The production performance of dairy cattle is closely related to their metabolic state. This study aims to provide a comprehensive understanding of the production performance and metabolic features of Sanhe dairy cattle across different parities, with a specific focus on evaluating variations in milk traits and metabolites in both milk and serum. Sanhe dairy cattle from parities 1 to 4 (S1, n = 10; S2, n = 9; S3, n = 10; and S4, n = 10) at mid-lactation were maintained under the same feeding and management conditions. The milk traits, hydrolyzed milk amino acid levels, serum biochemical parameters, and serum free amino acid levels of the Sanhe dairy cattle were determined. Multiparous Sanhe dairy cattle (S2, S3, and S4) had a greater milk protein content, lower milk lactose content, and lower solids-not-fat content than primiparous Sanhe dairy cattle (S1). Moreover, S1 had a higher ratio of essential to total amino acids (EAAs/TAAs) in both the serum and milk. The serum biochemical results showed the lower glucose and total protein levels in S1 cattle were associated with milk quality. Furthermore, ultra-high-resolution high-performance liquid chromatography with tandem MS analysis (UPLC-MS/MS) identified 86 and 105 differential metabolites in the serum and milk, respectively, and these were mainly involved in amino acid, carbohydrate, and lipid metabolism. S1 and S2/S3/S4 had significantly different metabolic patterns in the serum and milk, and more vitamin B-related metabolites were significantly higher identified in S1 than in multiparous cattle. Among 36 shared differential metabolites in the serum and milk, 10 and 7 metabolites were significantly and strongly correlated with differential physiological indices, respectively. The differential metabolites identified were enriched in key metabolic pathways, illustrating the metabolic characteristics of the serum and milk from Sanhe dairy cattle of different parities. L-phenylalanine, dehydroepiandrosterone, and linoleic acid in the milk and N-acetylornithine in the serum could be used as potential marker metabolites to distinguish between Sanhe dairy cattle with parities of 1–4. In addition, a metabolic map of the serum and milk from the three aspects of carbohydrates, amino acids, and lipids was created for the further analysis and exploration of their relationships. These results reveal significant variations in milk traits and metabolites across different parities of Sanhe dairy cattle, highlighting the influence of parity on the metabolic profiles and production performance. Tailored nutritional strategies based on parity-specific metabolic profiles are recommended to optimize milk production and quality in Sanhe cattle.

Utilizing straw feed is an effective strategy to optimize straw resource utilization by incorporating microbial degradation agents to expedite lignocellulose breakdown and enhance feed efficiency. Lignocellulose-degrading species and microbial communities are present in various Earth ecosystems, including the rumen of ruminants, insect digestive tracts, forest soil, and microbial populations in papermaking processes. The rumen of ruminants harbors a diverse range of microbial species, making it a promising source of lignocellulose-degrading microorganisms. Exploring alternative systems like insect intestines and forest soil is essential for future research. Current studies primarily rely on traditional microbial isolation techniques to identify lignocellulose-degrading strains, underscoring the necessity to transition to utilizing microbial culturomics and genome-editing technologies for discovering and manipulating cellulose-degrading microbes. This review provides an overview of lignocellulose-degrading microbial communities from diverse environments, encompassing bacterial and fungal populations. It also delves into the use of metagenomic, metatranscriptomic, and metaproteomic approaches to pinpoint highly efficient cellulase genes, along with the application of genome-editing tools for engineering lignocellulose-degrading microorganisms. The primary objective of this review is to offer insights for further exploration of potential lignocellulose-degrading microbial resources and high-performance cellulase genes to enhance roughage utilization in ruminant rumen ecosystems.

