various time intervals, particularly in the T80 group. This study demonstrates that CNM supplementation can enhance performance, physiological responses, and antioxidant status in heat-stressed fattening lambs, highlighting its potential to mitigate heat stress effects in sheep farming.

Strategies to combat heat stress in poultry production-A review

The effects of heat stress (HS) caused by high temperatures continue to be a global concern in poultry production. Poultry birds are homoeothermic, however, modern-day chickens are highly susceptible to HS due to their inefficiency in dissipating heat from their body due to the lack of sweat glands. During HS, the heat load is higher than the chickens' ability to regulate it. This can disturb normal physiological functioning, affect metabolism and cause behavioural changes, respiratory alkalosis and immune dysregulation in birds. These adverse effects cause gut dysbiosis and, therefore, reduce nutrient absorption and energy metabolism. This consequently reduces production performances and causes economic losses. Several strategies have been explored to combat the effects of HS. These include environmentally controlled houses, provision of clean cold water, low stocking density, supplementation of appropriate feed additives, dual and restricted feeding regimes, early heat conditioning and genetic selection of poultry lines to produce heat-resistant birds. Despite all these efforts, HS still remains a challenge in the poultry sector. Therefore, there is a need to explore effective strategies to address this long-lasting problem. The most recent strategy to ameliorate HS in poultry is early perinatal programming using the in ovo technology. Such an approach seems particularly justified in broilers because chick embryo development (21 days) equals half of the chickens' posthatch lifespan (42 days). As such, this strategy is expected to be more efficient and cost-effective to mitigate the effects of HS on poultry and improve the performance and health of birds. Therefore, this review discusses the impact of HS on poultry, the advantages and limitations of the different strategies. Finally recommend a promising strategy that could be efficient in ameliorating the adverse effects of HS in poultry.

Impact of Bacillus licheniformis-Fermented Products on Growth and Productivity in Heat-Stressed Laying Ducks

The purpose of this study was to assess the impact of various concentrations of Bacillus licheniformis-fermented products (BLFP) on the growth and productivity of laying ducks (Anas platyrhynchos) subjected to heat stress during eight weeks of a feeding trial. A total of 150 one-day-old Brown Tsaiya ducks of both sexes were divided into five groups, with each group having three replicates and 10 ducks each for evaluation of growth performance. The treatment groups received dietary supplements of BLFP at levels of 0.1%, 0.2%, and 0.3%, along with a group receiving flavomycin (F) at 5 ppm, all over a 24-week period. The fermentation process in this study utilized a B. licheniformis strain (ATCC 12713) for the production of the spores through solid-state fermentation. The control group was given a basal diet consisting of yellow corn and soybean meal. The results showed that as compared to the flavomycin group, ducks in the 0.3% BLFP group had significantly higher body weights and better feed conversion rates. In addition, during the three weeks, the BLFP group showed higher feed consumption as compared to the control group. The jejunum villi length was significantly increased in the 0.2% BLPF group as compared to the control and flavomycin groups. This study also found that the flavomycin group had a significantly higher egg conversion rate, while the 0.1-0.3% BLFP groups had improved feed intake and the 0.3% group had significantly enhanced egg yolk color. Additionally, the 0.2% BLFP group showed substantial decreases in IL-1β, TNF-α, IL-6, and IL-10 levels in the liver as well as an uptick in the tight junction protein Occludin gene expression in the colon when compared to the control group. Furthermore, the expression of the heat shock protein 70 in the gut upregulated in the 0.1% and 0.2% BLFP groups. In conclusion, these observations demonstrate that dietary supplementation of 0.2% BLFP is an ideal concentration to increase gut morphology, alleviate inflammatory response, and promote gut integrity in heat-stressed laying ducks.

Invited review: "Probiotic" approaches to improving dairy production: Reassessing "magic foo-foo dust"

The gastrointestinal microbial consortium in dairy cattle is critical to determining the energetic status of the dairy cow from birth through her final lactation. The ruminant's microbial community can degrade a wide variety of feedstuffs, which can affect growth, as well as production rate and efficiency on the farm, but can also affect food safety, animal health, and environmental impacts of dairy production. Gut microbial diversity and density are powerful tools that can be harnessed to benefit both producers and consumers. The incentives in the United States to develop Alternatives to Antibiotics for use in food-animal production have been largely driven by the Veterinary Feed Directive and have led to an increased use of probiotic approaches to alter the gastrointestinal microbial community composition, resulting in improved heifer growth, milk production and efficiency, and animal health. However, the efficacy of direct-fed microbials or probiotics in dairy cattle has been highly variable due to specific microbial ecological factors within the host gut and its native microflora. Interactions (both synergistic and antagonistic) between the microbial ecosystem and the host animal physiology (including epithelial cells, immune system, hormones, enzyme activities, and epigenetics) are critical to understanding why some probiotics work but others do not. Increasing availability of next-generation sequencing approaches provides novel insights into how probiotic approaches change the microbial community composition in the gut that can potentially affect animal health (e.g., diarrhea or scours, gut integrity, foodborne pathogens), as well as animal performance (e.g., growth, reproduction, productivity) and fermentation parameters (e.g., pH, short-chain fatty acids, methane production, and microbial profiles) of cattle. However, it remains clear that all direct-fed microbials are not created equal and their efficacy remains highly variable and dependent on stage of production and farm environment. Collectively, data have demonstrated that probiotic effects are not limited to the simple mechanisms that have been traditionally hypothesized, but instead are part of a complex cascade of microbial ecological and host animal physiological effects that ultimately impact dairy production and profitability.

Folic Acid and Taurine Alleviate the Impairment of Redox Status, Immunity, Rumen Microbial Composition and Fermentation of Lambs under Heat Stress

The aim of this study was to investigate if the supplementation of folic acid and taurine can relieve the adverse effects of different levels of heat stress (HS) on growth performance, physiological indices, antioxidative capacity, immunity, rumen fermentation and microbiota. A total of 24 Dorper × Hu crossbred lambs (27.51 ± 0.96 kg) were divided into four groups: control group (C, 25 °C), moderate HS group (MHS, 35 °C), severe HS group (SHS, 40 °C), and the treatment group, under severe HS (RHS, 40 °C, 4 and 40 mg/kg BW/d coated folic acid and taurine, respectively). Results showed that, compared with Group C, HS significantly decreased the ADG of lambs (p < 0.05), and the ADG in the RHS group was markedly higher than in the MHS and SHS group (p < 0.05). HS had significant detrimental effects on physiological indices, antioxidative indices and immune status on the 4th day (p < 0.05). The physiological indices, such as RR and ST, increased significantly (p < 0.05) with the HS level and were significantly decreased in the RHS group, compared to the SHS group (p < 0.05). HS induced the significant increase of MDA, TNF-α, and IL-β, and the decrease of T-AOC, SOD, GPx, IL-10, IL-13, IgA, IgG, and IgM (p < 0.05). However, there was a significant improvement in these indices after the supplementation of folic acid and taurine under HS. Moreover, there were a significant increase in Quinella and Succinivibrio, and an evident decrease of the genera Rikenellaceae_RC9_gut_group and Asteroleplasma under HS (p < 0.05). The LEfSe analysis showed that the genera Butyrivibrio, Eubacterium_ventriosum_group, and f_Bifidobacteriaceae were enriched in the MHS, SHS and RHS groups, respectively. Correlated analysis indicated that the genus Rikenellaceae_RC9_gut_group was positively associated with MDA, while it was negatively involved in IL-10, IgA, IgM, and SOD (p < 0.05); The genus Anaeroplasma was positively associated with the propionate and valerate, while the genus Succinivibrio was negatively involved in TNF-α (p < 0.05). In conclusion, folic acid and taurine may alleviate the adverse effects of HS on antioxidant capacity, immunomodulation, and rumen fermentation of lambs by inducing changes in the microbiome that improve animal growth performance.

