Rosemary extract (RE) has been used as an antioxidant in cosmetics and food additives, indicating its potential as a feed additive to improve adaptation in high-producing dairy cows. Here, we investigated the effects of RE supplementation on lactation performance and rumen fermentation in high-producing dairy cows. Thirty multiparous cows were blocked into 15 groups based on milk production and were randomly assigned to one of two treatments: 0 or 28 g/d of RE supplementation to the basic diet per cow. The experiment was conducted over a 74-day period, which included an initial two-week adaptation period. We observed significant increases in milk and milk lactose yields following RE supplementation. Somatic cell count tended to decrease by treatment. Additionally, superoxide dismutase concentration significantly increased and malonaldehyde level decreased after RE supplementation. Sequencing of 16S rRNA revealed that RE supplementation significantly affected the microbial composition and decreased the richness of the microbiota. Specifically, the abundance of the genus Prevotella was significantly decreased by RE supplementation and was correlated with volatile fatty acids in the Mantel test, whereas no significant correlation was found for other genera. Our findings provide fundamental information on the potential for RE as a feed additive for dairy cows to improve antioxidant status and enhance propionate generation.

This study aimed to evaluate the effects of concentrate supplementation on the growth performance, serum biochemical parameters, rumen fermentation, and bacterial community composition of grazing yaks during the warm season. Eight male yaks (body weight, 123.96 ± 7.43 kg; 3-years) were randomly allocated to two treatments groups: grazing (n = 4, GY) and concentrate supplement group (n = 4, GYS). Concentrate supplementation increased the average daily gain (ADG) (p < 0.05). Glucose (GLU), total protein (TP), and aspartate aminotransferase (AST) serum concentrations were significantly higher in the GYS group than in the GY group (p < 0.05). Ammonia-N, MCP: microbial protein, and total volatile fatty acid concentrations were significantly higher in the GYS group than in the GY group (p < 0.01), whereas the pH and acetate: propionate values were significantly decreased (p < 0.01). The relative abundance of Firmicutes in the rumen fluid was significantly higher in the GYS group than in the GY group (p < 0.01). At the genus level, the relative abundances of Succiniclasticum, Prevotellaceae_UCG_003, Prevotellaceae_UCG_005, and Ruminococcus_1 were significantly greater in the GY group than in the GYS group (p < 0.01). In conclusion, concentrate supplementation improved yaks’ growth potential during the warm season, improved ruminal fermentation, and altered core bacteria abundance.

Scutellariae radix flavonoid extract (SFE) has been acknowledged for its antioxidant, anti-inflammatory and antimicrobial properties in enhancing gastrointestinal microbial communities and improving the host's immunity. Nevertheless, the impacts of dietary supplementation with SFE on the gastrointestinal microbes and host metabolism in dairy cows remain uncertain. Therefore, the aim of this study was to assess the effects of dietary supplementation with SFE on the lactation performance, gastrointestinal microbes, and plasma biochemical parameters of dairy cows. Six ruminally and duodenally cannulated multiparous dairy cows were used in a crossover design over 28-d periods that included a 21-d adaptation and a 7-d sample collection period. Cows were fed a basal diet (CON group) or a basal diet supplemented with SFE at 25 g/d (SFE group). SFE supplementation tended to increase milk yield (P = 0.067) and milk urea N concentration (P = 0.079), and decreased the milk somatic cell counts (SCC, P = 0.036). Cows in the SFE group had lower plasma aspartate aminotransferase (AST), malondialdehyde (MDA), tumor necrosis factor (TNF-α), and interleukin-1β concentrations compared with the CON (P < 0.05). Meanwhile, SFE supplementation increased butyrate concentration in the rumen (P = 0.044). The microbial structure of rumen and duodenum were affected by SFE supplementation (P = 0.009 and P = 0.031; respectively), resulting in enrichment of Butyrivibrio in both parts of the SFE cows (P = 0.034 and P = 0.029; respectively). However, microbial structure and composition of feces were not affected by SFE supplementation. Overall, our study indicated that dietary supplementation with SFE could enhance lactation performance and milk quality in dairy cows by improving the gastrointestinal inner environment and health status.

