Jejunal mucosa proteomics unravel metabolic adaptive processes to mild chronic heat stress in dairy cows

Proteomic identification of potential biomarkers for heat tolerance in Caracu beef cattle using high and low thermotolerant groups

BACKGROUND

Heat stress has deleterious effects on physiological and performance traits in livestock. Within this context, using tropically adapted cattle breeds in pure herds or terminal crossbreeding schemes to explore heterosis is attractive for increasing animal production in warmer climate regions. This study aimed to identify biological processes, pathways, and potential biomarkers related to thermotolerance in Caracu, a tropically adapted beef cattle breed, by proteomic analysis of blood plasma. To achieve this goal, 61 bulls had their thermotolerance evaluated through a heat tolerance index. A subset of 14 extreme animals, including the seven most thermotolerant (HIGH group) and the seven least thermotolerant (LOW group), had their blood plasma samples used for proteomic analysis by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). The differentially regulated proteins detected between HIGH and LOW groups were used to perform functional enrichment analysis and a protein-protein interaction network analysis.

RESULTS

A total of 217 proteins were detected only in the HIGH thermotolerant group and 51 only in the LOW thermotolerant group. In addition, 81 and 87 proteins had significantly higher and lower abundancies in the HIGH group, respectively. Regarding proteins with the highest absolute log-fold change values, we highlighted those encoded by DUSP5, IGFALS, ROCK2, RTN4, IRAG1, and NNT genes based on their functions. The functional enrichment analysis detected several biological processes, molecular functions, and pathways related to cellular responses to stress, immune system, complement system, and hemostasis in both HIGH and LOW groups, in addition to terms and pathways related to lipids and calcium only in the HIGH group. Protein-protein interaction (PPI) network revealed as important nodes many proteins with roles in response to stress, hemostasis, immune system, inflammation, and homeostasis. Additionally, proteins with high absolute log-fold change values and proteins detected as essential nodes by PPI analysis highlighted herein are potential biomarkers for thermotolerance, such as ADRA1A, APOA1, APOB, APOC3, C4BPA, CAT, CFB, CFH, CLU, CXADR, DNAJB1, DNAJC13, DUSP5, FGA, FGB, FGG, HBA, HBB, HP, HSPD1, IGFALS, IRAG1, KNG1, NNT, OSGIN1, PROC, PROS1, ROCK2, RTN4, RYR1, TGFB2, VLDLR, VTN, and VWF.

CONCLUSIONS

Identifying potential biomarkers, molecular mechanisms and pathways that act in response to heat stress in tropically adapted beef cattle contributes to developing strategies to improve performance and welfare traits in livestock under tropical climates.

Genomic regions and biological mechanisms underlying climatic resilience traits derived from automatically-recorded vaginal temperature in lactating sows under heat stress conditions

Climate change poses a growing threat to the livestock industry, impacting animal productivity, animal welfare, and farm management practices. Thus, enhancing livestock climatic resilience (CR) is becoming a key priority in various breeding programs. CR can be defined as the ability of an animal to be minimally affected or rapidly return to euthermia under thermally stressful conditions. The primary study objectives were to perform genome-wide association studies for 12 CR indicators derived from variability in longitudinal vaginal temperature in lactating sows under heat stress conditions. A total of 31 single nucleotide polymorphisms (SNPs) located on nine chromosomes were considered as significantly associated with nine CR indicators based on different thresholds. Among them, only two SNPs were simultaneously identified for different CR indicators, SSC6:16,449,770 bp and SSC7:39,254,889 bp. These results highlighted the polygenic nature of CR indicators with small effects distributed across different chromosomes. Furthermore, we identified 434 positional genes associated with CR. Key candidate genes include SLC3A2, STX5, POLR2G, and GANAB, which were previously related to heat stress responses, protein folding, and cholesterol metabolism. Furthermore, the enriched KEGG pathways and Gene Ontology (GO) terms associated with these candidate genes are linked to stress responses, immune and inflammatory responses, neural system, and DNA damage and repair. The most enriched quantitative trait loci are related to "Meat and Carcass", followed by "Production", "Reproduction", "Health", and "Exterior (conformation and appearance)" traits. Multiple genomic regions were identified associated with different CR indicators, which reveals that CR is a highly polygenic trait with small effect sizes distributed across the genome. Many heat tolerance or HS related genes in our study, such as HSP90AB1, DMGDH, and HOMER1, have been identified. The complexity of CR encompasses a range of adaptive responses, from behavioral to cellular. These results highlight the possibility of selecting more heat-tolerant individuals based on the identified SNP for CR indicators.

