Effect of synbiotics on thyroid hormones, intestinal histomorphology, and heat shock protein 70 expression in broiler chickens reared under cyclic heat stress

Rutin Nanoparticles Alleviate Cadmium-Induced Oxidative and Immune Damage in Broilers' Bursa of Fabricius via Modulating Hsp70/TLR4/NF-κB Signaling Pathway

Cadmium (Cd) is a serious environmental pollutant affecting various tissues/organs in broilers and compromising their immunological function and productivity. Therefore, the current study aimed to investigate Cd-induced immunotoxicity and potential immunoprotective effect of rutin nanoparticles (RNPs) in the bursal tissue of broilers. A total number of 150 chicks from the Hubbard breed were randomly divided into 5 groups. Group I was fed on standard basal diet (SD) with normal drinking water (DW), Group II received SD containing RNPs (50 mg/kg feed) with DW, Group III fed on SD and DW containing Cd (150 mg/L), Group IV co-treated with rutin-enforced SD (50 mg/kg diet) and DW containing Cd (150 mg/L), and finally, Group V co-supplemented with RNP-enhanced SD (50 mg/kg diet) DW containing Cd (150 mg/L). Productive performance, economic efficiency, oxidative biomarkers, histopathological changes, and the expression level of TLR-4, HSP-70, caspase 3, NF-κB, Bcl-2, and Bax were assessed in the BF tissue. Cd led to severe production and economic losses in exposed birds with a marked surge of oxidative biomarkers, pro-inflammatory cytokines, and histopathological changes in the bursal tissue which could be explained through upregulation of the Hsp70/TLR4/NF-κB molecular pathway in the BF tissue. Meanwhile, RNPs could alleviate most of these changes and prevail optimistic immunomodulatory properties which subsequently could enhance broilers' productivity when incorporated in their diets.

Characterization and functionality of Ligilactobacillus agilis 1003 isolated from chicken cecum against Klebsiella pneumoniae

Lactic acid bacteria are widely regarded as safe alternatives to antibiotics in livestock and poultry farming and have probiotic potential. Ligilactobacillus agilis (L. agilis) is a prominent component of pigeon crop microbiota; however, its function is unknown. In this study, a strain of L. agilis 1003 from pigeon cecum was identified by combining whole genome sequencing and phenotypic analysis, and its safety and probiotic properties were studied. Whole-genome sequencing revealed that the L. agilis 1003 genome length is 2.58 Mb, its average percent guanine-cytosine is 40.43%, and it encodes 1,757 protein-coding genes. Annotation of clusters of orthologous groups classified predicted proteins from the assembled genome as having cellular, metabolic, and information-related functions. A gene cluster associated with the synthesis of a broad-spectrum antimicrobial compound confirmed by antibacterial spectrum testing was identified using genome mining tools. Based on hemolysis test results, the strain was determined to be safe. This strain exhibited a high survival rate in the presence of bile salts and acidic conditions and a significant self-aggregation propensity and hydrophobicity. In vivo animal experiments showed that L. agilis 1003 exhibits probiotic and antibacterial effects and that the substances exerting antibacterial effects are organic acids. Metabolomics analysis revealed that L. agilis 1003 supernatant contained seven organic acids, including butyric acid. L. agilis 1003 showed good safety and probiotic potential in genomics, physiological biochemistry, and animal experiments, and could be considered a suitable candidate for promoting livestock and poultry health.

Impact of dietary L-carnitine supplementation on blood parameters and duodenal alterations in laying hens at the end of production

L-carnitine is an important nutritional supplement in the poultry industry, contributing to improved growth, production, and overall health of the birds. However, by the end of the production cycle, the endogenous synthesis of L-carnitine (LC) is often insufficient. This study aimed to evaluate the effects of dietary L-carnitine supplementation on blood parameters and duodenal structure in Ross laying hens during the last production phase. A total of 40 Ross strain laying hens, aged 70 weeks, were selected. The control group was administered a basal diet, while the experimental groups received the same diet supplemented with 100, 250, or 500 mg of L-carnitine per kg of the basal diet. The experimental period lasted for 56 days. Serum concentrations of cholesterol and total protein were not significantly affected by L-carnitine supplementation; however, triglyceride concentration and LDL levels were notably reduced. Furthermore, L-carnitine supplementation enhanced the villus perimeter and increased the villus length/crypt depth ratio. Importantly, the supplementation of 250 mg/kg of L-carnitine had a positive impact on duodenum structure and led to decreased levels of AST and ALP. In conclusion, the incorporation of 250 mg/kg of L-carnitine into the diet of laying hens significantly improved duodenal structure, reduced lipid peroxidation, and demonstrated antioxidant effects.

Mechanisms of Heat Stress on Neuroendocrine and Organ Damage and Nutritional Measures of Prevention and Treatment in Poultry

Heat stress (HS) due to high temperatures has adverse effects on poultry, including decreased feed intake, lower feed efficiency, decreased body weight, and higher mortality. There are complex mechanisms behind heat stress in poultry involving the neuroendocrine system, organ damage, and other physiological systems. HS activates endocrine glands, such as the pituitary, adrenal, thyroid, and gonadal, by the action of the hypothalamus and sympathetic nerves, ultimately causing changes in hormone levels: HS leads to increased corticosterone levels, changes in triiodothyronine and thyroxine levels, decreased gonadotropin levels, reduced ovarian function, and the promotion of catecholamine release, which ultimately affects the normal productive performance of poultry. Meanwhile, heat stress also causes damage to the liver, lungs, intestines, and various immune organs, severely impairing organ function in poultry. Nutrient additives to feed are important measures of prevention and treatment, including natural plants and extracts, probiotics, amino acids, and other nutrients, which are effective in alleviating heat stress in poultry. Future studies need to explore the specific mechanisms through which heat stress impacts the neuroendocrine system in poultry and the interrelationships between the axes and organ damage so as to provide an effective theoretical basis for the development of preventive and treatment measures.

Probiotic strategies for mitigating heat stress effects on broiler chicken performance

The primary objective of this study was to evaluate the effects of liquid (Fructose-added lactic acid bacteria, F-LAB) and commercial (Commercial LAB, C-LAB) probiotics sourced from Rye-Grass Lactic Acid Bacteria (LAB) on broiler chickens experiencing heat stress (HS). The research involved 240 broiler chicks, divided into six groups: control, F-LAB, C-LAB (raised at 24 °C), HS, F-LAB/HS, and C-LAB/HS (exposed to 5-7 h of 34-36 °C daily). The study followed a randomized complete block design, with each group consisting of 40 chicks. F-LAB and HS/F-LAB groups received a natural probiotic added to their drinking water at a rate of 0.5 ml/L, while C-LAB and HS/C-LAB groups were supplemented with a commercial probiotic at the same dosage. Control and HS groups received no probiotic supplementation. The duration of the study was 42 days, with data collected on growth performance, feed intake, feed conversion ratio, and health parameters. Statistical analyses were performed using ANOVA, and significant differences between groups were determined using post hoc tests. The results revealed that without probiotic supplementation, heat stress led to a decrease in body weight gain, T3 levels, citrulline, and growth hormone levels, along with an increase in the feed conversion ratio, serum corticosterone, HSP70, ALT, AST, and leptin levels (p < 0.05 for all). Heat stress also adversely affected cecal microbiota, reducing lactic acid bacteria count (LABC) while increasing Escherichia coli and coliform bacteria (CBC) counts. However, in the groups receiving probiotic supplementation under heat stress (F-LAB/HS and C-LAB/HS), these effects were alleviated (p < 0.05 for all). Particularly noteworthy was the observation that broiler chickens supplemented with natural lactic acid bacteria (F-LAB) exhibited greater resilience to heat stress compared to those receiving the commercial probiotic, as evidenced by improvements in growth, liver function, hormonal balance, intestinal health, and cecal microbiome ecology (p < 0.05). These findings suggest that the supplementation of naturally sourced probiotics (F-LAB) may positively impact the intestinal health of broiler chickens exposed to heat stress, potentially supporting growth and health parameters.

Embryonic thermal manipulation and post-hatch dietary guanidinoacetic acid supplementation alleviated chronic heat stress impact on broiler chickens

The study investigated the effects of embryonic thermal manipulation (TM) and post-hatch guanidinoacetic acid (GAA) supplementation on male broiler chickens exposed to chronic heat stress (HS). Ross 308 eggs (n = 710) were randomly assigned to control (37.8 °C, 56% RH) or TM (39.5 °C, 65% RH for 12 h/day from embryonic day 7-16) treatments. After hatching, chicks were further assigned to four dietary treatments (n = 12 birds/pen, 5 replicates/treatment): control, control with 1.2 g/kg GAA supplementation (CS), TM, and TM with 1.2 g/kg GAA supplementation (TMS). All birds were subjected to chronic HS (32-36 °C and 55% RH for 6 h/day) from day 28-42. Embryonic TM treatment decreased hatchability, hatching weight (HW), and facial temperature (FT). During the pre-HS period (days 1-28), no significant differences in feed conversion ratio (FCR) and mortality were observed, although the TM group exhibited the lowest body weight gain (BWG). Following HS exposure (days 29-42), the TMS group displayed significantly higher BWG than the control and CS groups. The TM and TMS groups also demonstrated significantly lower FCR and mortality rates during this period. Across the entire period (days 1-42), BWG was significantly higher in the TMS group compared to other groups. Furthermore, TM and TMS treatments were associated with lower mortality rates, improved FCR, better European Performance Efficiency Index (EPEI), and reduced abdominal fat deposition. The experimental treatments did not significantly affect intestinal morphology or most blood parameters, except triiodothyronine (T3), thyroxine (T4), and uric acid. Plasma concentrations of T3, T4, and uric acid were significantly lower in the TM and TMS groups compared to the control and CS treatments. The findings suggest that a combined strategy of embryonic TM and post-hatch dietary GAA supplementation may not only alleviate the detrimental effects of HS but also promote beneficial physiological responses in broiler chickens.

