Resumo em Inglês:

ABSTRACT This study was conducted in order to determine the effects of different doses of resveratrol and curcumin added to the diet of broilers on the fatty acid profile of drumstick meat, and the microbial load and physicochemical criteria in drumstick and breast meat. In the study, a total of 200 male broiler chicks at the age of one days were equally distributed into five groups. The treatments consisted of a basal diet (Control) and the treatments, which added the following amounts of additives to the basal control diet: (R250) 250 mg kg-1 resveratrol, (R500) 500 mg kg-1 resveratrol, (C250) 250 mg kg-1 curcumin, and (C500) 500 mg kg-1 curcumin. It was found that resveratrol and curcumin significantly decreased the counts of total mesophilic aerobic bacteria (TMAB) (8th day), Lactobacillus spp. (6th day) and Lactococcus spp. (8th day) in drumstick meat. In breast meat, decreases were observed in the counts of Micrococcus/Staphylococcus (4th day) in the C500 group, and Enterobacteriaceae (8th day) in the R500 and C500 groups. The TBARS value in drumstick meat decreased significantly in the R250, R500 and C500 groups on the zeroth day. Myristic acid, myristoleic acid, γ-linolenic acid, unsaturated fatty acids (ΣUFA), and medium chain fatty acids (MCFA) percentages of total fatty acids in drumstick meat were found to increase in the R250 group according to other groups. In conclusion, it was observed that resveratrol and curcumin added to the diet at variable levels affected the meat in terms of microbial and fatty acid profiles, while the effect was limited effectiveness on physicochemical parameters.

Resumo em Inglês:

ABSTRACT The present study aimed to investigate the potential utilization of orange peel essential oil (OPEO), as a natural feed additive in poultry nutrition. The impact of incorporating OPEO into the diets of laying quails was examined with respect to various performance criteria, including feed consumption and efficiency, as well as egg production, weight, and shelf life. A total of 120 female egg quails, aged 16 weeks, were allocated into three main groups, and fed with control rations supplemented with OPEO at levels of 0 mg/kg (control group), 200 mg/kg, and 300 mg/kg. Throughout the study, egg production was monitored on a daily basis, feed consumption was recorded every two weeks, and egg weights were measured twice a week on consecutive days. Moreover, the levels of malondialdehyde, a lipid peroxidation marker, in the egg yolks were quantified. The results indicated that the inclusion of OPEO in quail rations did not exert a significant influence on feed consumption and efficiency. However, OPEO supplementation had a positive impact on egg production and weight, leading to substantial increases in both crucial performance parameters. Furthermore, the study elucidated a statistically significant impact of OPEO on the levels of malondialdehyde in the egg yolks. In summary, the incorporation of OPEO into quail diets showcased remarkable efficacy in significantly augmenting egg yield and weight, while leaving feed consumption unaffected. These results highlight the potential of utilizing OPEO as a natural feed additive to improve the performance and egg quality of laying quails in commercial production systems.

Resumo em Inglês:

ABSTRACT This study aimed to analyze 19 isolates of Salmonella spp., from broiler litter swabs in the State of São Paulo, by typing and analyzing the detection of resistance genes associated with ESBL’s (Extended Spectrum Beta Lactamase), AMPC (C-type cephalosporinases) and carbapenemases by molecular and phenotypic techniques. A PCR microarray platform (Check and Trace by Check-Points) was used to identify the isolated serotype. The isolates were also evaluated for identification of carbapenemase genes, MCR 1-2 (colistin resistance), AmpC (C-type cephalosporins), and ESBLs (β-lactamases resistance). To identify phenotypic antibiotic resistance, the minimal inhibitory concentration (MIC) was evaluated with the antibiotics meropenem, amoxicillin, and ceftriaxone. The most prevalent serotypes identified were S. Infantis and S. Saintpaul, with a prevalence of 15.07% (3/19). Other strains identified were S. Cerro, S. Sandiego, S. Kentucky, S. Alachua, S. Javiana, S. Livingstone, S. Typhimurium, S. Heidelberg, non-enteric Salmonella, and a Salmonella not typifiable by the typing kit. All samples were negative for identifying carba resistance genes, MCR, ESBL, and AmpC. In the phenotypic profile, meropenem was the least resistant, while amoxicillin and ceftriaxone showed a high resistance pattern. The results show that phenotypic resistance is not associated with the presence of resistance genes studied here. In addition, the resistant bacteria found in MIC have resistance mechanisms not associated with the genes studied here. Additional measures must be implemented to prevent the indiscriminate use of antimicrobial agents therapeutically or as growth promoters.

