Tea tree oil (TTO) plays an important role in lipid metabolism, alleviating the inflammatory responses. Fatty liver is associated with lipid accumulation in hepatocytes, leading to inflammation. However, there is very limited information on the effects of TTO on lipid accumulation, and inflammation in bovine hepatocytes. This study aimed to evaluate whether TTO alleviates palmitic acid (PA)-induced lipid accumulation in bovine hepatocytes. Hepatocytes isolated from mid-lactating Holstein cows were pretreated with 100 μM PA for 72 h. Cells were either pretreated with PA alone (PA group) or with PA followed by 0.00625% TTO treatment for 12 h (PT group). Expression of fatty acid oxidant genes increased (P < 0.05) while fatty acid synthesis genes decreased (P < 0.05) in the PT group compared with the PA group. PA treatment resulted in increased (P < 0.05) expression of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6), but these increases were less in the PT group (P < 0.05). Compared to the PA group, expression of phosphorylated (p)-p65 and p-inhibitor κBα (p-IκBα) was suppressed (P < 0.05) by TTO treatment. TTO treatment limited (P < 0.05) the increase in intracellular reactive oxygen species (ROS) and prevented (P < 0.05) a reduction in mitochondrial membrane potential observed in response to PA treatment. Expression of endoplasmic reticulum (ER) stress genes was reduced (P < 0.05) in the PT group compared with the PA group. Our results suggest that TTO treatment attenuates the effects of PA in hepatocytes, leading to fatty acid oxidation, decreased fatty acid synthesis, suppressed inflammatory response, and reduced ER stress. Taken together, the results of this study suggest that TTO treatment may be a promising therapeutic approach to imbalanced lipid homeostasis, inflammation and ER stress in dairy cows shortly before and after calving.

Histidine (His) is considered to be the first-limiting amino acid (AA) on grass silage-based diets in lactation cows, which correlate positively with lactose yield. The higher glucose requirements of lactating cows can be met through a combination of increased capacity for gluconeogenesis and increased supply of gluconeogenic precursors. However, the effect of His on the expression of gluconeogenic genes in the bovine hepatocytes is less known. Therefore, this study aimed to investigate the regulatory effect of His on the key gluconeogenic genes and glucose output in bovine hepatocytes. The addition of 0.15, 0.6, and 1.2 mM His in a medium significantly enhanced (p < 0.05) the viability of bovine hepatocytes. Remarkably, 1.2 mM His induced profound changes (p < 0.05) in the mRNA level of key genes involved in gluconeogenesis, including PCK1, PCK2, FBP1, and G6PC in vitro. Furthermore, the mRNA expression of PCK1 was significantly elevated (p < 0.05) by the addition of 1.2 mM His at 3, 6, 12, and 24 h of incubation. The hepatic glucose output increased (p < 0.05) linearly with increasing His concentration. These findings indicate that the addition of His may be efficiently converted into glucose via the upregulation of genes related to the gluconeogenic pathway.

Short-chain fatty acids (SCFAs) play a pivotal role in regulating the proliferation and development of bovine rumen epithelial cells (BRECs). G protein-coupled receptor 41 (GPR41) is involved in the signal transduction in BRECs as a receptor for SCFAs. Nevertheless, the impact of GPR41 on the proliferation of BRECs has not been reported. The results of this research showed that the knockdown of GPR41 (GRP41KD) decreased BRECs proliferation compared with the wild-type BRECs (WT) (p < 0.001). The RNA sequencing (RNA-seq) analysis showed that the gene expression profiles differed between WT and GPR41KD BRECs, with the major differential genes enriched in phosphatidylinositol 3-kinase (PIK3) signaling, cell cycle, and amino acid transport pathways (p < 0.05). The transcriptome data were further validated by Western blot and qRT-PCR. It was evident that the GPR41KD BRECs downregulated the level of the PIK3-Protein kinase B (AKT)-mammalian target of the rapamycin (mTOR) signaling pathway core genes, such as PIK3, AKT, eukaryotic translation initiation factor 4E binding protein 1 (4EBP1) and mTOR contrasted with the WT cells (p < 0.01). Furthermore, the GPR41KD BRECs downregulated the level of Cyclin D2 p < 0.001) and Cyclin E2 (p < 0.05) compared with the WT cells. Therefore, it was proposed that GPR41 may affect the proliferation of BRECs by mediating the PIK3-AKT-mTOR signaling pathway.