Impacts of access to legume- or grass-based pasture on behaviour, physiological responses and bacterial load of laying hens

Despite the plethora of studies on the impacts of access to runs on chickens, there is a paucity of information on the welfare and behavioural repertoire of hens raised in the deep litter houses with or without access to legume- or grass-based pasture. Therefore, this study aimed to evaluate the impact of access to grass or legume pastures by laying hens on behaviour, physiological responses and bacterial load. The study was conducted to evaluate the influence of exposure of egg-type chickens to runs on grass or legume pastures on their welfare and behaviours. The study involved the use of 240 ISA brown pullets from 12 weeks of age and and lasted for 48 weeks. The treatments were deep litter housing with grass-based pasture run (PG), deep litter housing with legume-based pasture run (PL) and deep litter housing without runs (LD) having 80 pullets with four replicates of twenty birds each. Behavioural observations of the hens in each pen were made at 52 weeks of age and tonic immobility was assessed by making the birds lie on their back with their head resting in a U-shaped wooden cradle. The measurements of the respiratory rate and rectal temperature of the hens were assessed at 1:00 p.m. at different laying phases. The gastrointestinal and egg bacterial counts were conducted at 60 weeks of age. Results revealed that the proportion of time spent eating was highest (p < 0.05) in the deep litter housing system, while the legume and grass pasture were similar. The hens spent most of their time standing and eating in the three treatments. However, the time spent standing in PL and PG was similar but significantly higher (p < 0.05) than in LD. Results on tonic immobility duration showed that the time spent by the hens in LD during the reaction was significantly longer than those of the PL and PG in the first, second and third phases of the experiments. However, the time spent by the hens in PL and PG was similar. The rectal temperatures of PL and PG birds were comparable and higher than those of LD during the second phase. On the other hand, there was no difference in the respiratory rate. Plasma triiodothyronine (T3) of the hens did not follow a consistent pattern. The bacterial count in the large intestine in LD and PL was similar but significantly (P < 0.05) higher than that of the PG. It was concluded that access to pasture influenced the behaviours of hens and that tonic immobility duration was shorter in the hens on the pasture, suggesting that access to pasture favoured hens' welfare.

Efficacy of liver free and Chitosan against Eimeria tenella in chickens

Eimeria spp. are the pathogen that causes coccidiosis, a significant disease that affects intensively reared livestock, especially poultry. Anticoccidial feed additives, chemicals, and ionophores have routinely been employed to reduce Eimeria infections in broiler production. Therefore, the shift to antibiotic-free and organic farming necessitates novel coccidiosis preventive strategies. The present study evaluated the effects of potential feed additives, liver free and chitosan, against Eimeria tenella infection in White Leghorn broiler female chickens. One hundred sixty-five 1-day-old White Leghorn broiler female chicks were divided into 11 groups (15 female chicks per group), including the positive control group (G1), the negative control group (G2), a chitosan-treated group (G3), a chitosan-treated-infected group (G4), the liver free-treated group (G5), the liver free-treated-infected group (G6), the liver free-and-chitosan-treated group (G7), the liver free-and-chitosan-infected group (G8), the therapeutic liver free-and-chitosan-treated-infected group (G9), the sulfaquinoxaline-treated group (G10), and the sulfaquinoxaline-treated-infected group (G11). Chitosan was fed to the chicks in G3 and G4 as a preventative measure at a dose of 250 mg/kg. The G5 and G6 groups received 1.5 mg/kg of Liverfree. The G7 and G8 groups received chitosan and Liverfree. The G10 and G11 groups were administered 2 g/L of sulfaquinoxaline. From the moment the chicks arrived at Foshan University (one-day-old chicks) until the completion of the experiment, all medications were given to them as a preventative measure. G8 did; however, receive chitosan and liver free as therapeutic supplements at 7 dpi. The current study showed that the combination of liver free and chitosan can achieve better prophylactic and therapeutic effects than either alone. In E. tenella challenged chickens, G8 and G9 chickens showed reduced oocyst shedding and lesion score, improved growth performance (body weight, body weight gain, feed intake, feed conversion ratio, and mortality rate), and cecal histology. The current study demonstrates that combining liver free and chitosan has superior preventive and therapeutic benefits than either alone, and they could also be used as alternative anticoccidial agents.

Influence of using synbiotics by various routes on Mandarah male chicks: intestinal bacterial counts, gut morphology and histological status

This experiment investigated the influence of different synbiotic processing methods on the intestinal bacterial count, morphology and histological status of developed male Mandarah chicks. Two hundred and ten male Mandarah line chicks aged 1 d were randomized to receive one of 7 chicks. The method and dose for 1-time synbiotics administration to the day-old chicks were as follows: G1: chicks on basal diet received no treatment (control); G2: 0.25 mL synbiotics sprayed; G3: 0.50 mL synbiotics sprayed; G4: 0.25 mL of synbiotics are added to drinking water; G5: 0.50 mL of synbiotics are added to drinking water; G6: 0.25 mL of synbiotics dripped into the mouth; and G7: 0.50 mL of synbiotics dripped into mouth drops. Lactic acid bacteria(LAB) were significantly increased (P<0.0001) compared to the control group and other treated groups and had the maximum values after the use of synbiotics via drinking water (0.25 or 0.50 mL). Furthermore, when comparing the treated birds (G4, G5) with the control birds, the Escherichia coli concentration in the drinking water containing synbiotics was significantly lower. In addition, treated chickens at (G7) showed a higher duodenum, ileum villus height (VH), and VH. - Ileum crypt depth (CD) ratio compared to other groups. In addition, birds treated with 0.50 mL of synbiotics in drinking water (G5) performed better in duodenum, ileum, CD and VH. - CD ratio than the other groups. Meanwhile, intestinal tract length and visceral pH did not differ significantly between groups. It can be concluded that the use of 0.25 mL of synbiotics in drinking water can improve the overall health of birds.

Potential of exogenous melatonin administration to mitigate heat stress induce pathophysiology of chicken

Melatonin (MT) is an amine hormone secreted by the body that has antioxidant and anti-inflammatory properties. The aim of this study was to investigate pathophysiological protection of MT in heat-stressed chickens. By modelling heat-stressed chickens and treating them with MT. After 21 days of administration, serum antioxidant enzymes, biochemical indices, inflammatory cytokine and heat-stress indices were detected, along with cardiopulmonary function indices and histological observations in chickens. The results show heat-stress induced a decrease (P < 0.05) in body weight and an increase in body temperature, which was reversed after MT intervention. Treatment with MT inhibited (P < 0.05) the secretion of pro-inflammatory factors interleukin-1β, interleukin-6, tumor necrosis factor α, serum heat shock protein 70, corticosterone, and elevated (P < 0.05) the levels of biochemical factors total protein, albumin, globulin, and increased (P < 0.05) the activities of antioxidant enzymes superoxide dismutase, glutathione peroxidase and catalase in chicken serum caused by heat stress, and the best effect was observed with the medium dose of MT. The heat-stress caused cardiac atrophy and pulmonary congestion, decreased (P < 0.05) the cardiac function indices creatine kinase isoenzyme, cardiac troponin I, angiotensin receptor I, creatine kinase and lung function indices myeloperoxidase, angiotensin-II, heat shock factor I, and increased (P < 0.05) the lung vascular endothelial growth factor II. Sections of the heart and lungs after administration of MT were observed to be more complete with more normal tissue indices. At the same time, compared with heat stress, heart and lung function indices of grade chickens after MT administration were significantly (P < 0.05)reduced and tended to normal levels, and the best effect was observed in the medium-dose MT. In conclusion, heat stress can cause pathophysiological damage in chickens, and 1 mg/kg/d of exogenous melatonin can attenuate this adverse effect.

Exploring the efficacy of a novel prebiotic-like growth promoter on broiler chicken production performance

This study attempts to isolate a candidate growth promoter from the ovine paunch waste and scrutinize its effects on the production performance of broiler chickens as compared to mannan-oligosaccharide (MOS), a prebiotic, and lincomycin, an antibiotic growth promoter (AB). The paunch waste collected from slaughtered sheep was processed to remove particulate matter. The clarified liquid was then added to an excess of ethanol (1:9 ratio), and the resultant precipitate {(novel growth-promoting paunch extract (NGPE)} was collected, dried, and stored. In vitro increase in cell density for probiotic bacteria viz. Lactobacillus rhamnosus and Enterococcus faecalis (Log10 CFU/ml) were significantly higher (P < 0.01) in NGPE supplemented media (2.78 ± 0.11 and 2.77 ± 0.10) as compared to that on MOS (1.28 ± 0.05 and 2.49 ± 0.09) and glucose (1.09 ± 0.04 and 1.12 ± 0.04) supplemented media. In the in-vivo trial of six weeks duration with broiler chickens (Cobb-400), NGPE supplementation resulted in significantly higher growth in weeks IV (P < 0.05) and VI (P < 0.01) of age in comparison to MOS and AGP supplemented groups, a lower (P < 0.01) cumulative feed conversion ratio in comparison to MOS supplemented groups, and a higher (P < 0.01) cumulative protein efficiency ratio compared to MOS and AGP supplementation. NGPE supplementation also lowered lipid peroxidation (P < 0.01), increased reduced glutathione activity (P < 0.01) in chicken erythrocytes, and boosted the lactic acid bacteria count in the cecal contents (P < 0.01). This is the first report of the isolation of a paunch waste extract that increased the in vitro growth of probiotic bacteria and improved the production performance of broiler chickens.

Synergism of fermented feed and ginseng polysaccharide on growth performance, intestinal development, and immunity of Xuefeng black-bone chickens

Microbial fermented feed (MF) is considered a valuable strategy to bring advantages to livestock and is widely practiced. Oral supplementation of Ginseng polysaccharide (Gps) eliminated weight loss in chickens following vaccination. This study investigated the effects of the combined use of Gps and MF on growth performance and immune indices in Xuefeng black-bone chickens. A total of 400 Xuefeng black-bone chickens at the age of 1 day were randomly assigned to four groups. Normal feed group (Control group), ginseng polysaccharide (200 mg/kg) group (Gps group), microbially fermented feed (completely replace the normal feed) group (MF group), and microbially fermented feed and add ginseng polysaccharide just before use (MF + Gps group). Each group contained 5 pens per treatment and 20 birds per pen. The body weight and average daily gain in the Gps, MF, and MF + Gps groups increased significantly (P < 0.01), while the feed conversion ratio decreased significantly (P < 0.01). The combined use of MF and Gps showed a synergistic effect. There was no significant difference in villus height (cecal) between the experimental group and the Con group. The crypt depth of the three experimental groups exhibited a significantly lower value compared to the Control group (P < 0.05). The V/C ratio of the Gps group and MF + Gps was significantly increased (P < 0.05), but there was no significant difference in the MF group. Moreover, the diarrhea rate of the Gps and the MF + Gps groups was lower than that of the Con group, while that of the MF + Gps group decreased the mortality rate (P < 0.05). The serum tumor necrosis factor-alpha (TNF-α) and interleukin 6 (IL-6) levels in the MF, Gps, and MF + Gps groups decreased significantly (P < 0.01), the serum immunoglobulin G (IgG) levels increased significantly (P < 0.01), while the combination of MF and Gps had a synergistic effect. The combined use of Gps and MF not only further improved growth performance and immune parameters, but also reduced the diarrhea rate and mortality.