Resumo em Inglês:

ABSTRACT This study aims to evaluate the impact of different cage densities and ages on the growth performance and quality traits of eggs for Hy-Line laying hens. For this experiment, a total of 216 laying hens were divided into three groups, with 9 replicates each. The cage densities were 1353 cm2/hen, 677 cm2/hen, and 451 cm2/hen representing groups T1, T2 and T3, respectively. The results of the study showed that feed conversion ratio (FCR) was significantly improved and egg weights were significantly increased in hens with low cage density (p<0.05). Moreover, cage density significantly affected final body weight. At the end of the experiment, hens in group T1 were about 35 and 70 g heavier than those in groups T2 and T3, respectively. On the other hand, cage density had no significant (p>0.05) effect on egg shape index, yolk index, albumin index, Haugh unit, eggshell thickness, yolk color, and shape index. In conclusion, high space availability for hens had positive effects on feed conversion and egg weight.

Resumo em Inglês:

ABSTRACT The aim of present study was to investigate the effect of phytase supplementation on growth performance, mineral digestibility, and tibia calcium and phosphorous in broilers fed low phosphorus diets. Three hundred broiler chicks were allotted to six different treatments with five replicates each (10 chicks/replicate). T1: Control, 0.5% available phosphorus (Av.P); T2: 0.35P, 0.35% Av.P; T3: 0.20P, 0.20% Av.P; T4: 0.35P-1Phy, diet 0.35P + 1000FTU/kg phytase; T5: 0.20P-2Phy, diet 0.20P + 2000 ftu/kg phytase; T6: 0.20P-3Phy, diet 0.20P + 3000 ftu/kg phytase. Feed intake and weight gain were higher (p=0.001) in broilers fed phytase supplemented diets. Feed conversion ratio was better (p<0.01) in the 0.35P-1Phy than in the others. Calcium and P digestibility was higher (p<0.05) in the 0.35P-1Phy than the 0.35P, 0.20P and 0.20P-2Phy, groups. The highest (p<0.05) tibia ash was observed in the 0.35P and 0.35P-1Phy groups rather than the 0.20P at 21st day, while at 33rd day it was higher (p<0.05) in the control than in 0.20P. At 21st day, tibia Ca content was higher (p<0.05) in the 0.35P-1Phy group as compared to 0.20P and 0.35P, while at 33rd day, tibia Ca content in the control and 0.20P-2Phy groups was higher (p<0.05) than that of 0.20P and 0.35P. Furthermore, tibia P content was higher (p<0.05) in all phytase supplemented groups. It could be concluded that dietary available phosphorus at 0.35% with phytase addition at 1000 FTU/kg reduces the cost per unit weight gain by 9.17%, with positive effects on growth performance.

Resumo em Inglês:

ABSTRACT This study examined the effects of lavender essential oil on performance, meat quality, microbial load, fatty acid profile and gut microbiota in quails. In the study, 200 quails (Coturnix coturnix Japonica) were divided into 4 groups and 5 subgroups. The groups consisted of a control group (0 mg/kg feed) and three lavender essential oil groups, namely Lav125 (125 mg/kg feed), Lav250 (250 mg/kg feed), and Lav500 (500 mg/kg feed). In terms of body weight change, Lav500 group had the best results after the control group (p>0.05). It was observed that, compared to the control group, pH levels were high (p<0.05) in Lav250 and Lav500 groups on the 9th day of storage. The effect of storage time on malondialdehyde (MDA) was used as a parameter of lipid peroxidation in meat, and the Lav250 and Lav500 groups presented lower concentrations as compared to the control group (p<0.05). In this study, the addition of lavender essential oil to the diet enriched the concentrations of n-3 and n-6 polyunsaturated fatty acids (PUFA). Moreover, the height of villi in the duodenum and jejunum, and consequently absorption, increased significantly in the Lav500 group as compared to the control group. The concentration of MDA, a blood serum antioxidant enzyme, decreased with the addition of lavender oil. Additionally, lavender essential oil added to quail diets was observed to increase the number of Lactobacillus spp. (probiotic bacteria) colonies (p<0.05).