Proteomic changes of the bovine blood plasma in response to heat stress in a tropically adapted cattle breed

Background

Identifying molecular mechanisms responsible for the response to heat stress is essential to increase production, reproduction, health, and welfare. This study aimed to identify early biological responses and potential biomarkers involved in the response to heat stress and animal's recovery in tropically adapted beef cattle through proteomic analysis of blood plasma.

Methods

Blood samples were collected from 14 Caracu males during the heat stress peak (HSP) and 16 h after it (heat stress recovery-HSR) assessed based on wet bulb globe temperature index and rectal temperature. Proteome was investigated by liquid chromatography-tandem mass spectrometry from plasma samples, and the differentially regulated proteins were evaluated by functional enrichment analysis using DAVID tool. The protein-protein interaction network was evaluated by STRING tool.

Results

A total of 1,550 proteins were detected in both time points, of which 84 and 65 were downregulated and upregulated during HSR, respectively. Among the differentially regulated proteins with the highest absolute log-fold change values, those encoded by the GABBR1, EPHA2, DUSP5, MUC2, DGCR8, MAP2K7, ADRA1A, CXADR, TOPBP1, and NEB genes were highlighted as potential biomarkers because of their roles in response to heat stress. The functional enrichment analysis revealed that 65 Gene Ontology terms and 34 pathways were significant (P < 0.05). We highlighted those that could be associated with the response to heat stress, such as those related to the immune system, complement system, hemostasis, calcium, ECM-receptor interaction, and PI3K-Akt and MAPK signaling pathways. In addition, the protein-protein interaction network analysis revealed several complement and coagulation proteins and acute-phase proteins as important nodes based on their centrality and edges.

Conclusion

Identifying differentially regulated proteins and their relationship, as well as their roles in key pathways contribute to improve the knowledge of the mechanisms behind the response to heat stress in naturally adapted cattle breeds. In addition, proteins highlighted herein are potential biomarkers involved in the early response and recovery from heat stress in tropically adapted beef cattle.

Heat stress and feeding effects on the mucosa-associated and digesta microbiome and their relationship to plasma and digesta fluid metabolites in the jejunum of dairy cows

The intestinal microbiota plays a pivotal role in digestive processes and maintains gut health and intestinal homeostasis. These functions may be compromised by increased environmental heat, which in turn reduces feed intake and gut integrity and activates the intestinal immune system. It remains unknown whether high ambient temperatures, which cause heat stress (HS) in dairy cows, disturb the eubiosis of the microbial community, and if so, to which extent the reduction in feed intake and the impairment of circulating and intestinal metabolites account for the alterations of the jejunal microbiota. To address these questions, jejunal digesta, mucosa, and plasma samples were collected from cows exposed to heat stress (HS; 28°C, temperature-humidity index [THI] = 76, n = 10), control conditions (CON; 16°C, THI = 60, n = 10), or pair-fed (PF; 16°C, THI = 60, n = 10) for 7 d. Digesta fluids were examined for pH, acetate, nonesterified fatty acids (NEFA), glucose, and lactate, and plasma samples were analyzed for glucose, lactate, BHB, triglycerides, NEFA, creatinine, and urea. The microbiota of the digesta and mucosa samples were analyzed by 16S rRNA sequencing. The α-diversity was higher in mucosa than digesta but was not affected by high ambient temperatures. However, the mucosa-associated microbiota appeared more responsive to ambient heat than the digesta microbiome. The adaptive responses under HS conditions comprised an increased mucosal abundance of Bifidobacteriaceae, Succinivibrionaceae UCG-001, Clostridia and Lactobacillus. In the digesta, HS has exerted effects on microbial abundance of Colidextribacter, and Lachnospiraceae UCG-008. Several correlations between plasma or intestinal metabolites and microbiota were elucidated, including Methanobacteriaceae correlating positively with plasma BHB and digesta glucose concentrations. Moreover, the reduction in feed intake during HS had non-negligible effects on microbial diversity and the abundance of certain taxa, underpinning the importance of nutrient supply on maintaining intestinal homeostasis.

