Repeated inoculation with rumen fluid accelerates the rumen bacterial transition with no benefit on production performance in postpartum Holstein dairy cows

Alanine Derived from Ruminococcus_E bovis Alleviates Energy Metabolic Disorders during the Peripartum Period by Providing Glucogenic Precursors

Peripartum dairy cows commonly experience energy metabolism disorders, which lead to passive culling of postpartum cows and a decrease in milk quality. By using ketosis peripartum dairy cows as a model, this study aims to elucidate the metabolic mechanism of peripartum cows and provide a novel way for managing energy metabolic disorders. From a cohort of 211 cows, we integrated multi-omics data (metagenomics, metabolomics, and transcriptomics) to identify key microbes and then utilized an in vitro rumen fermentation simulation system and ketogenic hepatic cells to validate the potential mechanisms and the effects of postbiotics derived from key microbes. Postpartum cows with metabolic disorders compensate for glucose deficiency through mobilizing muscle proteins, which leads to marked decreases in milk protein content. Concurrently, these cows experience rumen microbiota disturbance, with marked decreases in the concentrations of volatile fatty acids and microbial protein, and the deficiency of alanine (Ala) in microbial protein is correlated with the metabolic disorder phenotype. Metagenomic binning and in vitro fermentation assays reveal that Ruminococcus_E bovis (MAG 189) is enriched in amino acid biosynthesis functions and responsible for Ala synthesis. Furthermore, transcriptomic and metabolomic analyses of the liver in metabolic disorder cows also show impaired amino acid metabolism. Supplementation with Ala can alleviate ketogenesis in liver cell models by activating the gluconeogenesis pathway. This study reveals that Ruminococcus_E bovis is associated with host energy metabolism homeostasis by supplying glucogenic precursors to the liver and suggests the use of Ala as a method for the treatment of energy metabolism disorders in peripartum cows.

Effects of increasing n3:n6 ratio by replacing extruded soybeans with extruded flaxseed on dry matter intake, rumen fluid bacteria, and liver lipid metabolism in transition cows

BACKGROUND

The drop of dry matter intake (DMI) and rise of milk production in transitional dairy cows would mobilize reserved fat and disrupt lipid metabolism, eventually attributed to negative energy balance (NEB) and immune injury. The positive effect of n-3 polyunsaturated fatty acids (PUFA) on regulating energy metabolism and inflammation has been elucidated, however, the lack of regulatory mechanism of dairy cows deserves further investigation. In this study, 30 Holstein transition cows were divided into the control (CON) and HN3 groups based on the n-3: n-6 PUFA ratio in the diet.

RESULTS

The results showed that compared to the CON group, high n-3: n-6 PUFA ratio-supplemented cows in the prepartum phase reduced the relative abundance of gram-negative bacteria in the rumen, the concentration of lipopolysaccharide in the plasma and liver also significantly decreased (P < 0.05). Transcriptomic analysis of the liver showed that the NF-κB signaling pathway significantly down-regulated and the taste transduction pathway up-regulated (P < 0.05) in the HN3 group. In the postpartum phase, a high n-3/n-6 PUFA ratio in the diet increased the relative abundance of Prevotella, Succinimonas and Treponema in the rumen, at the same time, orexins in plasma were also changed (P < 0.05). Further, the insulin resistance pathway significantly down-regulated and the taste transduction pathway up-regulated (P < 0.05) in the liver.

CONCLUSIONS

Overall, these results showed that a high n-3: n-6 PUFA ratio in the diet attenuates inflammatory responses in the prepartum phase and increases milk protein in the postpartum phase of transitional dairy cows. Appropriate increase in the proportion of n-3: n-6 PUFA ratio in the diet may be an effective measure to alleviate postpartum metabolic disease in dairy cows.

Rumen microbiome associates with postpartum ketosis development in dairy cows: a prospective nested case-control study

BACKGROUND

Approximately, one-third of dairy cows suffer from postpartum diseases. Ketosis is considered an important inducer of other postpartum diseases by disrupting energy metabolism. Although the rumen microbiome may be involved in the etiology of ketosis by supplying volatile fatty acids, the rumen environmental dynamics of ketosis cows are unclear. Using multi-omics, this study aimed to elucidate changes in the rumen microbiome during parturition of ketosis cows and the association between the rumen microbiome and host energy metabolism. The study included 810 rumen content samples and 789 serum samples from day - 21 and 21 relative to calving day from 61 ketosis cows and 84 healthy cows.

RESULTS

In ketosis cows, the rumen bacterial composition after parturition changed dramatically and needed a longer time to restore. The molar proportions of propionate were lower in ketosis cows than those in healthy cows on days 3 and 7 and negatively correlated with the serum β-hydroxybutyrate (BHBA) levels. The fermentation sub-pathway of propionate metabolism and partial glucogenic amino acid pathways were downregulated on day 3. Prevotella, UBA1066, and microbiota diversity indices regulate serum BHBA and glucose (GLU) levels via arginine, alanine, glycine, or propionate. Propionate administration to ketosis cows potentially decreased the serum BHBA concentration.

CONCLUSIONS

Collectively, we found rumen disruption happened after calving among ketosis cows, and insufficient glycogenic substrates, such as propionate, may be related to ketosis development. The study findings have implications for the relationship between rumen microbiome dynamics and host energy metabolism, which lays the foundation for the future rumen microbiome investigation for improving postpartum management in cows. Video Abstract.

The Profound Influence of Gut Microbiome and Extracellular Vesicles on Animal Health and Disease

The animal gut microbiota, comprising a diverse array of microorganisms, plays a pivotal role in shaping host health and physiology. This review explores the intricate dynamics of the gut microbiome in animals, focusing on its composition, function, and impact on host-microbe interactions. The composition of the intestinal microbiota in animals is influenced by the host ecology, including factors such as temperature, pH, oxygen levels, and nutrient availability, as well as genetic makeup, diet, habitat, stressors, and husbandry practices. Dysbiosis can lead to various gastrointestinal and immune-related issues in animals, impacting overall health and productivity. Extracellular vesicles (EVs), particularly exosomes derived from gut microbiota, play a crucial role in intercellular communication, influencing host health by transporting bioactive molecules across barriers like the intestinal and brain barriers. Dysregulation of the gut-brain axis has implications for various disorders in animals, highlighting the potential role of microbiota-derived EVs in disease progression. Therapeutic approaches to modulate gut microbiota, such as probiotics, prebiotics, microbial transplants, and phage therapy, offer promising strategies for enhancing animal health and performance. Studies investigating the effects of phage therapy on gut microbiota composition have shown promising results, with potential implications for improving animal health and food safety in poultry production systems. Understanding the complex interactions between host ecology, gut microbiota, and EVs provides valuable insights into the mechanisms underlying host-microbe interactions and their impact on animal health and productivity. Further research in this field is essential for developing effective therapeutic interventions and management strategies to promote gut health and overall well-being in animals.