Effects of the supplemental chromium form on performance and metabolic profile in laying hens exposed to heat stress

Effects of naked neck and frizzle genes on growth and egg-laying performance of chickens in the tropics in an era of climate change

In regions characterized by tropical and subtropical climates, the elevated ambient temperatures exert adverse effects on both broiler and laying chickens, impacting their growth and egg production performance. To mitigate the challenges posed by heat stress, genetic strategies aimed at reducing feather coverage have gained prominence in hot climate areas. Among these approaches, the naked neck (Na) and frizzle (F) genes have emerged as particularly noteworthy. The Na and F genes play a pivotal role in facilitating heat dissipation and temperature regulation. By decreasing feather insulation, these genes enable efficient heat dissipation through exposed areas of the chickens' bodies. This reduction in feather coverage leads to elevated body surface temperature, which, in turn, enhances the capacity for heat loss and contributes to overall body temperature reduction. A substantial body of literature underscores the well-established positive impacts of the naked neck and frizzle genes on growth and egg-laying performance. As a result, these genes hold significant potential for integration into broiler and layer production systems, especially in regions characterized by high tropical temperatures. In the context of broiler farming under challenging heat conditions, the Na and F genes have demonstrated favorable effects on crucial parameters such as feed conversion ratio, body weight gain, disease resistance, and carcass attributes. Likewise, layers exposed to elevated temperatures exhibit enhanced egg production, eggshell quality, fertility, hatchability, and resistance to diseases when these genes are incorporated. Given that the prevalence of the naked neck and frizzle genes is primarily observed in indigenous chicken populations, it becomes imperative to prioritize measures for their conservation due to their exceptional performance in heat-stressed environments. To unlock the full genetic potential of exotic poultry reared in hot and humid conditions, the integration of the Na and F genes is a strongly recommended strategy.

Understanding Cr(III) Action on Mitochondrial ATP Synthase and AMPK Efficacy: Insights from Previous Studies-a Review

Chromium supplementation has been notably recognized for its potential health benefits, especially in enhancing insulin sensitivity and managing glucose metabolism. However, recent studies have begun to shed light on additional mechanisms of action for chromium, expanding our understanding beyond its classical effects on the insulin-signaling pathway. The beta subunit of mitochondrial ATP synthase is considered a novel site for Cr(III) action, influencing physiological effects apart from insulin signaling. The physiological effects of chromium supplementation have been extensively studied, particularly in its role in anti-oxidative efficacy and glucose metabolism. However, recent advancements have prompted a re-evaluation of chromium's mechanisms of action beyond the insulin signaling pathway. The discovery of the beta subunit of mitochondrial ATP synthase as a potential target for chromium action is discussed, emphasizing its crucial role in cellular energy production and metabolic regulation. A meticulous analysis of relevant studies that were earlier carried out could shed light on the relationship between chromium supplementation and mitochondrial ATP synthase. This review categorizes studies based on their primary investigations, encompassing areas such as muscle protein synthesis, glucose and lipid metabolism, and antioxidant properties. Findings from these studies are scrutinized to distinguish patterns aligning with the new hypothesis. Central to this exploration is the presentation of studies highlighting the physiological effects of chromium that extend beyond the insulin signaling pathway. Evaluating the various independent mechanisms of action that chromium impacts cellular energy metabolism and overall metabolic balance has become more important. In conclusion, this review is a paradigm shift in understanding chromium supplementation, paving the way for future investigations that leverage the intricate interplay between chromium and mitochondrial ATP synthase.

Impact of β-glucan dietary supplementation on productive, reproductive performance and physiological response of laying hens under heat stress conditions

