Warming climates and tightening water supplies are putting increasing strain on poultry production sustainability, especially in fast growing broilers that are highly susceptible to heat stress (HS). Boosting internal water use efficiency has therefore become a central goal for maintaining growth and performance under these conditions. However, the physiological mechanisms that support water-use efficiency, especially under chronic HS, remain poorly understood. In this study, we determined the effect of chronic HS on circulating hormone levels and gene expression in two broiler lines divergently selected for high (HWE) or low (LWE) water efficiency. From day 29 to 49, birds were raised under thermoneutral conditions (25°C) or exposed to daily HS- (36°C for 9 hours) in a 2 × 2 factorial design. On day 49, blood was collected for ELISA-based hormone analysis, and qPCR were used for gene expression. Data were analyzed by two-way ANOVA and Tukey multiple comparison test and significance was set at P < 0.05. The results illustrate that plasma corticosterone (CORT) and cortisol levels were significantly lower in HWE compared to their LWE counterparts, indicating a lower systemic stress status in HWE. Chronic HS significantly reduced the plasma levels of these stress hormones, suggesting potential physiological adaptation. At the molecular levels, chronic HS significantly down regulated the expression of adiponectin, glucagon, visfatin, orexin and its related receptors (ORXR1 and 2), arginine vasopressin system (AVT, V1aR, V1bR, V2R), and renin-angiotensin system (REN, AGT, AT1, AT2, and ACE). Together, these systemic changes suggest a shift and modulation in stress-, energy- and water-balance pathways toward adaptive, protective and homeostatic states.

Abstract Heat stress, driven by global warming and climate change, is a significant economic, welfare, and production burden to worldwide livestock and poultry production sustainability. In broiler chickens, which supports the livelihoods and provides food security for billions of people globally, the strong negative effect of heat stress on growth, feed efficiency, gut integrity, meat yield and mortality is well documented. Heat stress induces many cellular alterations such as protein misfolding and aggregation, cell cycle arrest, oxidative stress, and transcription modulation. Here, we will provide new insights and describe new molecular pathways involved in heat stress responses, including the role of dsRNA in mediating the effect of heat stress on gut barrier function and the mode of action of microalgae, Spirulina platensis, in mitigating the effect of heat stress and improving breast muscle yield in broilers.

BackgroundThe major goal of this study was to compare mRNA expression associated with water homeostasis in intestines of high water efficient (HWE) broilers to expression in unselected Modern Random Bred (MRB) broilers under thermoneutral (TN) and heat stress (HS) environments.MethodsA 2 × 2 factorial study was conducted with two lines (MRB and HWE) and environments (TN and HS). Males were raised in environmental chambers and maintained in TN conditions from 0 to 4 weeks. From 4 to 7 weeks, broilers were maintained under TN conditions (25C) or exposed to cyclic HS conditions (35C, 8 h/d). At 7 weeks, upper and lower duodenum, and cecum samples were obtained. mRNA was determined by RT-PCR for; 1) heat shock proteins (HSP70, HSP90), 2) the arginine vasotocin (AVT), mesotocin (MT) and receptors (VR2, VR1a, VR1b, MTR), 3) the renin angiotensin system (RAS): angiotensinogen (AGT), angiotensin receptors, (AT1, AT2), renin (REN), AGT converting enzyme (ACE), and Na+/+ATPase (ATP1B1), 4) aquaporins (AQP1-5 and 11), and 5) tight junction proteins occludin (OCLN), and claudins (CLDN2, CLDN15).ResultsA main effect of HS was observed for HSP70 and HSP90 expression in all three intestinal-segments. In lower duodenum, HS-induced upregulation of AVT was accompanied by elevations in VR2, VR1a, VRb, AT1, AQPs (1, 3, 11) OCLN, and CLND2, CLDN15. Main effects of broiler line were observed with HWE exhibiting increased mRNA expression of VR2, VR1a, VR1b, AQP1, AQP3 and AQP5 and CLDN2 in the upper duodenum. There was also higher VR2, MT and AQP5 and lower expression of CLDN15 in the lower duodenum but there were no differences in gene expression between MRB and HWE lines in the cecum. Heat stress upregulated AVT, VR1a, MTR, AVT/MT ratio, AQP1, and AQP3 but downregulated ACE in the upper duodenum. Heat stress also upregulated AVT, VR2, VR1a, VR1b, MTR, AT1, AT2 AQP3, ACP5, OCLN, CLDN2, CLDN15 in the lower duodenum and cecum.ConclusionThe results provide insight into mechanisms responsible for water efficiency in HWE broilers and provide new information in gene expression in the gastrointestinal tract of broilers exposed to chronic cyclic heat stress conditions.