Resveratrol alleviates heat-stress-induced impairment of the jejunal mucosa through TLR4/MAPK signaling pathway in black-boned chicken

Heat stress in chickens caused by high temperatures in summer is a serious issue faced by the poultry industry globally, which reduces product quality. The aim of this study is to investigate the role of resveratrol in alleviating heat stress injury and inflammatory response of jejunal mucosa in black-boned chickens through TLR4/MAPK signaling pathway. In total, 240 black-boned chickens (28-day old) were randomly divided into 4 treatment groups as follows. The normal temperature (NT) and normal temperature with resveratrol (NT+Res) groups received a basal diet without and with 400 mg/kg resveratrol, respectively, and treated at 24℃ ± 2℃, 24 h/d. The high temperature (HT) and high temperature with resveratrol (HT+Res) groups received basal diet without and with 400 mg/kg resveratrol, respectively, and treated at 37℃ ± 2℃ for 8 h/d and 24°C ± 2°C for the rest of the time for 12 d. The results revealed the heat-stress responses impaired the villous structure of the jejunum, causing a rough and uneven surface of the jejunal villus, and local intestinal villi were even more prone to rupture. However, resveratrol significantly improved the morphology and structure of jejunal mucosa under heat stress. Heat stress increased the mRNA levels of toll-like receptor 4 (TLR4), c-Jun, c-fos, caspase-3, and p38 (P < 0.05), reduced mRNA level of Bcl-2, and reduced the expression of tight junction proteins Occludin, ZO-1, and Claudin1 (P < 0.05) in the jejunal mucosa. However, resveratrol inhibited the TLR4/ mitogen-activated protein kinase (MAPK) signaling pathway via downregulating TLR4, c-Jun, p38, and caspase-3 (P < 0.05); upregulating Bcl-2 (P < 0.05); decreasing the protein levels of MKK3, p53, and myeloid differentiation factor 88 (MYD88); and increasing the protein levels of Occludin, ZO-1, and Claudin1. In addition, it reduced the levels of JNK and p38 proteins (P < 0.05) and inflammatory factors like tumor necrosis factor-α (TNF-α) in the jejunal mucosa of black-boned chickens under heat stress. In conclusion, resveratrol may play a regulatory role in heat-stress-induced damage and inflammatory response in the intestinal mucosa of black-boned chickens under heat stress.

Heat stress effects on the genetics of growth traits in Thai native chickens (Pradu Hang dum)

OBJECTIVE

The objective of this study was to investigate the effect of heat stress on the growth traits and genetic parameters of Thai native chickens.

METHODS

A total of 16,487 records for growth traits of Thai native chickens between 2017 and 2022 were used in this study. Data included the body weight at birth, body weight at 4, 8, and 12 weeks of age (BW0, BW4, BW8, BW12), average daily gain during 0 to 4, 4 to 8, and 8 to 12 weeks of age (ADG0-4, ADG4-8, ADG8-12), absolute growth rate at birth, at 4, 8, and 12 weeks of age (AGR0, AGR4, AGR8, AGR12). The repeatability test day model used the reaction-norm procedure to analyze the threshold point of heat stress, rate of decline of growth traits, and genetic parameters.

RESULTS

At temperature and humidity index (THI) of 76, Thai native chickens began to lose their growth traits, which was the onset of heat stress in this study. The estimated heritability, genetic correlation between animal and heat stress effect, and correlations between the intercept and slope of the permanent environmental effects were 0.27, -0.85, and -0.83 for BW, 0.17, -0.81, and -0.95 for ADG, 0.25, -0.61, and -0.83 for AGR, respectively. Male chickens are more affected by heat stress than female chickens with a greater reduction of BW, ADG, and AGR, values equal to -9.30, -0.23, -15.21 (in males) and -6.04, -0.21, -10.10 (in females) gram per 1 level increase of THI from the THI of 76.

CONCLUSION

The influence of thermal stress had a strong effect on the decline in growth traits and genetic parameters in Thai native chickens. This study indicated that genetic models used in conjunction with THI data are an effective method for the analysis and assessment of the effects of heat stress on the growth traits and genetics of native chickens.

Effects of dietary supplementation with tea polyphenols and probiotics on laying performance, biochemical parameters intestinal morphology and microflora of laying hens

This study was conducted to investigate the effects of tea polyphenols (TP) and probiotics (PB) on the production performance, biochemical indices, and gut health of laying hens. A total of 400 Hy-line Brown layers (45 weeks old) were randomly assigned to 8 diet groups for 8-week feeding trial. Compared with the control basal diet (CT), dietary high dosage of TP and PB (HTP-PB) increased egg mass (P < 0.05). Supplementation with HTP-PB improved the levels of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) and decreased the malonic dialdehyde (MDA) content (P < 0.05) without affecting the contents of immunoglobulins in the serum. The combination of HTP and PB supplementation promoted the secretion of estradiol (E2) and progesterone (PROG) compared with treatment with TP or PB alone (P < 0.05). The combined use of HTP and PB induced higher jejunal villus height (VH) than the CT group (P < 0.05). Dietary TP and PB could optimize the functional network of intestinal microflora and the interactions between the intestinal microflora and the host. Therefore, the combined use of the high dosage of TP and PB affected laying performance, improved antioxidant capacity, and promoted intestinal health, which may be associated with regulation of the intestinal microbiota.

Review: The role of heat shock proteins in chicken: Insights into stress adaptation and health

This review article aimed to provide readers with a comprehensive understanding of the function of heat shock proteins (HSPs) in chicken physiology, stress response, and overall poultry health. With the increasing challenges faced by the livestock industry, particularly the poultry sector, due to climate change-induced high ambient temperatures, heat stress (HS) has become a critical concern. HS disrupts the thermal balance in poultry, leading to detrimental effects on growth, immune function, and overall health. HSPs play a pivotal role in mitigating the impacts of HS in chickens. These molecular chaperones are involved in protein folding, unfolding, and assembly, and they are classified into several families based on their size, including small molecule HSPs, HSP40, HSP60, HSP70, HSP90, and HSP110. By maintaining cellular homeostasis and promoting stress tolerance, HSPs act as vital guardians in helping chickens cope with HS and its associated consequences. The review synthesized relevant literature to shed light on the importance of HSPs in stress adaptation, cellular homeostasis, and the maintenance of normal cell metabolism in chickens. The adverse effects of HS on chickens include oxidative stress and compromised immune systems, making them more susceptible to infections. So also, HS negatively affects production performance and meat quality in poultry. Understanding the functions of HSPs in chickens offers valuable insights into stress adaptation and health, and could potentially lead to the identification of HSP biomarkers, genetic selection for heat tolerance, investigations into the interplay between HSPs and immune function, and the development of nutritional interventions to enhance HSP activity. By exploring these potential research directions, the review aimed to contribute to the development of novel approaches to mitigate the negative effects of HS on poultry, ultimately improving productivity and animal welfare in a changing climate.

