This study was done to evaluate the effects of heat stress (HS) on production performance, redox status, small intestinal barrier-related parameters, cecal microbiota, and metabolome of indigenous broilers. A total of forty female indigenous broilers (56-day-old) were randomly and equally divided into normal treatment group (NT group, 21.3 ± 1.2°C, 24 h/day) and HS group (32.5 ± 1.4°C, 8 h/day) with five replicates of each for 4 weeks feeding trial. The results showed that the body weight gain (BWG) of broilers in HS group was lower than those in NT group during 3–4 weeks and 1–4 weeks (p < 0.05). The HS exposure increased the abdominal fat rate (p < 0.05) but decreased the thigh muscle rate (p < 0.01). Besides, broilers in HS group had higher drip loss of breast muscle than NT group (p < 0.01). Broilers exposed to HS had lower total antioxidant capacity (T-AOC) in serum and jejunum, activities of total superoxide dismutase (T-SOD) in the jejunum, glutathione peroxidase (GSH-Px) in the thigh muscle, duodenum, and jejunum; and catalase (CAT) in breast muscle, duodenum, and jejunum (p < 0.05). Whereas the malondialdehyde (MDA) contents in breast muscle, duodenum, and jejunum was elevated by HS exposure (p < 0.05). Moreover, the relative mRNA expression of Occludin and ZO-1 in the duodenum, Occludin, Claudin-1, Claudin-4, ZO-1, Mucin-2 in the jejunum, and the Claudin-4 and Mucin-2 in the ileum was down-regulated by HS exposure (p < 0.05). The 16S rRNA sequencing results showed that the HS group increased the relative abundance of Anaerovorax in the cecum at the genus level (p < 0.05). Cecal metabolomics analysis indicated 19 differential metabolites between the two groups (p < 0.10, VIP >1). The Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that the differential metabolites mainly enriched in 10 signaling pathways such as the Citrate cycle (TCA cycle) (p < 0.01). In summary, chronic HS exposure caused a decline of production performance, reduced antioxidant capacity, disrupted intestinal barrier function, and negatively affected cecal microbiota and metabolome in indigenous broilers.

The present study evaluated the effects of dietary supplementation of Enteromorpha polysaccharides (EP) on carcass traits of broilers and potential molecular mechanisms associated with it. This study used RNA-Sequencing (RNA-Seq) to detect modification in mRNA transcriptome and the cognate biological pathways affecting the carcass traits. A total of 396 one-day-old male broilers (Arbor Acres) were randomly assigned to one of six dietary treatments containing EP at 0 (CON), 1000 (EP_1000), 2500 (EP_2500), 4000 (EP_4000), 5500 (EP_5500), and 7000 (EP_7000) mg/kg levels for a 35-d feeding trial with 6 replicates/treatment. At the end of the feeding trial, six birds (one bird from each replicate cage) were randomly selected from each treatment and slaughtered for carcass traits analysis. The results showed that the dietary supplementation of EP_7000 improved the breast muscle yield (p < 0.05). Subsequently, six breast muscle samples from CON and EP_7000 groups (three samples from each group) were randomly selected for RNA-Seq analysis. Based on the RNA-Seq results, a total of 154 differentially expressed genes (DEGs) were identified (p < 0.05). Among the DEGs, 112 genes were significantly upregulated, whereas 42 genes were significantly down-regulated by EP_7000 supplementation. Gene Ontology enrichment analysis showed that the DEGs were mainly enriched in immune-related signaling pathways, macromolecule biosynthetic, DNA-templated, RNA biosynthetic, and metabolic process (p < 0.05). Kyoto Encyclopedia of Genes and Genomes pathway analysis showed that the DEGs were enriched in signaling pathways related to viral infectious diseases and cell adhesion molecules (p < 0.05). In conclusion, dietary inclusion of EP_7000 improves the breast muscle yield, which may be involved in improving the immunity and the cell differentiation of broilers, thus promoting the muscle growth of broilers. These findings could help understand the molecular mechanisms that enhance breast muscle yield by dietary supplementation of EP in broilers.

The present study was conducted to evaluate the effects of dietary supplementation of Enteromorpha polysaccharides (EP) on relative organ weight of broilers, and RNA‐seq technique was used to reveal the potential molecular mechanisms of the positive effects of EP on relative organ weight. A total of 396 1‐day‐old male chicks (Arbor Acres) were randomly assigned to six dietary treatments containing EP at 0 (EP0), 1000 (EP1000), 2500 (EP2500), 4000 (EP4000), 5500 (EP5500), and 7000 (EP7000) mg/kg levels for a 35‐day feeding trial. At the end of feeding trail, six birds (one bird from each replicate cage) were randomly selected from each treatment and then slaughtered for relative organ weight analysis. The results showed that the relative weight of bursa of Fabricius were increased in the EP1000 group (p < 0.05), and then three bursa of Fabricius samples from each group (EP0 and EP1000) were randomly selected for RNA‐seq analysis. The results of RNA‐seq analysis showed that there were 20 differentially expressed genes (DEGs) between EP0 and EP1000 groups, among the DEGs, 6 genes were upregulated and 14 genes were downregulated by EP1000 supplementation (p‐adjust < 0.05). Gene ontology (GO) enrichment analysis suggested that the DEGs were mainly enriched in negative regulation of toll‐like receptor 9 signaling pathway (p‐corrected < 0.05). Kyoto encyclopedia of genes and genomes (KEGG) enrichment analysis showed that the DEGs were mainly enriched in phagosome, mitophagy‐animal, Salmonella infection, autophagy‐animal signaling pathways (p‐corrected = 0.081). Taken together, dietary EP supplementation at 1000 mg/kg level promoted the relative weight of bursa of Fabricius may be involved in improving the immune function of broilers. These findings provided a reference for further exploring the specific molecular mechanism of EP that affecting the organ development in broilers.

The present study was conducted to investigate the effects of heat stress on microbial community in the duodenum of yellow-feather broiler chickens based on 16S rRNA sequencing. A total of 40 female Chinese indigenous yellow-feather broilers (56-day-old, average initial body weight of 840.75 ± 20.79 g) were randomly allocated to two groups, including the normal treatment group (NT group, 21.3 ± 1.2 C, 24 h/day) and the heat stress group (HS group, 32.5 ± 1.4 C, 10 h/day), and the relative humidity (RH) of both two groups was maintained at 65 ± 5%. The experiment conforms to a completely randomised trial design. Broilers in both of two groups were fed basal diet, each group consisted of five replicates, and four broilers in each replicate. The feeding trail lasted 4 weeks. The results showed that although the broilers in the HS group had lower abundance-based coverage estimators (ACE) and Chao1 richness estimator (Chao1) index of duodenal microbial, there were no significant differences in duodenal microbial alpha diversity index between NT and HS groups, including ACE, Chao1, Shannon and Simpson index (p > .05). Regarding the microbial composition and abundance, at the phylum level, heat stress exposure significantly decreased the relative abundance of Bacteroidetes in duodenum compared with NT group (p < .05). At the genus level, compared with the NT group, heat stress exposure significantly reduced the relative abundance of Cupriavidus, Leptothrix, Janthinobacterium, Pseudomonas, Stenotrophomonas, Desulfovibrio, Oscillospira and Dorea in the duodenum (p < .05). In conclusion, heat stress affected the duodenal microbial community in indigenous yellow-feather broilers. HIGHLIGHTSHeat stress had adverse effects on duodenal microbial composition of Chinese indigenous yellow-feather broilers. Strategies that improve the duodenal microbial balance may promote the gut health and reduce the economic losses caused by heat stress in broiler production.