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.

Herbal inclusions ameliorate effect of heat stress on haematology, proinflammatory cytokines, adipokines and oxidative stress of weaned rabbit does in humid tropics

A study was designed to evaluate the effect of Moringa oleifera, Phyllanthus amarus and Viscum album leaf meal as herbal inclusions to alleviate the detrimental outcomes of heat stress in weaned female rabbits. Forty (40) weaned rabbit does (527.99 ± 10.35 g; 28 days old) were randomly allotted to four dietary groups consisting of Diet 1(control diet; without leaf meal), Diets 2 (supplemented with 10% V. album); 3 (supplemented with 10% M. oleifera) and 4 (supplemented with 10% P. amarus) in an 84 days trial at the peak of heat stress in Southwest Nigeria. At the end of the trial, blood samples were collected to assess physiological responses and oxidative status of the rabbit does. The results obtained revealed that rabbit does were exposed to heat stress; rabbit does fed control diet had higher leucocyte and neutrophil/lymphocyte ratio compared to rabbit does fed on herbal inclusions. The herbal inclusions enhanced oxidative stability of rabbit does by lowering lipid peroxidation and enhancing antioxidant activities during heat stress conditions. Rabbit does fed control-based diet had significantly higher heat shock protein 70, leptin and adiponectin compared to rabbit does on M. oleifera, P. amarus and V. album supplemented diets. The herbal inclusions tend to suppress proinflammatory cytokines in rabbit does during heat stress condition. In conclusion, the herbal inclusions suppress inflammation, adipokines and promotes oxidative stability of rabbit does exposed to heat stress conditions.

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

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

A Technical Report on the Potential Effects of Heat Stress on Antioxidant Enzymes Activities, Performance and Small Intestinal Morphology in Broiler Chickens Administered Probiotic and Ascorbic Acid during the Hot Summer Season

Oxidative stress negatively affects the welfare of broiler chickens leading to poor productivity and even death. This study examined the negative effect of heat stress on antioxidant enzyme activities, small intestinal morphology and performance in broiler chickens administered probiotic and ascorbic acid during the hot summer season, under otherwise controlled conditions. The study made use of 56 broiler chickens; which were divided into control; probiotic (1 g/kg); ascorbic acid (200 mg/kg) and probiotic + ascorbic acid (1 g/kg and 200 mg/kg, respectively). All administrations were given via feed from D1 to D35 of this study. Superoxide dismutase, glutathione peroxidase and catalase activities were highly significant (p < 0.0001) in the treatment groups compared to the control. Performance indicators (water intake and body weight gain) were significantly higher (p < 0.05) in the probiotic and probiotic + ascorbic acid group. The height of duodenal, jejunal and ileal villi, and goblet cell counts of broiler chickens were significantly different in the treatment groups. In conclusion, the study showed that heat stress negatively affects the levels of endogenous antioxidant enzymes, performance and the morphology of small intestinal epithelium, while the antioxidants were efficacious in ameliorating these adverse effects.

Traditional halal meat production without stunning versus commercial slaughter with electrical stunning of slow-growing broiler chicken: impact on meat quality and proteome changes

Impact of traditional halal meat production without stunning (NST) and commercial slaughter with electrical stunning (ST) of 100 slow-growing broiler chicken on blood plasma and different biochemical, enzymatic, hormonal, meat quality, and proteomic changes was evaluated. The results revealed lower (P < 0.05) postmortem pH values and higher redness (a*) scores for ST samples relative to NST group. Myofibrillar fragmentation index and bleeding efficiency (%) were lower (P < 0.05) in ST compared to NST samples. The ST group had higher (P < 0.05) creatinine, total protein, alanine aminotransferase (ALT), and triiodothyronine (T3) than NST group, however, no difference (P > 0.05) in blood glucose, lactate dehydrogenase (LDH), creatine kinase (CK), thyroxine (T4), cortisol, and aspartate aminotransferase (AST) was observed relative to NST samples. The 2-dimensional gel electrophoresis (2-DE) coupled to MALDI-TOF MS of meat samples has identified 14 differentially abundant proteins between 2 groups. Proteins demonstrating positive correlation with stress namely adenylate kinase isoenzyme-1, Rho guanine nucleotide exchange factor (NST), and apolipoprotein A-I (ST) were overabundant. From the current study, it is concluded that electrical stunning of broilers prior to slaughter or traditional halal slaughter without stunning does not adversely affect the meat quality.

Diets Supplemented with Probiotics Improve the Performance of Broilers Exposed to Heat Stress from 15 Days of Age

The poultry sector demands alternative additives to antibiotics that can be used as performance enhancers. Therefore, this experiment was conducted to evaluate the probiotics effects on performance, intestinal health, and redox status of 720 broilers exposed to heat stress from 15 days of age. Eight dietary treatments were evaluated: basal diet (BD) without antibiotic and probiotic (T1); BD supplemented with antibiotic zinc bacitracin (T2), BD supplemented with commercial probiotic of Bacillus subtilis DSM 17,299 (T3), BD supplemented with non-commercial probiotic of Lactococcus lactis NCDO 2118, Lactobacillus delbrueckii CNRZ 327, Escherichia coli CEC15, or Saccharomyces boulardii (T4 to T7), and BD simultaneously supplemented with the four non-commercial probiotics (T8). Feed intake, weight gain, and feed conversion were determined in the period from 1 to 42 days of age. Carcass and cuts yield, abdominal fat deposition, cloacal temperature, weight and length of intestine, activity of myeloperoxidase and eosinophilic peroxidase enzymes in the jejunum, jejunal histomorphometry, relative gene expression in the jejunum (occludin, zonulin, interleukin-8, cholecystokinin, ghrelin, and heat shock protein-70), and liver (heat shock protein-70), in addition to malondialdehyde level and superoxide dismutase activity in the intestine, liver, and blood, were measured in broilers at 42 days old. As main results, broilers fed T1 diet exhibited lower weight gain (3.222 kg) and worse feed conversion (1.70 kg/kg). However, diets containing non-commercial probiotics resulted in up to 3.584 kg of weight gain and improved feed conversion by up to 10%, similar to that observed for broilers of the T2 and T3 groups.

Pequi Oil (Caryocar brasiliense Camb.) Attenuates the Adverse Effects of Cyclical Heat Stress and Modulates the Oxidative Stress-Related Genes in Broiler Chickens

The present study was conducted to determine the possible antioxidant protection of pequi oil (PO) against cyclic heat stress in broiler chickens and to highlight the application of PO as a promising additive in broiler feed. A total of 400 one-day-old male broiler chicks (Cobb 500) were randomly assigned to 2 × 5 factorially arranged treatments: two temperature-controlled rooms (thermoneutral-TN or heat stress-HS for 8 h/day) and five dietary PO levels (0, 1.5, 3.0, 4.5, or 6.0 g/kg diet) for 42 days. Each treatment consisted of eight replicates of five birds. The results showed that HS increased glucose (p = 0.006), triglycerides (p < 0.001), and HDL (p = 0.042) at 21 days and reduced (p = 0.005) serum total cholesterol at 42 days. The results also showed that HS increased the contents of alanine aminotransferase (ALT) and aspartate aminotransferase (AST). In contrast, PO linearly decreased AST (p = 0.048) and ALT (p = 0.020) at 21 and 42 days, respectively. The heterophil-to-lymphocyte ratio in the birds under HS was higher than in those in the TN environment (p = 0.046). Heat stress decreased (p = 0.032) the relative weight of their livers at 21 days. The superoxide dismutase activity increased (p = 0.010) in the HS treatments in comparison to the TN treatments, while the glutathione peroxidase activity in the liver decreased (p < 0.001) at 42 days; however, the activity of catalase had no significant effects. Meanwhile, increasing the dietary PO levels linearly decreased plasma malondialdehyde (p < 0.001) in the birds in the HS environment. In addition, PO reduced (p = 0.027) the expression of Hsp 70 in the liver by 92% when compared to the TN treatment without PO, mainly at the 6.0 g/kg diet level. The expression of Nrf2 was upregulated by 37% (p = 0.049) in response to PO with the 6.0 g/kg diet compared to the HS treatment without PO. In conclusion, PO supplementation alleviated the adverse effects of HS on broilers due to its antioxidant action and modulation of the genes related to oxidative stress, providing insights into its application as a potential feed additive in broiler production.

Modulation of the immune system of chickens a key factor in maintaining poultry production-a review

The awareness of poultry production safety is constantly increasing. The safety of poultry production is defined as biosecurity and the health status of birds. Hence the constant pursuit of developing new strategies in this area is necessary. Biosecurity is an element of good production practices that ensures adequate hygiene and maintaining the health status of poultry production. Poultry production is the world leader among all livestock species. Producers face many challenges during rearing, which depend on the utility type, the direction of use, and consumer requirements. For many years, the aim was to increase production results. Increasing attention is paid to the quality of the raw material and its safety. Therefore, it is crucial to ensure hygiene status during production. It can affect the immune system's functioning and birds' health status. Feed, water, and environmental conditions, including light, gases, dust, and temperature, play an essential role in poultry production. This review aims to look for stimulators and modulators of the poultry immune system while affecting the biosecurity of poultry production. Such challenges in current research by scientists aim to respond to the challenges posed as part of the One Health concept. The reviewed issues are a massive potential for an innovative approach to poultry production and related risks as part of the interaction of the animal-human ecosystem.

