A review of heat stress in chickens. Part II: Insights into protein and energy utilization and feeding

With the growing global demand for animal protein and rising temperatures caused by climate change, heat stress (HS) is one of the main emerging environmental challenges for the poultry industry. Commercially-reared birds are particularly sensitive to hot temperatures, so adopting production systems that mitigate the adverse effects of HS on bird performance is essential and requires a holistic approach. Feeding and nutrition can play important roles in limiting the heat load on birds; therefore, this review aims to describe the effects of HS on feed intake (FI) and nutrient digestibility and to highlight feeding strategies and nutritional solutions to potentially mitigate some of the deleterious effects of HS on broiler chickens. The reduction of FI is one of the main behavioral changes induced by hot temperatures as birds attempt to limit heat production associated with the digestion, absorption, and metabolism of nutrients. Although the intensity and length of the heat period influences the type and magnitude of responses, reduced FI explains most of the performance degradation observed in HS broilers, while reduced nutrient digestibility appears to only explain a small proportion of impaired feed efficiency following HS. Targeted feeding strategies, including feed restriction and withdrawal, dual feeding, and wet feeding, have showed some promising results under hot temperatures, but these can be difficult to implement in intensive rearing systems. Concerning diet composition, feeding increased nutrient and energy diets can potentially compensate for decreased FI during HS. Indeed, high energy and high crude protein diets have both been shown to improve bird performance under HS conditions. Specifically, positive results may be obtained with increased added fat concentrations since lipids have a lower thermogenic effect compared to proteins and carbohydrates. Moreover, increased supplementation of some essential amino acids can help support increased amino acid requirements for maintenance functions caused by HS. Further research to better characterize and advance these nutritional strategies will help establish economically viable solutions to enhance productivity, health, welfare, and meat quality of broilers facing HS

Effect of Cyclic Heat Stress on Feeding-Related Hypothalamic Neuropeptides of Three Broiler Populations and Their Ancestor Jungle Fowl

open6siThis study was supported by a grant from the Arkansas Division of Agriculture, Animal Health Awards (to SD and SO) and from USDA-AFRI Sustainable Agriculture Systems (2019-69012-29905) to SD.Heat stress (HS) has been increasingly jeopardizing the sustainability of the poultry production. Moreover, modern high-performing chickens are far less able to withstand HS than their predecessors due to higher growth rate and metabolic rates. Performance losses caused by HS are mainly ascribed to decreases in feed consumption. Since feed intake is tightly controlled by the hypothalamic centers of hunger and satiety, we sought to determine the effect of chronic cyclic HS on the expression of feedingrelated hypothalamic neuropeptides (FRHN) in unselected chickens (i.e., the ancestor junglefowl—JF) and three broiler lines from diverse stages of genetic selection (i.e., the slow growing ACRB, the moderate growing 95RN, and the fast growing MRB). From 29 to 56 days, birds (n = 150 birds for each population) were subjected to either thermoneutral (TN, 25C) or cyclic heat stress (HS, 36C, 0900–1,800 h) conditions. Molecular data were analyzed by two-way ANOVA with interaction between the main factors, namely environmental temperature and line. The expression of major FHRN, like neuropeptide Y, agouti-related peptide, proopiomelanocortin, and cocaine and amphetamine regulated transcript remained unchanged. However, melanocortin receptor 1 exhibited a line-dependent decreasing trend from JF to MRB under both TN and HS (p = 0.09), adiponectin expression showed a distinct trend toward significance with 95RB exhibiting the highest mRNA level irrespective of the environmental temperature (p = 0.08), and JF had a greater mRNA abundance of visfatin than ACRB under TN (p < 0.05). The hypothalamic integration of circadian information, acclimation to long-lasting HS exposure, stable ypothalamic pathways unaffected by evolution and genetic selection, focus on mRNA abundances, and use of the entire hypothalamus masking gene expression in specific hypothalamic nuclei are all possible explanations for the lack of variations observed in this study. In conclusion, this is the first assessment of the impacts of heat stress on feeding-related hypothalamic neuropeptides of chicken, with a valuable and informative comparison between the ancestor junglefowl and three differently performing broiler lines.openGiorgio Brugaletta, Elizabeth Greene, Travis Tabler, Sara Orlowski, Federico Sirri, Sami DridiGiorgio Brugaletta, Elizabeth Greene, Travis Tabler, Sara Orlowski, Federico Sirri, Sami Drid

