Hui He

Probiotics play an important role in animal production, providing health benefits to the host by improving intestinal microbial balance. In this study, we added three different probiotics, Saccharomyces cerevisiae (SC), Bacillus licheniformis (BL), and lactic acid bacteria (LAB), and compared them with the control group (CON), to investigate the effects of probiotic supplementation on growth performance, gut microbiology, and gut flora of S. trutta. Our results showed that feeding probiotics improved the survival, growth, development, and fattening of S. trutta. Additionally, probiotic treatment causes changes in the gut probiotic community, and the gut flora microorganisms that cause significant changes vary among the probiotic treatments. However, in all three groups, the abundance of Pseudomonas, Acinetobacter, and Rhizophagus bacterial genera was similar to that in the top three comparative controls. Furthermore, differences in the composition of intestinal microbiota among feed types were directly associated with significant changes in the metabolomic landscape, including lipids and lipid-like molecules, organic acids and derivatives, and organoheterocyclic compounds. The probiotic treatment altered the gut microbiome, gut metabolome, and growth performance of S. trutta. Using a multi-omics approach, we discovered that the addition of probiotics altered the composition of gut microbiota, potentially leading to modifications in gut function and host phenotype. Overall, our results highlight the importance of probiotics as a key factor in animal health and productivity, enabling us to better evaluate the functional potential of probiotics.

Supplementation of sodium butyrate (SB) has been proved to be beneficial for improving the growth performance and health of animals, but its effects on rabbits have not been well understood. Therefore, this study aimed to investigate the effects of SB supplementation on growth performance, meat quality, and intestinal health of rabbits by evaluating feed intake and efficiency, diarrhea index, blood and cecum metabolites, cecal pH and short‐chain fatty acids (SCFAs), histological staining, nutritional composition of meat, and gene expression profile of cecum. A total of 14 weaned male New Zealand White rabbits (35 ± 2 days, 1.70 ± 0.09 kg) were randomly divided into two groups: rabbits in Control group were fed normally with the basal diet, and rabbits in Butyrate group were supplemented with 0.75 g/kg SB on the basis of the basal diet. After a 1‐week acclimatization period, the formal trial lasted for 10 weeks. Results suggest that dietary SB reduced the feed conversion ratio and diarrhea index of rabbits ( p < 0.05). SB treatment significantly increased serum glutamyl transpeptidase, total bile acid, total cholesterol, triglyceride, and glucose levels and decreased tCO ₂ content relative to the Control group ( p < 0.05). Meanwhile, crude ash content in rabbits' meat was significantly increased by SB treatment ( p < 0.05). Furthermore, SB treatment significantly increased the integrity of epithelial villi and number of goblet cells in the cecum and decreased cecal pH compared with the Control group. Dietary SB also upregulated levels of Na ⁺ ‐K ⁺ ATPase, Ca ²⁺ ‐Mg ²⁺ ATPase, total superoxide dismutase, and glutathione peroxidase in cecum. SCFAs analysis revealed that dietary supplementation with SB increases butyric acid in the cecum contents. Furthermore, SB supplementation is demonstrated to stimulate the proliferation and migration of cecal epithelial cells through activating Wnt/β‐catenin pathways in rabbits both in vitro and in vivo by using transcriptome sequencing and gene function verification technologies. Taken together, our findings provide a theoretical basis for the application of SB as an alternative to antibiotics in livestock production.

