It is a widely known that heat stress induces a reduction in milk production in cows and impairs their overall health. Studies have shown that taurine protects tissues and organs under heat stress. However, there have yet to be studies showing the functions of taurine in mammary alveolar cells-large T antigen (MAC-T) (a bovine mammary epithelial cell line) cells under heat shock. Therefore, different concentrations of taurine (10 mM, 50 mM, and 100 mM) were tested to determine the effects on heat-induced MAC-T cells. The results showed that taurine protected the cells against heat-induced damage as shown by morphological observations in conjunction with suppressed the translocation and expression of heat shock factor 1 (HSF1). Moreover, taurine not only reversed the decline in antioxidase (superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX)) activities but also attenuated the accumulation of malondialdehyde (MDA). Meanwhile, mitochondrial damage (morphology and complex I activity) resulting from heat exposure was mitigated. Taurine also alleviated the rates of cell apoptosis and markedly depressed the mRNA expressions of BCL2 associated X, apoptosis regulator (BAX) and caspase3. Furthermore, compared with the heat stress (HS) group, the protein levels of caspase3 and cleaved caspase3 were decreased in all taurine groups. In summary, taurine improves the antioxidant and anti-apoptosis ability of MAC-T cells thereby alleviates damage of cells due to heat insults.

Non-coding RNAs (ncRNAs) serve as crucial regulatory elements in the process of adipogenesis in animals; however, the specific roles and interrelationships of ncRNAs in bovine fat deposition remain poorly understood. This study aims to investigate the differentially expressed ncRNAs in the longissimus dorsi muscle of Xinjiang Brown cattle (XB) and Angus $$\times$$ Wagyu cattle (AW), to elucidate the regulatory mechanisms underlying lipidogenesis that may involve ncRNAs. Four Xinjiang Brown cattle and four Angus $$\times$$ Wagyu cattle were selected, ensuring they are subjected to identical feeding conditions, in order to evaluate the intermuscular fat (IMF) of longissimus dorsi muscles. The fat content of muscle tissue was quantified using the Soxhlet extraction method, revealing that the fat levels in the AW group were significantly elevated compared to those in the XB group. Taking muscle samples for paraffin sectioning and observing their morphology, it was found that the fat richness of the AW group was significantly higher than that of the XB group. Utilizing high-throughput RNA sequencing technology, we conducted an extensive transcriptomic analysis of longissimus dorsi muscles of XB and AW to identify significant ncRNAs implicated in fat metabolism and adipogenesis. The miRNA analysis yielded between 109,343,831 117,258,570 clean reads, whereas the lncRNA and circRNA analyses produced between 81,607,756 102,917,174 clean reads. Subsequent analysis revealed the identification of 53 differentially expressed miRNAs, 176 differentially expressed lncRNAs, and 234 differentially expressed circRNAs. KEGG enrichment analysis revealed that the target genes of differentially expressed miRNAs, lncRNAs, and circRNAs are significantly enriched in 2, 17, and 22 distinct pathways, respectively. The pathways associated with the differential enrichment of miRNA target genes involve processes such as phosphorylation and protein modification. Concurrently, the pathways linked to the varying enrichment of lncRNA target genes encompass G protein-coupled receptor signaling, regulation of cell death and apoptosis, activities related to GTPase activation, and functions governing nucleotide triphosphatases, among others. The circRNA exhibiting differential expression are significantly enriched in a variety of biological processes, including signal transduction, nucleic acid synthesis, cellular architecture, GTPase activation, and phosphatase activities, among others. The analysis of the ncRNA interaction network suggests that AGBL1, THRB, and S100A13 may play pivotal roles in the formation and adipogenic differentiation of adipocytes. In conclusion, we conducted a comprehensive analysis and discussion of the complete transcriptome of intermuscular fat tissue from the longissimus dorsi muscles in Xinjiang Brown cattle and Angus $$\times$$ Wagyu cattle. This study provides a theoretical foundation for enhancing our understanding of the molecular mechanisms underlying fat metabolism and deposition in beef cattle.