A review of heat stress in chickens. Part I: Insights into physiology and gut health

Heat stress (HS) compromises the yield and quality of poultry products and endangers the sustainability of the poultry industry. Despite being homeothermic, chickens, especially fast-growing broiler lines, are particularly sensitive to HS due to the phylogenetic absence of sweat glands, along with the artificial selection-caused increase in metabolic rates and limited development of cardiovascular and respiratory systems. Clinical signs and consequences of HS are multifaceted and include alterations in behavior (e.g., lethargy, decreased feed intake, and panting), metabolism (e.g., catabolic state, fat accumulation, and reduced skeletal muscle accretion), general homeostasis (e.g., alkalosis, hormonal imbalance, immunodeficiency, inflammation, and oxidative stress), and gastrointestinal tract function (e.g., digestive and absorptive disorders, enteritis, paracellular barrier failure, and dysbiosis). Poultry scientists and companies have made great efforts to develop effective solutions to counteract the detrimental effects of HS on health and performance of chickens. Feeding and nutrition have been shown to play a key role in combating HS in chicken husbandry. Nutritional strategies that enhance protein and energy utilization as well as dietary interventions intended to restore intestinal eubiosis are of increasing interest because of the marked effects of HS on feed intake, nutrient metabolism, and gut health. Hence, the present review series, divided into Part I and Part II, seeks to synthesize information on the effects of HS on physiology, gut health, and performance of chickens, with emphasis on potential solutions adopted in broiler chicken nutrition to alleviate these effects. Part I provides introductory knowledge on HS physiology to make good use of the nutritional themes covered by Part II

Feeding broiler chickens with arginine above recommended levels: effects on growth performance, metabolism, and intestinal microbiota

BackgroundArginine is an essential amino acid for chickens and feeding diets with arginine beyond the recommended levels has been shown to influence the growth performance of broiler chickens in a positive way. Nonetheless, further research is required to understand how arginine supplementation above the widely adopted dosages affects metabolism and intestinal health of broilers. Therefore, this study was designed to assess the effects of arginine supplementation (i.e., total arginine to total lysine ratio of 1.20 instead of 1.06-1.08 recommended by the breeding company) on growth performance of broiler chickens and to explore its impacts on the hepatic and blood metabolic profiles, as well as on the intestinal microbiota. For this purpose, 630 one-day-old male Ross 308 broiler chicks were assigned to 2 treatments (7 replicates each) fed a control diet or a crystalline L-arginine-supplemented diet for 49 d.ResultsCompared to control birds, those supplemented with arginine performed significantly better exhibiting greater final body weight at D49 (3778 vs. 3937 g; P < 0.001), higher growth rate (76.15 vs. 79.46 g of body weight gained daily; P < 0.001), and lower cumulative feed conversion ratio (1.808 vs. 1.732; P < 0.05). Plasma concentrations of arginine, betaine, histidine, and creatine were greater in supplemented birds than in their control counterparts, as were those of creatine, leucine and other essential amino acids at the hepatic level. In contrast, leucine concentration was lower in the caecal content of supplemented birds. Reduced alpha diversity and relative abundance of Firmicutes and Proteobacteria (specifically Escherichia coli), as well as increased abundance of Bacteroidetes and Lactobacillus salivarius were found in the caecal content of supplemented birds.ConclusionsThe improvement in growth performance corroborates the advantages of supplementing arginine in broiler nutrition. It can be hypothesized that the performance enhancement found in this study is associated with the increased availability of arginine, betaine, histidine, and creatine in plasma and the liver, as well as to the ability of extra dietary arginine to potentially ameliorate intestinal conditions and microbiota of supplemented birds. However, the latter promising property, along with other research questions raised by this study, deserve further investigations