The exploration for effective in-feed additives is growing owing to the global climatic change trend to alleviate the negative effects of heat stress in laying hens. This research assessed the potential of using B-glucan (G) as an antiheat stress agent in Matrouh laying hens subjected to early heat shock programs during the growing period. Factorial design (3 × 3) was used, including 3 levels of heat stress (control, heat shock at 3 d and at 3 d and 8 wk of age) and 3 levels of β-glucan (0, 100, and 200 mg β-glucan /kg diet). During the first 12 wk of egg production (EP), treatments were exposed to heat challenge. The results revealed that heat shock program applications at 3 d and 8 wk of age significantly decreased body weight at 36 wk of age (P < 0.05) and reduced (P < 0.05) feed intake (FI). While significantly (P < 0.05) improved feed conversion ratio (FCR), hemoglobin, RBCs, WBCs, immunoglobulin M (IgM), immunoglobulin G (IgG), and Heat shock protein (HSP70) of the Liver (P < 0.01) as compared with the control group. At the same time, there was a decrease in lymphocyte%, H/L ratio, cortisol, and T3 compared to the thermo-neutral control. When compared to the control group, hens fed a diet containing 200 mg of βG significantly (P < 0.05) improved body weight at 16 wk and final weight at 36 wk, feed conversion (FCR) (g. feed/g. egg mass), hen-day egg production, and egg mass, as well as the digestibility coefficients of crude protein (CP), dry matter (DM), metabolizable energy (ME), and cortisol. The interactions between heat chock programs and βG levels were nonsignificant for the most studied traits except daily feed intake. Therefore, the early heat shock exposure 2 times and supplementation of Β-glucan (βG) at 200 mg/kg diet during the growth period for laying hens that are exposed to heat stress during the reproductive period could improve productive, reproductive performance, HSP70 level and enhance immunity responses.

The network regulation mechanism of the effects of heat stress on the production performance and egg quality of Jinding duck was analyzed by miRNA‒mRNA

To explore the differential regulation mechanism of heat stress on the egg production performance and egg quality of Jinding ducks, 200 Jinding ducks (360-day-old) in good health and with similar body weights and a normal appetite were selected and randomly divided into a control (normal temperature [NT]) group (20°C-25°C) and a heat stress (HS) group (32°C-36°C), with 4 replicates in each group and 25 ducks in each replicate. The pretrial period was 1 wk, and the formal trial period was 4 wk. At the end of the 4th wk, 12 duck eggs were collected from each replicate to determine egg quality. Pituitary and ovarian tissues of Jinding ducks were collected, transcriptome sequencing was performed to screen differentially expressed miRNAs and mRNAs related to high temperature and heat stress, and a competitive endogenous RNA regulatory network was constructed. The sequencing data were verified by qRT‒PCR method. The following results were obtained: (1) Compared with the NT group, the HS group had a significantly lower laying rate, total egg weight, average egg weight, total feed intake, and feed intake per duck (P < 0.01), an extremely significantly higher feed-to-egg ratio (P < 0.01), and a higher mortality rate. (2) Compared with the NT group, the HS group had an extremely significantly lower egg weight, egg yolk weight, eggshell weight, and eggshell strength (P < 0.01) and an extremely significantly lower yolk ratio and eggshell thickness (P < 0.01, P < 0.05); however, there was no significant difference in the egg shape index, Haugh unit or protein height (P > 0.05). (3) A total of 1,974 and 1,202 genes were identified in the pituitary and ovary, respectively, and there were 5 significantly differentially expressed miRNAs. The differentially expressed genes were involved in the arginine and proline metabolism pathways, ether lipid metabolism pathway, and drug metabolism-cytochrome P450 pathway, which are speculated to be related to the egg production performance of Jingding ducks under high-temperature heat stress. (4) Novel_221 may target the PRPS1 gene to participate in egg production performance; novel_168 and novel_289 may target PIGW; novel_289 may target Q3MUY2; and novel_289 and novel_208 may target PIGN or genes that may be related to high-temperature heat stress. (5) In pituitary tissue, upregulated novel_141 (center of the network) formed a regulatory network with HSPB1 and HSP30A, and downregulated novel_366 (center of the network) formed a regulatory network with the JIP1 gene. In ovarian tissue, downregulated novel_289 (center of the network) formed a regulatory network with the ZSWM7, ABI3, and K1C23 genes, novel_221 formed a regulatory network with the IGF1, BCL7B, SMC6, APOA4, and FARP2 genes, and upregulated novel_40 formed a regulatory network with the HA1FF10 gene. In summary, heat stress affects the production performance and egg quality of Jinding ducks by regulating the secretion of endocrine-related hormones and the release of neurotransmitters as well as the expression of miRNAs and mRNAs in pituitary and ovarian tissues. The miRNA‒mRNA regulatory network provides a theoretical basis for the molecular mechanism that regulates the stress response in pituitary and ovarian tissues, egg quality, and production performance under heat stress.

