Qi Liu

This exploratory study was designed to investigate associations between AM-containing high-concentrate diets and immune markers in Dumeng lambs and to generate hypotheses regarding concurrent changes in rumen fermentation, liquid-associated rumen microbial community structure, and metabolic profiles. Eighteen healthy male Dumeng lambs were randomly assigned to three groups with six lambs per group (n = 6). The CON group served as the control, while the T1 and T2 groups were supplemented with 1% and 2% AM, respectively. The results showed that compared with CON, lambs fed AM-containing diets had higher ruminal NH₃-N (10.88 vs. 12.01 and 12.10 mg/100 mL, p < 0.01) and TVFA (73.78 vs. 85.39 and 87.22 mmol/L, p < 0.05) concentrations, lower acetate proportion (52.16% vs. 47.64% and 46.55%) and acetate-to-propionate ratio (p < 0.01), and higher butyrate proportion in the 1% and 2% AM groups (5.58% vs. 8.55 and 9.31%, p < 0.01). Endpoint-level immune effects survived BH-FDR correction (q < 0.05); Tukey-adjusted pairwise comparisons showed that T2 lambs had lower IL-6 (58.97 vs. 91.35 pg/mL), TNF-α (137.80 vs. 182.38 pg/mL), rumen LPS (109.33 vs. 141.25 ng/mL), and serum LPS (59.67 vs. 81.07 ng/mL), and higher IL-10 (123.14 vs. 87.88 pg/mL), TP (73.50 vs. 67.72 g/L), ALB (28.69 vs. 24.47 g/L), IgA (15.42 vs. 8.52 μg/mL), and IgG (18.38 vs. 11.73 μg/mL) than CON. Exploratory 16S rRNA analysis showed nominally lower Proteobacteria and higher Shuttleworthia in T2; however, no taxon survived BH-FDR correction (q ≥ 0.05), and ANCOM W and LEfSe LDA results are exploratory sensitivity findings only. Exploratory metabolomics suggested associations with purine and nucleotide metabolism; KEGG analysis used uncorrected p values and is hypothesis-generating only. These correlational findings indicate that AM-containing high-concentrate diets are associated with changes in several immune markers; because diets also differed in ingredients other than AM, causality, clinical benefits, and the independent effect of AM remain to be established.

To systematically investigate the metabolic and microbial differences in feed efficiency between Hereford × Simmental (H × S) crossbred and purebred Simmental cattle (S × S), 20 steers (initial weight = 268.80 ± 30.88 kg; initial age = 273.00 ± 14.09 days) were used, which were housed in mixed pens and fed a low-energy diet (0.75 Mcal Neg/kg DM). This study revealed that the level of Hypoglycin B was related to a reduced T3, which could affect growth performance. Metabolomics analysis identified Hypoglycin B, lysoPC, and DHAP as key discriminative metabolites. Pathway enrichment analysis revealed that these metabolites were primarily mapped to glycine, serine, and threonine metabolism; alanine, aspartate, and glutamate metabolism; and pantothenate and CoA biosynthesis. In our study, the relative abundances of Succinivibrio and Clostridium_sensu_stricto_6 were significantly greater in the H × S group than in the S × S group; it may have stronger energy extraction abilities and matches their lower F/G. Romboutsia was positively correlated with Hypoglycin B and negatively correlated with LysoPC (20:2 (11Z,14Z)/0:0), which might be related to changes in blood metabolites. Nevertheless, these explanations remain correlational and require functional validation through targeted interventions.