Effect of probiotics and humate substances on blood parameters, intestinal development and immune organs of growing quail

This study aimed to evaluate impacts of dietary probiotics (Bacillus subtilis PB6) and humate substances (HS) supplementation on histomorphometry of small intestine and immune organs, blood parameters of growing quail. A total of 216 unsexed quails (seven days old) were randomly distributed to six groups. The 1st group did not receive any supplements (control), 2nd group received B. subtilis (CloSTAT: 0.5 g/kg diet), 3rd and 4th groups received HS (4 and 8 g/kg diet, respectively), 5th and 6th groups received CloSTAT + 4g HS and CloSTAT + 8g HS, respectively. Results showed that the inclusion of B. subtilis alone in quail diets significantly improved histomorphometry indices of intestine and immune organs compared to the control. Dietary supplementation of HS alone led to deteriorating histomorphometry indices of intestinal segments and immune organs compared to the control. CloSTAT, HS or both improved lipid profile and antioxidant parameters. Serum mineral levels did not differ significantly among groups except for Ca levels. In conclusion, dietary probiotics supplementation enhanced histomorphometry of intestine and immune organs and improved serum Ca, lipid profile and antioxidant indices. Moreover, the addition of HS (4 or 8 g/kg diet) improved lipid profile and antioxidant indices, but led to undesirable results in intestinal development and immune organs.

Heat stress and poultry production: a comprehensive review

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

Effectiveness of probiotics and clove essential oils in improving growth performance, immuno-antioxidant status, ileum morphometric, and microbial community structure for heat-stressed broilers

Recently, interest has increased in using bio-additives, herbs, and their extracts as feed additives because of their potential role in improving chick's health and productivity, especially during stress. Thus, our aim in this study is to examine whether nutritional supplementation (probiotics and clove essential oils) will help mitigate the negative effect of heat stress on the bird by modifying the microbial content, boosting immunity, oxidative status, metabolic, and growth. In this study, three hundred one-day-old broiler chicks (Ross 308) were fed the following experimental diet: (CON) basal diet (control diet); (CEO) CON with clove essential oils (300 mg/kg); (PRO) CON with probiotics (2 g/kg); (PC) CON with probiotics and clove essential oils. Our results showed a significant improvement (P < 0.05) in body weight gain, feed conversion ratio, nutrient digestibility, and digestive enzymes activities in broilers fed on PC, CEO, and PRO compared to the control group. Moreover, a significant decrease was recorded in the abdominal fat content and an increase in the relative weight of bursa of Fabricius, and higher antibody levels against Newcastle disease virus, as well as, there was an increase (P < 0.05) in interleukin 10 (IL-10) in all treated groups. Meanwhile, there was a decrease in tumor necrosis factor-α (TNF-α) in all supplemented groups compared with the control group. Serum triglycerides, cholesterol, low-density lipoprotein concentrations, and alanine aminotransferase activities were significantly lower in the treated groups. Superoxide dismutase and glutathione peroxidase levels were elevated (P < 0.05) and the malondialdehyde level value significantly decreased in all supplemented groups. The treated groups enhanced the ileum structure by increasing Lactobacillus, decreasing E. coli, and improving the morphometrically (P < 0.05). This study strongly suggests that clove essential oil and probiotic mixture can be used as a feed supplement to reduce the effects of heat stress by improving the growth performance and enhancing immuno-antioxidant status, ileum morphometric, as well as modifying the microbial community structure of the ileum of broilers.

Bacillus licheniformis reduces mortality, improves symptoms, and controls residual pathogenicity in juvenile sea cucumbers Apostichopus japonicus infected with skin ulceration syndrome

Mass mortality caused by skin ulceration syndrome (SUS) is the bottle-neck for the sustainable aquaculture of the sea cucumber Apostichopus japonicus. In the present study, probiotic Bacillus licheniformis (0.25 × 109 CFU/g) was used as the treatment for A. japonicus infected with the SUS that caused by Vibrio harveyi. We found that B. licheniformis significantly reduced the number of infected sea cucumbers 5 days and 7 days after the treatment (group B), compared to those without B. licheniformis treatment (group C) (P < 0.001; P < 0.001). Further, the sea cucumbers fed B. licheniformis had significantly lower mortality at the end of the experiment (<10%) than that of those without the B. licheniformis treatment (>60%) (P < 0.001). These results suggest that the treatment of B. licheniformis is an effective method to reduce the mass mortality resulted from SUS in sea cucumber aquaculture. Further, 3-5 days of treatment significantly improved the adverse symptoms of SUS on the physiology and behavior of sea cucumbers, including the righting behavior, adhesion behavior, food consumption, fecal output and mobility. This indicates B. licheniformis treatment has the advantage in the recovery of sea cucumbers after SUS. Moreover, there was no significant difference observed in the physiology and behavior of sea cucumbers between the SUS infected sea cucumbers after the 7-day treatment of B. licheniformis and the healthy individuals. SUS infected sea cucumbers effectively returned to a stage of normalcy. Further, we found a significantly lower infected rate in sea cucumbers exposed to the culture water of group B (∼5%) than that of those in exposure to the culture water of group C (∼60%). This indicates that the treatment of B. licheniformis efficiently controls the residual pathogenicity of SUS in culture water. The present study demonstrated the effectiveness of B. licheniformis treatment as an environmentally friendly approach to reducing mortality, improving symptoms, and controlling residual pathogenicity in sea cucumber aquaculture.

Alleviating heat stress effects in poultry: updates on methods and mechanisms of actions

Heat stress is a threat that can lead to significant financial losses in the production of poultry in the world's tropical and arid regions. The degree of heat stress (mild, moderate, severe) experienced by poultry depends mainly on thermal radiation, humidity, the animal's thermoregulatory ability, metabolic rate, age, intensity, and duration of the heat stress. Contemporary commercial broiler chickens have a rapid metabolism, which makes them produce higher heat and be prone to heat stress. The negative effect of heat stress on poultry birds' physiology, health, production, welfare, and behaviors are reviewed in detail in this work. The appropriate mitigation strategies for heat stress in poultry are equally explored in this review. Interestingly, each of these strategies finds its applicability at different stages of a poultry's lifecycle. For instance, gene mapping prior to breeding and genetic selection during breeding are promising tools for developing heat-resistant breeds. Thermal conditioning during embryonic development or early life enhances the ability of birds to tolerate heat during their adult life. Nutritional management such as dietary manipulations, nighttime feeding, and wet feeding often, applied with timely and effective correction of environmental conditions have been proven to ameliorate the effect of heat stress in chicks and adult birds. As long as the climatic crises persist, heat stress may continue to require considerable attention; thus, it is imperative to explore the current happenings and pay attention to the future trajectory of heat stress effects on poultry production.