Effect of Cyclic Heat Stress on Hypothalamic Oxygen Homeostasis and Inflammatory State in the Jungle Fowl and Three Broiler-Based Research Lines

Heat stress (HS) is devastating to poultry production sustainability due its detrimental effects on performance, welfare, meat quality, and profitability. One of the most known negative effects of HS is feed intake depression, which is more pronounced in modern high-performing broilers compared to their ancestor unselected birds, yet the underlying molecular mechanisms are not fully defined. The present study aimed, therefore, to determine the hypothalamic expression of a newly involved pathway, hypoxia/oxygen homeostasis, in heat-stressed broiler-based research lines and jungle fowl. Three populations of broilers (slow growing ACRB developed in 1956, moderate growing 95RB from broilers available in 1995, and modern fast growing MRB from 2015) and unselected Jungle fowl birds were exposed to cyclic heat stress (36 degrees C, 9 h/day for 4 weeks) in a 2 x 4 factorial experimental design. Total RNAs and proteins were extracted from the hypothalamic tissues and the expression of target genes and proteins was determined by real-time quantitative PCR and Western blot, respectively. It has been previously shown that HS increased core body temperature and decreased feed intake in 95RB and MRB, but not in ACRB or JF. HS exposure did not affect the hypothalamic expression of HIF complex, however there was a line effect for HIF-1 alpha (P = 0.02) with higher expression in JF under heat stress. HS significantly up regulated the hypothalamic expression of hemoglobin subunits (HBA1, HBBR, HBE, HBZ), and HJV in ACRB, HBA1 and HJV in 95RB and MRB, and HJV in JF, but it down regulated FPN1 in JF. Additionally, HS altered the hypothalamic expression of oxygen homeostasis- up and down-stream signaling cascades. Phospho-AMPK(Thr172) was activated by HS in JF hypothalamus, but it decreased in that of the broiler-based research lines. Under thermoneutral conditions, p-AMPK(Thr172) was higher in broiler-based research lines compared to JF. Ribosomal protein S6K1, however, was significantly upregulated in 95RB and MRB under both environmental conditions. HS significantly upregulated the hypothalamic expression of NF-kappa B2 in MRB, RelB, and TNF alpha in ACRB, abut it down regulated RelA in 95RB. The regulation of HSPs by HS seems to be family- and line-dependent. HS upregulated the hypothalamic expression of HSP60 in ACRB and 95RB, down regulated HSP90 in JF only, and decreased HSP70 in all studied lines. Taken together, this is the first report showing that HS modulated the hypothalamic expression of hypoxia- and oxygen homeostasis-associated genes as well as their up- and down-stream mediators in chickens, and suggests that hypoxia, thermotolerance, and feed intake are interconnected, which merit further in-depth investigations

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

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

Impact of trans-stent gradient on outcome after PCI: results from a HAWKEYE substudy

To test whether quantitative flow ratio (QFR)-based trans-stent gradient (TSG) is associated with adverse clinical events at follow-up. A post-hoc analysis of the multi-center HAWKEYE study was performed. Vessels post-PCI were divided into four groups (G) as follows: G1: QFR >= 0.90 TSG = 0 (n = 412, 54.8%); G2: QFR >= 0.90, TSG > 0 (n = 216, 28.7%); G3: QFR < 0.90, TSG = 0 (n = 37, 4.9%); G4: QFR < 0.90, TSG > 0 (n = 86, 11.4%). Cox proportional hazards regression model was used to analyze the effect of baseline and prognostic variables. The final reduced model was obtained by backward stepwise variable selection. Receiver operating characteristic (ROC) was plotted and area under the curve (AUC) was calculated and reported. Overall, 449 (59.8%) vessels had a TSG = 0 whereas (40.2%) had TSG > 0. Ten (2.2%) vessel-oriented composite endpoint (VOCE) occurred in vessels with TSG = 0, compared with 43 (14%) in vessels with TSG > 0 (p < 0.01). ROC analysis showed an AUC of 0.74 (95% CI: 0.67 to 0.80; p < 0.001). TSG > 0 was an independent predictor of the VOCE (HR 2.95 [95% CI 1.77-4.91]). The combination of higher TSG and lower final QFR (G4) showed the worst long-term outcome while low TSG and high QFR showed the best outcome (G1) while either high TSG or low QFR (G2, G3) showed intermediate and comparable outcomes. Higher trans-stent gradient was an independent predictor of adverse events and identified a subgroup of patients at higher risk for poor outcomes even when vessel QFR was optimal (> 0.90)

