D Nishino, S Khounsaknalath, K Saito, A Saito, T Abe, E Kobayashi, F Ebara, S Maak, E Albrecht, M W Pfaffl, R Saneshima, S Shimamoto, D Ijiri, S Koike, S Yasuo, T Gotoh . Early high nut2025 · 記述言語： 英語 掲載種別： 研究論文（学術雑誌） We previously reported that high nutrition early in life enhances the growth and intramuscular fat (IMF; i.e., marbling) content of grass-fattened beef cattle. The objectives of this study were to elucidate the mechanisms determining meat traits through comprehensive investigations from multiple perspectives. Specifically, we evaluated the long-term effects of early high nutrition on IMF adipogenesis, lipid metabolism, myofibre characteristics, rumen fermentation, and epigenetic regulation. Epigenetically mediated metabolism was investigated using integrated multiomics approaches including metabolites, gene expression, and DNA methylation. Wagyu (Japanese Black) steers were allocated to two groups: early roughage (ER, n = 11) steers fed a standard amount of milk replacer until 3 months of age (mo) and only roughage from 4 to 10 mo; and early high overall nutrition (EHN, n = 12) steers provided three times the standard amount of milk replacer until 3 mo and a high-concentrate diet from 4 to 10 mo. From 11 to 31 mo, all of the steers were fed only roughage (final BW, ER: 521.9 kg, EHN: 571.3 kg, P = 0.005; IMF in longissimus thoracis muscle (LM), ER: 9.4%, EHN: 13.2%, P = 0.039). The EHN LM contained larger adipocytes from the early to the finishing period (P < 0.055), with higher expression of adipogenesis-related genes (P < 0.032), including CCAAT/enhancer binding protein alpha (C/EBPα) and peroxisome proliferator-activated receptor gamma (PPARγ). During the finishing period, EHN adipose tissues contained more monounsaturated fatty acid (P < 0.018) and EHN LM contained fewer oxidative and more glycolytic myofibres (P < 0.054). The EHN steers had a higher proportion of rumen propionate and a lower acetate/propionate ratio during the high-nutrition and late fattening periods (P < 0.046). Multiomics analysis of metabolites, mRNA transcripts, and DNA methylation identified mitochondrial β-oxidation and biogenesis declines in EHN LM as candidate epigenetically regulated metabolism. These were indicated by accumulated 9-acylcarnitines and low gene expression of acyl-CoA synthetase medium-chain family member 1 (ACSM1), enoyl-CoA hydratase and 3-hydroxyacyl CoA dehydrogenase (EHHADH), 3-hydroxybutyrate dehydrogenase 1 (BDH1), and apelin receptor (APLNR; P < 0.059), all of which had differentially methylated DNA regions. These findings suggest that the increase in LM IMF might be the result of early adipocyte hyperplasia, greater nutrient supply through rumen programming of high propionate production, and epigenetic regulation of metabolism, involving decreased muscle mitochondrial function inducing a shift towards myofibres that consume less lipids. DOI： 10.1016/j.animal.2025.101551 PubMed
Daichi Ijiri, Yoshio Nishimura, Ayumi Katafuchi, Saki Shimamoto, Miyu Kamimura, Ichiro Oshima, Namiko Nakamura, Shozo Tomonaga, Shinya Ishihara, Akira Ohtsuka . Development and Validati2025 · 記述言語： 英語 掲載種別： 研究論文（学術雑誌） BACKGROUND: Nτ-methylhistidine released endogenously from muscle into urine is an index of muscle protein breakdown, and part of Nτ-methylhistidine is excreted as the acetylated derivative, N-acetyl-Nτ-methylhistidine. OBJECTIVES: The aim of this study was to measure the urinary concentrations of Nτ-methylhistidine and N-acetyl-Nτ-methylhistidine. A quantitative method was established using liquid chromatography-tandem mass spectrometry (LC-MS/MS) operated in Q1 single-ion monitoring (SIM) mode and multiple reaction monitoring (MRM) mode with stable-isotope dilution analysis. METHODS: We synthesized N-acetyl-Nτ-methylhistidine and its isotopic analog for stable-isotope dilution analysis. Then, we validated a method for quantifying urinary concentrations of intact Nτ-methylhistidine, N-acetyl-Nτ-methylhistidine, and creatinine to precisely determine their concentrations in rats, humans, cattle, and dogs. Creatinine correction was applied to normalize for urine volume. RESULTS: For both SIM and MRM analysis, the acceptable linear ranges of detection were 5 pmol/mL to 10 nmol/mL with r2 = 1.000 in SIM mode and MRM mode. The LC-MS/MS methods operated in both SIM and MRM transitions detected changes in the urinary excretion levels of Nτ-methylhistidine and N-acetyl-Nτ-methylhistidine in response to starvation and refeeding of rats. The methods also detected urinary concentrations of Nτ-methylhistidine and N-acetyl-Nτ-methylhistidine in cattle, humans, and dogs. CONCLUSIONS: These results suggest that the LC-MS/MS method operated in SIM mode and MRM mode can be used to measure urinary concentrations of Nτ-methylhistidine and N-acetyl-Nτ-methylhistidine. DOI： 10.1016/j.tjnut.2025.09.024 PubMed