Copper Super-Dosing Improves Performance of Heat-Stressed Broiler Chickens through Modulation of Expression of Proinflammatory Cytokine Genes

Continuous exposure to high ambient temperatures brings about a number of oxidative damages in chickens. Copper (Cu), an active component of a number of antioxidative defence components, should arrest these changes to take place although that may not be possible under the standard dosing regimen followed by the industry. To ascertain the optimum dose response that may be beneficial in sustaining the performance of chickens under heat stress (HS), broiler chickens (n = 400) were exposed to high ambient temperature (between 27.2°C and 35.3°C) during 1-35 d. Copper (Cu) as Cu proteinate (Cu-P) at concentrations of 37.5, 75, 112.5, and 150 mg/kg was supplemented to the diet. The negative control (NC) diet did not contain any supplemental Cu. Increasing dietary Cu improved (P < 0.001) body weight, feed intake, and conversion ratio. Serum concentrations of total cholesterol at 21 d (P = 0.009), HDL cholesterol at 35 d (P = 0.008), LDL cholesterol at 21 d (P = 0.015), and triacylglycerol at both 21 d (P = 0.033) and 35 d (P = 0.001) decreased as Cu in the diet increased. As Cu in the diet increased, hemoglobin increased (P = 0.003) at 21 d, and the heterophil to lymphocyte ratio decreased both at 21 d (P = 0.047) and 35 d (P = 0.001). Superoxide dismutase and glutathione peroxidase activities increased when dietary Cu increased to 150 mg/kg (P < 0.01). Liver Cu at 35 d increased linearly with the dose of Cu in the diet (P = 0.0001). Selected bacteria were enumerated in the digesta to ascertain if Cu super-dosing affected their population in any way in the absence of any enteric challenge. Escherichia coli and total Salmonella numbers decreased (P = 0.0001), and total Lactobacillus increased (P = 0.0001) proportionately with dietary Cu. Interleukin-6 and tumour necrosis factor-α gene expression increased linearly (P = 0.0001) as Cu in the diet increased though the response plateaued at 112.5 mg/kg. It was concluded from the present experiment that during conditions of impending HS, dietary supplementation of 112.5 to 150 mg Cu/kg diet as Cu-P may be a novel strategy to alleviate the negative effects of HS without involving any apparent risk of Cu toxicity.

Effects of dietary Lactobacillus rhamnosus GG supplementation on the production performance, egg quality, eggshell ultrastructure, and lipid metabolism of late-phase laying hens

BACKGROUND

Toward the late phase of laying, the production performance of laying hens decreases, egg quality deteriorates, lipid metabolism weakens, and hepatic lipid accumulation is exacerbated. Probiotics as an alternative to antimicrobials have been employed in poultry-related industries. Lactobacillus rhamnosus GG (LGG) is currently the most researched and clinically validated probiotic, showing promising effects in multiple application areas. However, few studies have been conducted on livestock (including poultry) production.

RESULTS

Compared with the CON group, the feed conversion ratio (P < 0.01) declined significantly in the LGG group. Eggshell strength (P < 0.001) and eggshell thickness (P < 0.001) were significantly increased by supplementation with LGG in the diet. The height (P < 0.001) and proportion (P < 0.05) of the effective layer and the mammillary knob density (P < 0.01) in the eggshell ultrastructure of the LGG group increased significantly, while the mammillary layer (P < 0.05) and knob width (P < 0.01) decreased significantly. The LGG-treated hens had significantly lower serum concentrations of low-density lipoprotein (P < 0.05), free fatty acids (P < 0.01), and liver triglyceride (P < 0.05) levels than those in the CON group.

CONCLUSIONS

LGG supplementation significantly decreases the feed conversion ratio, improves eggshell quality by altering the ultrastructure, and improves lipid metabolism in the late laying period.

Effects of dietary curcumin nano-micelles on growth performance, blood metabolites, antioxidant status, immune and physiological responses of fattening lambs under heat-stress conditions

The aim of the current study was to investigate the effects of dietary curcumin nano-micelles (C-NM) on the growth performance, blood metabolites, antioxidant status, and immune and physiological responses of fattening lambs under heat stress conditions. Thirty-two crossbred male lambs [Île-de-France × (Dalagh × Romanov)] with an average weight of 31.2 ± 1.55 kg and age of 4-5 months were assigned to experimental treatments in a completely randomized design including four treatments and eight replications. The treatments were T0, T20, T40, and T80, representing dietary supplementation of C-NM at 0, 20, 40, and 80 mg per head per day, respectively. The study lasted for 37 days including 7 days of adaptation period. Lambs were weighed on days 0 and 30 of the experiment before morning feeding to determine the average daily gain (ADG) and feed conversion ratio (FCR). Blood samples were collected from the jugular vein on day 30 of the experiment and physiological parameters, including rectal temperature (RT), skin temperature (ST), respiration rate (RR), and pulse rate (PR), were measured once a week on a certain day during the study. Lambs in the T40 group showed higher final live weight (FLW) and ADG, while exhibiting lower FCR (P < 0.01). Regression analysis predicted the optimum levels of dietary inclusion of C-NM to be 44.7, 38.3, and 42.0 mg/day for FLW, ADG, and FCR, respectively. Dietary supplementation of C-NM decreased RT, ST, and RR, while increasing PR (P < 0.01). The levels of immunoglobulins G (IgG) and A (IgA) increased linearly with the dietary inclusion of C-NM (P < 0.01), while levels of immunoglobulin M (IgM) remained unaffected (P > 0.05). Dietary inclusion of C-NM had a quadratic reducing effect on the serum concentration of malondialdehyde (MDA) and a cubic increasing effect on the serum activities of glutathione peroxidase (GPx) (P < 0.05). Superoxide dismutase (SOD) was linearly increased in T80, while total antioxidant capacity (TAC) showed a linear increase in T40 and T80 groups (P < 0.01). Based on the results of this study, we recommend the administration of C-NM in the diet of fattening lambs during hot months in tropical and subtropical areas. However, further studies are needed to assess the long-term effects of C-NM during various physiological and production statuses.

Understanding the ADHD-Gut Axis by Metabolic Network Analysis

Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder diagnosed with hyperactivity, impulsivity, and a lack of attention inconsistent with the patient's development level. The fact that people with ADHD frequently experience gastrointestinal (GI) dysfunction highlights the possibility that the gut microbiome may play a role in this condition. The proposed research aims to determine a biomarker for ADHD by reconstructing a model of the gut-microbial community. Genome-scale metabolic models (GEM) considering the relationship between gene-protein-reaction associations are used to simulate metabolic activities in organisms of gut. The production rates of dopamine and serotonin precursors and the key short chain fatty acids which affect the health status are determined under three diets (Western, Atkins', Vegan) and compared with those of healthy people. Elasticities are calculated to understand the sensitivity of exchange fluxes to changes in diet and bacterial abundance at the species level. The presence of Bacillota (genus Coprococcus and Subdoligranulum), Actinobacteria (genus Collinsella), Bacteroidetes (genus Bacteroides), and Bacteroidota (genus Alistipes) may be possible gut microbiota indicators of ADHD. This type of modeling approach taking microbial genome-environment interactions into account helps us understand the gastrointestinal mechanisms behind ADHD, and establish a path to improve the quality of life of ADHD patients.