Cellular and mitochondrial adaptation mechanisms in the colon of lactating dairy cows during hyperthermia

Heat stress causes barrier dysfunction and inflammation of the small intestine of several species. However, less is known about the molecular and cellular mechanisms underlying the response of the bovine large intestine to hyperthermia. We aimed to identify changes in the colon of dairy cows in response to constant heat stress using a proteomic approach. Eighteen lactating Holstein dairy cows were kept under constant thermoneutral conditions (16°C and 68% relative humidity [RH]; temperature-humidity index [THI] = 60) for 6 d (period 1) with free access to feed and water. Thereafter, 6 cows were equally allocated to (1) thermoneutral condition with ad libitum feeding (TNAL; 16°C, RH = 68%, THI = 60), (2) heat stress condition (HS; 28°C, RH = 50%, THI = 76) with ad libitum feeding, or (3) pair-feeding at thermoneutrality (TNPF; 16°C, RH = 68%, THI = 60) for another 7 d (period 2). Rectal temperature, milk yield, dry matter and water intake were monitored daily. Then, cows were slaughtered and colon mucosa samples were taken for proteomic analysis. Physiological data were analyzed by ANOVA and colon proteome data were processed using DESeq2 package in R. Rectal temperature was significantly higher in HS than in TNPF and TNAL cows in period 2. Proteomic analysis revealed an enrichment of activated pathways related to colonic barrier function and inflammation, heat shock proteins, AA metabolism, reduced overall protein synthesis rate, and post-transcriptional regulation induced by heat stress. Further regulations were found for enzymes of the tricarboxylic acid cycle and components of the mitochondrial electron transport chain, presumably to reduce the generation of reactive oxygen species, maintain cellular ATP levels, and prevent apoptosis in the colon of HS cows. These results highlight the cellular, extracellular, and mitochondrial adaptations of the colon during heat stress and suggest a dysfunction of the hindgut barrier integrity potentially resulting in a "leaky" colon.

Plasma and milk metabolomics revealed changes in amino acid metabolism in Holstein dairy cows under heat stress

Our understanding of metabolic alterations triggered by heat stress is incomplete, which limits the designing of nutritional strategies to mitigate negative productive and health effects. Thus, this study aimed to explore the metabolic responses of heat-stressed dairy cows to dietary supplementation with vitamin D3/Ca and vitamin E/Se. Twelve multiparous Holstein cows were enrolled in a split-plot Latin square design with two distinct vitamin E/Se supplementation levels, either at a low (ESe-, n = 6, 11.1 IU/kg vitamin E and 0.55 mg/kg Se) or a high dose (ESe+, n = 6 223 IU/kg vitamin E and 1.8 mg/kg Se) as the main plot. Treatment subplots, arranged in a replicated 3 × 3 Latin square design, comprised heat challenge (Temperature Humidity Index, THI: 72.0-82.0) supplemented with different levels of vitamin D3/Ca: either low (HS/DCa-, 1 012 IU/kg and 0.73%, respectively) or high (HS/DCa+, 3 764 IU/kg and 0.97%, respectively), and a pair-fed control group in thermoneutrality (THI = 61.0-64.0) receiving the low dose of vitamin D3/Ca (TN). The liquid chromatography-mass spectrometry-based metabolome profile was determined in blood plasma and milk sampled at the beginning (day 0) and end (day 14) of each experimental period. The results were analyzed for the effect of (1) TN vs. HS/ESe-/DCa-, and (2) the vitamin E/Se and vitamin D3/Ca supplementation. No group or group × day effects were detected in the plasma metabolome (false discovery rate, FDR > 0.05), except for triglyceride 52:2 being higher (FDR = 0.03) on day 0 than 14. Taurine, creatinine and butyryl-carnitine showed group × day interactions in the milk metabolome (FDR ≤ 0.05) as creatinine (+22%) and butyryl-carnitine (+190%) were increased (P < 0.01) on day 14, and taurine was decreased (-65%, P < 0.01) on day 14 in the heat stress (HS) cows, compared with day 0. Most compounds were unaffected by vitamin E/Se or vitamin D3/Ca supplementation level or their interaction (FDR > 0.05) in plasma and milk, except for milk alanine which was lower (-69%, FDR = 0.03) in the E/Se+ groups, compared with E/Se-. Our results indicated that HS triggered more prominent changes in the milk than in the plasma metabolome, with consistent results in milk suggesting increased muscle catabolism, as reflected by increased creatinine, alanine and citrulline levels. Supplementing with high levels of vitamin E/Se or vitamin D3/Ca or their combination did not appear to affect the metabolic remodeling triggered by HS.