Highly specific memory B cells generation after the 2nd dose of BNT162b2 vaccine compensate for the decline of serum antibodies and absence of mucosal IgA

Specific memory B cells and antibodies are a reliable read-out of vaccine efficacy. We analysed these biomarkers after one and two doses of BNT162b2 vaccine. The second dose significantly increases the level of highly specific memory B cells and antibodies. Two months after the second dose, specific antibody levels decline, but highly specific memory B cells continue to increase, thus predicting a sustained protection from COVID-19. We show that although mucosal IgA is not induced by the vaccination, memory B cells migrate in response to inflammation and secrete IgA at mucosal sites. We show that the first vaccine dose may lead to an insufficient number of highly specific memory B cells and low concentration of serum antibodies, thus leaving vaccinees without the immune robustness needed to ensure viral elimination and herd immunity. We also clarify that the reduction of serum antibodies does not diminish the force and duration of the immune protection induced by vaccination. The vaccine does not induce sterilizing immunity. Infection after vaccination may be caused by the lack of local preventive immunity because of the absence of mucosal IgA

Highly specific memory b cells generation after the 2nd dose of bnt162b2 vaccine compensate for the decline of serum antibodies and absence of mucosal iga

Specific memory B cells and antibodies are a reliable read-out of vaccine efficacy. We analysed these biomarkers after one and two doses of BNT162b2 vaccine. The second dose significantly increases the level of highly specific memory B cells and antibodies. Two months after the second dose, specific antibody levels decline, but highly specific memory B cells continue to increase, thus predicting a sustained protection from COVID-19. We show that although mucosal IgA is not induced by the vaccination, memory B cells migrate in response to inflammation and secrete IgA at mucosal sites. We show that the first vaccine dose may lead to an insufficient number of highly specific memory B cells and low concentration of serum antibodies, thus leaving vaccinees without the immune robustness needed to ensure viral elimination and herd immunity. We also clarify that the reduction of serum antibodies does not diminish the force and duration of the immune protection induced by vaccination. The vaccine does not induce sterilizing immunity. Infection after vaccination may be caused by the lack of local preventive immunity because of the absence of mucosal IgA

Evaluation of in-stent restenosis in the APPROACH trial (assessment on the prevention of progression by Rosiglitazone on atherosclerosis in diabetes patients with cardiovascular history)

To determine (1) the medium-term effect of rosiglitazone and glipizide on intra-stent neointima hyperplasia, (2) restenosis pattern as assessed by intra-vascular ultrasound (IVUS) and quantitative coronary angiography (QCA) in patients with T2DM and coronary artery disease. A total of 462 patients with T2DM were randomized to rosiglitazone or glipizide for up to 18 months in the APPROACH trial, and had evaluable baseline and follow-up IVUS examinations. There was no significant difference in the size of plaque behind stent between the rosiglitazone and glipizide groups at 18 months among those treated with a bare metal stent (−5.6 mm3 vs. 1.9 mm3; P = 0.61) or with a drug-eluting stent (12.1 mm3 vs. 5.5 mm3; P = 0.09). Similarly, there was no significant difference in percentage intimal hyperplasia volume between the rosiglitazone and glipizide groups at 18 months among those treated with a bare metal stent (24.1% vs. 19.8%; P = 0.38) or with a drug-eluting stent (9.8% vs. 8.3%; P = 0.57). QCA data (intra-stent late loss, intra-stent diameter stenosis or binary restenosis) were not different between the rosiglitazone and glipizide groups. This study suggests that both rosiglitazone and glipizide have a similar effect on neointimal growth at medium term follow-up, a finding that warrants investigation in dedicated randomized trials