Ellagic Acid Improves Antioxidant Capacity and Intestinal Barrier Function of Heat-Stressed Broilers via Regulating Gut Microbiota

Ellagic Acid and Gut Microbiota: Interactions, and Implications for Health

Ellagic acid (EA), a widely distributed natural polyphenolic acid existing in many kinds of plant-based foods, undergoes complex physical and chemical transformations during digestion and biotransformation. Particularly, EA is metabolized by gut microbiota and transformed into urolithins in the colon. These metabolites exhibit enhanced bioavailability and bioactivity. This review explores the intricate interactions between EA and gut microbiota, emphasizing their implications for human health. We discuss the role of gut microbiota in EA metabolism, resulting in distinct metabolic phenotypes associated with varying urolithin production profiles. EA and its gut-derived metabolites, urolithins, have been reported to have the potential to modulate the microbial community composition and function of gut microbiota, promoting beneficial bacteria while reducing harmful ones. Furthermore, EA and urolithins exhibit a spectrum of beneficial biological activities, including antioxidant, anti-inflammatory, and anticancer properties, along with enhancements to intestinal barrier function and modulatory effects on metabolic and cardiovascular systems, through molecular mechanisms such as activating Nrf2 and inhibiting NF-κB pathways. The review highlights and compares the potential of EA and its gut microbial metabolites in the prevention and treatment of various diseases. However, further studies are required to elucidate the underlying mechanisms of the interactions between EA and gut microbiota and their health benefits. Continued investigation into EA and its metabolites is essential for advancing our understanding of their role in promoting human health and developing novel therapeutic applications.

Dietary supplementary with ellagic acid improves the intestinal barrier function and flora structure of broiler chicken challenged with E. coli K88

Ellagic acid (EA) contributes to the immunity and anti-oxidant function of body, whereas there are few reports about its effect on the intestinal health and growth performance of broiler chickens. Hence, the present study was arranged to investigate the effect of dietary supplementary with EA on the intestinal barrier function and flora structure of broiler chickens challenged with Escherichia coli K88 (E. coli K88). A total of 216 healthy 1-day-old, Ross 308 broilers with uniform weight were randomly assigned into three treatment groups, six replicates in each group and twelve birds in each replicate. Broilers in the control (CTR) group and E. coli K88 infected group (ETEC) were fed with the basic diet, and 200 mg/kg EA was supplemented into the diet of the E. coli K88 infected group treated with EA (EAETEC). The animal trial had lasted for 42 days, and the outcomes showed that the ADG and ADFI during the animal trial, the jejunal villi height (VH) and the ratio of VH to crypt depth (CD) tended to be decreased with E. coli K88 treated (P< 0.05). Additionally, the level of serum diamine oxidase (DAO) and intestinal malondialdehyde (MDA) were elevated, the activity of intestinal total superoxide dismutase (T-SOD) and glutathione peroxidase (GSH-Px), the mRNA levels in jejunal claudin-1 and occludin were down-regulated with E. coli K88 treated as well as the transcription levels of ileal Mucin-2, aquaporin-3 (AQP-3) and Na+/H+ exchanger proteins-3 (NHE-3) (P< 0.05). In addition, E. coli K88 down-regulated the α-diversity index of cecal flora, the ratio of Bacteroidota to Firmicutes and the relative abundance of Barnesiella were up-regulated and it of Alistipes was descended with E. coli K88 treated (P< 0.05). Beyond that, the content of propionic acid in the cecal chyme was decreased and the amino acid metabolic pathways were inhibited with E. coli K88 challenged (P< 0.05). Additionally, there was a significant positive correlation between the relative abundance of Alistipes and the levels of butyric acid in the caecal chyme and the activity of GSH-Px in the intestine (P< 0.05). Interestingly, dietary supplementary with EA could reshape the intestinal flora structure and alleviate the above negative effects of E. coli K88 on broiler chickens. In conclusion, dietary supplementary with ellagic acid improved the intestinal barrier function and flora structure of broiler chickens challenged with E. coli K88.