Profiling the alterations of serum proteome in dairy cows with retained placenta using high-throughput tandem mass tags quantitative approach

BACKGROUND

Retained placenta (RP), a quite common disorder in dairy cows, shows a high negative impact on their health status and milk production.

AIM

To investigate the difference in the serum proteome between the cows with RP and the physiologic puerperium (PP).

MATERIAL & METHODS

Analysis of serum samples from nine cows with RP and six with PP using high-resolution liquid chromatography-tandem mass spectrometry approach. The proteins differing in the relative abundance between the PP and RP groups were classified using the Protein Analysis Through Evolutionary Relationship tool. For the pathway enrichment analysis, the REACTOME tool, with the human genome as the background, was employed. The criterion for significance was the false discovery rate corrected P-value less than 0.05.

RESULTS

In total 651 proteins were identified with altered relative abundance of ten proteins. Among them, seven had higher, and three showed lower relative abundance in RP than in the PP group. The differently abundant proteins participated in 15 pathways: six related to hemostasis, three involved in lipoprotein metabolism, and the remaining ones associated with for instance redox homeostasis, post-translational modification, and scavenging. Finally, the validation of the proteomic results showed that haptoglobin and lipopolysaccharide-binding protein levels reliably differentiated between the RP and PP groups.

CONCLUSION

The pattern of serum proteome alterations in the cows with RP mirrored several interplaying mechanisms underlying the systematic response to the presence of RP, therefore representing a source to mine for predictive or prognostic biomarkers.

Impact of carob (Ceratonia siliqua L.) pulp inclusion and warm season on gastrointestinal morphological parameters, immune-redox defences and coccidiosis in concentrate-fed light lambs

This study aimed to evaluate the effects of dietary carob (Ceratonia siliqua L.) pulp and warm season on gastrointestinal morphological parameters, immune-redox defences and coccidiosis in concentrate-fed light lambs. Weaned lambs were assigned to one of three concentrate-based diets: C0 (without carob pulp), C15 (150 g/kg of carob pulp) and C30 (300 g/kg of carob pulp) from 40 to 80 days of age in two consecutive cold and warm batches. Blood samples were collected at Day 80 to determine the metabolic status. Rectal faeces were sampled at Days 50, 65 and 80 to determine consistency and oocyst count per gram. Inclusion of carob pulp in lamb diets did not affect lamb growth but reduced coccidia oocyst excretion, improved faecal consistency and gastrointestinal morphological parameters, enhancing the ruminal thickness of the papilla living strata and reducing the darkness of the epithelium colour. Moreover, carob condensed tannins in the lambs' diet enhanced the expression of antioxidant SOD2 in rumen, while down-regulated NRF2, SOD1, CAT and PPARG in ileum. There was no interaction between the treatments and season in the evaluated variables. Lambs from the warm season exhibited reduced growth performance, altered ruminal epithelium, lower circulating iron levels, increased protein concentrations and higher coccidiosis susceptibility. In addition, regulatory immune and antioxidant mechanisms to counterbalance reactive oxygen species production in gastrointestinal tissues were evident. Dietary inclusion of carob pulp (150 and 300 g/kg) in lamb diets improved gastrointestinal health and homeostasis but did not ameliorate the deleterious effects of warm season.

