Archaea are an essential class of gut microorganisms in humans and animals. Despite the substantial progress in gut microbiome research in the last decade, most studies have focused on bacteria, and little is known about archaea in mammals. In this study, we investigated the composition, diversity, and functional potential of gut archaeal communities in pigs by re-analyzing a published metagenomic dataset including a total of 276 fecal samples from three countries: China (n = 76), Denmark (n = 100), and France (n = 100). For alpha diversity (Shannon Index) of the archaeal communities, Chinese pigs were less diverse than Danish and French pigs (p < 0.001). Consistently, Chinese pigs also possessed different archaeal community structures from the other two groups based on the Bray–Curtis distance matrix. Methanobrevibacter was the most dominant archaeal genus in Chinese pigs (44.94%) and French pigs (15.41%), while Candidatus methanomethylophilus was the most predominant in Danish pigs (15.71%). At the species level, the relative abundance of Candidatus methanomethylophilus alvus, Natrialbaceae archaeon XQ INN 246, and Methanobrevibacter gottschalkii were greatest in Danish, French, and Chinese pigs with a relative abundance of 14.32, 11.67, and 16.28%, respectively. In terms of metabolic potential, the top three pathways in the archaeal communities included the MetaCyc pathway related to the biosynthesis of L-valine, L-isoleucine, and isobutanol. Interestingly, the pathway related to hydrogen consumption (METHANOGENESIS-PWY) was only observed in archaeal reads, while the pathways participating in hydrogen production (FERMENTATION-PWY and PWY4LZ-257) were only detected in bacterial reads. Archaeal communities also possessed CAZyme gene families, with the top five being AA3, GH43, GT2, AA6, and CE9. In terms of antibiotic resistance genes (ARGs), the class of multidrug resistance was the most abundant ARG, accounting for 87.41% of archaeal ARG hits. Our study reveals the diverse composition and metabolic functions of archaea in pigs, suggesting that archaea might play important roles in swine nutrition and metabolism.

Chicken meat quality is primarily determined by genetics and nutrition, but recent evidence suggests that animal personality traits and the gut microbiota may also play crucial roles through their influence on muscle development and metabolism. However, the specific mechanisms linking behavior, gut microbiota, and meat flavor remain largely unexplored, particularly in native chicken breeds like the Qingyuan partridge chicken. This study investigated associations between personality traits, gut microbiome composition, metabolite profiles, and meat quality in 200 female Qingyuan partridge chickens. Chickens were monitored for daily step counts from 70 to 120 days of age and divided into three experimental groups: high-exercise (HE), moderate-exercise (ME), and low-exercise (LE). Behavioral tests (open-field, T-maze) revealed HE chickens exhibited enhanced exploration (p < 0.05), reduced latency to move (p < 0.05), and higher learning success rates (p < 0.05) compared to LE counterparts. Meat quality analysis showed HE chickens had brighter breast muscle (L* value, p < 0.05), firmer thigh muscle (shear force, p < 0.05), and reduced intramuscular fat (p < 0.01) relative to LE chickens. Gut microbiome profiling indicated HE chickens showed enrichment of beneficial taxa like Bifidobacterium (p < 0.01) and Intestinimonas (p < 0.05), alongside reduced levels of opportunistic pathogens such as Staphylococcus (p < 0.05). Metabolomic analysis (LC-MS) highlighted upregulated pathways including phenylalanine metabolism and tryptophan–serotonin signaling (VIP ≥ 1.0, p < 0.05). These findings confirm that exercise-related personality traits are associated with improved meat quality and flavor, with correlations linked to gut microbiota and metabolite remodeling, providing novel insights for optimizing poultry meat quality in commercial production.