Coprophagy prevention (CP) affects the growth performance, hepatic lipid synthesis, and gut microbiota in rabbits. Supplementation with Clostridium butyricum (C. butyricum, Strain number: CCTCC M 2019962) has been found to improve growth performance in rabbits. However, it remains unknown whether C. butyricum can ameliorate the effects of CP on hepatic lipid synthesis and the underlying mechanisms are yet to be elucidated. Therefore, this study aimed to investigate the impact of CP on hepatic lipid synthesis and the underlying mechanism based on the gut–liver axis. The findings revealed that supplementation with C. butyricum could reverse CP-related growth performance, lipid accumulation, bile acid synthesis, and inflammation. Furthermore, C. butyricum exerted protective effects on the gut by preserving intestinal barrier integrity and modulating gut microbiota composition; these factors may represent potential mechanisms through which C. butyricum improves CP-related outcomes. Specifically, C. butyricum reshaped the microbiota by increasing butyric acid levels, thereby maintaining secondary bile acid (deoxycholic acid, chenodeoxycholic acid) balance and attenuating the inhibitory effects of the FXR/SHP pathway on lipid synthesis (SREBP1c/ApoA1). Moreover, the activation of butyrate/GPR43pathway by C. butyricum reduced damage to the intestinal barrier (ZO-1/Occludin/Claudin1) and restored the gut immune microenvironment in CP rabbits. In summary, supplementation with C. butyricum can alleviate the adverse effects of CP on growth performance and hepatic lipid synthesis by modulating the gut–liver axis.

Background: In molecular biology studies, the selection of optimal reference genes is of vital importance for accurately quantifying gene expression. The purpose of the present study was to screen the most stable reference genes in different muscle tissues of New Zealand white rabbits and Yufeng yellow rabbits. Methods and results: Results indicated that the most stable reference genes in the muscle tissues of New Zealand white rabbits were HPRT1, ACTB and PPIC, while HPRT1, PPIC, and RPL13A were the most stable reference genes in muscle tissues of Yufeng yellow rabbits. However, in the longissimus dorsi muscle and the abdominal wall muscle of both varieties, the most stable reference genes were HPRT1, RPL13A, and SDHA. In the quadriceps femoris muscle, the most stable reference genes were ACTB, HPRT1, and SDHA. Furthermore, the relative abundance of MYOG, MYH3 and MSTN was used to confirm the suitability and reliability of the selected most stable reference genes and the most unstable reference gene. Results revealed the same expression patterns of these myogenic genes when normalized according to the most stable genes, while normalization against the unstable reference gene altered the observed expression patterns. Conclusions: Taken together, our results demonstrated that the most stable reference genes varied among different muscle tissues and different breeds of rabbits. However, HPRT1, PPIC and SDHA presented high stability among all examined reference genes; thus, the combined analysis of HPRT1/ PPIC/ SDHA gene provides the best reference for RT-qPCR in muscle tissues of New Zealand white rabbits and Yufeng yellow rabbits, while HPRT1 is a better choice than other reference genes when using a single reference gene to assess target gene expression. Our results provide basic data for better measuring target gene expression profiles in muscle tissues of rabbits.

The intestinal microbiota and its metabolites play vital roles in host growth, development, and immune regulation. This study analyzed the microbial community distribution and the cytokine and short‐chain fatty acid (SCFA) content of cecal contents (Con group), soft feces (SF group), and hard feces (HF group) of 60‐day‐old Hyplus rabbits and verified the effect of soft feces on the cecal immune microenvironment by coprophagy prevention (CP). The results showed that there were significant differences in the levels of phylum and genus composition, cytokines, and SCFAs among the Con group, SF group, and HF group. The correlation analysis of cytokines and SCFAs with differential microbial communities showed that Muribaculaceae, Ruminococcaceae_UCG-014, Ruminococcaceae_NK4A214_group, and Christensenellaceae_R-7_Group are closely related to cytokines and SCFAs. After CP treatment, the contents of propionic acid, butyric acid, IL‐4, and IL‐10 in cecum decreased significantly, whereas TNF‐α and IL‐1β increased significantly. Moreover, the inhibition of coprophagy led to the downregulation of the expression levels of tight junction proteins (Claudin‐1, Occludin, and ZO‐1) related to intestinal inflammation and intestinal barrier function, and the ring‐like structure of ZO‐1 was disrupted. In conclusion, coprophagy can not only help rabbits obtain more probiotics and SCFAs but also play an essential role in improving the immune microenvironment of cecum.