Endocannabinoid administration affects taste preference and the expression of cannabinoid and opioid receptors in the amygdala of early lactating cows

The aim of the study was to investigate the influence of intraperitoneal N-arachidonoylethanolamide (AEA) on taste preference for feed and water, tongue taste receptor signalling (TAS1R2, GNAT3), and endocannabinoid (CNR1, CNR2, GPR55) and opioid (OPRD1, OPRK1, OPRM1, OPRL1) receptors in the amygdala and nucleus accumbens in periparturient cows. We conducted taste preference tests using unaltered, umami-tasting, and sweet-tasting water and feed, before and after calving. After calving, eight cows received AEA injections (3 µg/(kg bodyweight × day), 25 days), whereas eight control (CON) cows received saline injections. Tissue was sampled 30 days after calving. Before calving, both cow groups preferred sweet-tasting feed and umami-tasting water. After calving, only the AEA-treated group preferred sweet-tasting feed, whereas the CON group showed no clear taste preference. In the amygdala, the mRNA expression of CNR1, OPRD1 (left hemisphere) and OPRK1 (right hemisphere) was lower in AEA animals than in CON animals, whereas no differences were found in the nucleus accumbens and tongue taste receptor expression. In conclusion, AEA administration enhanced existing taste preferences and reduced the expression of specific endocannabinoid and opioid receptors in the amygdala. The results support endocannabinoid-opioid interactions in the control of taste-dependent feed preference in early lactating cows.

Mild heat stress-induced adaptive immune response in blood mononuclear cells and leukocytes from mesenteric lymph nodes of primiparous lactating Holstein cows

Heat stress negatively affects the metabolism and physiology of the bovine gut. However, it is not known whether heat stress induces an inflammatory response in mesenteric lymph nodes (MLN), the primary origin of gut immune cells, and thus contributes to inflammatory processes in the circulation. Therefore, our objective was to elucidate the effects of chronic heat stress on the systemic activation of acute-phase response in blood, proinflammatory cytokine production in peripheral blood mononuclear cells (PBMC), and the activation of the toll-like receptor signaling (TLR) 2/4 pathway in MLN leucocytes and their chemokines and chemokine receptor profiles in Holstein cows. Primiparous Holstein cows (n = 30; 169 ± 9 d in milk) were exposed to a temperature-humidity index (THI) of 60 [16°C, 63% relative humidity (RH)] for 6 d. Thereafter, cows were evenly assigned to 3 groups: heat-stressed (HS; 28°C, 50% RH, THI = 76), control (CON; 16°C, 69% RH, THI = 60), or pair-feeding (PF; 16°C, 69% RH, THI = 60) for 7 d. On d 6, PBMC were isolated and on d 7 MLN. Plasma haptoglobin, TNFα, and IFNγ concentrations increased more in HS than CON cows. Concomitantly, TNFA mRNA abundance was higher in PBMC and MLN leucocytes of HS than PF cows, whereas IFNG mRNA abundance tended to be higher in MLN leucocytes of HS than PF cows, but not for chemokines (CCL20, CCL25) or chemokine receptors (ITGB7, CCR6, CCR7, CCR9). Furthermore, the TLR2 protein expression tended to be more abundant in MLN leucocytes of HS than PF cows. These results suggest that heat stress induced an adaptive immune response in blood, PBMC, and MLN leukocytes involving the acute-phase protein haptoglobin, proinflammatory cytokine production, and TLR2 signaling in MLN leucocytes. However, chemokines regulating the leucocyte trafficking between MLN and gut seem not to be involved in the adaptive immune response to heat stress.

Effects of Heat Stress in Dairy Cows Raised in the Confined System: A Scientometric Review