Microbiome research has shown significant potential in enhancing poultry health and productivity. Despite the increasing volume of data linking the microbiota with various host traits, challenges persist regarding the consistency and reproducibility of findings. A major underlying issue is the variability in methodologies employed across studies. As such, a need exists to establish a set of standardized guidelines that help guide experimental design, DNA extraction, sequencing, data analysis, and reporting in poultry microbiota research. Rather than advocating for a single standardized protocol, we propose a best practices framework designed to enhance methodological rigor while accommodating distinct research contexts. Such a framework emphasizes the use of appropriate positive and negative controls and improved data reporting to facilitate cross-study comparisons and reproducibility. As a companion to our previous review of the 16S rRNA gene sequencing landscape in poultry microbiota research, this manuscript represents a collaborative effort among experts from academia, industry, and government. It aims to offer a practical set of guidelines that serve as a checklist for designing, conducting, analyzing, and reporting poultry microbiota studies. These guidelines seek to improve consistency, reproducibility, and robustness of poultry microbiota research.

Abstract Bovine respiratory disease (BRD) presents substantial economic costs and risks to animal health in the U.S. beef cattle industry. The diversity in BRD-causing pathogens along with antibiotic overuse and resistance remains a significant challenge. Defensins are innate, antimicrobial proteins with potent immunoregulatory functions associated with the innate immune response and adaptive immunity activation. There are two primary defensin classes including α- and β-defensins. The α-defensins are highly concentrated in the granules of neutrophils or Paneth cells in the small intestine, while β-defensins are secreted by mucosal cells found in the eye, skin, oral mucosa, urogenital and respiratory tract. This preliminary study investigated β-defensin presence in nasal mucosal secretions. Understanding defensin’s biological activity against pathogens may provide a more effective strategy for mitigating BRD at the microbial level. Therefore, the objectives of this study were to 1) identify β-defensin expression in bovine mucosal secretions and 2) compare differential defensin expression in healthy and BRD-challenged calves. Nasal swabs were collected from healthy calves (n = 6) and calves exhibiting BRD symptoms (n = 6) including nasal discharge, heavy panting, and a body temperature at or above 39 °C. The initial defensins measured included DFEB401, 402, 403, 404, and 405. Defensin gene expression was determined by qPCR using 2-ΔΔCt method. The means were compared by Student T test and significance was set at P < 0.05. Calves infected with BRD demonstrated a defensin-associated immune response as indicated by DFEB403, 404, and 405 upregulation compared to healthy calves (P < 0.05). An inverse response was observed in healthy calves, with DFEB402 being the only defensin with upregulated expression (P < 0.05). The DFEB401 defensin was also observed, however its expression was not significantly different between healthy and BRD-challenged calves. These findings warrant further investigation. The preliminary results demonstrate that not only are β-defensins expressed in bovine nasal mucosal secretions but are also differentially expressed during BRD pathogen exposure. Therefore, identifying which defensins are upregulated during specific BRD pathogen presence, could be used as biomarkers to select calves with enhanced immune systems genetically predisposed to combating BRD-causing pathogens and reduce antibiotic use.