Resumo em Inglês:

ABSTRACT Infectious Bronchitis Virus (IBV) is a highly contagious pathogen that causes a serious illness with global circulation. While there is extensive data available on the virus’s existence and transmission in commercial chickens in Saudi Arabia, there is a lack of such information regarding guineafowls. Therefore, this study aimed to investigate possible IBV infection among guineafowls in the Al-Hassa Governorate of the Eastern Province, Saudi Arabia. Oropharyngeal and cloacal swabs were collected from several unvaccinated flocks of guinea fowls without respiratory clinical symptoms in November and December 2022, totaling 350 samples. Total RNA was extracted from the swab samples, and a conventional reverse transcription-polymerase chain reaction was employed to detect IBV. The results revealed varying amounts of IBV in oropharyngeal and cloacal swabs at different points in time, suggesting that IBV may be widely distributed among guineafowls without exhibiting any symptoms. These findings indicate that guineafowls could act as reservoirs, influencing the ecology and epidemiology of the disease. Notably, this study reports the first occurrence of IBV in the province of Al-Ahsa, highlighting that guineafowls have been naturally exposed to the virus. To support the development of effective vaccination techniques and control measures for the disease in Saudi Arabia, the recommendation for future research endeavors is conducting ongoing surveillance, viral isolation, sequencing, phylogenetic tree analysis, and serotype characterization of IBV in guineafowls.

Resumo em Inglês:

ABSTRACT Supplementation of Cv (clove) and Ts (tulsi) augments the growth rate and gut health of broilers. However, studies on their impact on the vital organs and male reproductive system remain scarce. Therefore, the current study aimed to investigate the impact of Cv and Ts supplementation on hematological profiles, as well as the heart, lungs, liver, kidney, and testes of broilers, both morphologically and biometrically. Sixty one-day-old broiler chicks, divided into four homogenous groups (control-T0 and three supplement groups-T1, T2, and T3), were fed 0.5% Cv and 2% Ts (T1), 1% Cv and 3% Ts (T2), and 1.5% Cv and 4% Ts (T3) with drinking water for 21 d. Organ samples were collected on d 14 and d 28 for macroscopic and microscopic (hematoxylin and eosin stain) investigation. Cv and Ts didn’t affect the hematological profile, organ weight gain, and their general histoarchitectures. However, the histomorphometric investigation showed an increased (p<0.05) parabronchus surface area of the lungs, size of the renal glomeruli, the diameter of the proximal and distal convoluted tubules of the kidney in the T1 and T2 groups, and size of the seminiferous tubules of the testes in group T1. These findings suggest that unlike antibiotic or steroid growth promoters (GPs), Cv and Ts have beneficial impacts on the vital organs as well as on the male gonad of broilers from the morphologic and biometric perspectives.

Resumo em Inglês:

ABSTRACT In this study, we evaluated some of the factors that affect mortality rate during transport from broiler poultry houses to slaughterhouses by conducting panel data analysis. We analyzed the data obtained from 26,599 broiler farms transported to the slaughterhouse from contracted broiler farms in 11 provinces in Turkey. Augmented Dickey-Fuller (ADF) and Phillips-Perron (PP) tests were performed to evaluate whether the series forming the dataset were stationary. To analyze individual effects, parameters were estimated using fixed and random effects models. To decide which of the two models was valid, the Hausman test and fixed effects panel data analysis were performed. The fixed effects model explained 90.93% of the changes in the mortality rate through the independent variables. In the non-periodical fixed-effect panel data analysis, the mortality rate shows a significant (p<0.01) effect between the number of animals alive, number of animals dead, mean and total live weight at poultry farm exit, mean live weight at slaughterhouse arrival, and different variables. Our results showed that the estimation equations developed using model parameters to determine the mortality rate during transportation from different provinces could contribute to effective production planning.

Resumo em Inglês:

ABSTRACT The aim of this study is to examine the osteometric measurements of the long and short bones in the fore and hind extremities of German mast geese using 3d reconstruction technique. For this purpose, 10 (5 female and 5 male) German mast goose were used. After the dissection process of the geese was completed, computerized tomography was taken and the reconstruction process was completed. In the measurements made, it was observed that male were longer than female in the GL parameter in all bones. Bd parameter and surface area in the humeral bone were statistically significant (p<0.05). The measurement points of the femur bone were analyzed, statistical significance was found in LM, BP, SC and volume parameters (p<0.05). The parameter Dp was highly significant (p<0.01). As a result, since this study is the first 3D study in geese, it will contribute to the taxonomy and the differences between the birds with the measurements made.