Effects of drinking water temperature in winter on growth performance, water consumption, surface temperature, and intestinal development of geese from 21 to 49 days of age

This research aimed to investigate the effects of drinking water temperatures on growth performance, water consumption, surface temperature, organ indices, blood parameters, and intestinal development of geese, and determine the optimal drinking water temperature for 21 to 49-d geese. A total of 192 twenty-one-day male Yuzhou white geese were allocated randomly to 4 groups with 8 replicate pens per group according to the drinking water temperature (drinking water temperature [7℃-12℃] at ambient temperature [T_C], 18℃ [T₁], 27℃ [T₂], and 36℃ [T₃], respectively). The results showed that increasing drinking water temperature did not significantly improve the BW, ADG, and ADFI of geese (P > 0.05), whereas drinking warm water of 36℃ for geese had a trend to increase FCR (0.05 < P < 0.1). Geese in group T₂ drank the most water per day on average, whereas geese in group T_C drank the least (P < 0.001). Geese in groups T₁, T₂, and T₃ had higher eyes temperatures than group T_C (P < 0.001). No significant differences were found on the organ indices and blood biochemical parameters (P > 0.05). Geese from group T₁ had higher crypt depth and muscularis thickness of duodenum (P < 0.05), and lower ratio of villus height to crypt depth than other groups (P < 0.001). Geese from group T₁ had higher activities of trypsin in duodenum and jejuna and amylase in jejuna at 49 d than other groups (P < 0.01). Overall, these data indicate drinking water at 18℃ can increase water consumption and eyes temperature, and improve the activity of digestive enzymes and promote intestinal development. Under our experimental conditions, we recommend that the optimal drinking water temperature for geese from 21 to 49 d of age is 18°C.

Chronic treatment with glucocorticoids does not affect egg quality but increases cortisol deposition into egg albumen and elicits changes to the heterophil to lymphocyte ratio in a sex-dependent manner

During chronic stress, there is an initial increase in glucocorticoid (GC) levels, but they then return to low, albeit not baseline, levels. Recent studies have renewed interest in cortisol in that it may also have important roles in the stress response. The purpose of our study was to test the hypothesis that chronic treatment with low levels of either corticosterone or cortisol would alter HLR and immune organ morphometrics. Further, we wanted to determine if chronic treatment with either GC would elicit an increase in cortisol levels in egg albumen. To test our hypotheses, we implanted silastic capsules that contained corticosterone, cortisol, or empty capsules as controls (N = 5/sex/treatment). Blood serum, smears, body weights, and egg quality data were collected. Ducks were then euthanized and body weight, weights of spleens, livers, and the number of active follicles were recorded. Albumen GC levels were assessed using mass spectrometry. Data were analyzed using a 2- or 3-way ANOVA as appropriate and post-hoc with Fishers PLSD. No treatment elicited differences in egg quality measures or body weight compared to controls. Corticosterone treatment did elicit an increase in serum corticosterone (p &lt; 0.05), but not cortisol, levels compared to controls in both sexes. Both cortisol and corticosterone treatments increased (p &lt; 0.05) serum levels of cortisol compared to controls. Relative spleen weights were higher (p &lt; 0.05) in hens following corticosterone but not cortisol treatment. No other organs showed any differences among the treatment groups. Both GCs elicited an increase (p &lt; 0.001) in HLR in hens at all time-points over the 2-week treatment period compared to controls. Cortisol, not corticosterone, only elicited an increase in HLR for drakes (p &lt; 0.05) compared to controls but only at day 1 after implants. Chronic treatment with cortisol, but not corticosterone, elicited an increase (p &lt; 0.01) in egg albumen cortisol levels compared to other groups. Corticosterone was not detected in any albumen samples. Our results suggest that glucocorticoids elicit differential effects and although corticosterone has been stated to be the predominant GC in avian species, cortisol may provide critical information to further understand bird welfare.

Biotechnological and food synthetic biology potential of platform strain: Bacillus licheniformis

Bacillus licheniformis is one of the most characteristic Gram-positive bacteria. Its unique genetic background and safety characteristics make it have important biologic applications in the food industry, including, the biosynthesis of high value-added bioproducts, probiotic functions, biological treatment of wastes derived from food production, etc. In this review, these recent advances are summarized and presented systematically for the first time. In addition, we highlight synthetic biology strategies as a potential driver of developing this strain for wider and more efficient application in the food industry. Finally, we present the current challenges faced and provide our unique perspective on relevant future research directions. In summary, this review will provide an illuminating and comprehensive perspective that will allow an in-depth understanding of B. licheniformis and promote its more effective development in the food industry.

An evaluation of the thermoregulatory potential of in ovo delivered bioactive substances (probiotic, folic acid, and essential oil) in broiler chickens

Mitigating the negative effects of heat stress (HS) is a critical challenge for the global poultry industry. This study evaluated the thermoregulatory potential of 3 in ovo delivered bioactive substances using selected gut health parameters. Eggs were incubated and allotted to 5 groups, and respective bioactive substances delivered. These groups included-the noninjected, in ovo saline, in ovo folic acid (FA), in ovo probiotics (P), and in ovo essential oil (EO). At hatch, chicks were assigned to 5 new posthatch treatment combinations, including A) Negative control (NC)-noninjected eggs offered a basal corn-wheat-soybean diet, B) Antibiotics-NC + 0.05% bacitracin methylene disalicylate, C) In ovo FA-eggs injected with FA + NC diet, D) In ovo probiotics-eggs injected with probiotics + NC diet, E) In ovo + in-water EO-eggs injected with EO and supplied EO via drinking water + NC diet. Birds were raised for 28 d in 8 replicate cages/treatment (6 birds/cage) and exposed to either a thermoneutral (24°C ± 0.2) or HS challenge (31°C) condition from d 21 to d 28. The in ovo delivered FA and EO treatments reduced (P < 0.001) hatchability by at least 26% compared to NC. Induced HS reduced (P < 0.001) total plasma protein, total antioxidant capacity, and villus width in the duodenum and jejunum. Independent of HS and compared to NC, the in ovo + in-water EO treatment resulted in (P < 0.05) at least a 15% increase in villus height: crypt depth across the 3 gut sections. The in ovo + in-water EO treatment also increased the relative mRNA expression of intestinal barrier-related genes (Claudin1,3,4, Occludin, Zona occludens-2, and Mucin 2). Under HS, the in ovo + in-water EO treatment recorded a 3.5-fold upregulation of amino acid transporter gene (SLC1A1), compared to NC. Subject to further hatchability optimization, the in ovo + in-water delivery of EO show potential to afford broiler chicken thermotolerance.