Heat stress (HS) is a significant economic, welfare, and production burden to worldwide poultry production sustainability. Therefore, effective and sustainable mitigating strategies are needed. Driven by consumer’s changing preferences and demand for natural products, microalgae have attracted substantial attention from the poultry industry and have become the fastest growing segment of animal feed additives, yet their modes of action are still not well defined. This study aimed to determine the effect of Arthrospira platensis (Spirulina, SP) on growth performance in heat-stressed broilers and to delineate its underlying mechanisms by using in vivo and in vitro studies. Six hundred one-day old male Cobb500 chicks were randomly allocated to 12 environmental chambers (2 floor pens/chamber, 24 pens in total, 25 birds/pen) and fed two diets (standard control diet, C vs. SP-supplemented diet at 0.5% inclusion rate). On day 29, birds were exposed for two weeks to 2 environmental conditions (thermoneutral, TN, 24°C vs. cyclic HS 36°C, 8h/day). Growth performances, carcass parameters, and muscle myopathy incidences were determined. Chicken primary embryonic myoblasts (CPEM) were isolated, cultured, and treated with either benzoic acid (BA) or quercetin (QCT)-compounds abundant in SP- prior to a 6-h exposure to HS (45°C) or control conditions (37°C). Gene and protein expressions involved in protein proteostasis network (synthesis, degradation, and chaperonin) were measured by qPCR, immunoblot, and immunofluorescence. Data were analyzed by two-way ANOVA and Tukey test, and significance was set at P < 0.05. Heat stress significantly increased core body temperature (CBT) and water intake and depressed feed intake and growth performance in broilers. In-feed SP supplementation reduced CBT, improved water conversion ratio (WCR) by 36.5 points, and enhanced breast yield, without affecting muscle (woody breast and white striping) myopathies. Supplementation of SP significantly increased the phosphorylated levels of mTORSer2481, mTORSer2448, and S6KThr421/Ser424, decreased p-eIF2αSer51, ubiquitin, and HSP60/90 in heat-stressed broilers. Treatments of CPEM with BA or QCT recapitulated the effects of SP. Collectively, supplementation of SP enhanced breast yield in heat-stressed broilers through modulation of proteostasis network by enhancing protein synthesis (mTOR-S6K-eIF2α pathway), reducing protein degradation (ubiquitin machinery), and regulating chaperonins.

We determined the effects of the winter season (cold stress), from October to March 2023, on the growth performance and expression profile of the blood chemo-cytokines and tight junction proteins in two cattle breeds [Bos indicus (Brahman) vs. Bos taurus (Angus)] reared under two feeding techniques or treatments: traditional with growth-promoting technology (GPT) (TRT treatment) vs. natural without GPT (NAT treatment) (n = 50 steers/breed per treatment) in Colorado State, USA. The body weight (BW), the average daily BW gain (ADG), the dry matter (DM) feed intake (DMI), and the feed efficiency (FE; kilograms gain/kilogram DMI) were monitored. Total RNA was extracted from blood at the end of each month and subjected to reverse transcription and real-time quantitative PCR to measure the relative expression of target genes using the 2−ΔΔCt method. There were no significant period-by-breed-by-feeding technique (P × B × T) interactions for BW, ADG, and FE. When the factors were analyzed separately, the data showed a significant increase of BW for both breeds during the study period. However, Angus cattle had higher BW, ADG, and FE compared with their Brahman counterparts. These differences were associated with higher feed intake (p < 0.0001) in Angus versus Brahman. The blood expression levels of heat shock protein 90 (Hsp90), interleukin 6 (IL6), chemokines (Ccl4, Cxcl12, and Xcl1), and chemokine receptor (Cxcr2) were significantly upregulated in November, which coincided with the lower environmental temperature. The abundance of occludin (Ocln) mRNAs peaked in January after an initial increase from October, followed by a downward trend through March. Brahman cattle exhibited a significant higher expression of Hsp90, Ccl4, and Xcl1 compared with their Angus counterparts. The TRT treatment significantly downregulated the expression of the Cxcr2 gene compared with the NAT feeding technique. Together, to the best of our knowledge, this is the first study showing a differential expression of Hsp90 and chemokines between a cold-resilient (Angus) and a cold-sensitive (Brahman) cattle. This work provides novel opportunities and offers new avenues for the identification of molecular signatures for marker-assisted selection.