The aim of this study was to investigate the differentially expressed genes associated with intramuscular fat deposition in the longissimus dorsi muscle of Xinjiang Brown Bulls. The longissimus dorsi muscles of 10 Xinjiang Brown Bulls were selected under the same feeding conditions. The intramuscular fat content of muscle samples was determined by the Soxhlet extraction method, for which 5 samples with high intramuscular fat content (HIMF group) and 5 samples with low intramuscular fat content (LIMF group) were selected. It was found that the intramuscular fat content of the HIMF group was 46.054% higher than that of the LIMF group. Muscle samples produced by paraffin sectioning were selected for morphological observation. It was found that the fat richness of the HIMF group was better than that of the LIMF group. Transcriptome sequencing technology was used to analyze the gene expression differences of longissimus dorsi muscle. Through in-depth analysis of the longissimus dorsi muscle by transcriptome sequencing technology, we screened a total of 165 differentially expressed genes. The results of Gene Ontology (GO) enrichment analysis showed that the differentially expressed genes in the two groups were mainly clustered in biological pathways related to carbohydrate metabolic processes, redox processes and oxidoreductase activities. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed that the differentially expressed genes were significantly clustered in 15 metabolic pathways, which mainly covered fatty acid metabolism (related to lipid metabolism and glucose metabolism), the pentose phosphate pathway, the Peroxisome Proliferator-Activated Receptor (PPAR) signaling pathway and other important metabolic processes. The three genes that were predominantly enriched in the glycolipid metabolic pathway by analysis were SCD5, CPT1C and FBP2, all of which directly or indirectly affect intramuscular fat deposition. In summary, the present study investigated the differences in gene expression between high and low intramuscular fat content in the longissimus dorsi muscle of Xinjiang Brown Bulls by transcriptome sequencing technology and revealed the related signaling pathways. Therefore, we hypothesized that SCD5, CPT1C and FBP2 were the key genes responsible for the significant differences in intramuscular fat content of the longissimus dorsi muscles in a population of Xinjiang Brown Bulls. We expect that these findings will provide fundamental support for subsequent studies exploring key genes affecting fat deposition characteristics in Xinjiang Brown Bulls.

This study utilized MAC-T cells cultured in vitro as a model to investigate the effects of varying concentrations of valine on α-casein synthesis and its underlying regulatory mechanisms. In this experiment, MAC-T cells were subjected to a 12 h starvation period, followed by the addition of valine in a range of concentrations (a total of seven concentrations: 0.000, 1.596, 3.192, 6.384, 12.768, 25.536, and 51.072 mM, as well as in 10% Fetal Bovine Serum). The suitable range of valine concentrations was determined using enzyme-linked immunosorbent assays (ELISAs). Real-time fluorescent quantitative PCR (RT-qPCR) and Western blot analyses were employed to evaluate the expression levels and phosphorylation states of the casein alpha s1 gene (CSN1S1), casein alpha s2 gene (CSN1S2) and mTOR signaling pathway-related genes. The functionality of the mTOR signaling pathway was further validated through rapamycin (100.000 nM) inhibition experiments. Results indicated that 1× Val (6.384 mM), 2× Val (12.768 mM), 4× Val (25.536 mM), and 8× Val (51.072 mM) significantly enhanced α-casein synthesis (p < 0.01). Within this concentration range, valine significantly upregulated the expression of CSN1S1, CSN1S2, and mTOR signaling pathway-related genes including the RagA gene (RRAGA), RagB gene (RRAGB), RagC gene (RRAGC), RagD gene (RRAGD), mTOR, raptor gene (RPTOR), and 4EBP1 gene (EIF4EBP1), eukaryotic initiation factor 4E (EIF4E), and S6 Kinase 1 (S6K1) (p < 0.01). Notably, the expression of the eukaryotic elongation factor 2 (EEF2) gene peaked at 1× Val (6.384 mM), while the expression of other genes reached their maximum at 4× Val (25.536 mM). Additionally, valine significantly increased the phosphorylation levels of mTOR, S6K1, 4E-binding protein-1 (4EBP1), ribosomal protein S6 (RPS6), and eEF2 (p < 0.01), with the highest phosphorylation levels of mTOR, S6K1, and RPS6 observed at 4× Val (25.536 mM). Rapamycin treatment significantly inhibited mTOR phosphorylation and α-casein synthesis (p < 0.01); however, the addition of 4× Val (25.536 mM) partially mitigated this inhibitory effect. In conclusion, valine promotes α-casein synthesis by activating the mTOR signaling pathway, with an optimal concentration of 4× Val (25.536 mM).