Shotgun proteomics reveals changes in the pectoralis major muscle of broilers supplemented with passion fruit seed oil under cyclic heat stress conditions

The aim of this study was to characterize the proteins differentially expressed in the pectoralis major muscle of broilers supplemented with passion fruit seed oil (PFSO) under cyclic heat stress conditions. Ninety one-day-old male chicks were housed in cages arranged in a climatic chamber, where they were kept under cyclic heat stress for eight hours a day from the beginning to the end of the experiment. The birds were divided into two experimental groups, one group supplemented with 0.9% PFSO and a control group (CON) without PFSO supplementation. At 36 days of age, 18 birds were slaughtered to collect muscle samples. From pools of breast fillet samples from each group, proteolytic cleavage of the protein extracts was performed, and later, the peptides were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The 0.9% PFSO supplementation revealed the modulation of 57 proteins in the pectoralis major muscle of broilers exposed to cyclic heat stress. Among them, four proteins were upregulated, and 46 proteins were downregulated. In addition, seven proteins were expressed only in the CON group. These results suggest that PFSO may increase heat tolerance, with a possible reduction in oxidative stress, activation of neuroprotective mechanisms, protection against apoptosis, decrease in inflammatory responses, and regulation of energy metabolism.

Investigating the heat tolerance and production performance in local chicken breed having normal and dwarf size

Heat stress significantly impairs the growth performance of broilers, which causes serious losses to the poultry industry every year. Thus, understanding the performance of indigenous chicken breeds under such environment is crucial to address heat stress problem. The purpose of this study was to investigate the effects of heat stress (HS) on production performance, tissue histology, heat shock response (HSP70, HSP90), and muscle growth-related genes (GHR, IGF-1, and IGF-1R) of Normal yellow chicken (NYC) and Dwarf yellow chicken (DYC). Seventy-two female birds from each strain were raised under normal environmental conditions up to 84 days, with birds from each strain being divided into two groups (HS and control). In the HS group, birds were subjected to high temperature at 35 ± 1 °C for 8 h daily and lasted for a week, while in the control group, birds were raised at 28 ± 1 °C. At 91 days old, bird's liver, hypothalamus, and breast muscle tissues were collected to evaluate the gene expression, histological changes, and the production performance. The Feed intake, weight gain ratio, total protein intake and protein efficiency ratio showed a significant reduction in the treatments (P < 0.01) and treatment × strain interaction (P < 0.05) with breast muscle rate significantly reducing among the treatments (P < 0.01) after 7 days of HS. Correspondingly, total abdominal fat showed significant change among treatment and strain (P < 0.01, P < 0.05), respectively. Besides, HS markedly upregulated the mRNA expression of HSP70 and HSP90 in the pectoralis major of both chicken strains, but no significant increase (P < 0.05) was found in mRNA expression of HSP90 in liver and hypothalamus tissues of both chicken strains. Moreover, HS significantly upregulated (P < 0.05) the expression of lipogenic genes (FASN, ACC) in liver tissues of NYC, while mRNA expression of these genes showed no variation in DYC. Similarly, HS downregulated the mRNA expression of muscle growth-related genes (GHR, IGF-1, and IGF-1R). Consequently, the histopathological analysis showed that histological changes were accompanied by inflammatory cell infiltration in liver tissues of both chicken strains; however, histopathological changes were more severe in NYC than dwarf chicken strain. Conclusively, this study depicted that the production performance and growth rate varied significantly between treatment and control group of NYC. However, heat treatment in DYC has not shown significant damaging consequences as compared to the control group that signifies the vital role of the dwarf trait in thermal tolerance.

Dietary supplementation with synbiotics improves growth performance, antioxidant status, immune function, and intestinal barrier function in broilers subjected to cyclic heat stress

This study investigated the effects of synbiotics supplementation on growth performance, antioxidant status, immune function, and intestinal barrier function in broilers subjected to cyclic heat stress. One hundred and forty-four 22-day-old male broilers were randomly assigned to one of three treatment groups of six replicates each for a 21-day study, with eight birds per replicate. Broilers in the control group were reared at a thermoneutral temperature and received a basal diet. Broilers in the other two heat-stressed groups were fed a basal diet supplemented without (heat-stressed group) and with 1.5 g/kg synbiotic (synbiotic group). One and a half gram of the synbiotic consisted with 3 × 10⁹ colony forming units (CFU) Clostridium butyricum, 1.5 × 10⁹ CFU Bacillus licheniformis, 4.5 × 10¹⁰ CFU Bacillus subtilis, 600 mg yeast cell wall, and 150 mg xylooligosaccharide. Compared with the control group, heat stress increased rectal temperatures at 28, 35, and 42 days of age, respectively (P < 0.05). Birds subjected to heat stress had reduced weight gain, feed intake, and feed efficiency during 22 to 42 days (P < 0.05). In contrast, supplementation with the synbiotic decreased rectal temperature at 42 days of age and elevated weight gain of heat stress-challenged broilers (P < 0.05). Heat-stressed broilers exhibited a lower superoxide dismutase (SOD) activity in jejunal mucosa and a higher malondialdehyde accumulation in serum, liver and jejunal mucosa (P < 0.05), and the regressive SOD activity was normalized to control level when supplementing synbiotic (P < 0.05). Heat stress increased interleukin-1β (IL-1β) and interferon-γ (IFN-γ) levels in serum and IL-1β content in jejunal mucosa of broilers (P < 0.05). Synbiotic reduced IL-1β level in serum of broilers subjected to heat stress (P < 0.05). Compared with the control group, elevated serum diamine oxidase activity and reduced jejunal villus height were observed in broilers of the heat-stressed group (P < 0.05), and the values of these two parameters in the synbiotic group were intermediate (P > 0.05). Heat stress upregulated mRNA abundance of IL-1β and IFN-γ and downregulated gene expression levels of occluding and zonula occluden-1 (ZO-1) in jejunal mucosa of broilers (P < 0.05). The alterations in the mRNA expression levels of jejunal IL-1β and ZO-1 were reversed by the synbiotic (P > 0.05). In conclusion, dietary synbiotics could improve growth performance, antioxidant capacity, immune function, and intestinal barrier function in heat-stressed broilers.

Heat Shock Protein Response to Stress in Poultry: A Review

Compared to other animal species, production has dramatically increased in the poultry sector. However, in intensive production systems, poultry are subjected to stress conditions that may compromise their well-being. Much like other living organisms, poultry respond to various stressors by synthesising a group of evolutionarily conserved polypeptides named heat shock proteins (HSPs) to maintain homeostasis. These proteins, as chaperones, play a pivotal role in protecting animals against stress by re-establishing normal protein conformation and, thus, cellular homeostasis. In the last few decades, many advances have been made in ascertaining the HSP response to thermal and non-thermal stressors in poultry. The present review focuses on what is currently known about the HSP response to thermal and non-thermal stressors in poultry and discusses the factors that modulate its induction and regulatory mechanisms. The development of practical strategies to alleviate the detrimental effects of environmental stresses on poultry will benefit from detailed studies that describe the mechanisms of stress resilience and enhance our understanding of the nature of heat shock signalling proteins and gene expression.

Dietary supplementation of dimethyl itaconate protects against chronic heat stress-induced growth performance impairment and lipid metabolism disorder in broiler chickens

This study aimed to investigate the protective effects of dietary supplementation of dimethyl itaconate (DI) on chronic heat stress (HS)-induced impairment of the growth performance and lipid metabolism in broiler chickens. 21 days old male Ross 308 broiler chickens (a total of 120, about 700 g body weight) were randomly divided into five treatment groups, including control group, HS group, HS + 50 mg/kg DI group, HS + 150 mg/kg DI group, and HS + 200 mg/kg DI group, and each group contains eight cages of twenty-four broilers. The broiler chickens in the control group were raised in the room (21 ± 1 °C) and fed with a finisher diet for 21 days. The broiler chickens of the HS group and the HS + DI groups were raised in the room (32 ± 1 °C for 8 h/day) and fed with a finisher diet containing DI at 0, 50, 150, and 200 mg/kg diet for 21 days. The results showed that HS-induced decreases in the final body weight (P < 0.01), average daily gain (P < 0.01), and average daily feed intake (P < 0.01) were alleviated by dietary supplementation of DI (P < 0.05). In addition, dietary supplementation of DI attenuated the increases in the liver index (P < 0.01) and abdominal fat rate (P < 0.01) caused by HS in broilers (P < 0.05). Treatment with DI ameliorated HS-induced lipid accumulation in the liver and serum of broiler chickens (P < 0.05). The upregulation of mRNA levels of fat synthesis factors (P < 0.01) and downregulation of mRNA levels of lipolysis-related factors (P < 0.01) caused by HS were markedly blunted after treatment with DI in the liver of broilers (P < 0.05). Broilers exposed to HS exhibited lower phosphorylated protein levels of AMP-activated protein kinase α and acetyl-CoA carboxylase α compared to the control group (P < 0.01), which were improved by treatment with DI (P < 0.01). Collectively, these results demonstrated that dietary supplementation of DI protects against chronic HS-induced growth performance impairment and lipid metabolism disorder in broiler chickens. These results not only provide a theoretical basis for DI to alleviate metabolic disorders but also provide a reference value for DI as a feed additive to improve heat stress in poultry caused by high temperature.

Efficacy of mono- and multistrain synbiotics supplementation in modifying performance, caecal fermentation, intestinal health, meat and bone quality, and some blood biochemical indices in broilers

The superiority of synbiotics in terms of their biological effects depends primarily on a suitable combination of both components, pro-biotic and pre-biotic. The present study was conducted to compare the efficacy of mono- and multistrain synbiotics on overall performance, caecal fermentation, intestinal health, meat and bone quality along with some blood biochemical indices in broilers. A total of 231, 1-day-old male Ross 308, broiler chicks were randomly assigned to three experimental groups using 11 replicates each and seven chicks/replicate. The dietary treatments included control group with no synbiotic supplementation, monostrain (Maflor) and multistrain (Maflor plus) synbiotic groups with 1 g/kg of added synbiotics each. Synbiotics feeding significantly improved animal performance with a clear impact on meat quality in terms of low-fat, optimum ultimate pH24, higher water holding capacity, and lower drip and cooking losses. Of the two synbiotics, multistrain seemed to have responded better in modifying small intestinal epithelia and fermentation metabolites, although both synbiotics were comparable in reducing the pathogen load. Load-bearing capacity of both leg bones (femur and tibia) was also enhanced with synbiotics supplementation, which was also reflected in their mineral profile. The blood serum biochemical analysis showed a reduction in circulating cholesterol and triglycerides levels and an increment in IgA and IgG concentrations. In conclusion, the remarkable efficacy of tested synbiotics in providing higher growth, better meat quality in tandem with the optimum gut environment, lower pathogen load, healthy epithelia, immunomodulation, hypocholesterolemic, and hypotriglyceridemic effects affirms their great potential to be used as feed additives in broiler diets. Contrary to our expectations, the effectiveness of a mono-strain in comparison to multistrain synbiotic in improving almost all the features investigated was also notable. Further evaluation under challenging conditions should be explicitly conducted to achieve more comprehensive results.