In-feed beta-mannanase supplementation has been used for decades to improve gut health and growth performances in poultry, yet its underlying molecular mechanisms are not completely defined. The aim of the present study was to determine the effect and potential mode of action of a new endo-1,4-β-D-mannanase (Natupulse® TS, NPU) on gut integrity and growth performances of turkeys. A total of 640 one-day-old male Hybrid Converter poults were randomly assigned to two dietary treatments without (control, CON) or with Natupulse® TS (NPU, 800 TMU/kg feed) for a 49 day-trial, each treatment having 16 replicate pens of 20 birds each. Body weight (BW), BW gain (BWG), feed intake (FI), and feed conversion ratio (FCR) and intestinal permeability using fluorescein isothiocyanate-dextran (FITC-d) were measured on days 21 and 49. Jejunal samples (16 birds/treatment) were analyzed for markers of stress, inflammation, and gut barrier integrity using real-time quantitative PCR and immunoblot. Dietary NPU supplementation significantly reduced serum FITC-D levels in turkey at day 49 and increased BWG at both day 21 and day 49 compared to the CON group. Molecular analyses showed that dietary NPU supplementation significantly increased jejunal protein levels of HSP60/70/90 on day 21. On day 49, HSP60 remained unchanged, HSP70 was high and HSP90 protein levels were significantly decreased compared to the CON diet. In-feed NPU administration significantly downregulated the jejunal expression of IL8, IL18, Crp and Tnfsf4 genes on day 21, and only IL8 gene on day 49. In addition, NPU supplementation decreased jejunal protein levels of claudins (CLDN1/4/5) on day 21 and CLDN5 on day 49. The expression of genes coding for gap junction proteins was also affected by NPU supplementation, with a significant downregulation of Gja1, Gjb1, Gjc1, and Gjd2 on day 21, and Gjc1 and Gjd2 on day 49. Dietary supplantation of NPU significantly downregulated the jejunal expression of the adherens junction protein afadin (afdn1) gene on day 49 compared to the CON group.In summary, dietary NPU supplementation improved growth performance and jejunal barrier integrity potentially through modulation of the expression of HSPs, pro-inflammatory cytokines, tight junction, gap junction, and adherens junction proteins.

Widespread heat waves, driven by climate change, pose significant production, welfare, and economic burdens to sustainability of cattle production systems. However, some cattle breeds, primarily those with Bos indicus genetics (e.g. Brahmans), have developed a superior thermoregulation capability and physiological robustness traits to withstand harsh and hot environments, yet the underpinning mechanisms are still not well delineated. Here, we determined the expression profile of heat shock proteins, (chemo)cytokines, tight junction proteins, and coat color-associated genes in hair follicles (HF) of the thermotolerant Brahmans and their more thermosensitive Angus counterparts, reared under two production systems, with (CON) or without (TRT) growth-promoting technology during the summer (April-October, 2023) season in Colorado, USA. Body weight significantly increased with days on feed for both breeds, with higher growth rate in Angus compared to the Brahmans. The HF expressions of coat color (Mc1r, Bmp2), Hsp90, pro-inflammatory cytokines (IL-1β, IL6, Crp), chemokines (Xcl1, Ccl20, Cxcl14), and tight junction proteins (Cldn1, Ocln) were significantly upregulated during the month of June, which coincided with higher clear-sky solar radiation (RSO >370 W/m2), indicating potential higher heat load. The Angus cattle exhibited a significantly higher expression of HF IL6, Crp, Xcl1, Ccl20, Cxcl14, Cldn1, and Ocln, which might be associated with inflammatory signals from rapid cell proliferation and metabolic changes in growing cells and/or with the divergent hair- and skin-characteristics of the cattle breeds. The use of TRT technology significantly down regulated the HF expression of Mcr1, Ccl20, Cldn1, and Ocln, which might result from the anabolic implants and beta-agonist administration. This is the first report showing that (chemo)cytokines and TJs are expressed in cattle HFs, and are regulated in a season-, breed-, and or production system-dependent manner.