Bacillus coagulans MF-06 alleviates intestinal mucosal barrier from damage in chicks infected with Salmonella pullorum via activating the Wnt/β-catenin pathway

Introduction

This study aimed to assess the protective efficacy of Bacillus coagulans MF-06 as a potential alternative to antibiotics in mitigating intestinal mucosal damage in chicks infected with Salmonella pullorum.

Methods

A total of 150 one-day-old SPF chicks were selected and randomly divided into five groups: control group (CK), probiotics group (EM), probiotics treatment group (PT), antibiotic treatment group (AT), Salmonella pullorum group (SI), CK, AT and SI groups were fed a basal diet, EM and PT groups were fed a basal diet supplemented with 1.0 × 108 CFU/g Bacillus coagulans; PT, AT and SI groups were gavaged with 1.0 × 109 CFU/0.5 mL Salmonella pullorum at 7 days of age; AT group were fed with 0.375 g/kg neomycin sulfate in the basal diet from days 7-14.

Results

Subsequently, the study evaluated alterations in growth performance, the integrity of the intestinal mucosal barrier, cytokines associated with the Wnt/β-catenin signaling pathway, and gut microbiota composition. The results revealed that the administration of Bacillus coagulans MF-06 significantly reduced the feed conversion ratio of chicks (p < 0.05), and significantly increased the average daily weight gain and average daily feed intake in chicks challenged with Salmonella Pullorum (p < 0.05). Furthermore, Bacillus coagulans MF-06 treatment diminished the presence of Salmonella pullorum colonies in the intestinal tract. Additionally, the administration of Bacillus coagulans MF-06 restored levels of (Diamine oxidase) DAO and (D-lactic acid) D-LA levels, as well as the levels of tight junction protein, including TJP1, CLDN1, CLDN2, Occludin, and MUC2 (p < 0.05). The study noted a significant decrease in cell apoptosis (p < 0.05) and a significant increase in the expression of Proliferating Cell Nuclear Antigen (PCNA) and v-myc avian myelocytomatosis viral oncogene homolog (C-MYC) (p < 0.05), which activated the Wnt/β-catenin signaling pathway. Analysis through 16S rRNA sequencing revealed that the intake of Bacillus coagulans MF-06 led to a significant decrease in the relative abundance of Lachnoclostridium, Shuttleworthia, and unidentified-Eggerthellaceae (p < 0.05).

Discussion

Collectively, the Bacillus coagulans MF-06 may provide a protective effect against Salmonella pullorum infection in chicks by enhancing growth performance, strengthening the integrity of the intestinal mucosal barrier, and stabilizing the gut microbiota.

Regulation Progression on Ellagic Acid Improving Poultry Production Performance by Regulating Redox Homeostasis, Inflammatory Response, and Cell Apoptosis

It has been approximately 2000 years since the medicinal homologous theory, which primarily holds that food has the same therapeutic value as medicine in order to improve the health of both humans and animals. In recent years, this theory has also been proposed to be used in poultry breeding. Ellagic acid (EA), a natural compound primarily extracted from medicinal homologous foods such as raspberries and pomegranates, is reported to have incomparable advantages in improving the production performance and disease resistance of poultry due to its pharmacological properties, which regulate the processes of redox homeostasis, inflammatory response, and cell apoptotic death. However, the application and research of EA in poultry production are still in the initial stage, and the potential mechanisms of its biological functions affecting animal health have not been clearly identified, which requires more attention worldwide. This mini-review collects the latest 10-year achievements of research on the effects of EA on poultry health, aiming to promote the practical application of EA in maintaining animal health and formulating corresponding targeted strategies.