Background: Metabolic disorders in peripartum ruminants affect health and productivity, with gut microbiota playing a key role in host metabolism. Therefore, our study aimed to characterize the gut microbiota of peripartum dairy cows to better understand the relationship between metabolic phenotypes and the rumen and fecal microbiomes during the peripartum period. Results: In a longitudinal study of 91 peripartum cows, we analyzed rumen and fecal microbiomes via 16S rRNA and metagenomic sequencing across six time points. By using enterotype classification, ecological model, and random forest analysis, we identified distinct deterministic succession patterns in the rumen and fecal microbiomes (rumen: rapid transition–transition–stable; hindgut: stable–transition–stable). Key microbes, such as Succiniclasticum and Bifidobacterium, were found to drive microbial succession by balancing stochastic and deterministic processes. Notably, we observed that changes in gut microbiota succession patterns significantly influenced metabolic phenotypes (e.g., serum non-esterified fatty acid, glucose, and insulin levels). Mediation analysis suggested that specific gut microbes (e.g., Prevotella sp900315525 in the rumen and Alistipes sp015059845 in the hindgut) and metabolic pathways (e.g., glucose-related pathway) were associated with host metabolic phenotypes. Conclusions: Overall, utilizing a large gut microbiome dataset and enterotype- and ecological model-based microbiome analyses, we comprehensively elucidated the succession and assembly of the gut microbiota in peripartum dairy cows. We further confirmed that changes in gut microbiota succession patterns were significantly related to the metabolic phenotypes of peripartum dairy cows. These findings provide valuable insights for developing health management strategies for peripartum ruminants.

Currently, information available on the comprehensive changes in the rumen bacteria and metabolites of yaks fed high-grain diets is limited. This study aimed to investigate the effects of high-grain diet feeding on the blood metabolites, rumen microbiome, and metabolomics of yaks by using 16S rDNA gene sequencing and liquid chromatography–mass spectrometry (LC/MS). Here, fourteen healthy male yaks (body weight, 249.61 ± 8.13 kg) were randomly assigned to two different diets: a hay diet (0% grain, CON, n = 7), or a high-grain diet (70% grain, HG, n = 7). At the 74th day of treatment, blood and ruminal fluid samples were collected for the blood metabolites, rumen microbiome, and metabolomics analyses. The HG diet increased lipopolysaccharides (LPS), aspartate aminotransferase (AST), gamma-glutamyltransferase (GGT), haptoglobin (HPT), serum amyloid-A (SAA), interleukin-1β (IL1-β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) serum concentrations (p < 0.05). Compared with the CON diet, the HG diet decreased rumen pH (p < 0.05), and increased total volatile fatty acids concentration, and proportion of butyrate (p < 0.05). The relative abundance of Firmicutes and Saccharibacteria were higher (p < 0.05), while Bacteroidetes was lower (p < 0.05) in the HG group than those in the CON group. At the genus level, the relative abundance of Christensenelaceae_R-7_group, Ruminococcaceae_NK4A214_group, Lachnospiraceae_NK3A20_group, and Acetitomaculum were higher than in those in the HG diet (p < 0.05). Compared with the CON group, the HG diet increased the concentrations of biogenic amines (histamine, tyramine, and putrescine), common amino acids (phenylalanine, threonine, serine, etc.), and arachidonic acid (prostaglandin H2, prostaglandin E2, 12(S)-HPETE, etc.). Collectively, these findings demonstrate that the HG diet altered the microbiota and metabolites, as well as potentially damaged their rumen health and induced inflammation in yaks.

Supplementation with saccharomyces cerevisiae culture products (SCs) has shown effectiveness in alleviating or improving the health and productivity of ruminants at a high risk of digestive and metabolic problems as a consequence of their physiological state and feeding system (i.e., Holstein cows during peak lactation). However, the effects of SC supplementation on ruminal digestion and microbial population are not yet well-understood. Hence, this study aimed to contribute to the knowledge of the effects of in vitro SC supplementation on ruminal nutrient digestibility and microbial community. This study included three treatment groups: a control group (CON, 0% SC proportion of substrate DM), a low-dose SC group (LSC, 0.10% SC proportion of substrate DM), and a high-dose SC group (HSC, 0.30% SC proportion of substrate DM). The SC product contained 7.0 × 10⁹ CFU/g. After 48 h of fermentation at 39 °C, the incubation fluid and residue were collected to measure the ruminal nutrient digestibility and microbial community. The results showed that supplemental SC tended (p = 0.096) to increase DM digestibility due to an increase (9.6%, p = 0.03) in CP digestibility and via a tendency (0.05 < p < 0.08) to increase the fiber fraction. Additionally, the 16S rRNA high-throughput sequencing results revealed that the richness and diversity of the microbiota were unchanged by SC supplementation, while the abundances of Spirochaetes, Tenericutes, and Spirochaetaceae were lower in the SC groups than those in the CON group (p < 0.05). At the genus level, the abundances of Selenomonas and Succinivibrio were increased by SC supplementation (p < 0.05), while SC supplementation decreased the abundances of Ruminococcaceae_UCG-014 and Treponema_2 (p < 0.05). Furthermore, the predicted function of the microbiota showed that carbohydrate metabolism and lipid metabolism were enriched in the SC groups compared with the CON group (p < 0.05). Except for the increases in ADF digestibility (p = 0.032) and pH (p = 0.076) at 0.30%, the supplemental level did not result in additional effects. In summary, our results demonstrate that SC supplementation could improve ruminal nutrient degradation digestibility and alter microbiota composition.