Divergent selection of broilers for water conversion ratio has established and high-(HWE) and low- water efficient (LWE) broiler lines. Two 2 × 2 factorial experiments were conducted to assess the gene expression profile of systems involved in renal water homeostasis. In Exp. 1, male and female HWE and LWE broilers were individually phenotyped between 4 and 6 wks of age to determine growth performance and water conversion ratio (g water intake/g body weight gain). Kidney samples were obtained from 5 males and 5 females from each line. In Exp. 2, HWE and modern random bred (MRB) broilers were placed in 12 controlled-environmental chambers (2 floor pens/chamber, 6 chambers/line, 11 birds per pen, 132 birds/line) on day of hatch. The broilers were brooded at thermoneutral temperatures from 0 to 4 wks. From 4 to 7 wks, broilers were maintained at thermoneutral (TN, 25 °C) or exposed to cyclic heat stress (HS, 35 °C, 8h/day) conditions. Body weight, feed intake, and water intake were recorded. Kidney samples were collected, flash frozen in liquid nitrogen, and kept at -80 °C for gene expression analysis. Data were analyzed by Two-way ANOVA and means compared by Tukey's HSD multiple comparison test. Molecular analyses from Exp. 1 showed that the renal expression of arginine vasopressin (AVP), angiotensinogen (AGT), angiotensin II receptor type 1 and 2 (AT1/2), sodium-potassium ATPase subunit B1 (ATP1B1), and aquaporin 3 (AQP3) were upregulated in HWE compared to the LWE line. In contrast, mRNA expression of mesotocin receptor (MTR), AT1/2, AQP1/2, and occludin were significantly higher in females than in males. In Exp. 2, target genes were regulated in environment and/or line-dependent manner. The renal expression of heat shock proteins 70 and 90, AVP receptor 2 (AVPR2), AGT, renin, AT1/2, and AQP1was significantly upregulated in HS compared to TN birds, however AVPR2 expression was significantly higher in HWE compared to MRB birds. Together, the up-regulation of AVP, the renin-angiotensin system (RAS), and AQP in HWE, female, or under HS conditions suggests a better renal water reabsorption to support water use efficiency.

Bacteria are the major component of poultry gastrointestinal tract (GIT) microbiota and play an important role in host health, nutrition, physiology regulation, intestinal development, and growth. Bacterial community profiling based on the 16S ribosomal RNA (rRNA) gene amplicon sequencing approach has become the most popular method to determine the taxonomic composition and diversity of the poultry microbiota. The 16S rRNA gene profiling involves numerous steps, including sample collection and storage, DNA isolation, 16S rRNA gene primer selection, Polymerase Chain Reaction (PCR), library preparation, sequencing, raw sequencing reads processing, taxonomic classification, α- and β-diversity calculations, and statistical analysis. However, there is currently no standardized protocol for 16S rRNA gene analysis profiling and data deposition for poultry microbiota studies. Variations in DNA storage and isolation, primer design, and library preparation are known to introduce biases, affecting community structure and microbial population analysis leading to over- or under-representation of individual bacteria within communities. Additionally, different sequencing platforms, bioinformatics pipeline, and taxonomic database selection can affect classification and determination of the microbial taxa. Moreover, detailed experimental design and DNA processing and sequencing methods are often inadequately reported in poultry 16S rRNA gene sequencing studies. Consequently, poultry microbiota results are often difficult to reproduce and compare across studies. This manuscript reviews current practices in profiling poultry microbiota using 16S rRNA gene amplicon sequencing and proposes the development of guidelines for protocol for 16S rRNA gene sequencing that spans from sample collection through data deposition to achieve more reliable data comparisons across studies and allow for comparisons and/or interpretations of poultry studies conducted worldwide.