Hesperidin Helps Improve the Intestinal Structure, Maintain Barrier Function, and Reduce Inflammation in Yellow-Feathered Broilers Exposed to High Temperatures

To investigate the possible protective effect of hesperidin on intestinal damage caused by high-temperature heat stress in yellow-feathered broilers, 960 broilers aged 21 days were randomly divided into four groups: HT, HT300, HT450, and HT600, with each group receiving different amounts of hesperidin supplementation (0, 300, 450, and 600 mg/kg). The dietary supplementation of hesperidin could mitigate the elevation of corticosterone (CORT) and adrenocorticotropic hormone (ATCH) levels in serum from yellow-feathered broilers induced by heat stress. The supplementation of 300 mg/kg and 450 mg/kg of hesperidin reduced crypt depth and increased the V/C ratio in the small intestine compared to the HT group. The dietary supplementation of hesperidin decreased endotoxin and D-lactic acid levels in the blood, and dietary supplementation of 300 mg/kg of hesperidin increased the expression of claudin-1 and ZO-1 mRNA in the jejunum compared with the HT group. Furthermore, the dietary supplementation of 300 mg/kg of hesperidin decreased serum IL-1β and IL-6 levels. In comparison, supplementation with 300 mg/kg and 450 mg/kg of hesperidin decreased serum TNF-α levels in yellow-feathered broilers compared to the HT group. Moreover, the dietary supplementation of hesperidin decreased NF-κB mRNA levels. Overall, these data suggest that dietary supplementation with hesperidin potentially improves intestinal injury caused by heat stress in yellow-feathered broilers.

Effects of Heat-Induced Oxidative Stress and Astaxanthin on the NF-kB, NFE2L2 and PPARα Transcription Factors and Cytoprotective Capacity in the Thymus of Broilers

The thymus, a central lymphoid organ in animals, serves as the site for T cell development, differentiation and maturation, vital to adaptive immunity. The thymus is critical for maintaining tissue homeostasis to protect against tumors and tissue damage. An overactive or prolonged immune response can lead to oxidative stress from increased production of reactive oxygen species. Heat stress induces oxidative stress and overwhelms the natural antioxidant defense mechanisms. This study's objectives were to investigate the protective properties of astaxanthin against heat-induced oxidative stress and apoptosis in the chicken thymus, by comparing the growth performance and gene signaling pathways among three groups: thermal neutral, heat stress, and heat stress with astaxanthin. The thermal neutral temperature was 21-22 °C, and the heat stress temperature was 32-35 °C. Both heat stress groups experienced reduced growth performance, while the astaxanthin-treated group showed a slightly lesser decline. The inflammatory response and antioxidant defense system were activated by the upregulation of the NF-kB, NFE2L2, PPARα, cytoprotective capacity, and apoptotic gene pathways during heat stress compared to the thermal neutral group. However, expression levels showed no significant differences between the thermal neutral and heat stress with antioxidant groups, suggesting that astaxanthin may mitigate inflammation and oxidative stress damage.

Zinc alleviates thermal stress-induced damage to the integrity and barrier function of cultured chicken embryonic primary jejunal epithelial cells via the MAPK and PI3K/AKT/mTOR signaling pathways

Zinc (Zn) could alleviate the adverse effect of high temperature (HT) on intestinal integrity and barrier function of broilers, but the underlying mechanisms remain unclear. We aimed to investigate the possible protective mechanisms of Zn on primary cultured broiler jejunal epithelial cells exposed to thermal stress (TS). In Exp.1, jejunal epithelial cells were exposed to 40℃ (normal temperature, NT) and 44℃ (HT) for 1, 2, 4, 6, or 8 h. Cells incubated for 8 h had the lowest transepithelial resistance (TEER) and the highest phenol red permeability under HT. In Exp.2, the cells were preincubated with different Zn sources (Zn sulfate as iZn and Zn proteinate with the moderate chelation strength as oZn) and Zn supplemental levels (50 and 100 µmol/L) under NT for 24 h, and then continuously incubated under HT for another 8 h. TS increased phenol red permeability, lactate dehydrogenase (LDH) activity and p-PKC/PKC level, and decreased TEER, cell proliferation, mRNA levels of claudin-1, occludin, zona occludens-1 (ZO-1), PI3K, AKT and mTOR, protein levels of claudin-1, ZO-1 and junctional adhesion molecule-A (JAM-A), and the levels of p-ERK/ERK, p-PI3K/PI3K and p-AKT/AKT. Under HT, oZn was more effective than iZn in increasing TEER, occludin, ZO-1, PI3K, and AKT mRNA levels, ZO-1 protein level, and p-AKT/AKT level; supplementation with 50 μmol Zn/L was more effective than 100 μmol Zn/L in increasing cell proliferation, JAM-A, PI3K, AKT, and PKC mRNA levels, JAM-A protein level, and the levels of p-ERK/ERK and p-PI3K/PI3K; furthermore, supplementation with 50 μmol Zn/L as oZn had the lowest LDH activity, and the highest ERK, JNK-1, and mTOR mRNA levels. Therefore, supplemental Zn, especially 50 μmol Zn/L as oZn, could alleviate the TS-induced integrity and barrier function damage of broiler jejunal epithelial cells possibly by promoting cell proliferation and tight junction protein expression via the MAPK and PI3K/AKT/mTOR signaling pathways.

