Staphylococcus aureus (S. aureus) is the major pathogen responsible for mastitis in dairy cows, an important threat to their health, but prevention of S. aureus infection of the mammary gland remains challenging. Berberine hydrochloride (BH), a naturally occurring phytochemical, exhibits a wide range of activities, including antibacterial effects on S. aureus. In this study, we prepared a novel berberine hydrochloride-carboxymethyl chitosan hydrogel (BH-CMCH) with excellent thermosensitivity, injectability and in vitro antibacterial activity. In a rat model of mastitis induced by S. aureus, mammary duct injection of BH-CMCH reduced the bacterial load in infected mammary gland tissue and protected the tissue from damage from infection. In addition, proteomics analysis showed that mammary duct injection of BH-CMCH enhanced autolysosome degradation and promoted the innate immune response by activating the lysosomal pathway and up-regulating related significantly differentially expressed proteins (SDEPs). Taken together, the findings support the potential of BH-CMCH as an antibacterial agent against S. aureus-induced mastitis.

As the largest parenchymal organ, the liver is a target for bacterial and viral infections, nonalcoholic fatty liver disease (NAFLD), cirrhosis, cancer, and many other diseases, constituting a serious worldwide problem. The treatment for many of these diseases involves hepatectomy.

Staphylococcus aureus is one of the most important pathogens causing mastitis in dairy cows. The objective of this study was to establish a rat model of mastitis induced by S. aureus infection and to explore changes in the proteomes of mammary tissue in different udder states, providing a better understanding of the host immune response to S. aureus mastitis. On day 3 post-partum, 6 rats were randomly divided into two groups (n = 3), with either 100 μL of PBS (blank group) or a S. aureus suspension containing 2×10⁷ CFU·mL⁻¹ (challenge group) infused into the mammary gland duct. After 24 h of infection, the rats were sacrificed, and mammary gland tissue was collected. Tandem mass tag (TMT)-based technology was applied to compare the proteomes of healthy and mastitic mammary tissues. Compared with the control group, the challenge group had 555 proteins with significant differences in expression, of which 428 were significantly upregulated (FC>1.2 and p0.83 and p<0.05 or p<0.01). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses revealed that upregulated differentially significant expressed proteins (DSEPs) were associated with mainly immune responses, including integrin alpha M, inter-α-trypsin inhibitor heavy chain 4, and alpha-2-macroglobulin. This study is the first in which a rat model of S. aureus-induced mastitis was used to explore the proteins related to mastitis in dairy cows by TMT technology, providing a model for replication of dairy cow S. aureus-induced mastitis experiments.

In this study, differences in the ruminal bacterial community between high-yield and low-yield lactating dairy cows fed the same diets were investigated. Sixteen lactating dairy cows with similar parity were divided into two groups based on their milk yield: high-yield (HY) and low-yield (LY) groups. On day 21, rumen content samples were collected, and the microbiota composition was determined using Illumina MiSeq sequencing of the 16S rRNA gene. During the study period, dry matter intake (DMI) and milk yield were measured daily, and milk composition was assessed 3 times per week. The results showed that the milk of the LY group tended to have higher fat ( P =0.08), protein ( P =0.01) and total solid ( P =0.04) contents than that of the HY group, though the HY group had higher ruminal acetate ( P =0.05), propionate ( P =0.02) and volatile fatty acid (VFA) ( P =0.02) concentrations. Principal coordinate analysis indicated significant differences in ruminal bacterial community composition and structure between the HY group and LY group. Overall, Bacteroidetes (HY group: 52.91±3.06%; LY group: 61.88±3.03%) was the predominant phylum, followed by Firmicutes (HY group: 41.10±2.74%; LY group: 32.11±2.97%). The abundances of Ruminococcus 2 , Lachnospiraceae and Eubacterium coprostanoligenes were significantly higher in the HY group than in the LY group. In addition, 3 genera— Anaerostipes , Bacteroidales and Anaeroplasma —were identified as biomarker species with the greatest impacts on the ruminal community structure in the LY group. These findings facilitate the understanding of bacterial synthesis within the rumen and reveal an important mechanism underlying differences in milk production in dairy cows.

We evaluated the effects of propylene glycol (PG) on in vitro ruminal fermentation, methanogenesis, and microbial community structure. A completely randomized design was conducted in the in vitro incubation, and 4 culture PG dose levels (0, 7.5, 15, and 22.5 μL/g of dry matter) were used in the trial. Based on the fermentation results, the control group (0 μL/g of dry matter, CON) and the second treatment group (15.0 μL/g of dry matter, TRT) were chosen for further analysis to explore the effects of PG on the bacterial and archaeal community structure. The concentrations of propanol, propanal, and succinate increased linearly, whereas the concentration of l-lactate decreased linearly as PG doses increased. The molar proportion of propionate demonstrated a linear increase with increasing PG doses. In contrast with propionate, the molar proportion of acetate and butyrate, and acetate-to-propionate ratio decreased linearly with increasing PG doses. The addition of PG markedly decreased methane production without negative effects on nutrient degradability. In the archaeal level, the relative abundance of Methanobrevibacter tended to decrease, but that of Methanomassiliicoccus significantly increased in TRT group. At the bacterial level, the relative abundance of Bacteroidetes and Prevotella in TRT group was numerically higher than that in CON group. The analysis of the Negativicutes class showed that the relative abundance of Succiniclasticum tended to increase, whereas that of Selenomonas tended to decrease in TRT group. These results demonstrated that PG might be used as an inhibitor to mitigate methane emission. However, the small decrease in methane production will limit the application of PG as a methane inhibitor in production practices. Further research is needed to determine whether use together with other inhibitors may improve the effects of PG on the utilization of reducing equivalents ([H]) and methane production.

The overuse of antibiotics in livestock production poses a significant threat to public health, primarily by accelerating the emergence of antibiotic-resistant bacteria-a critical global issue. Therefore, the development of effective alternatives to antibiotics is urgently required to address this problem. In this study, BLfcin-NPs@CS/β-GP thermosensitive hydrogels were developed by incorporating bovine lactoferricin-loaded chitosan nanoparticles into a chitosan/β-GP hydrogel matrix. Scanning electron microscopy (SEM) revealed the formation of a three-dimensional porous structure. Fourier-transform infrared (FTIR) spectroscopy confirmed successful synthesis, while X-ray diffraction (XRD) analysis indicated that nanoparticle incorporation did not alter the crystallinity of the hydrogel. The rheological properties, in vitro degradation, biocompatibility, and antibacterial activity of the composite hydrogels were systematically evaluated, and the results demonstrated that the composite hydrogels exhibited temperature sensitivity, enhanced degradation rates, low cytotoxicity, and strong antibacterial activity. These findings suggest that BLfcin-NPs@CS/β-GP hydrogels present a promising alternative to antibiotics for treating bacterial infections, such as bovine mastitis, offering an innovative and effective strategy to reduce antibiotic use and mitigate the risk of antibiotic resistance in livestock production.