Coprophagy is of great significance to the growth, development, and reproductive performance of rabbits. This study is aimed at exploring the effect of coprophagy on the reproductive performance of New Zealand white rabbits by coprophagy prevention (CP). The results showed that CP treatment significantly decreased the growth and development performance of female rabbits and the live birth rate of embryos. The results of blood biochemical indexes showed that CP treatment significantly increased the contents of serum ALB, ALP, and MDA, while serum SOD activity was significantly decreased. Transcriptome analysis showed that GO terms were mainly enriched in transport function and reproductive function after CP treatment. In addition, KEGG results showed that inflammation related signal pathways were activated and the expression level of genes related to tight junction proteins was downregulated by CP treatment. Concurrently, western blot further confirmed the results of KEGG. In short, fecal feeding is an important survival strategy for some small rodents, coprophagy prevention will affect the inflammatory level of the body, change the oxidative stress level of the body, and then activate NOX4‐ROS‐NF‐κB pathway, increase the expression level of adhesion protein ICAM‐1 and VCAM‐1, lead to the damage of uterine epithelial barrier, and then affect the reproductive performance of rabbits.

Background The selection and validation of stably expressed reference genes is key for accurately quantifying the mRNA abundance of genes under different treatments. In the rabbit model of fasting caecotrophy, reports about the selection of stable reference genes are not available. Methods and results This study aims to screen suitable reference genes in different tissues (including uterus, cecum, and liver) of rabbits between control and fasting caecotrophy groups. RT-qPCR was used to analyze the expression levels of eight commonly used reference genes (including GAPDH, 18S rRNA, B2M, CYP, HPRT1, β-actin, H2afz, Ywhaz), and RefFinder (including geNorm, NormFinder, and BestKeeper) was used to analyze the expression stability of these reference genes. Our results showed that the most stable reference genes were different in different tissues and treatments. In the control and fasting caecotrophy groups, CYP, GAPDH and HPRT1 were proven to be the top stable reference genes in the uterus, cecum, and liver tissues, respectively. GAPDH and Ywhaz were proven to be the top two stable reference genes among uterus, cecum, and liver in both control and fasting caecotrophy groups. Conclusions Our results indicated that the combined analysis of three or more reference genes (GAPDH, HPRT1, and Ywhaz) are recommended to be used for RT-qPCR normalization in the rabbit model of fasting caecotrophy, and that GAPDH is a better choice than the other reference genes for normalizing the relative expression of target genes in different tissues of fasting caecotrophy rabbits.

Zeaxanthin, an oxygenized carotenoid, exerts antioxidant properties in human nutrition and metabolism. Likely other carotenoids, zeaxanthin is poorly absorbed in the small intestine. The large portion of zeaxanthin reaches the colon and is not fully recovered in the colon. In this study, we aimed to investigate the association of zeaxanthin intake with the gut microbiome homeostasis and metabolomic responses in mice. Six-week-old male and female C57BL/6J wild type (WT), beta-carotene oxygenase 2 (BCO2) knockout mice were fed with AIN93M chow diets supplemented with or without zeaxanthin (0.02% w/w) for 10 weeks. At the termination of the study, mice were fasted for 3 hrs prior to euthanization. Cecal contents, colon, serum, feces, and other tissues were collected for laboratory assessments.16S rRNA sequencing and LC-MS/MS were performed for gut microbiota profiling and serum and fecal metabolomics analysis, respectively. Significant zeaxanthin accumulation occurred in BCO2 KO, but not WT mice. Zeaxanthin accumulation was associated with the alteration of colonic gut microbiota composition, for example, zeaxanthin-increased abundance in Lachnospiraceae, Proteobacteria, and Parabacteroides, indicating enhanced short-chain production, improved intestinal integrity, and anaerobic bacterial colonization. The results of fecal and serum metabolomics revealed that zeaxanthin significantly altered tyrosine metabolism, branched-chain fatty acid oxidation, fatty acid biosynthesis, and phospholipid biosynthesis, and suppressed levels of kynurenine and trimethylamine N-oxide (TMAO). The results suggested that zeaxanthin accumulation promotes gut microbiome homeostasis and alters the gut microbial metabolites as signals in stimulating the host-gut microbe interplay. USDA/NIFA 2021-67018-34023 and 2020-67017-30842.