State of the art in research on the gut-liver and gut-brain axis in poultry

The relationship between the intestines and their microbiota, the liver, and the neuronal system is called the gut-liver-brain axis. This relationship has been studied and observed for a relatively short time but is considered in the development of research focused on, e.g., liver diseases and intestinal dysbiosis. The role of the gut microbiota in this relationship is crucial, as it acts on poultry's performance and feed utilization, affecting meat and egg quality. The correct composition of the intestinal microbiota makes it possible to determine the essential metabolic pathways and biological processes of the individual components of the microbiota, allowing further speculation of the role of microbial populations on internal organs such as the liver and brain in the organism. The gut microbiota forms a complex, dense axis with the autonomic and enteric nervous systems. The symbiotic relationship between the liver and gut microbiota is based on immune, metabolic and neuroendocrine regulation, and stabilization. On the other hand, the gut-brain axis is a bidirectional interaction and information transfer system between the gastrointestinal tract and the central nervous system. The following paper will discuss the current state of knowledge of the gut-liver-brain axis of poultry, including factors that may affect this complex relationship.

Spatial Variability of External Egg Quality in Vertical Naturally Ventilated Caged Aviaries

External egg quality is an essential parameter of egg production as it relates directly to economic losses. This study evaluated the spatial variability of external egg quality in five naturally ventilated caged vertical aviaries. Differences caused by bird age and thermal and luminous variability within aviaries during winter and summer were analyzed. Data on aviary air temperature, relative humidity, light intensity, and external egg quality were collected at evenly distributed points along the aviary length within three levels of cages. The experimental design was completely randomized in a factorial scheme. In the summer, the highest air temperature and lowest relative humidity were found in central cages, mainly in upper center cages; hens produced eggs with a lower weight and shape index in this area. Similar results were obtained in the winter. In the summer, eggs with lower shell weight and thickness were also produced by hens housed in the central cages, but in the winter, the opposite result was obtained. This study of the spatial variability of external egg quality proved efficient in detecting areas within an aviary with poor quality eggs; improvements to design and management in these areas could help management improve production efficiency and contribute to a sustainable egg supply.

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.

Alleviating effect of dietary supplementation of benzoic acid, Enterococcus faecium and essential oil complex on coccidia and Clostridium perfringens challenge in laying hens

The purpose of this experiment is to explore the effects of dietary supplementation of benzoic acid, Enterococcus faecium, and essential oil complex (BEC) on coccidia and Clostridium perfringens challenge in laying hens. A total of 80 Lohmann gray laying hens (35 wk old) were allocated to 4 treatments in a 2 × 2 factorial arrangement with the main effects of Clostridium perfringens type A (CP) and coccidia challenge (with or without challenge) and 2 BEC levels (0 and 1,000 mg/kg). The total experimental period was 6 wk. The results showed that: the challenge group significantly decreased the laying rate and average daily feed intake (ADFI) of laying hens (P_Challenge < 0.01). The BEC + challenge group significantly increased the laying rate and decreased the feed conversion ratio (FCR) of laying hens (P_BEC < 0.05). The challenge significantly decreased the thickness, strength, and relative weight of eggshell (P_Challenge < 0.05). The BCE + challenge group significantly increased the relative weight and strength of the eggshell (P_BEC < 0.05). The challenge significantly increased the crypt depth of the duodenum, jejunum and ileum, and decreased the villus-to-crypt ratio (V/C) (P_Challenge < 0.01). The BEC + challenge group decreased the crypt depth of the duodenum and jejunum, and increased the V/C of the duodenum (P_BEC < 0.01). The pathological scores of duodenum and jejunum of the challenge group were significantly higher than other groups (P_Challenge < 0.01), while the BEC + challenge group had lower pathological scores of jejunum (P_BEC < 0.01). The challenge significantly decreased the mRNA expression of Occludin, Mucin-2, Zonula occluden-1 (ZO-1) (P_challenge < 0.05); whereas the BEC group significantly increased the expression of Occludin, Mucin-2, and Claudin-1 mRNA (P_BEC < 0.05). The challenge significantly increased the level of interleukin 1β (IL-1β) in the jejunum (P_Challenge < 0.05). Taken together, adding BEC to the diet can improved production performance and egg quality of layers, by protecting intestinal health against Clostridium perfringens type A (CP) and coccidia challenge.