Resumo em Inglês:

ABSTRACT The animal feed industry is continuously researching new feed additives to substitute other materials, reduce costs, or add value to the final product. The microalgae Arthrospira maxima, cultivated using wastewater as a nutritional source, was evaluated as a feed additive by including 2, 4, and 6% in isocaloric and isoprotein diets for laying hens. Five replicates per treatment with 5 hens per cage were used during an experimental period of 28 days. Productive behavior and egg characteristics (quality, fatty acid profile, cholesterol level) were evaluated. The inclusion of microalgae up to 4% in diets for 52-week-old laying hens did not affect productive performance (egg production, egg weight, egg mass, FCR, shell thickness, and Haugh units). No effects were observed on the cholesterol level or the concentration of fatty acids in the eggs, but more information is needed to determine if the microalgae drying or storage process can generate variations of these results. The inclusion of 6% microalgae produced an acceptable egg yolk color for the local market. The results indicate that this material can be used as a protein source up to an inclusion of 4% in the diet, and hens may need an adaptation period to maintain production at the 6% inclusion level.

Resumo em Inglês:

ABSTRACT The aim of the present study was to analyze the histomorphology and histopathology of broiler chicken tracheas submitted to different levels of ammonia gas. The experiment was conducted during different seasons in 2019 in the city of Garanhuns, Brazil. Three sheds with rice hull bedding were used: Shed 1, new bedding; Shed 2, reused bedding; Shed 3, reused bedding with an increase in moisture. Twenty-eight birds were housed per shed for a 42-day production cycle. On days D0 (control group), D7, D21, D35 and D42, seven birds per shed were euthanized. Fragments of the trachea were collected and placed into plastic containers with 10% buffered formalin solution (pH 7) for 24 h, subsequently undergoing routine histological processing. The thickness of the tracheal mucosa was measured using digital images, considering ten equidistant points as being separated by 100 µm. Histopathological lesions were analyzed considering distribution and intensity. The birds in Shed 2 (reused bedding) had greater quantity and severity of histopathological lesions, but the differences did not reach statistical significance. Regarding histomorphometry, birds reared in the higher temperature period had thicker tracheal mucosa at the end of the production cycle (D35 and D42) compared to those raised in the cooler temperature period. In conclusion, the difference in bedding did not significantly alter the tracheal mucosa of the birds, whereas temperature exerted an influence on the thickness of the trachea at the end of the production cycle.

Resumo em Inglês:

ABSTRACT Emulsifiers and exogenous lipases are feed additives used to increase lipid utilization in broiler diets. A meta-analysis was carried out to quantify the effects of the supplementation of emulsifiers and exogenous lipases on broiler weight gain (BWG, g/broiler/d) and feed conversion ratio (FCR, g/g) during the whole production cycle. Studies were obtained from the PubMed, Scielo, Science Direct, Scopus, and Web of Science databases. A total of 2669 studies were identified, 25 of which composed the database for the meta-analysis, representing data from a total of 14,643 broilers. These results demonstrate that there is evidence in the literature supporting that supplementation with emulsifiers or lipases improves broiler weight gain and feed conversion during the whole production cycle. However, the effect of the additives is influenced by bird sex, lipid source and concentration, type of additive and concentration, energy level of the feed, and bird strains. The isolated use of emulsifiers increases weight gain by 1.62g/day and reduces feed conversion by 0.04. However, there is no evidence that exogenous lipase use alone improves weight gain or feed conversion in broilers during the whole production cycle. The latter result may be due to the small number of studies with the additive in question, rather than its possible effects on weight gain and feed conversion. Therefore, further investigation should be conducted on this topic, especially studies on females fed diets supplemented with lipases.

Resumo em Inglês:

ABSTRACT This research aimed to study the effect of light regime on performance and egg quality of white laying hens applied at the start laying phase. A total of 420 Hy line White laying hens, at 19 weeks of age were used, distributed in a completely randomized design, during 5 periods of 28 days, extending from January to June, corresponding to the age of 19 to 38 weeks of age of the birds. Three lighting programs were evaluated: continuous 16 h of light and 8 h of dark (CONT); intermittent program with two 2-min photophases equidistant at 16 h between natural light and 8 h of dark (INT) and continuous program only using decreasing natural light (LND). Feed intake (g/bird/day), egg production (%bird/day), egg weight (g), egg mass (g/bird/day), feed conversion (g/g) and egg density (g/cm3) were evaluated. Feed intake and feed conversion were higher (p<0.05) in birds submitted to the CONT program compared to the LND program, however the CONT and LND programs did not differ (p>0.05) from the INT. Egg production, egg weight, egg mass and egg density were similar (p>0.05) between programs. Intermittent program with two photophases of 2 min equidistant 16 h between natural light can be applied in light layers at the start laying phase without impairing the productive performance and eggshell quality.