Administration of a Multi-Genus Synbiotic to Broilers: Effects on Gut Health, Microbial Composition and Performance

In recent years, the applicability of prebiotics, probiotics and their mixtures, defined as synbiotics, in poultry production has received considerable attention. Following the increasing regulation of antibiotic use, these nutraceuticals are seen as an alternative way to sustain production efficiency and resistance to pathogens and stressors by modulating birds' gut health. The aim of this study was to evaluate the benefits provided under field conditions by administering the multi-species synbiotic PoultryStar^® sol to broilers in drinking water. To this purpose, three Ross 308 broiler flocks, representing separate progenies of a breeder flock which was treated with the same synbiotic, were housed in separate farms, divided into treatment and control groups, and followed throughout the productive cycle. Synbiotic administration was shown to improve gut health even in absence of a challenge, with limited changes in terms of macroscopic intestinal lesions and more overt differences related to histopathological scores and villi length. Synbiotic-fed chickens performed consistently better in terms of body weight gain, feed conversion ratio and survivability. Lastly, the evaluation of the caecal microbiome through next-generation sequencing highlighted the effects of synbiotic supplementation on the composition of the bacterial population, the implications of which will, however, require further studies to be better comprehended.

Effects of a synbiotic as an antibiotic alternative on behavior, production performance, cecal microbial ecology, and jejunal histomorphology of broiler chickens under heat stress

The aim of this study was to examine if synbiotics present similar efficiency to a common antibiotic used in poultry production under heat stress (HS) conditions. Two hundred and forty-one-day-old male Ross 708 broiler chicks were distributed among 3 treatments with 8 pens per treatment of 80 birds each for a 42-day trial. From day 15, birds were heat stressed (32°C for 9 h daily, HS) and fed the basal diet (CONT), the basal diet mixed with an antibiotic (Bactiracin Methylene Disalicylate) (0.05 g/kg of feed, BMD) or a synbiotic (0.5 g/kg of feed, SYN). The treatment effects on bird behavior, production performance, jejunal histomorphology, and cecal microbial ecology were examined. Behavioral observation was recorded by using instantaneous scan sampling technique. Production parameters were measured on day 14, 28, and 42. Cecal microbial populations of Escherichia coli and Lactobacilli and jejunal histomorphological parameters were measured at day 42. The results showed that, SYN birds exhibited more feeding and preening but less drinking and panting behaviors compared with both BMD and CONT birds (P < 0.05). The SYN birds also had higher body weight (BW) at both day 28 and 42 compared to CONT birds (P < 0.05). At the end of the experiment, the counts of Escherichia coli of SYN birds were at the similar levels of BMD but were lower than that of CONT birds (P < 0.05); while there were no treatment effects on the populations of Lactobacilli (P > 0.05). In addition, SYN birds had greater villus height compared with both CONT and BMD birds (P < 0.05). These findings suggest that the dietary synbiotic supplement has significant performance and welfare benefits, with the potential to be used as an alternative to antibiotics for poultry meat production, especially during hot seasons.

L-serine improves lipid profile, performance, carcass weight and intestinal parameters in feed restricted broiler chickens during the hot-dry season

The study evaluated effects of L-serine on lipid profile, performance, carcass weight and small intestinal parameters in heat-stressed broiler chickens subjected to feed restriction. Broiler chickens were divided into four groups, comprising 30 each. Group 1, feed restriction (FR); Group 2, feed restriction + L-serine (200 mg/kg) (FR + L-serine); Group 3, ad libitum (AL); Group 4, ad libitum + L-serine (200 mg/kg) (AL + L-serine). L-serine was administered orally from days 1 to 14, and feed restriction was performed on days 7-14. Serum harvested from blood samples on days 21, 28 and 35 was evaluated for lipid profile. Feed and water intake, live weight gain, organ and carcass weight were measured. At 35 days old, broiler chickens (n = 7) per group were sacrificed to evaluate small intestinal morphology. Temperature-humidity index in the pen (30.88 ± 0.81) was above thermoneutral zone, indicating that chickens were subjected to heat stress. Concentrations of low-density lipoprotein, total cholesterol and total triglycerides were lower (p < 0.05), while higher concentration of high-density lipoprotein was recorded in L-serine groups than in the controls. Feed intake and live weight gain on day 35 in L-serine groups were higher (p < 0.05) than in controls. In L-serine groups, liver, spleen, pancreas and heart weight were higher, but abdominal fat was lower than in FR and AL groups. Villus height:crypt height ratio and area of villus surface were highest in L-serine groups than any other group. In conclusion, L-serine decreased low-density lipoprotein, increased feed intake, live weight, organ and carcass weight, villus height:crypt height ratio and villus surface area.

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.

The effects of L-carnitine-loaded solid lipid nanoparticles on performance, antioxidant parameters, and expression of genes associated with cholesterol metabolism in laying hens

The purpose of this study was to investigate the production performance, antioxidant parameters, egg yolk cholesterol content, and expression of genes related to cholesterol metabolism in laying hens fed L-carnitine (LC) and L-carnitine-loaded solid lipid nanoparticles (LC-SLNs). A total of 350 Hy-Line (w-36) laying hens at 50 wk of age (1520.0 ± 0.7 g) were randomly assigned to 35 units (5 replicates and 50 hens in each treatment) with seven dietary treatments as a completely randomized design. The dietary treatments were corn-soybean meal-based diets, including 1) Control (basal diet); 2) Basal diet +50 mg/kg LC (50LC); 3) Basal diet +100 mg/kg LC (100LC); 4) Basal diet +150 mg/kg LC (150LC); 5) Basal diet +50 mg/kg LC-SLNs (50LC-SLNs); 6) Basal diet +100 mg/kg LC-SLNs (100LC-SLNs) and 7) Basal diet +150 mg/kg LC-SLNs (150LC-SLNs). Results showed that the 50LC-SLNs had the least feed conversion ratio (FCR) in all groups (P < 0.05). The dietary supplementation of 100LC-SLNs decreased (P < 0.01) the egg yolk cholesterol concentration from 14.71 to 11.76 mg/g yolk (25%). The 50LC-SLNs group produced the most total antioxidant capacity with a difference of 58.44% compared to the control group (P < 0.01). The greatest amount of total superoxide dismutase was found for 50LC-SLNs (P < 0.05), while the glutathione peroxidase was not affected by the experimental treatments (P > 0.05). Serum malondialdehyde levels were reduced by 50.52% in laying hens fed 50LC-SLNs compared to the control group (P < 0.05). The transcript level of 3-hydroxy-3-methylglutaryl coenzyme A reductase was significantly decreased (P < 0.01) in the LC and LC-SLNs groups. The expression of cholesterol 7α-hydroxylase was significantly increased (P < 0.01) in the plain LC (∼83%) and LC-SLNs (∼91%) groups. The inclusion of LC-SLNs in the diet increased (P < 0.05) the villus height and decreased villus width in all three parts of the small intestine. Dietary inclusion of LC was found to reduce egg yolk and serum cholesterol content by improving the production performance and antioxidant status. The LC-SLNs groups were more affected than the plain LC groups, which may be attributed to the increased bioavailability of LC.

Effect of Heat Stress on Egg Production, Steroid Hormone Synthesis, and Related Gene Expression in Chicken Preovulatory Follicular Granulosa Cells

Simple Summary

The debilitating effects of heat stress on poultry production have been well documented. Heat stress already results in severe economic loss worldwide. Regarding the decline in the reproductive performance of heat-stressed hens, the exact mechanisms involved are still unknown. The present study was conducted to elucidate the molecular mechanisms underlying heat-stress-induced abnormal egg production in laying hens. Our results confirmed that laying hens reared under heat stress had impaired laying performance. Follicular granulosa cells cultured in vitro are sensitive to the effects of heat stress, showing an increase in apoptosis and cellular ultrastructural changes. These effects appeared in the form of heat-stress-elevated progesterone, with the increased expression of steroidogenic acute regulatory protein, cytochrome P450 family 11 subfamily A member 1, and 3b-hydroxysteroid dehydrogenase, along with inhibited estradiol synthesis through the decreased expression of follicle-stimulating hormone receptor and the cytochrome P450 family 19 subfamily A member 1. Collectively, laying hens exposed to high temperatures showed damage to granulosa cells that brought about a decline in egg production. This study provides a molecular mechanism for the abnormal laying performance of hens subjected to heat stress, which may help when developing novel strategies to reverse the adverse impact.

Abstract

This study was conducted to elucidate the molecular mechanisms underlying heat stress (HS)-induced abnormal egg-laying in laying hens. Hy-Line brown laying hens were exposed to HS at 32 °C or maintained at 22 °C (control) for 14 days. In addition, granulosa cells (GCs) from preovulatory follicles were subjected to normal (37 °C) or high (41 °C or 43 °C) temperatures in vitro. Proliferation, apoptosis, and steroidogenesis were investigated, and the expression of estrogen and progesterone synthesis-related genes was detected. The results confirmed that laying hens reared under HS had impaired laying performance. HS inhibited proliferation, increased apoptosis, and altered the GC ultrastructure. HS also elevated progesterone secretion by increasing the expression of steroidogenic acute regulatory protein (StAR), cytochrome P450 family 11 subfamily A member 1 (CYP11A1), and 3b-hydroxysteroid dehydrogenase (3β-HSD). In addition, HS inhibited estrogen synthesis in GCs by decreasing the expression of the follicle-stimulating hormone receptor (FSHR) and cytochrome P450 family 19 subfamily A member 1 (CYP19A1). The upregulation of heat shock 70 kDa protein (HSP70) under HS was also observed. Collectively, laying hens exposed to high temperatures experienced damage to follicular GCs and steroidogenesis dysfunction, which reduced their laying performance. This study provides a molecular mechanism for the abnormal laying performance of hens subjected to HS.