Effects of Supplemental Chromium Nanoparticles on IFN-γ expression of Heat Stress Broilers

The aim of present study was to investigate the beneficial effect of chromium (III) picolinate (CrPic) and chromium (III) picolinate nanoparticles (NCrPic) addition on growth performance, stress-related hormonal changes, and serum levels of various immunity biomarkers, as well as the gene expression of IFN-γ in broilers exposed to heat stress conditions. Treatments included T1 which received the basal diet with no feed additive; T2 exposed to heat stress; T3, T4, and T5 containing 500, 1000, and 1500 ppb CrPic; as well as T6, T7, and T8 containing 500, 1000, and 1500 ppb NCrPic, respectively. After 2 weeks from CrPic and NCrPic supplementation, IFN-γ mRNA expression was assayed using the RT-PCR technique. The results showed that the lower body weight, daily weight gain, daily feed intake by heat stress, and the feed conversion ratio were recovered remarkably by CrPic and NCrPic supplements. The stress-elevated levels of cortisol and immunoglobulin were reduced significantly using CrPic and NCrPic supplementation (P ≤ 0.05). The gene expression profile showed that the upregulated expression of IFN-γ was regulated by the addition of CrPic and NCrPic, in particular, to the diet; however, a full downregulation of IFN-γ expression was observed after week 2 of NCrPic supplementation. In conclusion, the results indicated that nanoparticle supplementation could be effective in reducing heat stress-induced detrimental alterations, thereby attributing to substantial changes to the immune system, including IFN-γ expression.

The Microbiota-Gut-Brain Axis During Heat Stress in Chickens: A Review

Heat stress is a global issue for the poultry industries with substantial annual economic losses and threats to bird health and welfare. When chickens are exposed to high ambient temperatures, like other species they undergo multiple physiological alterations, including behavioral changes, such as cessation of feeding, initiation of a stress signaling cascade, and intestinal immune, and inflammatory responses. The brain and gut are connected and participate in bidirectional communication via the nervous and humoral systems, this network collectively known as the gut-brain axis. Moreover, heat stress not only induces hyperthermia and oxidative stress at the gut epithelium, leading to impaired permeability and then susceptibility to infection and inflammation, but also alters the composition and abundance of the microbiome. The gut microflora, primarily via bacterially derived metabolites and hormones and neurotransmitters, also communicate via similar pathways to regulate host metabolic homeostasis, health, and behavior. Thus, it stands to reason that reshaping the composition of the gut microbiota will impact intestinal health and modulate host brain circuits via multiple reinforcing and complementary mechanisms. In this review, we describe the structure and function of the microbiota-gut-brain axis, with an emphasis on physiological changes that occur in heat-stressed poultry.

Tea Polyphenols Enhanced the Antioxidant Capacity and Induced Hsps to Relieve Heat Stress Injury

Keap1-Nrf2-ARE and heat shock proteins (Hsps) are important endogenous protection mechanisms initiated by heat stress to play a double protective role for cell adaptation and survival. H9C2 cells and 80 300-day-old specific pathogen-free chickens were randomly divided into the control and tea polyphenol groups and used to establish a heat stress model in vitro and in vivo. This task was conducted to explore the protection and mechanism of tea polyphenols in relieving thermal injury. A supplement with 10 μg/mL tea polyphenols could effectively relieve the heat damage of H9C2 cells at 42°C. Accordingly, weaker granular degeneration, vacuolar degeneration, and nucleus deep staining were shown. A strong antioxidant capacity was manifested in the upregulation of the total antioxidant capacity (T-AOC) (at 5 h, P < 0.05), Hemeoxygenase-1 mRNA (at 2 h, P < 0.01), superoxide dismutase (SOD) (at 2, 3, and 5 h, P < 0.05), and Nrf2 (at 0 and 5 h, P < 0.01). A high expression of Hsps was reflected in CRYAB at 3 h; Hsp27 at 0, 2, and 3 h (P < 0.01); and Hsp70 at 3 and 5 h (P < 0.01). The supplement with 0.2 g/L tea polyphenols in the drinking water also had a good effect in alleviating the heat stress damage of the myocardial cells of hens at 38°C. Accordingly, light pathological lesions and downregulation of the myocardial injury-related indicators (LDH, CK, CK-MB, and TNF-α) were shown. The mechanism was related to the upregulation of T-AOC (at 0 h, P < 0.05), GSH-PX (at 0.5 d, P < 0.01), SOD (at 0.5 d), and Nrf2 (at 0 d with P < 0.01 and 2 d with P < 0.05) and the induced expression of CRYAB (at 0.5 and 2 d), Hsp27 (at 0, 0.5, and 5 d), and Hsp70 (at 0 and 0.5 d). In conclusion, the tea polyphenols enhanced the antioxidant capacity and induced Hsps to relieve heat stress injury.