Dietary Bacillus licheniformis shapes the foregut microbiota, improving nutrient digestibility and intestinal health in broiler chickens

Bacillus licheniformis is considered a potential alternative to antibiotic growth promoters of animal growth and health. However, the effects of Bacillus licheniformis on the foregut and hindgut microbiota, and their relationships with nutrient digestion and health, in broiler chickens remain unclear. In this study, we aimed to identify the effects of Bacillus licheniformis BCG on intestinal digestion and absorption, tight junctions, inflammation, and the fore- and hind-gut microbiota. We randomly assigned 240 1-day-old male AA broilers into three treatment groups: CT (basal diet), BCG1 (basal diet + 1.0 × 10⁸ CFU/kg B. licheniformis BCG), and BCG2 (basal diet + 1.0 × 10⁹ CFU/kg B. licheniformis BCG). On day 42, the jejunal and ileal chyme and mucosa were subjected to analysis of digestive enzyme activity, nutrient transporters, tight junctions, and signaling molecules associated with inflammation. The ileal and cecal chyme were subjected to microbiota analysis. Compared with the CT group, the B. licheniformis BCG group showed significantly greater jejunal and ileal α-amylase, maltase, and sucrase activity; moreover, the α-amylase activity in the BCG2 group was higher than that in the BCG1 group (P < 0.05). The transcript abundance of FABP-1 and FATP-1 in the BCG2 group was significantly greater than that in the CT and BCG1 groups, and the GLUT-2 and LAT-1 relative mRNA levels were greater in the BCG2 group than the CT group (P < 0.05). Dietary B. licheniformis BCG resulted in significantly higher ileal occludin, and lower IL-8 and TLR-4 mRNA levels than observed in the CT group (P < 0.05). B. licheniformis BCG supplementation significantly decreased bacterial community richness and diversity in the ileum (P < 0.05). Dietary B. licheniformis BCG shaped the ileac microbiota by increasing the prevalence of f_Sphingomonadaceae, Sphingomonas, and Limosilactobacillus, and contributed to nutrient digestion and absorption; moreover, it enhanced the intestinal barrier by increasing the prevalence of f_Lactobacillaceae, Lactobacillus, and Limosilactobacillus. Dietary B. licheniformis BCG decreased microbial community diversity by diminishing Desulfovibrio, Alistipes, Campylobacter, Vibrio, Streptococcus, and Escherichia coli-Shigella levels, and down-regulating inflammatory associated molecule expression. Therefore, dietary B. licheniformis BCG contributed to digestion and absorption of nutrients, enhanced the intestinal physical barrier, and decreased intestinal inflammation in broilers by decreasing microbial diversity and optimizing the microbiota structure.

Cold Drinking Water Boosts the Cellular and Humoral Immunity in Heat-Exposed Laying Hens

This study aimed to investigate the effects of cold drinking water on cellular and humoral immunity in heat-exposed laying hens. One hundred and eight laying hens at 19 weeks old were placed into three treatments with six replicates of six hens in each group as follows: (1) hens were provided with normal drinking water (NW) under the control of thermoneutral temperature (CT: 25 ± 1 °C; CT + NW), (2) hens were provided with NW under high ambient temperature (HT: 35 ± 1 °C; HT + NW) for 8 h/d for a month, and (3) hens were treated under HT with cold drinking water (CW: 15 ± 1 °C; HT + CW) for 8 h/d for a 4-weeks. Then, the feed consumption, egg production, egg weight, feed conversion ratio, and blood immune parameters were investigated. The results showed that cold drinking water (CW) caused a significant (p < 0.05) recovery in the reduction of food intake and egg production due to heat stress; however, there was no significant effect (p > 0.05) on egg weight and feed conversion ratio. Moreover, CW significantly (p < 0.05) restored the immune-suppressing effects of heat stress on the contents of peripheral blood mononuclear cells, including B-cell (BU-Ia), helper T cell (CD4), and the ratio of helper/cytotoxic T cell (CD4/CD8). In addition, CW significantly (p < 0.05) recovered the reduction on the level of mRNA expression of interleukin-2 (IL-2) and interferon-gamma (IFN-γ), as well as significantly (p < 0.05) restored the reduction of plasma concentration of IL-2, IFN-γ and immunoglobulin G in heat-stressed laying hens. These results prove that CW increased heat dissipation and enhanced feed intake, egg production, and cellular and humoral immunity in heat-exposed laying hens.

The genetic impact of heat stress on the egg production of Thai native chickens (Pradu Hang dum)

Sustainable poultry production in adverse weather conditions is a widely debated issue, which has led to research into the development of breeds of poultry that are genetically resistant to heat. This study aimed to investigate the effects of heat stress on the genetics of monthly egg production and examine the threshold point of heat stress for preventing thermal stress and its effects on chicken productivity. The data of 5,965 monthly egg production records of 629 Thai native Pradu Hang dum chickens were used for analysis in combination with the temperature-humidity index (THI) calculated by meteorological data near the testing station. The average THI throughout the year was 76.6, and the highest was 82. The THI data were subsequently used to find the threshold point of heat stress. The THI equation used in this study was chosen by its highest correlation (-0.306) between THI values and monthly egg production. At a THI of 74, the lowest -2 logL was found and was considered the threshold point of heat stress. This means that monthly egg production would start decreasing when the THI was 74. Heritability was 0.15±0.03, and genetic and permanent environmental correlations were -0.29 and -0.48, respectively. The threshold point was used to estimate the estimated breeding values (EBVs) of the monthly egg production and heat stress individually, and EBVs were calculated into the selection index. The selection index values when the animal was selected for the replacement herd for all chickens (top 50%, 30%, 20%, and 10%) were 0.14, 0.90, 1.27, 1.53, and 1.91, respectively, and the genetic progress was 0.55, 0.60, 0.68, 0.75, and 0.77, respectively. This shows that the selection index values are lower if there are many selected animals. The recommendation for animal genetic selection is that the top 10% is appropriately because it seems to be most preferred. Therefore, using a selection index for high egg production and heat tolerance in Thai native chickens is possible to achieve genetic assessment in a large population.

Probiotic mediated intestinal microbiota and improved performance, egg quality and ovarian immune function of laying hens at different laying stage

In order to investigate the effects of dietary probiotics supplementation on laying performance, egg quality, serum hormone levels, immunity, antioxidant, and gut microbiota of layers at different laying stages, a total of 168 Tianfu green shell laying hens (28-day-old) were randomly divided into 2 treatments: a non-supplemented control diet (NC), and diet supplemented with 10 g/kg of probiotics, respectively. Each treatment had 6 replicates with 14 hens per replicate. The feeding trial lasted for 54 weeks. The results showed that the supplementation of probiotics significantly increased the average egg weight, improved egg quality (p < 0.05) and ovarian development. Meanwhile, probiotics increased the serum hormone levels of E2 and FSH, and antioxidant indices T-AOC and T-SOD (p < 0.05) of laying hens at different laying stages (p < 0.05), decreased the expression of proinflammatory factors including IL-1, IL-6 and TNF-α (p < 0.05). Furthermore, using 16S rRNA sequencing, we observed that the addition of probiotics increased the distribution of Firmicutes, Bacteroidota and Synergistota at early laying period. Meanwhile, Bacteroidota, Actinobacteriota, Verrucomicrobiota and Deferribacterota showed an increasing trend at the peak of egg production. The relative abundance of Firmicutes, Desulfobacterota and Actinobacteriota were significantly increased at the late laying period. Moreover, PICRUSt2 and BugBase analysis revealed that at the late laying period, the probiotics supplementation not only enriched many significant gene clusters of the metabolism of terpenoids and polyketide, genetic information processing, enzyme families, translation, transcription, replication and repair, and nucleotide metabolism, but also decreased the proportion of potential pathogenic bacteria. To sum up, these data show that the addition of probiotics not only improves the performance, egg quality, ovarian development and immune function of laying hens at different laying period, but also improves the gut microbiota of layers, thus enhances production efficiency.