Drought and water scarcity, exacerbated by global warming, are enormous threats to global food sustainability and security. Poultry, in particular, are highly impacted by adverse environmental stressors. As nutrient absorption and intestinal integrity are critical for growth and performance, understanding the impact on the broiler gastrointestinal tract is highly relevant. Here, we examined the effect of chronic cyclic heat stress (HS) on the jejunal expression profile of tight-junction, gap-junction, adherens, and desmosome genes in the 4th generation of broiler lines divergently selected for low (LWE)- and high-water efficiency (HWE). Male HWE and LWE broilers (n = 240/line) were allotted to 12 environmental chambers (2 floor pens/chamber, 6 chambers/line, 20 birds/pen) and were exposed to cyclic HS (36°C for 9h/day from 9:00 am to 6:00 pm) or thermoneutral conditions (25°C) from day 29 to 49 of age in a 2 × 2 factorial design. Growth performance and mortality were recorded. At day 49, jejunal tissues were collected for molecular analyses using real-time quantitative PCR and immunoblot. Jejunal gene expression of multiple gut integrity factors were higher (P < 0.05) in the HWE as compared to the LWE lines, including claudin 22 (CLDN22), -34, occluding (OCDN), zona-occludin-2 (ZO-2), gap junction alpha1 (GJA1), GJA3, GJC1, and cadherin 1 (CDH1). CLDN8, -20, -25, -4, GJC2, and GJD2 were also greater (P < 0.05) in HWE, but were additionally downregulated (P < 0.05) during HS. Conversely PALS1-associated tight junction protein (PATJ) and desmocollin 1 (DSC1) mRNAs were significantly downregulated in the HWE as compared to the LWE broilers. Significant interactions between the line and environment were seen in CLDN1, where the expression was decreased in the LWE but increased in the HWE in HS. Additionally, CLDN15 and -16 genes were greatest in the HWE under TN conditions, while catenin alpha 2 (CTNNA2) was highest in the HWE during HS. Overall, the jejunal expression profile of key genes associated with intestinal barrier integrity likely contributes to the water efficiency phenotype and the response of these birds to HS.

The woody breast (WB) myopathy poses significant economic and welfare concerns to the poultry industry, however, there is no effective strategy to mitigate this pathology due to its unknown etiology. After showing previously that hypoxia is a key factor in WB progression, we used here various techniques demonstrating dysregulated mitochondria (morphology, biogenesis, tethering, function, and bioenergetics) in WB-affected muscles and in hypoxic myoblasts compared to healthy tissues and normoxic cells, respectively. The increased levels of calcium (Ca2+) in both WB-affected tissues and hypoxic myoblasts suggested that mitochondrial Ca2+ overload is likely a leading cause for mitochondrial dysfunction that merits further in-depth investigation. These findings are the first, to the best of our knowledge, to provide fundamental insights into the underlying molecular mechanisms of WB and open new vistas for understanding the interplay between calcium, mitochondrial (dys)function, and avian muscle health for subsequent development of effective preventative/corrective strategies.

Chronic heat stress (HS) is known to depress feed intake (FI) and growth in broiler chickens, and may alter the gut microbiota and health, however, the amplitude and duration of each (HS and depressed FI) effect on gut microbiota is still unclear. This study aimed to determine the effects of chronic and acute HS on the cecal and ileal microbiota profiles. Broilers were subjected to thermoneutral (TN, 23°C) or chronic cyclic HS (CHS, 8 h/d, 35°C) condition from d29-42, and one group to acute HS (AHS, 2 h, 35°C) at d42. To distinguish between the effect of HS and FI, one pair-fed (PF) group (maintained at TN condition but had similar FI as CHS birds) was used from d29-42. Chronic HS decreased richness in the cecal microbiota compared to TN, while PF did not, and AHS led to higher richness compared to CHS. Acute HS and PF altered cecal microbiota profiles similarly to CHS under weighted UniFrac. In the ileum, PF altered microbiota under unweighted UniFrac, and CHS further altered microbiota. Decreased Lactobacillus and increased Ligilactobacillus were observed with CHS, AHS, and PF in the cecum. Chronic HS may influence different predicted metabolic pathways compared to PF, while AHS shared some similarities with CHS. Understanding both the direct effects of CHS and indirect effects through depressed FI, along with the short-term effects from AHS, will be of importance in devising nutritional strategies to maintain gut microbial balance and limit negative effects to broiler chickens’ performance and health.