Dietary supplementation with ellagic acid improves the growth performance, meat quality, and metabolomics profile of yellow-feathered broiler chickens

The aim of this research was to explore the effects of ellagic acid (EA) on growth performance, meat quality, and metabolomics profile of broiler chickens. 240 healthy yellow-feathered broilers were randomly divided into 4 groups (6 replicates/group and 10 broilers /replicate): 1) a standard diet (CON); 2) CON+0.01% EA; 3) CON+0.02% EA; 4) CON+0.04% EA. Compared with the CON group, dietary 0.02% EA increased linearly and quadratically the ADG and lowered F/G ratio from 29 to 56 d and from 1 to 56 d of age (P < 0.05). The EA groups had higher spleen index and showed linear and quadratic improve thymus index (P < 0.05). A total of 0.02% EA linearly and quadratically increased the leg muscle percentage and quadratically increased the breast muscle percentage (P < 0.05). Compared to the control diet, 0.02% EA decreased quadratically the L* and increased a* of breast muscle at 45 min postslaughter (P < 0.05), and quadratically decreased (P < 0.05) the b* and increased linearly and quadratically (P < 0.05) drip loss. Additionally, EA improved linearly and quadratically (P < 0.05) serum total protein concentration and reduced linearly and quadratically (P < 0.05) serum blood urea nitrogen concentration. A total of 0.02% EA quadratically increased catalase activity and decreased malondialdehyde concentration in breast muscle compared with the control diet (P < 0.05). 0.02% and 0.04% EA could linearly and quadratically increase (P < 0.05) the concentrations of histidine, leucine and essential amino acids (EAA), 0.02% EA could linearly and quadratically increase (P < 0.05) the concentrations of threonine, glutamate, and flavored amino acids in breast muscle. 0.02% EA linearly and quadratically improved the C20:3n6, C22:6n3, polyunsaturated fatty acid (PUFA) concentrations, and the ratio of PUFA to saturated fatty acids (SFA), but reduced the C16:0 and the SFA concentrations in breast muscle than the CON group (P < 0.05). The EA diet linearly increased (P = 0.035) and quadratically tended (P = 0.068) to regulate the C18:2n6c concentration of breast muscle. Metabolomics showed that alanine metabolism, aspartate and glutamate metabolism, arginine and proline metabolism, taurine and hypotaurine metabolism, and glycerophospholipid metabolism were the most differentially abundant. These results showed that EA supported moderate positive effects on growth performance, meat quality, and metabolomics profile of broilers.