Non-proteinogenic amino acids, such as L-citrulline and L-theanine, have garnered attention for their potential health benefits, including enhanced immunity, antioxidant activity, and cardiovascular support. The application of natural amino acids in disease treatment and health supplementation is and will remain a research hotspot in pharmaceutics. Plant-derived L-citrulline and L-theanine have demonstrated multifaceted benefits, primarily through mechanisms involving nitric oxide (NO) bioavailability (for L-citrulline) and mitochondrial regulation or immune modulation (for both). Critical gaps are identified: (1) the role of D-amino acids (e.g., D-citrulline and D-theanine) in health and metabolism remains underexplored, particularly regarding chiral-specific bioactivity; (2) derivatives and co-administration strategies of L-forms warrant systematic evaluation for drug. However, while these compounds show promise, evidence is predominantly from animal and cell studies, with limited long-term human data on efficacy and safety. Potential side effects, dosing limitations, and sourcing challenges are discussed. This review emphasizes the need for cautious interpretation of their benefits, acknowledging that while promising, some effects, such as those on muscle protein synthesis, require further validation compared to established nutrients like branched-chain amino acids. By bridging mechanistic insights with translational challenges, this work aims to guide future research toward sustainable nutraceutical production.

Glycerol fatty acid esters (GFAEs) are recognized for their potential to improve lipid metabolism, energy utilization, and gut health due to their excellent emulsifying and antimicrobial properties. The objective of this research was to investigate the effects of dietary GFAE supplementation on production performance, serum biochemical profiles, and rumen fermentation in beef cattle. Thirty crossbred Simmental bulls, averaging 507.42 ± 9.59 kg in body weight, were assigned to three distinct cohorts, with 10 animals in each cohort. The CON cohort was fed a basal diet devoid of GFAE, whereas the treatment cohorts (GFAE1 and GFAE2) received GFAE supplements at concentrations of 0.1% and 0.2% of the dietary dry matter, respectively. Compared with the control group, supplementation with 0.1% GFAE significantly increased the ADG of beef cattle by 12.14% (p < 0.05); compared with the GFAE2 group, ADG was 7.86% higher (p > 0.05). The digestibility of NDF and ADF was significantly enhanced in the GFAE1 group relative to the control group (p < 0.05). Dietary GFAE supplementation significantly elevated rumen acetate, propionate, and total volatile fatty acid concentrations in both the GFAE1 and GFAE2 groups compared to the control group (p < 0.05). In contrast to the control group, there was a notable rise in serum levels of T-AOC, UREA, and TG in both GFAE1 and GFAE2 groups (p < 0.05). Conversely, the concentration of HDL-C was significantly decreased in the GFAE2 group. Additionally, at the phylum level, the abundance of Fibrobacterota was significantly higher in the GFAE1 group than in the control group (p < 0.01). At the genus level, the proportions of Bacteroides and Fibrobacter were significantly higher in the GFAE1 group compared to the control group (p < 0.05). In conclusion, this study demonstrates that the addition of 0.1% GFAE to beef cattle diets significantly enhances the digestibility of ADF and NDF nutrients, increases serum total antioxidant capacity, urea, and triglycerides, optimizes rumen fermentation parameters and microbial community structure, and ultimately improves production performance. As a result of the findings from this research, it is suggested that 0.1% GFAE be incorporated into the diet for beef cattle.

