Ruminal microbiota-host interaction and its effect on nutrient metabolism

Rumen microbiota has a close and intensive interaction with the ruminants.Microbiota residing in the rumen digests and ferments plant organic matters into nutrients that are subsequently utilized by the host,making ruminants a unique group of animals that can convert plant materials indigestible by humans into high-quality animal protein as meat and milk.Many studies using meta-omics technologies have demonstrated the relationships between rumen microbiome and animal phenotypes associated with nutrient metabolism.Recently,the causality and physiological mechanisms underpinning the host-microbiota interactions have attracted tremendous research interest among researchers.This review discusses the host-microbiota interactions and the factors affecting these interactions in ruminants and provides a summary of the advances in research on animal husbandry.Understanding the microbiota composition,the functions of key bacteria,and the host-microbiota interaction is crucial for the development of knowledge-based strategies to enhance animal productivity and host health.

Effect of seasonal thermal stress on oxidative status,immune response and stress hormones of lactating dairy cows

This study aimed to assess the impact of seasonal thermal stress on oxidative stress,immune response,and stress hormones of lactating dairy cows in subtropical regions with different levels of temperature-humidity index(THI).A total of 32 healthy lactating Holstein dairy cows experienced 4 seasons(8 cows/season).The physiological parameters were categorized into low THI(LTHI,THI=42.97±0.95)in winter,moderate THI(MTHI,THI=61.84±0.42)in spring and autumn,and high THI period(HTHI,THI=86.09±0.23)in summer.The blood samples were collected twice in each season to measure oxidative stress,inflammatory and hormonal parameters.Our results showed THI had a positive cor-relation with the rectal temperature(R2=0.821,P<0.001)and respiratory rate(R2=0.816,P<0.001).Dry matter intake,milk yield and fat percentage also significantly differed among groups(P<0.05).Compared with the MTHI group,the LTHI group exhibited a significant increase in malondialdehyde(MDA)level(P<0.001),and the HTHI group displayed a significant increase in levels of cortisol,interleukin(IL)-10,IL-1βand tumor necrosis factor-α(P<0.001).Opposite changes in serum endotoxin and immunoglobulin G levels were observed with the increasing THI(P<0.001).LTHI notably increased the triiodothyronine level,although the thyroxine level was reduced by LTHI and HTHI compared with the MTHI group.In conclusion,LTHI and HTHI conditions may induce different degrees of oxidative stress,inflammation response,and stress hormone imbalances on lactating dairy cows,therefore envi-ronmental management is necessary for the health of dairy cows in extreme weather conditions.

Ruminal bacterial community is associated with the variations of total milk solid content in Holstein lactating cows

Total milk solid(TMS)content directly reflects the quality of milk.Rumen bacteria ferment dietary components,the process of which generates the precursors for the synthesis of milk solid,therefore,the variation in rumen bacterial community could be associated with milk solid in dairy cows.In this study,45 healthy mid-lactation Holstein dairy cows with the similar body weight,lactation stage,and milk yield were initially used for the selection of 10 cows with high TMS(HS)and 10 cows with low TMS(LS).All those animals were under the same feeding management,and the individual milk yield was recorded for 14 consecutive days before milk and rumen fluid were sampled.Rumen fluid was used to determine bacterial community by 16S rRNA gene sequencing technique.The HS cows had significantly greater feed intake and milk TMS,fat,protein content than LS cows(P<0.05).Among the volatile fatty acids(VFA),propionic acid and valeric acid concentrations were significantly greater in HS cows than those in LS cows(P<0.05).There was no significant difference in the concentrations of acetate,butyrate,isobutyrate,valerate,and the total VFA(P>0.05),nor was the acetate-to-propionate ratio,pH value,ammonia nitrogen and microbial crude protein concentrations(P>0.05).Significant differences in the relative abundances of some bacterial genera were found between HS and LS cows.Spearman’s rank correlation analysis revealed that TMS content was correlated positively with the abundances of Ruminococcaceae UCG-014,Ruminococcaceae NK4A214 group,Prevotellaceae UCG-001,Butyrivibrio 2,Prevotellaceae UCG-003,Candidatus Saccharimonas,Ruminococcus 2,Lachnospiraceae XPB1014 group,probable genus 10,Eubacterium ventriosum group,but negatively correlated with Pyramidobacte.In addition,Ruminococcaceae UCG-014,Ruminococcus 2,Ruminococcaceae UCG001,probable genus 10 and Eubacterium ventriosum group might boost the total VFA production in the rumen.In conclusion,the dry matter intake of dairy cows and some special bacteria in rumen were significantly associated with TMS content,which suggests the potential function of rumen bacteria contributing to TMS content in dairy cows.