Due to climate change, heat stress is a growing problem for the dairy industry. Based on this, annual economic losses in the dairy sector are verified mainly on a large scale. Despite several publications on thermal stress in lactating dairy cows in confinement systems, there need to be published reviews addressing this issue systematically. Our objective was to scientometrically analyze the effects of heat stress in dairy cows managed in a confinement system. Based on PRISMA guidelines, research articles were identified, screened, and summarized based on inclusion criteria for heat stress in a confinement system. Data was obtained from the Web of Science. A total of 604 scientific articles published between 2000 and April 2022 were considered. Data was then analyzed using Microsoft Excel and CiteSpace. The results pointed to a significant increase in studies on heat stress in lactating cows housed in confinement systems. The main research areas were Agriculture, Dairy Animal Science and Veterinary Sciences. The USA showed the highest concentration of studies (31.12%), followed by China (14.90%). Emerging themes included heat stress and behavior. The most influential journals were the Journal of Dairy Science and the Journal of Animal Science. The top authors were L. H. Baumgard and R. J. Collier. The leading institutions were the Chinese Academy of Agricultural Sciences, followed by the State University System of Florida and the University of Florida. The study maps the significant research domains on heat stress of lactating cows in confinement systems, discusses implications and explanations and highlights emerging trends.

Effects of rumen cannulation combined with different pre-weaning feeding intensities on the intestinal, splenic and thymic immune system in heifer calves several month after surgery

Fistulation is a helpful procedure in animal nutritional research and also common practise in human medicine. However, there are indications that alterations in the upper gastrointestinal tract contribute to intestinal immune modulations. The present study aimed to investigate effects of a rumen cannulation in week 3 of life on the intestinal and tissue specific immune system of 34-week old heifers. Nutrition influences the development of the neonatal intestinal immune system to a high extent. Therefore, rumen cannulation was investigated in combination with different pre-weaning milk feeding intensities (20% (20MR) vs. 10% milk replacer feeding (10MR). Heifers of 20MR without rumen cannula (NRC) showed higher cluster of differentiation (CD)8⁺ T cell subsets in mesenteric lymph nodes (MSL) compared to heifers with rumen cannula (RC) and 10MRNRC heifers. CD4⁺ T cell subsets in jejunal intraepithelial lymphocytes (IELs) were higher in 10MRNRC heifers compared to 10MRRC heifers. CD4⁺ T cell subsets in ileal IELs were lower and CD21⁺ B cell subsets were higher in NRC heifers compared to RC heifers. CD8⁺ T cell subsets in spleen tended to be lower in 20MRNRC heifers compared to all other groups. Splenic CD21⁺ B cell subsets were higher in 20MRNRC heifers compared to RC heifers. Splenic toll like receptor (TLR) 6 expression was increased and IL4 expression tended to be increased in RC heifers than NRC heifers. Splenic TLR2, 3 and 10 gene expression was higher in 20MR compared to 10MR heifers. Jejunal prostaglandin endoperoxide synthase 2 expression was higher in RC heifers than NRC heifers, and MUC2 expression tended to increase in 20MR heifers compared to 10MR heifers. In conclusion, rumen cannulation modulated T and B cell subsets in the down streaming gastrointestinal tract and spleen. Pre-weaning feeding intensity seemed to affect intestinal mucin secretion and T and B cell subsets in MSL, spleen and thymus until several month later. Interestingly, in MSL, spleen and thymus the 10MR feeding regime evoked similar modulations of T and B cell subsets like rumen cannulation.

Developmental programming: prenatal and postnatal consequences of hyperthermia in dairy cows and calves

With global warming, the incidence of heat stress in dairy cows is increasing in many countries. Temperatures outside the thermoneutral zone (heat stress) are one of the environmental factors with the greatest impact on milk production and reproductive performance of dairy cows. In addition to several biological mechanisms that may contribute to the effects of fetal programming, epigenetic modifications have also been investigated as possible mediators of the observed associations between maternal heat stress during late gestation and performance and health later in life. In utero programming of these offspring may coordinate changes in thermoregulation, mammary gland development, and milk production ability at different developmental stages. This review examines the effects of prenatal and postnatal hyperthermia on the developmental outcomes of dairy cows, as well as the physiological and molecular mechanisms that may be responsible for the negative phenotypic consequences of heat stress that persist throughout the neonatal and adult periods and may have multigenerational implications. The physiological and molecular mechanisms underlying the negative phenotypic consequences of heat stress are discussed. Research challenges in this area, future research recommendations, and therapeutic applications are also discussed. In summary, strategies to reduce heat stress during the dry period should consider not only the productivity of the pregnant cow but also the well-being of the newborn calf.

Duodenal Metabolic Profile Changes in Heat-Stressed Broilers

Simple Summary

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

Abstract

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