This study aimed to collaboratively investigate the mechanism of variations in intramuscular fat (IMF) content in Wandong cattle using transcriptomics and metabolomics techniques. Longissimus dorsi (LD) muscle samples were collected from thirteen free-range Wandong cattle in Fengyang County, Anhui Province, China. From this initial cohort, eight animals closely matched in age and body weight were selected. Based on IMF content measured by Soxhlet extraction, these eight cattle were divided into two groups: the high-IMF (HF, n = 4) and low-IMF (LF, n = 4) groups. Subsequent analyses were performed on integrated datasets comprising the transcriptome, metabolome, and fatty acid profile. The results revealed a significant increase in IMF in the HF group compared to the LF group (p < 0.05). Specifically, α-linolenic acid (C18:3n3) and γ-linolenic acid (C18:3n6) were significantly more abundant in the LF group compared to the HF group (p < 0.05), whereas oleic acid (C18:1n9c) and cis-9-palmitoleic acid (C16:1) predominated in the HF group. However, saturated fatty acids (SFAs), such as myristic acid (C14:0), palmitic acid (C16:0), stearic acid (C18:0), and Margaric acid (C17:0), did not show significant differences (p > 0.05). A total of 9164 differentially expressed genes (DEGs) were identified via transcriptome analysis, with 2202 genes upregulated and 6962 genes downregulated in the HF group compared to the LF group. The expression profiles exhibited a distinct pattern, characterized by the upregulation of genes such as FABP1, SREBF1, and LIPE, while genes including SCD, PPARGC1A, and LEP were downregulated. GO enrichment analysis demonstrated that the majority of DEGs were predominantly abundant across 25 distinct functional categories distributed across the three primary ontologies. KEGG pathway analysis further identified 341 significantly enriched signaling pathways in the HF group (p < 0.05), predominantly involving metabolic pathways, FoxO, AMPK, and PPAR signaling pathways. Untargeted liquid chromatography-tandem mass spectrometry (LC-MS/MS) metabolomics analysis revealed 404 differential accumulated metabolites (DAMs), with 187 in positive ion mode and 217 in negative ion mode (p < 0.05). These DAMs were notably enriched in pathways such as glycerophospholipid metabolism, terpene and steroid biosynthesis, fatty acid degradation, and fatty acid metabolism. Notably, C16:1, C18:1n9c, arachidonic acid (peroxide free) (C20:4n6), oleoyl-L-carnitine, and linoleoyl-carnitine were identified as key players in lipid metabolism. Integrating transcriptomics with metabolomics data unveiled significant associations between DAMs linked to lipid metabolism and DEGs. Specifically, C18:1n9c exhibited a positive correlation with LPIN3, while C16:1 showed negative associations with PPAP2B, PPAP2A, CDS2, HADHA, LPL, HSD17B12, ELOVL5, ACSL1, and ACOX1, and positive correlations with PLA2G15, CDIPT, AGPSBG1, and GPD1. In summary, the variation in IMF content in Wandong cattle is co-regulated by key genes (SREBF1, ACSL1, SCD) via the AMPK, PPAR, and FoxO signaling pathways, coupled with alterations in specific fatty acid metabolites such as C18:1n9c, C16:1, and C20:4n6. These findings provide critical molecular insights for the genetic selection and breeding of Wandong cattle, which are renowned for their superior meat quality.

This study evaluated the effects of dietary glycerol fatty acid esters (GFAs) on growth performance, nutrient digestibility, nitrogen metabolism, jejunal microbiota, and intestinal transcriptome in Hu sheep. Thirty-six 4–5-month-old male Hu sheep were randomly assigned to three groups receiving a basal diet (GFA0%) or diets supplemented with 0.15% (GFA0.15%) or 0.20% (GFA0.20%) GFA for 52 days following a 7-day adaptation period. Growth performance parameters were unaffected (p > 0.05); however, feed-to-gain ratio decreased linearly and quadratically with increasing GFA levels (p < 0.001). GFA supplementation improved ether extract (EE) and neutral detergent fiber (NDF) digestibility (p < 0.05), neutral detergent fiber ADF digestibility showed a linear increase(linear = 0.025), significantly reduced fecal and urinary nitrogen excretion, and enhanced nitrogen utilization (p < 0.05). Jejunal microbiota analysis revealed significant genus-level separation among groups, with increased Bacillota abundance and the enrichment of Acetitomaculum and [Ruminococcus]_gauvreauii_group in the GFA0.20% group. Functional prediction indicated enhanced fiber degradation, nitrogen metabolism, and host interaction functions. Transcriptomic analysis showed dose-dependent gene regulation, with GFA0.15% primarily enriching immune-related pathways, while GFA0.20% additionally activated lipid and steroid metabolism pathways. Integrated microbiome-host analyses demonstrated coordinated regulation of nutrient metabolism and immune responses. Overall, dietary inclusion of 0.20% GFAs optimized feed efficiency, nutrient utilization, and intestinal metabolic-immune function in Hu sheep.