Lactic acid bacteria (LAB) is a collective term for bacteria capable of producing lactic acid from fermentable carbohydrates. Despite their widespread presence in the gastrointestinal tracts of humans and animals, where they play important physiological roles, functional analysis of specific strains from particular sources requires further enrichment. The objective of this study was to explore the differences between Pediococcus acidilactici OM681363 and Lacticaseibacillus paracasei ON606241, both isolated from the rumen of Chinese Holstein dairy cows, using whole-genome sequencing. The results indicate that P. acidilactici OM681363 contained three CRISPR fragments and numerous enzymes involved in carbohydrate degradation. Additionally, P. acidilactici OM681363 possessed more genes related to fiber degradation, especially cellobiose, and the sole carbon source experiment also confirmed this. However, it lacked genes associated with polysaccharide lyase. In contrast, L. paracasei ON606241 was found to be more specialized in breaking down non-fiber carbohydrates, producing more acetic and lactic acids. Overall, P. acidilactici OM681363 may have a greater capacity to degrade complex carbohydrates, while L. paracasei ON606241 appears to specifically target non-fiber carbohydrates.

Objective: This research aims to explore the effects of incorporating Saccharomyces cerevisiae fermentation products (SCFP) on growth performance, nutrient digestibility, antioxidant capacity, fecal short-chain fatty acids, and microbial composition of pre-weaning calves.Methods: Twenty Holstein calves, 10 days old and weighing an average of 48.63±0.91 kg, were randomly assigned to either the control group (CON) or the SCFP group, with 10 calves in each group. The CON group received only a basal diet, while the SCFP group received the starter diet supplemented with 5 g/head/d of SCFP products. The pre-trial period lasted for 5 days, followed by a main experimental period of 45 days.Results: The SCFP group had significantly higher final weight, average daily gain, and feed efficiency compared to the CON group (p<0.05). Moreover, the SCFP group exhibited increased apparent digestibility of dry matter, crude protein, ether extract, acid detergent fiber, Ca, and P (p<0.05). Additionally, supplementation with SCFP led to elevated content of growth hormone, insulin-like growth factor-1, and glucagon-like peptide-1 in serum. The inclusion of SCFP also raised serum catalase content and reduced serum malondialdehyde content in pre-weaning calves. Furthermore, SCFP supplementation influenced the composition of intestinal microflora by decreasing Actinobacteriota abundance and increasing the abundance of Ruminococcus, Lachnospiraceae_AC2044_group, Parabacteroides, and Butyricimonas.Conclusion: The addition of SCFP has a positive impact on the growth performance, nutrient digestibility, antioxidant capacity, and intestinal microflora composition of pre-weaning calves.

Rumen bacteria have the ability to efficiently degrade and acidify lignocellulosic biomass, among which rumen solid-phase bacteria are more dominant. However, the effectiveness of in vitro cultured ruminal solid-phase bacteria in producing volatile fatty acids (VFA) during lignocellulosic biomass degradation remains unclear. This study presents a feasibility analysis of the long-term subculture of rumen solid-phase bacteria in vitro for VFA production. The results indicated that VFA production could reach 0.20–0.30 g/g dry matter. After 40 generations (200 days) of subculturing, the bacterial community underwent alterations. The relative abundance of certain fiber-degrading, acid-producing bacteria, which were less abundant in rumen solids, such as Oribacterium and Victivallis, was significantly upregulated following subculturing in vitro. The success of this study in subculturing rumen solid-phase bacteria in vitro over an extended period and achieving efficient VFA production is of considerable importance for the practical application of rumen microorganisms in production settings.