Protective effects of ferulic acid on embryonic development by improving antioxidant function in broilers embryo of thermal manipulation

This study aimed to elucidate the effects of broiler embryos soaked in ferulic acid (FA) solution on alleviating the negative impact of thermal manipulation (TM) on chicken embryo development and to provide a theoretical and experimental basis for applying TM and FA in the poultry feeding industry. A total of 120 broiler fertilized eggs were randomly divided into three groups: control group, TM group, and comprehensive group (TM + FA), with 40 eggs in each group. The TM group and the comprehensive group from the 7th embryonic age to the 16th embryonic age received TM for ten days, treated with a temperature of 39.5 °C and relative humidity of 65% for 18 h a day. In the comprehensive group, broiler embryos were immersed in FA solution at a concentration of 80 mg/L for 6 min at 16:00 every day from the 6th to the 8th embryo age. They were incubated continuously after being soaked until the chicks hatched. The results showed that the rates of dead embryos and weak chicks in the TM group were significantly higher than those in the control group and comprehensive group. Chick body temperatures of the TM group and comprehensive group were significantly lower than those of the control group. The heart weights of the TM group and comprehensive group were significantly lower than those of the control group, and the leg weights of the TM group were significantly decreased compared with those of the control group and comprehensive group. The SOD activity of serum in the comprehensive group was significantly higher than that in the control group and TM group, while the CAT activity of serum in the comprehensive group and control group was significantly higher than that in the TM group; however, there was no difference between the comprehensive group and control group. The activities of SOD and CAT in the liver were significantly higher than those of the TM group; however, the MDA content of the liver in the comprehensive group and control group was significantly lower than that of the TM group. The gene expression of Nrf2 and SOD in the comprehensive group and TM group was significantly higher than that in the control group; however, there was no significant difference between the comprehensive group and TM group. Soaking broiler embryonic eggs in an FA solution can improve the antioxidant capacity of the liver by upregulating Nrf2-Keap1 signal pathway-related gene expression. FA can effectively alleviate the side effects of TM on chicken embryos and does not impact the effects of TM.

Effects of dietary addition of ellagic acid on rumen metabolism, nutrient apparent digestibility, and growth performance in Kazakh sheep

Plant extracts have shown promise as natural feed additives to improve animal health and growth. Ellagic acid (EA), widely present in various plant tissues, offers diverse biological benefits. However, limited research has explored its effects on ruminants. This study aimed to investigate the effects of dietary addition EA on rumen metabolism, apparent digestibility of nutrients, and growth performance in Kazakh sheep. Ten 5-month-old Kazakh sheep with similar body weight (BW), fitted with rumen fistulas, were randomly assigned to two groups: the CON group (basal diet) and the EA group (basal diet + 30 mg/kg BW EA). The experiment lasted 30 days, and individual growth performance was assessed under identical feeding and management conditions. During the experimental period, rumen fluid, fecal, and blood samples were collected for analysis. The results indicated a trend toward increased average daily gain in the EA group compared to the CON group (p = 0.094). Compared with the CON group, the rumen contents of acetic acid and propionic acid were significantly increased in the EA group and reached the highest value at 2 h to 4 h after feeding (p < 0.05). Moreover, the relative abundances of specific rumen microbiota (Ruminococcaceae, uncultured_rumen_bacterium, unclassified_Prevotella, Bacteroidales, Bacteroidota, Bacteroidia, unclassified_Rikenellaceae, and Prevotella_spBP1_145) at the family and genus levels were significantly higher in the EA group (p < 0.05) compared to the CON group. The EA group exhibited significantly higher dry matter intake (p < 0.05) and increased the digestibility of neutral detergent fiber and ether extract when compared with the CON group (p < 0.05). Additionally, the plasma activities of total antioxidant capacity (T-AOC), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) were significantly higher, while malondialdehyde (MDA) concentration was significantly lower in the EA group compared to the CON group (p < 0.05). In conclusion, dietary supplementation with 30 mg/kg BW EA in 5-month-old Kazakh sheep increased the dry matter intakQ16e, apparent digestibility of neutral detergent fiber, and ether extract, as well as the contents of acetic acid and propionic acid in rumen fluid. Moreover, EA supplementation regulated the ruminal microbiota, enhanced antioxidant capacity, and improved daily weight gain.