Effects of synbiotics preparations added to Pengging duck diets on egg production and egg quality and hematological traits

Background and Aim: Duck eggs have high cholesterol levels; inulin addition combined with probiotic is known in several studies to lower cholesterol, while maintaining egg production capacity and blood hematology. This study aimed to investigate the effect of the addition of synbiotic preparations on egg production, egg quality, and hematology of Pengging ducks. Materials and Methods: A total of 200 female Pengging ducks aged 75 weeks (late production phase) and weighing 1467±90.87 g were maintained in litter cages, each measuring 1×1 ducks. The treatment included the addition of synbiotics between the inulin of gembili tuber (Dioscorea esculenta L. and Lactobacillus plantarum Ina CC B76) as follows: T0=control feed ("farmer feed"), T1=control feed+synbiotics 1 mL/100 g, T2=control feed+synbiotics 1.5 mL/g, and T3=control feed+synbiotics 2 mL/100 g in the feed. A completely randomized design was used in this study. The production performance, physical and chemical qualities of eggs, and hematological parameters of Pengging ducks were evaluated. Results: The addition of synbiotics had no significant impact on the production performance, physical and chemical qualities of eggs, and hematological parameters (p>0.05), except for the egg yolk cholesterol content. The cholesterol content decreased significantly (p<0.05) with T2 and T3 treatments, but they had no significant effect (p>0.05). A significant decrease (p<0.01) in cholesterol levels was observed when the synbiotic dose was given at 1.5 ml/100 g feed (T2). However, there was no further decrease in cholesterol level when the synbiotic dose was increased to 2 ml/100g fed (T3). Conclusion: The addition of synbiotics preparations at 1.5 mL/100 g reduced the cholesterol content but did not improve egg production, egg physical quality, and hematology of Pengging ducks.

Effects of early-life cecal microbiota transplantation from divergently selected inbred chicken lines on growth, gut serotonin, and immune parameters in recipient chickens

Recent studies have revealed that fecal microbiota transplantation exerts beneficial effects on modulating stress-related inflammation and gastrointestinal health of the host. The aim of this study was to examine if cecal microbiota transplantation (CMT) presents similar efficiency in improving the health status of egg-laying strain chickens. Chicken lines 6₃ and 7₂ divergently selected for resistance or susceptibility to Marek's disease were used as CMT donors. Eighty-four d-old male recipient chicks (a commercial DeKalb XL layer strain) were randomly assigned into 3 treatments with 7 replicates per treatment and 4 birds per replicate (n = 7): saline (control, CTRL), cecal solution of line 6₃ (6₃-CMT), and cecal solution of line 7₂ (7₂-CMT) for a 16-wk trial. Cecal transplant gavage was conducted once daily from d 1 to d 10, then boosted once weekly from wk 3 to wk 5. The results indicated that 7₂-CMT birds had the highest body weight and ileal villus/crypt ratio among the treatments at wk 5 (P ≤ 0.05); and higher heterophil/lymphocyte ratios than that of 6₃-CMT birds at wk 16 (P < 0.05). 7₂-CMT birds also had higher levels of plasma natural IgG and Interleukin (IL)-6 at wk 16, while 6₃-CMT birds had higher concentrations of ileal mucosal secretory IgA at wk 5 and plasma IL-10 at wk 16 (P < 0.05), with a tendency for lower mRNA abundance of splenic IL-6 and tumor necrosis factor (TNF)-α at wk 16 (P = 0.08 and 0.07, respectively). In addition, 7₂-CMT birds tended to have the lowest serotonin concentrations (P = 0.07) with the highest serotonin turnover in the ileum at wk 5 (P < 0.05). There were no treatment effects on the levels of plasma corticosterone and testosterone at wk 16 (P > 0.05). In conclusion, early postnatal CMT from different donors led to different patterns of growth and health status through the regulation of ileal morphological structures, gut-derived serotonergic activities, peripheral cytokines, and antibody production in recipient chickens.

Bacillus subtilis inhibits intestinal inflammation and oxidative stress by regulating gut flora and related metabolites in laying hens

Bacillus subtilis is one of the most popular commercial probiotics used in farm animal production. However, its potential mechanisms are not very clear. The aim of this study was to investigate the effects of dietary Bacillus subtilis on intestinal histomorphology, innate immunity, microbiota composition, transcriptomics, and related metabolomics. Twenty-four 48-week-old Lohman Pink-shell laying hens were randomly divided into two groups: a basic diet and the basic diet supplemented with Bacillus subtilis (0.5 g/kg) for a 9-week experiment. At the end of the experiment, tissues of the duodenum, ileum, and jejunum as well as cecal content of each bird were collected for microstructure, PCR, transcriptome, metabolome, and 16S rRNA analyses. The results showed that dietary Bacillus subtilis supplement had no effect on the intestinal microstructure. However, Bacillus subtilis increased mRNA expression of tight junction protein occludin (P < 0.05), while reduced mRNA expression of lipopolysaccharide-induced TNF factor (P < 0.01) in the duodenum. Moreover, transcriptomic results indicated that most of Bacillus subtilis supplement-induced differential genes were associated with inflammation and immunity, including cytochrome b-245 beta chain, transferrin, and purinergic receptor P2X 7, resulting in a decrease in Malondialdehyde level (P < 0.05) in the duodenum. In addition, at the genus level, Bacillus subtilis supplement enriched the potential beneficial bacteria, Candidatus_Soleaferrea (P = 0.02) but inhibited the harmful bacteria including Lachnospiraceae_FCS020_group, Ruminiclostridium, Lachnospiraceae_UCG-010, and Oxalobacter. Metabolomic results revealed that N-Acetylneuraminic acid and ADP were increased by fed Bacillus subtilis. These results suggest that dietary Bacillus subtilis could inhibit gut inflammation and improve antioxidative status and barrier integrity of the duodenum via regulating gut microbial composition in laying hens.

Embryonic Exposure to Tryptophan Yields Bullying Victimization via Reprogramming the Microbiota-Gut-Brain Axis in a Chicken Model

Maternal metabolic disorder during early pregnancy may give rise to emotional and behavioral disorders in the child, vulnerable to bullying. Placental tryptophan fluctuation consequently disrupts offspring gut microbiome and brain neurogenesis with long-lasting physiological and social behavioral impacts. The aim of this study was to examine the hypothesis that the excess gestational tryptophan may affect children’s mental and physical development via modifying the microbiota-gut-brain axis, which lays the foundation of their mental status. Chicken embryo was employed due to its robust microbiota and independence of maternal influences during embryogenesis. The results indicated that embryonic tryptophan exposure reduced body weight and aggressiveness in the male offspring before and during adolescence. Additionally, the relative gut length and crypt depth were increased, while the villus/crypt ratio was decreased in tryptophan treated roosters, which was corresponding to the changes in the cecal microbiota composition. Furthermore, the catecholamine concentrations were increased in tryptophan group, which may be associated with the alterations in the gut microbiome and the gut-brain axis’s function. These changes may underlie the sociometric status of bullying; clarify how gestational tryptophan fluctuation compromises bullying and provide a strategy to prevent bullying by controlling dietary tryptophan and medication therapy during pregnancy.

The Efficiency of Probiotics Administrated via Different Routes and Doses in Enhancing Production Performance, Meat Quality, Gut Morphology, and Microbial Profile of Broiler Chickens

Simple Summary

Antimicrobial growth promoters (AGPs) have been used in the animal production industry around the world for decades, with the consequence of a high potential of antibiotic-resistant bacteria transfer to humans. Efficiently raising broiler chickens in an antibiotic-free production system is a challenge, and identifying an effective nutritional alternative to support growth performance, gut health, and functionality without administrating AGPs is of essence. Several antimicrobial alternative options that are commercially available include herbal essential oils, exogenous enzymes, organic acids, plant secondary metabolites, probiotics, and prebiotics. Probiotics in animal feed is projected to attain a massive global growth, reaching USD 6.24 billion by 2026. This study tested the efficiency of probiotics when supplemented via different administration routes (feed or water) and doses, or in combination with prebiotics, on growth performance, meat quality, gut morphology, and microbial profile of broiler chickens. The outcomes revealed that probiotics enhance production performance, and compared to AGPs, do not reduce the beta-diversity of the gut microbial community. Water-soluble probiotics seemed to be more effective in improving growth performance.

Abstract

To study the efficiency of Bacillus spp. probiotics administered via different routes and doses, a 6-week grow-out trial was conducted using a total of 378 day-old mixed-sex ROSS308 broiler chickens in a completely randomized block design. Six experimental diets included probiotics added at two different inclusion rates into the feed (250 g/ton; PRO250, or 500 g/ton; PRO500), or in the drinking water (25 g/L; PRO-WS), or as a feed synbiotic (250 g probiotic + 250 g/ton prebiotic; SYN), compared to a negative (NC; without additives) and positive control (PC; with antibiotics) diets. The PRO-WS enhanced feed intake (p < 0.05) and tended to improve average daily gain and final body weight (p = 0.14). Broiler gut morphology in the duodenum including the villus height (p = 0.04), villus width (p = 0.05) and crypt depth (p = 0.02) were improved by PRO500. Firmicutes was the most abundant phylum, followed by Bacteroidetes. Streptococcaceae, Lachnoospiraceae, Peptostreptococcaceae, Ruminococcaceae, and Erysipe-lotrichaceae were the top five most abundant families. Antibiotic inclusion in PC reduced microbial beta-diversity and increased similarity compared to probiotic inclusion (p = 0.05). Probiotic inclusion reduced the relative abundance of Bacteroides fragilis, which is a commonly isolated pathogen and is considered as a marker for antimicrobial resistance. Overall, probiotic supplementation via feed or water may potentially improve the production performance of the broiler chickens, and water-soluble probiotics are potentially more effective. Probiotics, especially when added to water, suggest a promising feed additive to support gut microbial maturation and diversity, and may reduce resistant bacteria in broiler chickens. However, it is suggested that the best route for the administration of probiotics be further examined under commercial conditions to find the most effective and practical application method that yields the most consistent results.