This study aimed to investigate the effects of feeding high-moisture corn (HMC) on weight performance, serum immune and antioxidant indices, rumen fermentation, microbial community, and metabolomics in Kazakh rams. A total of 32 healthy Kazakh rams were randomly divided into a control group (CT, diet with only ordinary crushed corn) and an experimental group (GS, diet with 50% ordinary crushed corn + 50% HMC), following a 7-day adaptation period and a 120-day trial period. Results showed that the F/G was significantly lower in the GS group than in the CT group (p < 0.05). FBW, net weight gain and ADG increased by 4.58%, 8.69%, and 8.70%, respectively, while ADFI decreased by 7.04% (p > 0.05). Regarding serum immune indices, IgA in the GS group was significantly higher at 40 d (p < 0.01), and IgM was significantly higher at 40, 80, and 120 d (p < 0.05). For antioxidant indices, the SOD activity in the GS group was significantly higher than that in the CT group at 120 d (p < 0.01). The CAT activity in the GS group was significantly higher at 40, 80, and 120 d (p < 0.01). Among rumen fermentation parameters, the concentration of butyric acid in the GS group was significantly lower than in the CT group (p < 0.01). Microbial diversity analysis indicated no significant differences in Alpha- and Beta-diversity of rumen microorganisms between the two groups. However, the relative abundance of Firmicutes_A at the phylum level was significantly higher in the GS group (p < 0.05), and the abundance of Cryptobacteroides was significantly higher than in the CT group (p < 0.01). Rumen metabolomic analysis identified a total of 1357 differential metabolites, among which 1130 showed significant differences, with 459 upregulated and 671 downregulated. These were mainly enriched in pathways such as Glutathione metabolism, Beta-alanine metabolism, Sphingolipid metabolism, and lysine degradation. In conclusion, feeding HMC can improve feed conversion efficiency and weight performance in Kazakh rams, regulate the structure of dominant rumen microorganisms, and enhance immune and antioxidant capacities.

Amino acids play a dual role in milk protein synthesis, functioning as both metabolic precursors and signaling molecules. This study aimed to elucidate the molecular mechanism by which glycine regulates α-casein production in bovine mammary epithelial cells (MAC-T). Under serum-free conditions, MAC-T cells were exposed to graded concentrations of glycine (1.105, 2.209, 4.418, 8.836, 17.673, and 35.345 mM) for 24 h. α-Casein levels in cell lysates and culture supernatants were quantified by ELISA. Transcriptional activity of casein-encoding genes (CSN1S1, CSN1S2) and PI3K-AKT-mTOR pathway components was assessed by RT-qPCR. Phosphorylation status of pathway proteins was analyzed by Western blot. The functional involvement of the PI3K-AKT-mTOR pathway was validated using the specific inhibitor LY294002. Glycine stimulated α-casein synthesis and secretion in a concentration-dependent manner, with maximal efficacy at 4.418 mM. At this concentration, glycine upregulated CSN1S1, CSN1S2, and PI3K-AKT-mTOR pathway gene expression, and enhanced phosphorylation of the corresponding proteins. Inhibition of PI3K-AKT-mTOR signaling by LY294002 abolished glycine-induced α-casein synthesis, and this effect was reversed by glycine co-treatment. These findings demonstrate that glycine enhances α-casein synthesis through activation of the PI3K-AKT-mTOR pathway.