Effect of white jade snail secretion on antioxidant capacity and intestinal microbial diversity in mouse model of acute gastric ulcer

BACKGROUND

In the present work, acute gastric ulcer models were constructed by administering hydrochloric acid/ethanol. The mice ingested white jade snail secretion (WJSS) through gastric infusion. Ulcer areas in gastric tissue were recorded, and malondialdehyde (MDA) and superoxide dismutase (SOD) were also measured. Notably, high-throughput 16S rDNA analysis of intestinal flora and determination of amino acid composition in feces were performed to understand the effect of WJSS on model mice.

RESULTS

Compared with the control group, the ulcer area in the WJSS low-, medium- and high-concentration groups declined by 28.02%, 39.57% and 77.85%, respectively. MDA content decreased by 24.71%, 49.58% and 64.25%, and SOD relative enzyme activity fell by 28.19%, 43.37% and 9.60%, respectively. The amounts of amino acids in the low-, medium- and high-concentration groups were slightly lower, and probiotic bacteria such as Bacteroidetes and Lactobacillales increased in different-concentration WJSS groups. Adding WJSS contributes to the establishment of beneficial intestinal flora and the absorption of amino acids.

CONCLUSION

Our results showed that WJSS has a beneficial effect on inhibiting hydrochloric acid-ethanolic gastric ulcers, suggesting that WJSS has excellent potential as a novel anti-ulcer agent. Combined with ulcer area, MDA content, SOD content, gut probiotics and other indicators, a high concentration of WJSS had the best protective effect on acute gastric ulcer. © 2023 Society of Chemical Industry.

Intermittent and Mild Cold Stimulation Maintains Immune Function Stability through Increasing the Levels of Intestinal Barrier Genes of Broilers

In order to improve the adaptability of broilers to low-temperature environments and their ability to resist acute cold stress (ACS), 240 one-day-old broilers were selected and randomly divided into three groups. The control treatment (CC) group was raised at the conventional feeding temperature from 1-43 days (d), the cold stimulation treatment (CS) group was kept at 3 °C below the temperature of CC at 1 d intervals for 3 and 6 h from 15 to 35 d, namely, CS3 and CS6, respectively. Then, all broilers were kept at 20 °C from 36 to 43 d. ACS was then carried out at 44 d, and the ambient temperature was dropped to 10 °C for 6 h. The study investigated the production performance, as well as levels of intestinal barrier genes (including Claudin-1, E-cadherin, Occludin, ZO-1, ZO-2 and Mucin2), secretory IgA in duodenum and jejunum, and immunoglobulins (IgA and IgG) in serum. The results showed that IMCS could increase the daily weight gain and decrease the feed conversion ratio. During IMCS, the expression levels of intestinal barrier genes were up-regulated and the content of secretory IgA was increased. When IMCS ceased for one week, the level of immunoglobulins in serum stabilized, and the expression levels of Occludin, ZO-2 and Mucin2 still maintained high levels. After ACS, broilers that received IMCS training maintained high levels of intestinal barrier genes and secretory IgA.

Chicken embryo thermal manipulation alleviates postnatal heat stress-induced jejunal inflammation by inhibiting Transient Receptor Potential V4

