This study aimed to explore the dynamic variations of rumen fermentation characteristics and bacterial community composition during a 24 h in vitro fermentation. A total of twenty-three samples were collected from original rumen fluid (ORF, n = 3), fermentation at 12 h (R12, n = 10), and fermentation at 24 h (R24, n = 10). Results showed that gas production, concentrations of microbial crude protein, ammonia nitrogen, and individual volatile fatty acids (VFA), as well as total VFA and branched-chain VFA concentrations, were higher in R24 when compared with R12 (p < 0.05). However, no significant differences were observed in acetate to propionate ratio and fermentation efficiency between R12 and R24 (p > 0.05). Bacterial diversity analysis found that Shannon index and Simpson index were higher in R24 (p < 0.05), and obvious clusters were observed in rumen bacterial community between R12 and R24. Taxonomic analysis at the phylum level showed that the abundances of Proteobacteria and Fibrobacteres were higher in R12 than that in R24, and inverse results were observed in Bacteroidetes, Firmicutes, Cyanobacteria, Verrucomicrobia, Lentisphaerae, and Synergistetes abundances. Taxonomic analysis at the genus level revealed that the abundances of Rikenellaceae RC9 gut group, Succiniclasticum, Prevotellaceae UCG-003, Christensenellaceae R-7 group, Ruminococcaceae UCG-002, Veillonellaceae UCG-001, and Ruminococcaceae NK4A214 group were higher in R24, whereas higher abundances of Succinivibrionaceae UCG-002, Ruminobacter, and Fibrobacter, were found in R12. Correlation analysis revealed the negative associations between gas production and abundances of Proteobacteria, Succinivibrionaceae UCG-002, and Ruminobacter. Moreover, the abundances of Firmicutes, Rikenellaceae RC9 gut group, Christensenellaceae R-7 group, and Ruminococcaceae UCG-002 positively correlated with VFA production. These results indicate that both rumen fermentation characteristics and bacterial community composition were dynamic during in vitro fermentation, whereas the fermentation pattern, efficiency, and bacterial richness remained similar. This study provide insight into the dynamics of rumen fermentation characteristics and bacterial composition during in vitro fermentation. This study may also provide a reference for decision-making for the sampling time point when conducting an in vitro fermentation for bacterial community investigation.

Background: Minimizing mortality losses due to multiple stress and obtaining maximum performance are the production goals for newly received cattle. In recent years, vaccination and metaphylaxis treatment significantly decreased the mortality rate of newly received cattle, while the growth block induced by treatment is still obvious. Assessment of blood metabolites and behavior monitoring offer potential for early identification of morbid animals. Moreover, the ruminal microorganisms’ homeostasis is a guarantee of beef steers’ growth and health. The most critical period for newly received cattle is the first-month post-transport. Therefore, analyzing rumen metagenomics, rumen metabolomics, host metabolomics, and their interaction during receiving period (1 day before transport and at days 1/4, 16, and 30 after transport) is key to revealing the mechanism of growth retardation, and then to formulating management and nutritional practices for newly received cattle. Results: The levels of serum hormones (COR and ACTH), and pro-inflammatory factors (IL-1β, TNF-α, and IL-6) were highest at day 16, and lowest at day 30 after arrival. Meanwhile, the antioxidant capacity (SOD, GSH-Px, and T-AOC) was significantly decreased at day 16 and increased at day 30 after arrival. Metagenomics analysis revealed that rumen microbes, bacteria, archaea, and eukaryota had different trends among the four different time points. At day 16 post-transport, cattle had a higher abundance of ruminal bacteria and archaea than those before transport, but the eukaryote abundance was highest at day 30 post-transport. Before transport, most bacteria were mainly involved in polysaccharides digestion. At day 4 post-transport, the most significantly enriched KEGG pathways were nucleotide metabolism (pyrimidine metabolism and purine metabolism). At day 16 post-transport, the energy metabolism (glycolysis/gluconeogenesis, pyruvate metabolism) and ruminal contents of MCP and VFAs were significantly increased, but at the same time, energy loss induced by methane yields (Methanobrevibacter) together with pathogenic bacteria (Saccharopolyspora rectivirgula) were also significantly increased. At this time, the most upregulated ruminal L-ornithine produces more catabolite polyamines, which cause oxidative stress to rumen microbes and their host; the most downregulated ruminal 2',3'-cAMP provided favorable growth conditions for pathogenic bacteria, and the downregulated ruminal vitamin B6 metabolism and serum PC/LysoPC disrupt immune function and inflammation reaction. At day 30 post-transport, the ruminal L-ornithine and its catabolites (mainly spermidine and 1,3-propanediamine) were decreased, and the serum PC/LysoPC and 2',3'-cNMPs pools were increased. This is also consistent with the changes in redox, inflammation, and immune status of the host. Conclusions: This study provides new ideas for regulating the health and performance of newly received cattle during the receiving period. The key point is to manage the newly received cattle about day 16 post-transport, specifically to inhibit the production of methane and polyamines, and the reproduction of harmful bacteria in the rumen, therefore improving the immunity and performance of newly received cattle.