The Protective Effects of a Combination of an Arginine Silicate Complex and Magnesium Biotinate Against UV-Induced Skin Damage in Rats

The purpose of this study was to observe the effects of a novel combination of inositol-stabilized arginine silicate complex (ASI) and magnesium biotinate (MgB) on the prevention of skin damage after UVB exposure in rats. Forty-nine Sprague-Dawley rats were randomized into one of the following groups: (1) NC, normal control, (2) SC, shaved control, (3) UVB (exposed to UVB radiation), (4) ASI+MgB-L (Low Dose), (5) ASI+MgB-H (High Dose), (6) ASI+MgB-L+MgB cream, (7) ASI+MgB-H+MgB cream. The results showed that ASI+MgB treatment alleviated the macroscopic and histopathological damages in the skin of rats caused by UVB exposure. Skin elasticity evaluation showed a similar trend. ASI+MgB increased serum Mg, Fe, Zn, Cu, Si, biotin, and arginine concentrations and skin hydroxyproline and biotinidase levels while decreasing skin elastase activity (p < 0.05) and malondialdehyde (MDA) concentration (p < 0.001). Moreover, ASI+MgB treatment increased skin levels of biotin-dependent carboxylases (ACC1, ACC2, PC, PCC, MCC) and decreased mammalian target of rapamycin (mTOR) pathways and matrix metalloproteinase protein levels by the regulation of the activator protein 1 (AP-1), and mitogen activated protein kinases (MAPKs) signaling pathways. In addition, ASI+MgB caused lower levels of inflammatory factors, including TNF-α, NFκB, IL-6, IL-8, and COX-2 in the skin samples (p < 0.05). The levels of Bax and caspase-3 were increased, while anti-apoptotic protein Bcl-2 was decreased by UVB exposure, which was reversed by ASI+MgB treatment. These results show that treatment with ASI and MgB protects against skin damage by improving skin appearance, elasticity, inflammation, apoptosis, and overall health.

Heat stress on microbiota composition, barrier integrity, and nutrient transport in gut, production performance, and its amelioration in farm animals

Livestock species experience several stresses, particularly weaning, transportation, overproduction, crowding, temperature, and diseases in their life. Heat stress (HS) is one of the most stressors, which is encountered in livestock production systems throughout the world, especially in the tropical regions and is likely to be intensified due to global rise in environmental temperature. The gut has emerged as one of the major target organs affected by HS. The alpha- and beta-diversity of gut microbiota composition are altered due to heat exposure to animals with greater colonization of pathogenic microbiota groups. HS also induces several changes in the gut including damages of microstructures of the mucosal epithelia, increased oxidative insults, reduced immunity, and increased permeability of the gut to toxins and pathogens. Vulnerability of the intestinal barrier integrity leads to invasion of pathogenic microbes and translocation of antigens to the blood circulations, which ultimately may cause systematic inflammations and immune responses. Moreover, digestion of nutrients in the guts may be impaired due to reduced enzymatic activity in the digesta, reduced surface areas for absorption and injury to the mucosal structure and altered expressions of the nutrient transport proteins and genes. The systematic hormonal changes due to HS along with alterations in immune and inflammatory responses often cause reduced feed intake and production performance in livestock and poultry. The altered microbiome likely orchestrates to the hosts for various relevant biological phenomena occurring in the body, but the exact mechanisms how functional communications occur between the microbiota and HS responses are yet to be elucidated. This review aims to discuss the effects of HS on microbiota composition, mucosal structure, oxidant-antioxidant balance mechanism, immunity, and barrier integrity in the gut, and production performance of farm animals along with the dietary ameliorations of HS. Also, this review attempts to explain the mechanisms how these biological responses are affected by HS.