Resumo em Inglês:

ABSTRACT In Experiment one, a total of 60 blue peacocks were randomly assigned into the control group (12.00 MJ/kg) and treatment group (12.30 MJ/kg). Each group consisted of three repeats and each replicate contained 10 peacocks (2 males and 8 females). In Experiment two, based on better metabolic energy (ME) (12.30 MJ/kg), 90 blue peacocks were randomly assigned to three dietary treatments with 18.00%, 19.00% and 20.00% crude protein (CP) levels. The results of Experiment one revealed that the different dietary ME levels had minor effect on productive performance of peacocks (p>0.05). Decreasing dietary ME levels decreased the concentration of estradiol (E2) and increased the concentrations of follicle stimulating hormone (FSH) and luteinizing hormone (LH) (p<0.01). However, 12.00 MJ/kg ME stimulated creatinine levels of blue peacock, which exceeded normal values. Based on this result, blue peacocks fed with 12.30 MJ/kg ME had better performance. Results from Experiment two indicated that egg production of blue peacocks was significantly improved by the 20.00% CP diet. The concentrations of FSH, LH, and E2 remained at high levels fed with the 20.00% CP diet. Changes in serum biochemical indices such as total cholesterol, creatinine and globulin of peacocks supplied with 18.00% and 19.00% CP diets were abnormal (p<0.05). Based on the results of two experiments, the optimal dietary ME and CP levels of blue peacocks were 12.30 MJ/kg ME and 20.00% CP.

Resumo em Inglês:

ABSTRACT In order to explore the effect of estrogen receptor (ESR) gene polymorphism on the egg production performance of quails, the polymorphisms of exon 1, exon 4 and exon 8 of the ESR gene in three Laying Quail Populations of Chinese Yellow quail, Korean quail and Beijing white quail were detected by PCR-RFLP, and their association with the egg production performance of quails was analyzed. The results showed that three genotypes were detected in exon 1, exon 4 and exon 8 of the ESR gene in three quail populations, namely TT, CC and CT genotypes. Among them, the frequency of CC genotype in exon 1 of the ESR gene was the highest in Chinese Yellow quail, Beijing white quail and Korean quail (0.515, 0.600 and 0.723); Exon 4 of the ESR gene had the highest frequency of TT genotype (0.409, 0.617) in Chinese yellow and Korean quails, while CC genotype was the highest in Beijing white quails (0.667).The frequency of TT genotype in exon 8 of the ESR gene was the highest in Beijing white quail and Korean quail (0.708, 0.500), while the frequency of CT gene was the highest in Chinese yellow quail (0.521). The results of association analysis showed that there was no correlation between exon 1 of the ESR gene and quail egg production performance (p>0.05). Exon 4 of the ESR gene was significantly correlated with laying traits such as feed-egg ratio, egg laying number, laying rate and starting weight of quails (p<0.05). Exon 8 of the ESR gene was significantly correlated with feed-egg ratio, egg laying number and egg laying rate of quails (p<0.05).In conclusion, the research shows that the ESR gene can be used as a candidate gene for marker assisted selection of egg production performance of Laying Quails, which provides a theoretical basis for cultivating new egg laying quail lines with better egg production performance.

Resumo em Inglês:

ABSTRACT The objective was to examine the effects of supplementing different levels of zeolite in the diet of laying hens during the laying phase, at 54 weeks of age, on production performance, egg quality, ammonia volatilization, excreta pH, blood parameters, weight, and organ morphometry. The treatments consisted of a control diet free of zeolite and five diets including increasing levels of zeolite (0.7, 1.4, 2.1, 2.8, and 3.5%). A completely randomized design was adopted with eight replicates of five birds per plot, totaling 240 laying hens, for four 28-day periods. Results were subjected to ANOVA, Dunnett’s test, and regression analysis at 5% probability. The zeolite levels had no significant effect on production performance, egg quality, and blood parameters. The zeolite levels have a significant effect on ammonia volatilization, excreta pH, liver weight, and organ morphometry specifically on the intestinal length. Ammonia and pH reached a linear plateau. Ammoniacal nitrogen levels in the excreta differed from that observed in the control group at all zeolite levels, whereas the pH was lowest at the zeolite inclusion levels of 0.7 and 1.4%. Ammonia volatilization and the pH value of the excreta decreased by 46.9% and 4.6%, when the laying hens consumed diets with 0.93% and 1.19% zeolite, respectively. There was an effect on the relative weight of the organs, with higher liver yield and intestinal length provided by zeolite inclusion. Therefore, zeolite can be included in the diet of commercial layers at up to 0.93% without affecting their production performance or egg quality.