Heat stress (HS) has long posed a significant challenge to the poultry industry due to its adverse effects, such as depressed feed intake, decreased growth performance, and increased water consumption. Water efficiency (WE, conversion of water intake into body weight gain), although often neglected, is a key economic and production trait that is significantly affected by HS. Recently, we selected two broiler lines for high WE (HWE) and low WE (LWE) and showed a differential hypothalamic expression of genes involved in water homeostasis regulation. As the gut also plays a significant role in water absorption, the present study aimed to determine the effect of chronic HS on duodenal barrier integrity in LWE and HWE broilers. Male HWE and LWE chicks (240 chicks/line) were individually wing-banded for line identification, weighed, and placed in 12 controlled environmental chambers (2 pens/chambers). On day 29, birds were subjected to thermoneutral conditions (TN, 25 °C) or cyclic HS conditions (HS, 36 °C for 9 h/day from 9:00 a.m. to 6:00 p.m.) (120 birds/line/environment) for 3 weeks. On day 49, duodenal tissues were collected for histological, biochemical, and molecular analyses. Hematoxylin and eosin (H&E) staining revealed that HS significantly reduced villus height in the duodenum. Further analysis using qPCR showed that the mRNA expressions of intestinal barrier integrity-related genes, including claudins (CLDN1, 4, 5, 8, 16, and 22), PALS1-associated tight junction protein (PATJ), gap junction alpha 1 and 3 (GJA1/3), cadherin 2 (CDH2), and catenin alpha 2 (CTNNA2), were significantly upregulated by HS, and this effect was more pronounced in the HWE line than in its LWE counterpart. The findings of this study indicate that HS induces duodenal morphometric alterations. Based on the reduced serum fluorescein isothiocyanate-dextran (FITC-D) levels previously reported in the HWE line, the increased abundances of CLDN, PATJ, GJA1, CDH2, and CTNNA2 mRNAs in the HWE line suggest an enhancement of its duodenal barrier integrity for better nutrient and water absorption and, consequently, better growth efficiency.

Our study aimed to investigate an injectable zinc alternative administered at weaning for castration and its impact on growth performance during the feedlot phase and carcass quality. Crossbred male beef calves (n = 74) were assigned randomly at birth to treatments: 1) surgically castrated at birth (SURG) or 2) a 1 mL intratesticular Zn (100 mg Zn) injection administered into each testicle at weaning (INJ). Calves were backgrounded in a dry lot for the initial 43 d post weaning and grazed cool season forages for the remainder of the 168-d period; followed by a 140-d finishing phase. Testicular thickness (TT) and BW were recorded every 28 d during the finishing phase until slaughter. Once harvested, hot carcass weight (HCW), dressed carcass yield (DCY), lean muscle area, marbling score (MS), fat thickness (FT) and yield grade (YG) were recorded. Data were analyzed using the Mixed procedures of SAS (α = 0.05); pen served as the experimental unit for all analysis. Testicular thickness measured on INJ was similar (P = 0.16) on d 0 and when calves exited the feedyard (d 380). Testosterone concentrations in INJ calves were greater compared to SURG calves throughout the feedlot period (P = 0.02). Zinc injected calves were heavier on days 168 (feedlot entry), 224, 280, 308 and 318 (P ≤ 0.04) and had greater overall ADG (P < 0.01). Furthermore, INJ calves had heavier HCW (P = 0.01) and greater lean muscle area (P = 0.01) but a lower MS (P < 0.01; small vs modest). The remaining variables such as DCY, FT and YG were similar between treatments (P ≥ 0.14). Injecting zinc did not eliminate testicular function, as indicated by elevated testosterone levels. Zinc-injected calves were heavier at the study’s conclusion and produced heavier carcasses with greater lean muscle area. These findings suggest that intratesticular zinc injections at weaning improve growth performance and certain carcass attributes throughout the finishing period, although they do not result in complete sterilization and thus cannot be considered a true castration alternative.

Although poultry meat production supports the livelihood and provides food security for billions of people worldwide, it is facing substantial challenges. The emergence of broiler breast myopathies (white striping, woody breast, spaghetti meat) at large scale is one of the most significant economic and welfare challenges that menace poultry production sustainability and for which there is currently no effective prevention, due to its unknown aetiologies. Here, by inviting and gathering several experts with diverse, but complementary disciplines, the objective of the present review is to highlight the current progress and knowledge on these myopathies. Five sections are presented, describing in detail the history and geographic occurrence of these breast myopathies, their macroscopic morphologies and microscopic characteristics, their putative aetiologies and causes as well as their underlying molecular mechanisms, and potential strategies and solutions. The is review summarizes both descriptive and functional mechanistic studies, highlights the complexity of these myopathies and the kinship between broiler genome, nutrition, and management, and outlines some of the promising molecular signatures. It aims to offer new fundamental frameworks for future investigations.