Climate change and heat stress: Impact on production, reproduction and growth performance of poultry and its mitigation using genetic strategies

Heat stress is an important environmental determinant which adversely affects the performance of poultry worldwide. The present communication reviews the impact of heat stress on production, reproduction and growth performance of poultry, and its alleviation using genetic strategies. The adverse effects of high environmental temperature on poultry include decrease in growth rate, body weight, egg production, egg weight, egg quality, meat quality, semen quality, fertility and hatchability, which cause vast financial losses to the poultry industry. High ambient temperature has an antagonistic effect on performance traits of the poultry. Thus, selection of birds for high performance has increased their susceptibility to heat stress. Additionally, heat burden during transportation of birds from one place to another leads to reduced meat quality, increased mortality and welfare issues. Molecular markers are being explored nowadays to recognize the potential candidate genes related to production, reproduction and growth traits for selecting poultry birds to enhance thermo-tolerance and resistance against diseases. In conclusion, there is a critical need of formulating selection strategies based on genetic markers and exploring more genes in addition to HSP25, 70, 90, H1, RB1CC, BAG3, PDK, ID1, Na, F, dw and K responsible for thermoregulation, to improve the overall performance of poultry along with their ability to tolerate heat stress conditions.

Effects of dietary chromium propionate on laying performance, egg quality, serum biochemical parameters and antioxidant status of laying ducks under heat stress

Recent studies have shown that chromium (Cr) could alleviate the negative effects of heat stress on livestock and poultry, but there is little information available to laying ducks. This study aimed to investigate the effects of dietary addition of chromium propionate on laying performance, egg quality, serum biochemical parameters and antioxidant status of laying ducks under hot (average 32 °C) and humid (average 75% relative humidity) summer conditions. A total of 900 66-week-old weight- and laying-matched Shanma laying ducks were randomly divided into five treatments, each with 6 replicates of 30 individually caged birds. The birds were fed either a basal diet or the basal diet supplemented with either 200, 400, 600, or 800 μg/kg Cr as chromium propionate. All laying ducks were given feed and water ad libitum for 5 weeks. The results showed that dietary supplementation with chromium propionate significantly increased the laying rate and yolk colour score (P < 0.05). Treatment with 400 μg/kg Cr as chromium propionate significantly decreased the feed/egg ratio by 5.4% (P < 0.05). Increased supplemental Cr from 0 to 800 μg/kg resulted in an increase in albumen height and the Haugh unit linearly (P < 0.05). Increased supplemental Cr decreased serum cortisol (P < 0.001, linear; P = 0.008, quadratic), heat shock protein-70 (P < 0.001, linear; P = 0.007, quadratic) and glucose (P = 0.007, linear), whereas it increased serum insulin (P = 0.011, Linear), total protein (P = 0.006, linear; P = 0.048, quadratic) and albumin (P = 0.035, linear; P = 0.088, quadratic). Dietary Cr levels increased the activities of superoxide dismutase and glutathione peroxidase, the total antioxidant capacity linearly and quadratically (P < 0.05). A linear and quadratic (P < 0.05) decrease of the malondialdehyde concentrations in response to dietary Cr level was observed. These results indicated that dietary supplementation of Cr as chromium propionate, particularly at 800 μg/kg could beneficially affect the laying rate, egg quality and antioxidant function, as well as modulate the blood biochemical parameters of laying ducks under heat stress conditions.

Estimated intestinal absorption of phosphorus and its deposition in chosen tissues, bones and feathers of chickens receiving chromium picolinate or chromium nanoparticles in diet

The aim of the study was to determine whether the level and form of Cr in the diet of chickens influences its accumulation in tissues as well as intestinal absorption of P and its deposition in tissues. The experiment was carried out on 405 one-day-old male Ross 308 chickens that were randomly divided into five treatment groups. Control group was fed the diet without supplemental chromium; experimental groups were fed the diet with 3 or 6 mg/kg chromium picolinate (Cr-Pic) and with 3 or 6 mg/kg chromium nanoparticles (Cr-NP). Chromium was found to accumulate in the tissues of the ileum, liver, breast muscle, bones skin and in feathers of chickens. Chromium deposited in the ileum of chickens does not affect the ex vivo estimated intestinal absorption of P. The use of Cr in the diet of chickens carries the risk of lowering P levels in femur.