To evoke positive human emotions is a critical goal of blue spaces in urban wetland parks. However, information is still scarce on how people self-express across the spatiotemporal spectrum when they come across wetlands which include varying levels of elevation in a single landscape and microclimate. In this study, 30 urban wetland parks were selected from 17 cities in Central China, where a total of 1,184 portrait photos of visitors were obtained from a social media platform (Sina Weibo) to analyze their expressed sentiments by rating facial expression scores of happy and sad emotions and net positive emotion index (NPE; happy-score minus sad-score) in 2020. Landscape metrics were remotely evaluated for every wetland park, and microclimatic factors were obtained for the days when the photos were taken. Based on regressions of park-level data, blue-space areas could be perceived as a positive driver to trigger happiness in spring (regression coefficient [RC] of 0.20), but it triggered negative emotions in autumn (RC of −2.98). The higher elevation areas triggered positive emotions in summer and autumn (RC of 1.35 × 10⁻³), but extreme daily temperature, air humidity, and wind velocity together triggered sadness (RC of 0.11, 0.03, and 0.51, respectively). Mapped distribution of the area and corresponding emotions showed that visiting blue space evoked more smiles in wetland parks of northern Hunan, southern Hubei, and eastern Anhui in spring. Blue spaces in Shanxi and northwestern Hebei evoked better moods in autumn. Smaller blue spaces in wetlands located at higher elevations were recommended for nature enthusiasts in warm seasons to overcome the prevalent sadness characteristic of that time of the year and location.

Background: The fasting and stress associated with road transportation contributes to a lack of energy and a decline in the immune system of beef cattle. Therefore, it is essential for beef cattle to enhance energy reserves before transportation. Creatine pyruvate (CrPyr) is a new multifunctional nutrient that can provide both pyruvate and creatine, which are two intermediate products of energy metabolism. To investigate the effects of transport and rumen-protected (RP)-CrPyr on the blood biochemical parameters and rumen fluid characteristics of beef cattle, twenty male Simmental crossbred cattle (659 ± 16 kg) aged 18 months were randomly allocated to four groups (n = 5) using a 2 × 2 factorial arrangement with two RP-CrPyr supplemental levels (0 or 140 g/d) and two transport treatments (5 min or 12 h): T_CrPyr140, T_CrPyr0, NT_CrPyr140, and NT_CrPyr0. After feeding for 30 days, three cattle per treatment were slaughtered. Results: Compared with nontransport, transport decreased the total antioxidant capacity, catalase activity, contents of IgA, interferon γ, interleukin-1β (IL-1β), and IL-6 in serum, and the amounts of total volatile fatty acids (TVFA), acetate, and butyrate in rumen (P < 0.05); increased the serum lipopolysaccharide (LPS) level, contents of rumen LPS and ammonia nitrogen (P < 0.05). RP-CrPyr supplementation decreased the levels of cortisol and LPS in serum and the butyrate concentration in the rumen of beef cattle compared with those in the unsupplemented groups (P < 0.05). RP-CrPyr and transport interaction had a significant effect on the contents of serum tumour necrosis factor-α, IL-6, LPS, ruminal pH, acetate content, and acetate/propionate (P < 0.05). In terms of ruminal bacterial composition, group T_CrPyr0 increased the Prevotella genus abundance compared with group NT_CrPyr0 (P < 0.05), while group T_CrPyr140 increased Firmicutes phylum abundance and decreased Bacteroidetes phylum and genus Prevotella abundance compared with group T_CrPyr0 (P < 0.05). Moreover, Bacteroidetes was positively correlated with serum LPS. Conclusions: These results indicated that dietary supplementation with RP-CrPyr might be beneficial to alleviate transport stress by decreasing serum cortisol and LPS levels and promoting the restoration of the rumen natural flora.

Recent studies have revealed that LuxS/AI-2 quorum sensing (QS) is the most universal cell-to-cell communication in rumen bacteria; however, it remains unknown how they respond to nutritional stress from a diet shift. This study aimed to explore whether a diet shift could trigger rumen bacterial LuxS/AI-2 QS and its influences on rumen fermentation characteristics and bacterial community diversity and composition. A total of fifteen Hu sheep were selected to undergo a pre-shift diet (Pre, concentrate to forage ratio 75:25) for one month and then abruptly switch to a post-shift diet (Post, concentrate to forage ratio 49:51). Results showed that the serum cortisol and immunoglobulin G concentrations were higher in Post than in Pre (p < 0.05). The microbial density, AI-2 concentration, biofilm formation, and the gene expression of ftsH were higher in Post when compared with Pre (p < 0.05), whilst the gene expression of luxS tended to be lower in Post (p = 0.054). The molar concentration of valerate and fermentation efficiency decreased after the diet shift, while the acetate to propionate ratio and the molar proportion of butyrate were higher in Post compared to Pre (p < 0.05). Moreover, the diet shift increased the richness of ruminal bacteria and the relative abundances of Roseburia, Prevotellaceae UCG-001, and Lachnospira, and decreased the relative abundances of Prevotella, Megasphaera, and Dialister (p < 0.05). A difference in trends was also observed in an analysis of similarity (R = 0.1208 and p = 0.064). This study suggests that a diet shift could trigger rumen bacterial LuxS/AI-2 QS by altering microbial density, AI-2 concentration, biofilm formation, and related gene expression, as well as affect the rumen fermentation pattern and bacterial community diversity and composition. This study may provide insight into a potential strategy for relieving nutritional stress via regulating bacterial communication.