Modulation of Intestinal Histology by Probiotics, Prebiotics and Synbiotics Delivered In Ovo in Distinct Chicken Genotypes

Simple Summary

Probiotics, prebiotics and synbiotics are biologically active substances that are commonly used in poultry feeding as an alternative to antibiotic growth promoters. It was found that they could improve the intestinal microstructure as well as the health status and productivity of animals. The aim of this study was to determine the effect of probiotics, prebiotics and synbiotics administrated in ovo on the 12th day of embryonic development on selected morphological parameters of the small intestine in broiler and native chickens. After hatching, the chicks were placed in pens and housed for 42 days. On the last day of the experiment, all birds were individually weighed and slaughtered, and samples for histological analysis were taken from the duodenum, jejunum and ileum. The following parameters were determined: the height, width and surface area of the villi, the thickness of the muscular layer and the depth of the crypts, as well as the ratio of the villi height to the crypt depth. Based on the obtained data, it can be concluded that the substances used have an impact on the production parameters and intestinal morphology in various utility types of poultry. In addition, the obtained results indicate that chickens with different genotypes react differently to a given substance; therefore, the substances should be chosen in relation to the genotype.

Abstract

The aim of the study was to determine the effect of probiotics, prebiotics and synbiotics administered in ovo on selected morphological parameters of the small intestine (duodenum, jejunum, ileum) in broiler chickens (Ross 308) and native chickens (Green-legged Partridge, GP). On the 12th day of embryonic development (the incubation period), an aqueous solution of a suitable bioactive substance was supplied in ovo to the egg’s air cell: probiotic—Lactococcus lactis subsp. cremoris (PRO), prebiotic—GOS, galacto-oligosaccharides (PRE) or symbiotic—GOS + Lactococcus lactis subsp. cremoris (SYN). Sterile saline was injected into control (CON) eggs. After hatching, the chicks were placed in pens (8 birds/pen, 4 replicates/group) and housed for 42 days. On the last day of the experiment, all birds were individually weighed and slaughtered. Samples for histological analysis were taken directly after slaughter from three sections of the small intestine. In samples from the duodenum, jejunum and ileum, the height and width of the intestinal villi (VH) were measured and their area (VA) was calculated, the depth of the intestinal crypts (CD) was determined, the thickness of the muscularis was measured and the ratio of the villus height to the crypt depth (V/C) was calculated. On the basis of the obtained data, it can be concluded that the applied substances administered in ovo affect the production parameters and intestinal morphology in broiler chickens and GP. The experiment showed a beneficial effect of in ovo stimulation with a prebiotic on the final body weight of Ross 308 compared to CON, while the effect of the administered substances on the intestinal microstructure is not unequivocal. In GP, the best effect in terms of villi height and V/C ratio was found in the in ovo synbiotic group. Taking into account the obtained results, it can be concluded that chickens of different genotypes react differently to a given substance; therefore, the substances should be adapted to the genotype.

The Effect of Adding Herbal Extracts to Drinking Water on Body Temperature, Level of Thyroid Hormones and H:L Ratio in the Blood of Broiler Chickens Exposed to Elevated Ambient Temperature

The aim of the study was to determine the effect of supplementing drinking water with extracts from lemon balm, sage and nettle on body temperature, level of thyroid hormones and the heterophil to lymphocyte (H:L) ratio in the blood of broiler chickens exposed to elevated rearing temperature. One-day-old Ross 308 chicks were divided into four groups: group I (CON) and experimental groups II (LB), II (S) and IV (N), in which, from 22 to 42 days of rearing, drinkers were supplemented with lemon balm extract, sage extract or nettle extract (2 ml/l water), respectively. In addition, at 5 weeks of growth, all the groups were exposed to elevated ambient temperature (up to 30°C) for 5 days, after which the recommended thermal conditions were reinstated. During the study, mortality, rectal temperature and radiated temperature of the broilers were monitored. Blood was collected from 10 birds per group to determine the concentration of thyroid hormones (T3 and T4) and to make blood smears. The H:L ratio was determined based on the percentage of heterophils (H) and lymphocytes (L). The herbal extracts from lemon balm, sage and nettle, added to drinking water at 2 ml/l, reduced the blood level of the thyroid hormone (triiodothyronine) and rectal temperature in the experimental broilers during the initial period of thermal stress. Chickens receiving the nettle extract were also characterised by lower radiated temperature of the unfeathered body, a lower H:L ratio in the blood during the increase in ambient temperature, and the lowest mortality percentage. It can therefore be considered that the dietary supplementation of nettle, in the form and concentration used in this study, had the most favourable effect on the physiological status of the birds (body temperature, level of thyroid hormones and H:L ratio) exposed to elevated ambient temperatures (30°C), and thus on their welfare.

Proteome changes upon in ovo stimulation with Lactobacillus synbiotic in chicken liver

The liver, as the main metabolic organ, plays a key role in many vital processes, including nutrient metabolism, fat digestion, blood protein synthesis, and endocrine management. As one of the immune organs, it has a remarkable ability to adequately activate the immune cells in response to metabolic signals. The anatomy of the liver ensures its close interaction with the gut so that nutrients and gut microbiota contribute to normal metabolism. In chickens, the intestinal microbiota plays an important role in supporting health and improving production parameters. The most effective method of stimulating the microbiota is to administer an appropriate bioactive compound during embryonic development. In ovo stimulation on d 12 of egg incubation involves the delivery of the substance into the air chamber. The aim of the study was to analyze the changes at the protein level after in ovo administration of the synbiotic on d 12 of egg incubation. Our study is the first to conduct a proteome analysis in liver after the administration of a Lactobacillus synbiotic in ovo. Eggs of broiler chickens were injected with a synbiotic—Lactobacillus plantarum with raffinose family oligosaccharides (RFO). On d 21 posthatching liver was collected. We performed analyses based on two-dimensional electrophoresis, matrix-assisted laser desorption/ionization (MALDI) time-of-flight, and MALDI Fourier-transform ion cyclotron resonance to obtain a global view of the hepatic proteome changes in response to in ovo injection. A representative pattern of significantly altered liver proteins was observed after stimulation with the synbiotic. A total of 16 protein spots were differentially expressed, with 5 downregulated and 11 upregulated spots. We conclude that the in ovo synbiotic treatment had the potential to accelerate the major energy-yielding metabolic pathways in the liver of adult broilers.

Effect of heat stress on growth and production performance of livestock and poultry: Mechanism to prevention

Heat stress is a widespread phenomenon in domestic animal feeding in tropical and sub-tropical areas that are subjected to a growing negative effect in livestock and poultry due to global warming. It leads to reduced food intake, retarded growth, intestinal disequilibrium, lower reproductive performance, immunity and endocrine disorders in livestock and poultry. Many studies show that the pathogenesis of heat stress is mainly related to oxidative stress, hormone secretion disorder, cytokine imbalance, cell apoptosis, cell autophagy, and abnormal cell function. Its mechanism refers to activation of mitogen-activated protein kinase (MAPK) signaling pathway and nuclear factor kappa B (NF-κB) signaling pathway, the fluctuation of tight junction protein and heat shock protein expression, and protein epigenetic modification. This manuscript reviews the mechanism of heat stress through an insight into the digestive, reproductive, immune, and endocrine system. Lastly, the progress in prevention and control techniques of heat stress has been summarized.

Cloacal temperature responses of broiler chickens administered with fisetin and probiotic (Saccharomyces cerevisiae) and exposed to heat stress

There is dearth information on the role of fisetin as an antistress agent in ameliorating heat stress in broiler chickens. Here, we experimentally compared probiotic, an antioxidant and antistress agent, with fisetin, an antioxidant agent with little or no report on its antistress effect. Sixty-day-old broiler chickens (Arbo Acre breed) were allotted into 4 groups of 15 birds each as follows; control, fisetin, probiotic, and fisetin + probiotic groups, respectively. All administrations were performed orally through gavage for the treatment groups. The environmental and cloacal temperature (CT) parameters were measured bi-hourly at Days 21, 28, and 35 from 7:00 to 7:00 hr, during the period of study. The environmental parameters exceeded the thermoneutral zone for broiler chickens. The probiotic-supplemented group had the least overall mean CT values all through the experimental period. Based on our findings, fisetin was not a potent antistress agent in mitigating heat stress in birds.

Poultry Response to Heat Stress: Its Physiological, Metabolic, and Genetic Implications on Meat Production and Quality Including Strategies to Improve Broiler Production in a Warming World

The continuous increase in poultry production over the last decades to meet the high growing demand and provide food security has attracted much concern due to the recent negative impacts of the most challenging environmental stressor, heat stress (HS), on birds. The poultry industry has responded by adopting different environmental strategies such as the use of environmentally controlled sheds and modern ventilation systems. However, such strategies are not long-term solutions and it cost so much for farmers to practice. The detrimental effects of HS include the reduction in growth, deterioration of meat quality as it reduces water-holding capacity, pH and increases drip loss in meat consequently changing the normal color, taste and texture of chicken meat. HS causes poor meat quality by impairing protein synthesis and augmenting undesirable fat in meat. Studies previously conducted show that HS negatively affects the skeletal muscle growth and development by changing its effects on myogenic regulatory factors, insulin growth factor-1, and heat-shock proteins. The focus of this article is in 3-fold: (1) to identify the mechanism of heat stress that causes meat production and quality loss in chicken; (2) to discuss the physiological, metabolic and genetic changes triggered by HS causing setback to the world poultry industry; (3) to identify the research gaps to be addressed in future studies.