Thermal stress consequences on growth performance, immunological response, antioxidant status, and profitability of finishing broilers: transcriptomic profile change of stress-related genes

The current study was conducted to investigate the impact of thermal stress on growth performance, blood biomarkers, metabolic hormones, immunological response, antioxidant activity, and expression of stress-related genes in broilers. One hundred and fifty one-day-old chicks (Ross 308) were utilized in this work. On the 21st day of age, birds were subjected to three environmentally controlled treatments with five replicate pens of 10 birds per each, representing an initial density of 10 birds/m²-control: reared in a thermoneutral condition; THS₁ and THS_2: exposed to 4 and 6 h of daily thermal stress at 40 ± 1 °C, respectively, until the 42 days of age. The results demonstrated that thermal stress for 4 and 6 h significantly reduced (P < 0.001) daily weight gain, daily feed intake, blood leukocyte and lymphocyte counts, serum immunoglobulins (IgM, IgA, IgG), and insulin-like growth factor-1 (IGF-1), while serum levels of aspartate aminotransferase, alanine aminotransferase, glucose, cholesterol, low-density lipoprotein, and lactate dehydrogenase were elevated relative to the thermoneutral group. Additionally, the corticosterone level and the ratio of heterophil:lymphocyte increased significantly (P < 0.001) in thermal-stressed groups. The antioxidant enzymes were affected by thermal stress as represented by a significant decrease in the activity of serum catalase (CAT) and glutathione peroxidase (GSH-Px) along with an increase in malonaldehyde concentration. Thermal stress affected gene expression by upregulating heat shock protein 70, heat shock factors 1 and 3, nuclear factor kappa B, interleukin-4, and uncoupling protein, and downregulating GSH-Px, CAT, and IGF-1 transcript levels. However, no changes were observed in interleukin-2 expression levels. It can be concluded that thermal stress destructively influences productivity, physiological status, and gene expression by upregulating heat shock protein 70, heat shock factors 1 and 3, nuclear factor kappa B, interleukin-4, and uncoupling protein, and downregulating GSH-Px, CAT, and IGF-1 transcript levels of broiler chickens.

Changes in the cecal microbiota of laying hens during heat stress is mainly associated with reduced feed intake

The aim of the present study was to examine the effect of high temperature on the cecal microbiota of laying hens and analyze the correlation between variation in feed intake, body temperature, and the relative abundance of specific bacterial genera. Two hundred and sixteen 28-wk-old Hy-Line laying hens were randomly divided into 3 groups with 6 replicates and raised in 3 controlled climate chambers. Birds were allocated to either a thermoneutral group (TC, 21 ± 1°C, ad libitum), high cyclic temperature group (HT, 29-35°C, ad libitum), or a pair-feeding group (PF, 21 ± 1°C, pair-feeding on the daily feed intake of HT hens) for 4 wk. There was no significant difference in diversity estimators of laying hens between the HT and TC or PF groups (P > 0.05). Principal component analysis (PCoA) based on unweighted UniFrac distance showed that the HT group did not form a distinct cluster that was clearly separated from the PF group, but was separated from the TC group. Similarity analysis (ANOSIM) confirmed that the TC group was significantly different from the HT (R = 0.259, P = 0.020) and the PF (R = 0.348, P = 0.011) groups, but the HT group was similar with the PF group (R = 0.107, P = 0.153). In addition, there was a significant correlation between feed intake and principal coordinate 1 (PC1) in PCoA (R = -0.494, P = 0.037), but no correlation between core temperature and PC1 (R = 0.025, P = 0.923). Linear discriminant analysis identified 15 genera that discriminated between the HT and TC groups (score ≥2). Among these, the feed intake was significantly related with the relative abundance of 10 genera, however, the core temperature was only significantly correlated with one specific genus. In conclusion, a high cyclic temperature of 29-35°C had significant effects on microbial composition and structure of laying hens, which was mainly related with decreased feed intake.