Resumo em Inglês:

ABSTRACT Exposure to increasing concentrations of CO2 in the first 10 days of incubation may have effects on the development of bird cardiac and respiratory organs. Moreover, the age of breeders can influence hatching performances. This study aimed to investigate the effect of exposure to increasing concentrations of CO2 in the first 10 days of incubation on the morphophysiological development of the digestive system of embryos and chicks from broiler breeders aged 31 and 41 weeks. A total of 860 fertile eggs from the Cobb strain were distributed in a completely randomized design, in a 2 x 2 factorial arrangement, with 2 different gaseous environments (Control (C) - no increase in CO2 concentration and, Hypercapnia (CO2) - a gradual increase in CO2 concentration until reaching 1% on the 10th day) and 2 different broiler breeder ages (31 and 41 weeks). Half of the eggs were obtained from 31-week-old breeders, and the other half from 41-week-old breeders. Compared to the control group, incubation in an atmosphere with 1% CO2 led to an increase in villus heights in the duodenum, jejunum, and ileum of the embryos, with a reduction in villus density in the same segments. Chicks from 41-week-old broiler breeders showed higher villus heights in the duodenum, jejunum, and ileum at day 1 post-hatching, and lower villus density at 7 days. It was concluded that the incubation of fertile eggs in hypercapnia conditions could positively affect the small intestine of embryos and post-hatch chicks.

Resumo em Inglês:

ABSTRACT To better understand the effects of conjugated linoleic acid (CLA) administered at the early stages of embryonic development in poultry, it is necessary to analyze the molecular background. The molecular interpretation of poultry muscle after in-ovo administration of CLA remains to be reported. The purpose of the present study was to analyze the molecular background of muscle development based on gene expression parameters. On embryonic day (E) 11, the eggs were randomly divided into two groups (20 eggs per replicate). The CLA group was injected with 4.5 mg CLA in 100 mL of ethanol. The control group was injected with 100 mL of ethanol. At hatch, breast muscle samples were collected from four individuals per group for RNA-Seq. The result showed that 278 genes were differentially expressed (p<0.01, fold change >2) between the control group and the CLA group. 112 genes were upregulated in the CLA group, while 166 genes were upregulated in the control group. Function annotation showed that muscle activity (Ventricular cardiac muscle tissue morphogenesis, Adrenergic signaling in cardiomyocytes, Cardiac muscle contraction) and metabolism (Aromatic amino acid family metabolic process, Tyrosine metabolism, Retinol metabolism, Nitrogen metabolism, Cysteine, and methionine metabolism) were significantly enriched, including 11 genes(such as TNNI1, TNNC1, and MYL3) that were considerably upregulated in CLA group likely related to CLA processing by influencing the muscle activity processes and metabolic processes. It was concluded that in ovo, CLA supplementation could change the gene expression pattern of the breast muscle, and might affect muscle development.

Resumo em Inglês:

ABSTRACT Gut microbiota plays an important role in animal health, production and diseases. Little is known about whether heat stress alters the composition of quail gut microbiota; therefore, we studied the effects of heat stress on growth performance, antioxidant functions, heat shock proteins and caecal microbiota. Two groups of 40 (20-day-old) quails were set up, including a control reared at 24 ± 2°C and a heat stress group subjected to heat stress at 36 ± 2°C for 4 h per day for 7 consecutive days. We found that heat stress significantly elevated the relative expression levels of HSP70 and HSP90 mRNA in the thymus, bursa and spleen by real-time fluorescence quantitative PCR assay, indicating successful establishment of the experimental model. Heat stress was found to have an effect on gut microbiota composition. At the genus level, Alistipes were significantly increased in the heat stress group. PICRUSt2 function prediction revealed that most of the KEGG pathways with high temperature-induced abundance differences are metabolism-related. These data indicated that heat stress reduced the production performance of quails by affecting antioxidant functions, as well as the composition and structure of the intestinal microbiota. The results of this study provide technical information for conducting research on heat stress prevention and control techniques in quails.