The effect of Bacillus subtilis and its delivery route on hatch and growth performance, blood biochemistry, immune status, gut morphology, and microbiota of broiler chickens

This study evaluated the effect of probiotics (Bacillus subtilis fermentation extract) and its delivery route (in-feed or in ovo) on hatch and growth performance, blood biochemistry, immune status, gut morphology, and microbiota of broiler chickens. Hatching eggs were incubated for 21 d. On d 12, viable eggs were randomly allotted to 4 groups: the noninjected, in ovo saline (S), in ovo Bacillus subtilis 1 (P1), and in ovo Bacillus subtilis 2 (P2). On d 18, S, P1, and P2 groups received 0.2 mL saline diluent, 10 × 10⁶, and 20 × 10⁶ CFU of the bacterium via the amnion, respectively. At hatch, chicks were re-allotted to 5 new treatment groups: P1, P2, 0.005% in-feed Bacillus subtilis extract (P3), 0.05% in-feed bacitracin methylene disalicylate (BMD,), and corn-wheat-soybean diet negative control (NC) in 9 replicate pens (22 birds/pen) and raised for 35 d. Hatch parameters were assessed on d 0, and growth performance indices measured weekly. On d 25, 1 bird/cage was euthanized, and samples collected for further analysis. Data were analyzed by generalized linear model. Treatments S and P2 recorded higher (P = 0.01) chick BW/ Egg Weight values compared to the non-injected eggs. P3 and P2 reduced (P = 0.02) FI at week 5 compared to the NC treatment. However, no change in average body weight gain (ABG) and feed conversion ratio (FCR) were observed during the same period. At d 35, while BMD treatment showed a tendency (P = 0.09) to increase FI compared to the NC treatment, ABG and FCR were similar for all treatments. Blood sodium and chloride levels were increased (P < 0.05) by the BMD treatment compared to the NC treatment. Compared to other treatments, BMD and P3 treatments increased (P < 0.001) jejunal and ileal villus height to crypt depth ratios, respectively. However, P1 and P2 increased (P < 0.001) villus height to crypt depth ratio in the duodenum compared to NC treatment. Treatments did not affect gut microbial diversity; however, BMD treatment increased (P < 0.05) the proportion of bacteria in the genus Enterococcus in the ileum and reduced (P < 0.05) the proportion of bacteria in the genus Streptococcus in the ceca. All probiotics treatments (irrespective of route and dose) reduced (P < 0.001) the levels of serum IgG compared to the NC treatment. However, P1 and P2 had the lowest numerical decrease in serum IgG concentrations, suggesting that Bacillus subtilis (especially in ovo delivered) might provide broiler chickens with better immunological protection by neutralizing pathogenic organisms that could result in the production of natural antibodies.

Dietary replacement of soybean meal by fermented feedstuffs for aged laying hens: effects on laying performance, egg quality, nutrient digestibility, intestinal health, follicle development, and biological parameters in a long-term feeding period

This study aimed to investigate the effects of dietary supplementation with fermented soybean meal (FSM) or fermented miscellaneous meal (FMM, cottonseed meal: coconut meal = at a 1:1 ratio) on the intestinal health, laying performance, egg quality, and follicle development of laying hens. A total of 1,008 54-wk-old laying hens were randomly divided into 7 treatment groups and fed a corn-soybean base diet in addition to 2%, 4%, and 8% FSM or FMM. The results showed that fermentation increased the contents of crude protein, amino acids (Ser, Gly, Cys, Leu, Lys, His, and Arg), and organic acids (butyric acid, citric acid, succinic acid) and decreased the contents of neutral and acid detergent fiber in the soybean and miscellaneous meals (P < 0.05). Compared with the results found for the control group, feeding with 4% FSM increased the egg production, egg mass and average daily feed intake (ADFI), and feeding with 4% FMM increased the ADFI of laying hens (P < 0.05). Furthermore, feeding with 8% FMM reduced the productive performance and laying performance, supplementation with 4% FSM increased the eggshell strength and weight, and 2 to 4% FSM increased the egg albumen height and Haugh unit (P < 0.05). Moreover, 2 to 8% FSM or 2 to 4% FMM enhanced the apparent digestibility of dry matter, crude protein, and NDF for laying hens (P < 0.05). The relative weight, villus height, crypt depth, and villus:crypt ratio of the jejunum were higher in the 4% FSM- and FMM-fed groups (P < 0.05). Moreover, diamine oxidase (DAO) activity, transepithelial electrical resistance (TEER), and the expression of tight junction proteins (ZO-1, Occluding, and Claudin1), the intestinal stem cell marker Lgr5, and the proliferation cell marker proliferating cell nuclear antigen (PCNA) was upregulated in the jejunum of laying hens fed 4% FSM and FMM (P < 0.05). The relative weight of the ovaries, and the number of small yellow follicles and large white follicles were elevated after 4% FSM or FMM supplementation. Furthermore, the levels of serum follicle-stimulating hormone and luteinizing hormone were increased in the 4% FSM and FMM groups (P < 0.05). In conclusion, the supplementation of laying hen feed with FSM and FMM improved the laying performance, egg quality, intestinal barrier function, and follicle development of aged laying hens, and 4% FSM supplementation was optimal.

Gene expression networks and functionally enriched pathways involved in the response of domestic chicken to acute heat stress

Heat stress in poultry houses, especially in warm areas, is one of the main environmental factors that restrict the growth of broilers or laying performance of layers, suppresses the immune system, and deteriorates egg quality and feed conversion ratio. The molecular mechanisms underlying the response of chicken to acute heat stress (AHS) have not been comprehensively elucidated. Therefore, the main object of the current work was to investigate the liver gene expression profile of chickens under AHS in comparison with their corresponding control groups, using four RNA-seq datasets. The meta-analysis, GO and KEGG pathway enrichment, WGCNA, machine-learning, and eGWAS analyses were performed. The results revealed 77 meta-genes that were mainly related to protein biosynthesis, protein folding, and protein transport between cellular organelles. In other words, under AHS, the expression of genes involving in the structure of rough reticulum membrane and in the process of protein folding was adversely influenced. In addition, genes related to biological processes such as "response to unfolded proteins," "response to reticulum stress" and "ERAD pathway" were differentially regulated. We introduce here a couple of genes such as HSPA5, SSR1, SDF2L1, and SEC23B, as the most significantly differentiated under AHS, which could be used as bio-signatures of AHS. Besides the mentioned genes, the main findings of the current work may shed light to the identification of the effects of AHS on gene expression profiling of domestic chicken as well as the adaptive response of chicken to environmental stresses.