Effects of Sampling and Storage Method on Chicken Blood Glucose Measurement

Glucose is a major circulating carbohydrate in birds and its level in the blood is often used as a biometric indicator in clinical diagnosis and various studies. Notably, hypoglycemia is often associated with Spiking Mortality Syndrome in broilers; therefore, blood glucose levels need to be correctly evaluated in clinical diagnosis. In the present study, we investigated the effect of different blood treatment methods after blood collection on chicken blood glucose measurements. The blood glucose level of plasma separated from blood cell components immediately after blood collection was used as a reference and compared with glucose levels in serum and stored plasma. The mean glucose level in plasma separated from blood cell components immediately after blood collection was 236.1±15.9 mg/dL and remained stable for at least one week in refrigerated storage (between 2°C and 5°C). However, glucose levels decreased slowly in plasma unseparated from blood cell components in storage with ice water. Mean glucose level in serum separated from blood cell components 1 h after blood collection was 206.4±9.2 mg/dL and fell to 108.3±30.0 mg/dL after 24 h. Therefore, the chicken blood serum glucose level was significantly lower than the level in plasma immediately after blood collection, regardless of elapsed time after blood collection. For the measurement of glucose in chicken blood, it is necessary to use refrigeration, use plasma from which blood cell components have been removed, and take measurements within at least 30 min.

Heat stress management in poultry farms: A comprehensive overview

Heat stress causes significant economic losses in poultry production, especially in tropical and arid regions of the world. Several studies have investigated the effects of heat stress on the welfare and productivity of poultry. The harmful impacts of heat stress on different poultry types include decreased growth rates, appetites, feed utilization and laying and impaired meat and egg qualities. Recent studies have focused on the deleterious influences of heat stress on bird behaviour, welfare and reproduction. The primary strategies for mitigating heat stress in poultry farms have included feed supplements and management, but the results have not been consistent. This review article discusses the physiological effects of heat stress on poultry health and production and various management and nutritional approaches to cope with it.

Organic Chromium Form Alleviates the Detrimental Effects of Heat Stress on Nutrient Digestibility and Nutrient Transporters in Laying Hens

In the present study, we investigated the effects of chromium-picolinate (CrPic) and chromium-histidinate (CrHis) on nutrient digestibility and nutrient transporters in laying hens exposed to heat stress (HS). Hens (n = 1800; 16 weeks old) were kept in cages in temperature-controlled rooms at either 22 ± 2 °C for 24 h/day (thermoneutral (TN)) or 34 ± 2 °C for 8 h/day, from 08:00 to 17:00, followed by 22 °C for 16 h (HS) for 12 weeks. Hens reared under both environmental conditions were fed one of three diets: a basal diet and the basal diet supplemented with either 1.600 mg of CrPic (12.43% Cr) or 0.788 mg of CrHis (25.22% Cr) per kg of diet, delivering 200 μg elemental Cr per kg of diet. HS impaired the nutrient digestibility and nutrient transports in laying hens (P < 0.001). However, both Cr sources increased digestibility of dry matter (DM; P < 0.001), organic matter (OM; P < 0.05), crude protein (CP; P < 0.001), and crude fat (CF; P < 0.001). Both Cr sources partially alleviated detrimental effects of HS on fatty acid-binding and transport protein1 (FABP1, FATP1), glucose (SGLT1, GLUT1, GLUT10), protein (PepT1, PepT2), and amino acid transporters (ASCT1, b^o,+AT1, CAT1, EAAT1, LAT1) of the ileum (P < 0.0001). The efficacy of Cr as CrHis was more notable than Cr as CrPic, which could be attributed to higher bioavailability. Finally, the detrimental effects of HS on nutrient digestibility and nutrient transporters were alleviated by CrPic and CrHis. These findings may justify the use of CrPic and CrHis in poultry.

Systematic Review of the Effects of Chromium(III) on Chickens

Chromium supplementation has been proposed to have beneficial effects in farm animals, particularly when under stress. The last two decades, in particular, have seen an emphasis on examining the effects of supplemental chromium on a variety of variables in chicks and chickens. Thus, given the recent approval of a Cr(III) compound for use in chicken feed in the United States and the recent surge in papers on the use of Cr in chicken feed, the need for a systematic review of studies utilizing chickens is extremely urgent and timely. With the exception of studies on cold-stressed laying hens, the results of studies of Cr supplementation of chickens, whether broilers or laying hens, were found to be too inconsistent for any firm conclusions to be drawn other than that Cr supplementation generally leads to accumulation of Cr in tissues. Few potential trends in terms or beneficial or deleterious effects from Cr supplementation were found regardless of strain of chicken, Cr source, Cr dose, duration of supplementation, or variable examined. Hence, in summary, no recommendation for the use of Cr as a supplement for the diet of chickens can be made at this time.