Metabolomic analysis reveals biogenic selenium nanoparticles improve the meat quality of thigh muscle in heat-stressed broilers is related to the regulation of ferroptosis pathway.

Heat stress (HS) causes oxidative damage and abnormal metabolism of muscle, thus impairing the meat quality in broilers. Selenium is an indispensable element for enhancing antioxidant systems. In our previous study, we synthesized a novel type of biogenic selenium nanoparticles synthesized with alginate oligosaccharides (SeNPs-AOS), and found that the particle size of Se is 80 nm and the Se content is 8% in the SeNPs-AOS; and dietary 5 mg/kg SeNPs-AOS has been shown to be effective against HS in broilers. However, whether SeNPs-AOS can mitigate HS-induced the impairment of thigh muscle quality in broilers is still unclear. Therefore, the purpose of this study was to investigate the protective effects of dietary SeNPs-AOS on meat quality, antioxidant capacity, and metabolomics of thigh muscle in broilers under HS. A total of 192 twenty-one-day-old Arbor Acres broilers were randomly divided into 4 groups with 6 replicates per group (8 broilers per replicate) according to a 2 × 2 experimental design: thermoneutral group (TN, broilers raised under 23±1.5°C); TN+SeNPs-AOS group (TN group supplemented 5 mg/kg SeNPS-AOS); HS group (broilers raised under 33 ± 2°C for 10 h/d); and HS + SeNPs-AOS group (HS group supplemented 5 mg/kg SeNPS-AOS). The results showed that HS increased the freezing loss, cooking loss, and malondialdehyde (MDA) content of thigh muscle, whereas decreased the total superoxide dismutase (T-SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) activities, as well as downregulated the mRNA expression of SOD2, CAT, GPX3, nuclear factor erythroid 2-related factor 2 (Nrf2), selenoprotein S (SELENOS), solute carrier family 7 member 11 (SLC7A11), GPX4, and ferroportin 1 (Fpn1) of thigh muscle (P < 0.05). Dietary SeNPS-AOS reduced the b* value, elevated the pH0min value and the activities of T-SOD, GSH-Px, glutathione S-transferase (GST) and the mRNA expression levels of GSTT1, GSTA3, GPX1, GPX3, ferritin heavy polypeptide-1 (FTH1), and Fpn1 of thigh muscle in broilers under HS (P < 0.05). Nontargeted metabolomics analysis identified a total of 79 metabolites with significant differences among the four groups, and the differential metabolites were mainly enriched in 8 metabolic pathways including glutathione metabolism and ferroptosis (P < 0.05). In summary, dietary 5 mg/kg SeNPs-AOS (Se content of 8%) could alleviate HS-induced impairment of meat quality by improving the oxidative damage, metabolic disorders and ferroptosis of thigh muscle in broilers challenged with HS. Suggesting that the SeNPs-AOS may be used as a novel nano-modifier for meat quality in broilers raised in thermal environment.

Biogenic Selenium Nanoparticles Synthesized with Alginate Oligosaccharides Alleviate Heat Stress-Induced Oxidative Damage to Organs in Broilers through Activating Nrf2-Mediated Anti-Oxidation and Anti-Ferroptosis Pathways.

Selenium (Se) is an essential trace element for maintaining health due to its ideal antioxidant properties. We previously prepared a new type of biogenic selenium nanoparticles based on alginate oligosaccharides (SeNPs-AOS), and this study aimed to investigate the protective effects of SeNPs-AOS (Se particle size = 80 nm, Se content = 8%) on organ health in broilers challenged with HS. A total of 192 21-day-old Arbor Acres broilers were randomly divided into four groups according to a 2 × 2 experimental design, including a thermoneutral zone group (TN, raised under 23 ± 1.5 °C); TN + SeNPs-AOS group (TN group supplemented 5 mg/kg SeNPS-AOS); HS group (HS, raised under 33 ± 2 °C for 10 h/day); and HS + SeNPs-AOS group (HS group supplemented 5 mg/kg SeNPS-AOS). There were six replicates in each group (eight broilers per replicate). The results showed that SeNPs-AOS improved the splenic histomorphology, enhanced the activity of catalase (CAT) and glutathione peroxidase (GSH-Px) of the spleen, as well as upregulating the splenic mRNA expression of antioxidant-related genes in broilers under HS. In addition, SeNPs-AOS reversed the pathological changes in bursa caused by HS increased the activity of GST, GSH-Px, and CAT and upregulated the mRNA expression of Nrf2 and antioxidant-related genes in the bursa of heat-stressed broilers. In addition, dietary SeNPs-AOS improved the hepatic damage, increased the activity of GSH-Px in the liver, and upregulated the mRNA expression of antioxidant-related genes while downregulating the Keap1 gene expression of the liver in broilers during HS. Moreover, dietary SeNPs-AOS upregulated the anti-ferroptosis-related genes expression of liver in broilers under HS. In conclusion, dietary SeNPs-AOS could relieve HS-induced oxidative damage to the spleen, bursa of Fabricius and liver in broilers by upregulating the Nrf2-mediated antioxidant gene expression and SeNPs-AOS could also upregulate the expression of hepatic Nrf2-related anti-ferroptosis genes in heat-stressed broilers. These findings are beneficial for the development of new nano-antioxidants in broilers.

Effects of Heat Stress on Production Performance, Redox Status, Intestinal Morphology and Barrier-Related Gene Expression, Cecal Microbiome, and Metabolome in Indigenous Broiler Chickens.

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.

Transcriptome analysis reveals potential mechanisms of the effects of dietary Enteromorpha polysaccharides on bursa of Fabricius 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.

Dietary Enteromorpha Polysaccharides Supplementation Improves Breast Muscle Yield and Is Associated With Modification of mRNA Transcriptome in Broiler Chickens.

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.