Chronic heat stress part 1: Decrease in egg quality, increase in cortisol levels in egg albumen, and reduction in fertility of breeder pekin ducks

Global warming poses detrimental effects on poultry production leading to substantial economic losses. The goal of our experiment was to test the hypothesis that heat stress (HS) would alter welfare and egg quality (EQ) of breeder ducks. Furthermore, we wanted to test if HS would increase cortisol levels in egg albumen. Adult Pekin ducks were randomly assigned to two different rooms at 85% lay with 60 hens and 20 drakes per room. Baseline data including body weight, body condition scores (BCS), and egg production/quality were collected the week preceding heat treatment. Ducks were subjected to cyclic HS of 35°C for 10h/day and 29.5°C for the remaining 14h/day for 3 weeks while the control room was maintained at 22°C. Eggs were collected daily and analyzed weekly for quality assessment, and for albumen glucocorticoid (GCs) levels using mass spectrometry. One week before the exposure to HS, 10 hens and 5 drakes were euthanized and the same number again after 3 weeks and birds necropsied. Data analyses were done by 1- or 2-way ANOVA as appropriate with a Tukey-Kramer post hoc test. BCS were analyzed using a chi-squared test. A p ≤ 0.05 was considered significant. Circulating levels of corticosterone were significantly (p < 0.01) elevated at week 1 only in the HS hens. The circulating levels of cortisol increased significantly at week 1 and 2 (p < 0.05), and week 3 (p < 0.01) in the hens and at weeks 2 and 3 only (p < 0.05) in the drakes. Feather quality scores (p < 0.01), feather cleanliness scores (p < 0.001) and footpad quality scores (p < 0.05) increased significantly in the HS group. HS elicited a significant (p < 0.001) decrease in egg production at weeks 1 and 3. Hens in the HS group showed significantly decreased BW (p < 0.001) and number of follicles (p < 0.05). Shell weight decreased significantly at week 1 only (p < 0.05) compared to controls. Yolk weight decreased significantly at week 3 (p < 0.01) compared to controls. HS elicited a significant increase in albumen cortisol levels at week 1 (p < 0.05) and week 3 (p < 0.05). Thus, cortisol may provide critical information to further understand and to improve welfare.

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.

Effects of Dietary Rutin Supplementation on the Intestinal Morphology, Antioxidant Capacity, Immunity, and Microbiota of Aged Laying Hens

This research investigated the effects of dietary rutin supplementation on the intestinal morphology, antioxidant capacity, immunity, and microbiota of aged laying hens. The results showed that 500 mg/kg rutin supplementation increased the villus height of jejunum (P < 0.05). Rutin affected the immune system of the ileum and the jejunum. In the jejunum, a diet with 500 mg/kg rutin supplementation enhanced secretory immunoglobulin A (sIgA) and reduced tumor necrosis factor-α (TNF-α) levels (P < 0.05). A diet with 1000 mg/kg rutin supplementation increased jejunal sIgA, immunologlobulin M (IgM), and interleukin-4 (IL-4) levels while decreasing interleukin-1β (IL-1β), TNF-α, and interferon-γ (IFN-γ) levels (P < 0.05). Meanwhile, a diet with 500 mg/kg rutin increased sIgA, immunologlobulin G (IgG), IgM, and interleukin-10 (IL-10) levels and reduced TNF-α and IFN-γ levels in the ileum (P < 0.05). In the ileum, a diet with 1000 mg/kg rutin supplementation raised sIgA, IgG, IgM, IL-4, and IL-10 levels while decreasing IL-1β, TNF-α, and IFN-γ levels (P < 0.05). At the family level, a diet with 500 mg/kg rutin supplementation raised the relative abundance of Monoglobaceae and decreased the relative abundance of Eubacteriaceae (P < 0.05) compared to the control group. In the 1000 mg/kg rutin group, the relative abundance of Lactobacillaceae and Unclassified Coriobacteriale was considerably lower and the relative abundance of Monoglobaceae was higher than the control group (P < 0.05). This study showed that a diet with rutin supplementation can improve the intestinal health of aged laying hens, and the mechanism is related to improving the intestinal morphology and intestinal immune status, and regulating the intestinal microbes.

Influence of Heat Stress on Poultry Growth Performance, Intestinal Inflammation, and Immune Function and Potential Mitigation by Probiotics

Simple Summary

The poultry industry sustains severe economic loss under heat stress conditions. Heat stress adversely affects the productivity, physiological status, and immunity of birds. To date, several mitigation measures have been adopted to minimize the negative effects of heat stress in poultry. Nutritional strategies have been explored as a promising approach to mitigate heat stress-associated deleterious impacts. Of these, probiotic feeding has a strong potential as a nutritional strategy, and this approach warrants further investigation to improve thermotolerance in poultry.

Abstract

Heat stress has emerged as a serious threat to the global poultry industry due to climate change. Heat stress can negatively impact the growth, gut health, immune function, and production and reproductive performances of poultry. Different strategies have been explored to mitigate heat stress in poultry; however, only a few have shown potential. Probiotics are gaining the attention of poultry nutritionists, as they are capable of improving the physiology, gut health, and immune system of poultry under heat stress. Therefore, application of probiotics along with proper management are considered to potentially help negate some of the negative impacts of heat stress on poultry. This review presents scientific insight into the impact of heat stress on poultry health and growth performance as well as the application of probiotics as a promising approach to alleviate the negative effects of heat stress in poultry.

Effect of chronic heat stress on gastrointestinal histology and expression of feed intake-regulatory hormones in broiler chickens

Heat stress (HS) dramatically impairs the growth performance of broiler chickens, mainly as a consequence of reduced feed intake due to the loss of appetite. This study was aimed at evaluating the alterations induced by chronic HS conditions on the morphological and morphometric features of the gastrointestinal (GI) tract and on the expression of some enteroendocrine cells (EECs) involved in the regulation of feed intake in chickens. Three hundred male chickens (Ross 308) were divided into two experimental groups and raised either in thermoneutral environment for the whole fattening period (0-41 days) (TNT group) or subjected to chronic HS conditions (30 °C for 24 h/day) from 35 to 41 days (HS group). Samples of proventriculus, duodenum, jejunum and cecum were collected from 24 broilers (12/group). Haematoxylin-eosin was used for the morphometric evaluations, while immunohistochemistry was applied for the evaluation of EECs expressing ghrelin (GHR), cholecystokinin (CCK), neuropeptide Y (NPY), glucagon-like peptide-1 (GLP-1), and serotonin (5-HT). In the proventriculus, HS reduced total wall thickness and mucous layer height (P ≤ 0.01) as well as mean diameter, circumference, and area of the compound tubular glands (P ≤ 0.001) with respect to TNT. The small intestine of HS birds was characterised by decreased villous height and total thickness (duodenum, P ≤ 0.01; jejunum, P ≤ 0.001), whereas crypt depth and width were reduced only in the jejunum (P ≤ 0.01). HS had negligible effects on the morphological aspects of the cecum. In the proventriculus, an increase in GHR and NPY EECs was observed in response to HS (P ≤ 0.001). Similarly, the small intestine villi of the HS group showed greater GLP-1 (P ≤ 0.05), 5-HT (P ≤ 0.001) and CCK (P ≤ 0.01) EECs. Moreover, the expression of 5-HT EECs was higher in the duodenal (P ≤ 0.01) and jejunal (P ≤ 0.01) crypts of HS birds, whereas GLP-1 and CCK EECs increased only in jejunal crypts (P ≤ 0.05). Finally, 5-HT EEC expression was increased in the cecum of HS group (P ≤ 0.01). In conclusion, these outcomes demonstrate that chronic HS induces morphometric alterations not only in the small intestine but also in a key organ such as the proventriculus. Furthermore, HS conditions affect the presence and distribution of EECs, suggesting that some GI peptides and biogenic amine may be implicated in the regulation of appetite and voluntary feed intake in heat-stressed broiler chickens.