Intestinal inflammation induced by heat stress is an important factor restricting the healthy growth of broilers. The aim of this study was to evaluate the effect of chicken embryo thermal manipulation (39.5 ℃ and 65 % RH for 3 h daily during 16-18 th embryonic age) on intestinal inflammation in broilers under postnatal heat stress and to investigate whether transient receptor potential V4 (TRPV4) plays a role in this process. Our results suggest that broilers with embryo thermal manipulation experience could delay the rising of rectal temperature during postnatal heat stress (P < 0.05), and had better production performance (P < 0.05), intestinal morphological parameters (P < 0.05) and higher expression of tight junction related genes (P < 0.05). The increased serum lipopolysaccharide (LPS) content, activation of nuclear factor-kappa B (NF-κB) signaling pathway and the increased expression of pro-inflammatory cytokines interleukin (IL)-1β, IL-6 and tumor necrosis factor alpha (TNF-α) in jejunum during postnatal heat stress were alleviated by embryo thermal manipulation (P < 0.05). Postnatal heat stress induced an increase in mRNA and protein expression of TRPV4 in jejunum (P < 0.05), but had no effect on broilers which experienced embryo thermal manipulation (P > 0.05). Inhibition of TRPV4 reduced LPS-induced Ca²⁺ influx and restrained the activation of NF-κB signaling pathway and the expression of downstream pro-inflammatory cytokines (P < 0.05). The expression of DNA methyltransferase (DNMT) in the jejunum of broilers exposed to postnatal heat stress was increased by embryo thermal manipulation (P < 0.05). The DNA methylation level of TRPV4 promoter region was detected, and the results showed that embryo thermal manipulation increased the DNA methylation level of TRPV4 promoter region (P < 0.05). In conclusion, Chicken embryo thermal manipulation can alleviate jejunal inflammation in broilers under postnatal heat stress. This may be due to the decreased circulating LPS or the increased DNA methylation level in the promoter region of TRPV4, which inhibits TRPV4 expression, thereby reducing Ca²⁺ influx, and finally alleviating inflammation by affecting NF-κB signaling pathway. The work is an attempt to understand the mechanism involved in alleviation of adverse effects of heat stress during postnatal life through prenatal thermal manipulation and to reveal the important role of epigenetics.

A comparative study on feeding timing and additive types of broilers in a high-temperature environment

Antioxidants such as vitamin C (VC) and green tea extract (GTE) have been reported to have various antioxidant functions and are used as one of the nutritional approaches to alleviate heat stress (HS) in chickens. However, studies on the feeding timing that can produce optimal effects have not been reported. In this study, the stress-relieving effect of VC and GTE addition timing was investigated in high-temperature broiler chickens. A total of 880 1-d-old male chickens were used, and the treatments were as follows: no feed additives provided, CON; VC 250 mg/kg added from 1 d, VC1; GTE 600 mg/kg added from 1 d, GTE1; VC 250 mg/kg added from 22 d, VC22; GTE 600 mg/kg added from 22 d, GTE22. The HS environment was provided for 2 wk from the 22 d and was set at 33 ± 1 °C, 55 ± 10% for 24 h. Feed and water were provided ad libitum. Broiler production was similar in all treatments. In chicken meat quality, the addition of VC and GTE had an effect on meat color and pH (P < 0.05). In particular, GTE had a positive effect on the antioxidant capacity and quality preservation of breast meat (P < 0.05). In blood characteristics, GTE1 significantly lowered the level of total cholesterol, and VC1 affected AST and IgM (P < 0.05). Interestingly, the VC1 group had a positive effect on the maintenance and development of intestinal morphology, a lower rectal temperature, and showed to relieve stress. In conclusion, the addition of VC and GTE has been shown to alleviate the high-temperature stress of broilers, and in the case of VC in particular, feeding from 1 d appeared to alleviate stress more effectively. This study suggests that it is important to determine the appropriate timing of addition of functional substances in order to effectively reduce various stresses that occur in livestock rearing.

A comprehensive review on natural phenolic compounds as alternatives to in-feed antibiotics

Intensive livestock and poultry farming in China largely relied on the use of in-feed antibiotics until July 2020. The consequences of antibiotic overuse in animal feed include accumulation in animal products and the development of bacterial antibiotic resistance, both of which threaten food safety and human health. China has now completely banned the circulation of commercial feed containing growth-promoting drug additives (except Chinese herbal medicine). Therefore, alternatives to in-feed antibiotics in animal production are greatly needed. Natural phenolic compounds (NPCs) exist widely in plants and are non-toxic, non-polluting, highly reproducible, and leave little residue. Many natural flavonoids, phenolic acids, lignans, and stilbenes have polyphenol chemical structures and exhibit great potential as alternatives to antibiotics. In this review we delineate the characteristics of plant-derived NPCs and summarize their current applications as alternatives to in-feed antibiotics, aiming to provide new strategies for antibiotic-free feeding and promote the development of more sustainable animal husbandry practices.