Yan Wang

The impact of varying antibiotic residue levels on antibiotic resistance gene (ARG) removal during composting is still unclear. This study investigated the impact of different residue levels of tilmicosin (TIM), a common veterinary macrolide antibiotic, on ARG removal during pig manure composting. Three groups were used: the CK group (no TIM), the L group (246.49 ± 22.83 mg/kg TIM), and the H group (529.99 ± 16.15 mg/kg TIM). Composting removed most targeted macrolide resistance genes (MRGs) like ereA, ermC, and ermF (>90% removal), and reduced ermB, ermX, ermQ, acrA, acrB, and mefA (30–70% removal). However, ermA increased in abundance. TIM altered compost community structure, driving succession through a deterministic process. At low doses, TIM reduced MRG–bacteria co-occurrence, with horizontal gene transfer via intI1 being the main cause of ermA rebound. In conclusion, composting reduces many MRG levels in pig manure, but the persistence and rebound of genes like ermA reveal the complex interactions between composting conditions and microbial gene transfer.

Odors from pet cats can negatively affect the quality of life of cat owners. The diverse bioactive compounds in plant extracts make them a promising candidate for effective odor reduction. This study evaluated twelve plant extracts for deodorizing efficacy via in vitro fermentation tests. Rosemary extract and licorice extract exhibited better deodorizing effects, with fractions of rosemary extract below 100 Da demonstrating the most effective deodorizing performance. Based on these findings, subsequent feeding trials were conducted using rosemary extract and its fractions below 100 Da. In the feeding trial, adult British Shorthair cats were divided into three groups (Control Check, RE, and RE100) and housed in a controlled-environment respiration chamber for 30 days. Measurements included odor emissions, fecal and blood physicochemical parameters, immune parameters, microbiota composition based on 16S rRNA sequencing, and metabolome analysis. The results of the feeding trial indicated that rosemary extract significantly reduced ammonia and hydrogen sulfide emissions (46.84%, 41.64%), while fractions below 100 Da of rosemary extract achieved even greater reductions (55.62%, 53.87%). Rosemary extract regulated the intestinal microbial community, significantly increasing the relative abundance of the intestinal probiotic Bifidobacterium (p < 0.05) and reducing the population of sulfate-reducing bacteria (p < 0.05). It also significantly reduced urease and uricase activities (p < 0.05) to reduce ammonia production and inhibited the degradation of sulfur-containing proteins and sulfate reduction to reduce hydrogen sulfide emissions. Furthermore, rosemary extract significantly enhanced the immune function of British Shorthair cats (p < 0.05). This study suggests that rosemary extract, particularly its fractions below 100 Da, is a highly promising pet deodorizer.

Animal welfare is one of the core concerns in the field of animal science, with behavior serving as a direct reflection of emotional state and health, and thus a key indicator for welfare assessment. With the widespread adoption of intensive farming systems, abnormal behaviors in pigs have become a prominent marker of compromised welfare. In the past few years, the role of gut microbes in the regulation of animal behavior has received increasing attention. This review summarizes the strong relationship between pig behavior and welfare, and focuses on the emerging research linking gut microbiota to behavioral expression in pigs. Furthermore, it outlines the mechanisms by which the microbiota modulates behavior through the microbiota–gut–brain axis (MGBA), including immune, endocrine, and neural pathways. Additionally, the potential of microbiota-targeted interventions to improve pig welfare, including probiotics and prebiotics, will be evaluated. As a critical bridge connecting physiology and psychology, the gut microbiota shows significant promise for advancing welfare regulation in pigs.