Heat stress (HS) is a global serious issue in the poultry industry with numerous adverse effects, including increased stress, depressed feed intake (FI), poor growth performance and higher mortality. Herbal adaptogens, plant extracts considered as stress response modifiers, are metabolic regulators that improve an organism's ability to adapt to and minimize damage from environmental stresses. Previously, we showed that herbal adaptogen supplementation increased FI and body weight (BW) of broiler (meat-type) chickens reared under HS conditions. Therefore, we hypothesized that these effects may be mediated through modulation of hypothalamic feeding-related neuropeptides. Male Cobb 500 chicks were reared in 12 environmental chambers with three diets: a corn-soybean-based diet (C) and two herbal adaptogen-supplemented diets at 500 g/1000 kg (NR-PHY500) and 1 kg/1000 kg (NR-PHY-1000). Broilers in 9 chambers were exposed to chronic cyclic HS (35 degrees C for 8 h/ day) from d29 to d42, while 3 chambers were maintained at 24 degrees C (thermoneutral, TN) for all 42 days. Hypothalamic samples were collected on d42 from each group, both before the onset of HS (Pre-HS) that day and after 3 h of HS (post-HS). Hypothalamic expressions of neuropeptide Y (NPY) receptors Y4 and Y7, Corticotropinreleasing hormone (CRH), orexin receptor 1 (ORXR1), melanocortin receptors (MC1R, MC4R, and MC5R), visfatin and neurosecretory protein GL (NPGL) genes were significantly upregulated by adaptogen supplementation. The hypothalamic expression of MC2R was affect by period, with a significant upregulation during post-HS phase. There was a significant period by treatment interaction for hypothalamic orexin and adiponectin expression. The hypothalamic expression of NPY, Y1, Y2, Y5, Y6, proopiomelanocortin (POMC), cocaine and amphetamine regulated transcript (CART), agouti-related peptide (AgRP), ORXR2, AdipR1/2, MC3R, and ghrelin was not affected by diet supplementation nor by HS exposure. In conclusion, these findings suggest that in-feed supplementation of adaptogen might improve FI and growth via modulation of hypothalamic feeding-related neuropeptides in heat-stressed broilers.

Lameness due to bacterial chondronecrosis with osteomyelitis (BCO) is an infection of weak bone by opportunistic bacteria that infiltrate the circulation as a result of immune suppression or gastrointestinal deterioration. One mitigating strategy is the dietary inclusion of products to support overall broiler robustness and bone health. To test the ability of phytase and stimbiotic supplements to alleviate lameness, broilers were reared for 56 days on either litter flooring or wire ramps to induce BCO and fed one of 6 diets: positive control (PC); negative control (NC, Ca and P deficient); PC plus stimbiotic; PC plus stimbiotic and phytase; NC plus phytase; NC plus stimbiotic and phytase. Stimbiotic was added at 100 g/tonne, and phytase at 3000 FTU/kg. Birds were scored for BCO on d56, or when culled for lameness. All-cause mortality was higher on ramp as compared to litter, regardless of treatment. Lameness was significantly induced by wire ramps, with the greatest incidence in the NC diet. Importantly, the addition of stimbiotic and phytase to the NC diet reduced lameness by similar to 50%. Femur BCO scores were similarly reduced, with similar to 60% of femurs scored >= 1 in the NC group compared to 30-37% in stimbiotic and phytase supplemented groups, indicating that these supplements can impact the onset/progression of lameness in poultry. There was no correlation between plasma and bone inositol levels; however, wire flooring reduced bone inositol, regardless of diet. Additionally, blood pH was greater and circulating PCO2, HCO3, BE, TCO2, K, haematocrit, and haemoglobin were lower on ramp compared to litter flooring.RESEARCH HIGHLIGHTSWire ramp model reproducibly induced lameness/BCO in broilers.Treatments did not affect growth, but phytase with stimbiotic significantly reduced BCO.Phytase increased circulating inositol, and wire flooring decreased bone inositol.