The functions of Patchouli and Elsholtzia in the repair of hen follicular granular cells after heat stress

The objective of this experimental study was to examine the effects of the Chinese herbal medicines Patchouli and Elsholtzia on the follicular granulosa cells of hens undergoing heat stress conditions. In the current investigation, hen follicular granulosa cells were isolated from the prehierarchical follicles of layer hens and then cultured in-vitro. The cells were randomly divided into the 6 groups. Following the completion of this study's experiments using different heat stress and medicinal treatments, the cell activities of each group were measured using an MTT method. The levels of the heat shock protein 70 (HSP70) were detected using ELISA. The expressions of the steroidogenic acute regulatory protein (StAR) mRNA; cytochrome P450 family 11, subfamily A, member 1 (CYP11A1) mRNA; proliferating cell nuclear antigen (PCNA) mRNA; and the follicle stimulating hormone receptor (FSHR) were detected using the real-time quantitative polymerase chain reactions. The concentration levels of estrogen and progesterone in the cell supernatant of each group were measured using ELISA. The results showed that cell activity had significantly decreased following the heat stress treatments at 43℃, 44℃, and 45℃ (P < 0.01), respectively. Meanwhile, cell activities observed in Patchouli and Elsholtzia were found to be much better than those of heat stress group (P < 0.05). In addition, the expression levels of HSP70 in the follicular granulosa cells of Patchouli and Elsholtzia groups were lower than those of heat stress group. Patchouli and Elsholtzia can maintain expressions of the receptor at 43℃. This study determined that the estrogen and progesterone in the supernatant fluid of Patchouli and Elsholtzia were higher than those observed in heat stress. Therefore, the results obtained in this study indicated that the Patchouli and Elsholtzia treatments administered prior the heat stress experiments had successfully protected the follicular granulosa cells from heat damages while maintaining the normal secretory functions of the granulosa cells.

Effect of Selenium Sources on Laying Performance, Egg Quality Characteristics, Intestinal Morphology, Microbial Population and Digesta Volatile Fatty Acids in Laying Hens

The use of toxic and less bioavailable inorganic selenium can now be supplemented with an alternative organic source from bacterial species in nutrition for human and animal benefit. This study investigated the effects of selenium sources on laying performance, egg quality characteristics, intestinal morphology, caecum microbial population, and digesta volatile fatty acids in laying hens. One hundred and forty-four Lohman Brown Classic laying hens, at 23 weeks of age, were divided into four experimental groups (36 hens in each), differing in form of Se supplementation: no Se supplementation (Con), 0.3 mg/kg of inorganic Se in the form of sodium selenite (Na2SeO3), 0.3 mg/kg of organic Se from selenium yeast (Se-Yeast), and 0.3 mg/kg of organic Se from Stenotrophomonas maltophilia (bacterial organic Se, ADS18). The results showed that different dietary Se sources significantly affected laying rate, average egg weight, daily egg mass, feed conversion ratio (FCR), and live bodyweight (LBW) (p < 0.05). However, average daily feed intake and shell-less and broken eggs were unaffected (p > 0.05) among the treatment groups. The findings revealed that selenium sources had no (p > 0.05) effect on egg quality (external and internal) parameters. However, eggshell breaking strength and Haugh unit were significantly (p < 0.05) improved with organic (ADS18 or Se-yeast) Se-fed hens compared to the control group. In addition, egg yolk and breast tissue Se concentrations were higher (p < 0.05) in the dietary Se supplemented group compared to the control. Intestinal histomorphology revealed that hens fed ADS18 or Se-Yeast groups had significantly (p < 0.05) higher villi height in the duodenum and jejunum compared to those fed Na2SeO3 or a basal diet. However, when compared to organic Se fed (ADS18 or Se-Yeast) hens, the ileum villus height was higher (p < 0.05) in the basal diet group; with the lowest in the SS among the treatment groups. A significant increase (p < 0.05) of Lactobacilli spp. and Bifidobacteria spp., and a decrease of Escherichia coli and Salmonella spp. population were observed in the organic (ADS18 or Se-yeast) compared to inorganic supplemented and control hens. The individual digesta volatile fatty acid (VFA) was significantly different, but with no total VFA differences. Thus, bacterial selenoprotein or Se-yeast improved the performance index, egg quality characteristics, egg yolk and tissue Se contents, and intestinal villus height in laying hens. Moreover, caecum beneficial microbes increased with a decrease in the harmful microbe population and affected individual cecal volatile fatty acids without affecting the total VFA of the laying hens digesta.

Myostatin and Related Factors Are Involved in Skeletal Muscle Protein Breakdown in Growing Broilers Exposed to Constant Heat Stress

Simple Summary

Our results showed that constant heat stress could affect the expression of myostatin and related factors involved in skeletal muscle protein breakdown in growing broilers, resulting in a decrease in muscle protein deposition. These findings suggest a new strategy for regulating muscle protein breakdown in growing broilers, which could benefit the modern broiler industry in combating constant heat stress.

Abstract

Heat stress has an adverse effect on the development of poultry farming, which has always aroused great concern. This study was carried out to investigate the protein breakdown mechanism responsible for the suppressive effect of constant heat stress on muscle growth in growing broilers. A total of 96, 29-day-old, Arbor Acres male broilers were randomly divided into two groups, a thermoneutral control (21 ± 1 °C, TC) and a heat stress (31 ± 1 °C, HS) group, with six replicates in each group and eight birds in each replicate. The trial period lasted for 14 d, and the trial was performed at 60 ± 7% relative humidity, a wind speed of <0.5 m/s and an ammonia level of <5 ppm. The results showed that the average daily feed intake and average daily gain in the HS group were distinctly lower than those in the TC group (p < 0.05), whereas the HS group showed a significantly increased feed conversion ratio, nitrogen excretion per weight gain and nitrogen excretion per feed intake compared to the TC group (p < 0.05). In addition, the HS group showed a significantly reduced breast muscle yield and nitrogen utilization in the broilers (p < 0.05). The HS group showed an increase in the serum corticosterone level (p < 0.05) and a decrease in the thyroxine levels in the broiler chickens (p < 0.05) compared to the TC group, whereas the HS group showed no significant changes in the serum 3,5,3′-triiodothyronine levels compared to the TC group (p > 0.05). Moreover, the HS group showed increased mRNA expression levels of myostatin, Smad3, forkhead box O 4, muscle atrophy F-box and muscle ring-finger 1, but reduced mRNA expression levels of the mammalian target of rapamycin, the protein kinase B and the myogenic determination factor 1 (p < 0.05). In conclusion, the poor growth performance of birds under constant heat stress may be due to an increased protein breakdown via an mRNA expression of myostatin and related factors.

Stress and immunity in poultry: light management and nanotechnology as effective immune enhancers to fight stress

The poultry industry plays a significant role in boosting the economy of several countries, particularly developing countries, and acts as a good, cheap, and affordable source of animal protein. A stress-free environment is the main target in poultry production. There are several stressors, such as cold stress, heat stress, high stocking density, and diseases that can affect birds and cause several deleterious changes. Stress reduces feed intake and growth, as well as impairs immune response and function, resulting in high disease susceptibility. These effects are correlated with higher corticosteroid levels that modulate several immune pathways such as cytokine-cytokine receptor interaction and Toll-like receptor signaling along with induction of excessive production of reactive oxygen species (ROS) and thus oxidative stress. Several approaches have been considered to boost bird immunity to overcome stress-associated effects. Of these, dietary supplementation of certain nutrients and management modifications, such as light management, are commonly considered. Dietary supplementations improve bird immunity by improving the development of lymphoid tissues and triggering beneficial immune modulators and responses. Since nano-minerals have higher bioavailability compared to inorganic or organic forms, they are highly recommended to be included in the bird's diet during stress. Additionally, light management is considered a cheap and safe approach to control stress. Changing light from continuous to intermittent and using monochromatic light instead of the normal light improve bird performance and health. Such changes in light management are associated with a reduction of ROS production and increased antioxidant production. In this review, we discuss the impact of stress on the immune system of birds and the transcriptome of oxidative stress and immune-related genes, in addition, how nano-minerals supplementations and light system modulate or mitigate stress-associated effects.

Potential role of important nutraceuticals in poultry performance and health - A comprehensive review

Antibiotics use in poultry as a growth promoter leads to the propagation of antibiotic-resistant microorganisms and incorporation of drug residues in foods; therefore, it has been restricted in different countries. There is a global trend to limit the use of antibiotics in the animal products. Prevention of the antibiotics use in the poultry diets led to the reduction in the growth performance. Consequently, there is a high demand for natural substances that lead to the same growth enhancement and beneficially affect poultry health. These constituents play essential roles in regulating the normal physiological functions of animals including the protection from infectious ailments. Nutraceuticals administration resulted beneficial in both infectious and noninfectious diseases. Being the natural components of diet, they are compatible with it and do not pose risks associated with antibiotics or other drugs. Nutraceuticals are categorized as commercial additives obtained from natural products as an alternative feed supplement for the improvement of animal welfare. This group includes enzymes, synbiotics, phytobiotics, organic acids and polyunsaturated fatty acids. In the present review, the summary of various bioactive ingredients that act as nutraceuticals and their mode of action in growth promotion and elevation of the immune system has been presented.

Transcriptome Analysis Revealed Ameliorative Effects of Bacillus Based Probiotic on Immunity, Gut Barrier System, and Metabolism of Chicken under an Experimentally Induced Eimeria tenella Infection

In this study, we performed transcriptome analysis in the cecum tissues of negative control untreated non-challenged (NC), positive control untreated challenged (PC), and Bacillus subtilis (B. subtilis) fed challenged chickens (BS + ET) in order to examine the underlying potential therapeutic mechanisms of Bacillus based probiotic feeding under an experimental Eimeria tenella (E. tenella) infection. Our results for clinical parameters showed that birds in probiotic diet decreased the bloody diarrhea scores, oocyst shedding, and lesion scores compared to positive control birds. RNA-sequencing (RNA-seq) analysis revealed that in total, 2509 up-regulated and 2465 down-regulated differentially expressed genes (DEGs) were detected in the PC group versus NC group comparison. In the comparison of BS + ET group versus PC group, a total of 784 up-regulated and 493 down-regulated DEGs were found. Among them, several DEGs encoding proteins involved in immunity, gut barrier integrity, homeostasis, and metabolism were up-regulated by the treatment of probiotic. Functional analysis of DEGs also revealed that some gene ontology (GO) terms related with immunity, metabolism and cellular development were significantly affected by the exposure of probiotic. Kyoto encyclopedia of genes and genomes (KEGG) pathway analysis showed that the DEGs in the cecum of B. subtilis-fed challenged group were mainly participated in the pathways related with immunity and gut barrier integrity, included mitogen-activated protein kinase (MAPK) signaling pathway, toll-like receptor (TLR) signaling pathway, extracellular matrix (ECM)–receptor interaction, tight junction, and so on. Taken together, these results suggest that Bacillus based probiotic modulate the immunity, maintain gut homeostasis as well as barrier system and improve chicken metabolism during E. tenella infection.