Feather pecking (FP) is a significant welfare and economic problem in laying hen husbandry. While there is growing evidence that the glutamatergic system plays a crucial role in regulating FP behavior, the biological mechanisms remain unclear, largely due to the limited uptake of peripheral glutamate across the blood–brain barrier (BBB). Here, we applied a multi-omics approach combined with physiology assays to answer this question from the perspective of the gut–brain axis. A total of 108 hens were randomly assigned to two groups (treatment and control) with six replicates each, and the treatment group was subjected to chronic environmental stressors including re-housing, noise, and transport. We found that chronic exposure to environmental stressors induced severe FP, accompanied by reduced production performance and increased anxiety- and depression-related behaviors, compared to controls. In addition, the immune system was potentially disrupted in FP chickens. Notably, gut microbiota diversity and composition were significantly altered, leading to decreased microbial community stability. Non-targeted metabolomic analysis identified a variety of differential metabolites, primarily associated with arginine and histidine biosynthesis. A significant increase in glutamate levels was also observed in the hippocampus of FP chickens. Transcriptome analysis revealed the upregulated expressions of glutamate-related receptors GRIN2A and SLC17A6 in the hippocampus. Correlation analysis indicated that GRIN2A and SLC17A6 are positively associated with arginine levels in the duodenum, while Romboutsia in the duodenum is negatively correlated with arginine. These findings suggest that intestinal bacteria, including Romboutsia, may influence FP behavior by altering plasma arginine and histidine levels. These changes, in turn, affect glutamate levels and receptor gene expression in the hippocampus, thereby regulating the glutamatergic system. Our research offers insights into novel strategies for mitigating harmful behaviors in poultry farming, with potential benefits for animal performance and welfare.

Astragalus extract plays a dual role in gut microbiome regulation and ammonia (NH₃) emission mitigation in laying hens. This study explored its effects through feeding experiments, with a focus on gut microbial metabolic pathways and NH₃ reduction mechanisms. To achieve this, both in vitro fermentation experiments and in vivo feeding trials were conducted. In the in vitro study, cecal contents from laying hens were incubated with different concentrations of AE and Yucca extract (YE) to evaluate NH₃ production, while in the feeding trial, 58-week-old Lohmann Pink laying hens were allocated into three groups (control, 0.1% YE, and 0.1% AE) and housed in controlled-environment respiration chambers for 21 days. Measurements included NH₃ emissions, serum biochemical indices, immune parameters, gut physicochemical properties, and 16S rRNA-based microbiota analysis. Results showed that Astragalus extract reduced NH₃ emissions by 29.3%, achieved by lowering urease and uricase activities and promoting the conversion of ammonium nitrogen to nitrate nitrogen. Additionally, it significantly enhanced gut immune function by increasing intestinal immunoglobulin levels. Microbial community analysis revealed an increased relative abundance of Bacteroides, Muribaculaceae, and Faecalibacterium, which are negatively correlated with NH₃ emissions. These microbial shifts improved ammonium nitrogen utilization via the upregulation of CTP synthase and GMP synthase activities, contributing to higher NH₃ reduction efficiency. This study highlights Astragalus extract as a cost-effective and sustainable strategy to regulate gut microbiota, optimize nitrogen metabolism, and mitigate NH₃ emissions in laying hens.

The impact of antibiotic therapy on the spread of antibiotic resistance genes (ARGs) and its relationship to gut microbiota remains unclear. This study investigated changes in ARGs, mobile genetic elements (MGEs), and gut microbial composition following tilmicosin administration in pigs. Thirty pigs were randomly divided into control (CK), low-concentration (0.2 g/kg; L), and high-concentration (0.4 g/kg; H) groups. Tilmicosin concentration in manure peaked on day 16 of dosing and dropped below detectable levels by day 13 of the withdrawal period. While tilmicosin did not significantly affect the total abundance of macrolide resistance genes (MRGs) (p > 0.05), it significantly increased the abundance of the multidrug resistance gene tolC in the H group compared with the L and CK groups during the withdrawal period (p < 0.05). This increase was associated with a coincidental rise in the abundance of MGEs (e.g., int1 and int2) and the growth of potential tolC-hosting bacteria such as Paenalcaligenes and Proteiniclasticum. Redundancy analysis showed gut microbial composition as the primary driver of MRG abundance, with MGEs, tilmicosin concentration, and manure physicochemical properties playing secondary roles. These findings suggest that high-dose tilmicosin may alter the gut microbiota and promote ARG spread via MGE-mediated transfer.