Diet and monensin influence the temporal dynamics of the rumen microbiome in stocker and finishing cattle

Background Stocker cattle diet and management influence beef cattle performance during the finishing stage,but knowledge of the dynamics of the rumen microbiome associated with the host are lacking.A longitudinal study was conducted to determine how the feeding strategy from the stocker to the finishing stages of production affects the temporal dynamics of rumen microbiota.During the stocker phase,either dry hay or wheat pasture were provided,and three levels of monensin were administrated.All calves were then transported to a feedlot and received similar finishing diets with or without monensin.Rumen microbial samples were collected on d 0,28,85 during the stocker stage(S0,S28 and S85)and d 0,14,28,56,30 d before slaughter and the end of the trial during the finishing stage(F0,F14,F28,F56,Pre-Ba,and Final).The V4 region of the bacterial 16S rRNA gene of 263 rumen samples was sequenced.Results Higher alpha diversity,including the number of observed bacterial features and the Shannon index,was observed in the stocker phase compared to the finishing phase.The bacterial amplicon sequence variants(ASVs)differentiating different sampling time points were identified.Dietary treatments during the stocker stage temporally impact the dynamics of rumen microbiota.For example,shared bacteria,including Bacteroidales(ASV19)and Streptococcus infantarius(ASV94),were significantly higher in hay rumen on S28,S85,and F0,while Bacteroidaceae(ASV11)and Limivicinus(ASV15)were more abundant in wheat.Monensin affected rumen microbial composition at a specific time.Transportation to feedlot significantly influenced microbiome structure and diversity in hay-fed calves.Bacterial taxa associated with body weight were classified,and core microbiotas interacted with each other during the trial.Conclusions In summary,the temporal dynamics of the rumen microbiome in cattle at the stocker and finishing stage are influenced by multiple factors of the feeding strategy.Diet at the stocker phase may temporarily affect the microbial composition during this stage.Modulating the rumen microbiome in the steers at the stocker stage affects the microbial interactions and performance in the finishing stage.

The vaginal and fecal microbiomes are related to pregnancy status in beef heifers

Background:The greatest impact on profitability of a commercial beef operation is reproduction.However,in beef heifers,little is known about the vaginal and fecal microbiota with respect to their relationship with fertility.To this end,we followed heifers through gestation to examine the dynamics of vaginal and fecal microbial composition throughout pregnancy.Results:Heifers were exposed to an estrus synchronization protocol,observed over a 12-day period,artificially inseminated 12 h to 18 h after observed estrus,and subsequently exposed to bulls for a 50-day breeding season.Vaginal samples were taken at pre-breeding(n=72),during the first(n=72),and second trimester(n=72)for all individuals,and third trimester for individuals with confirmed pregnancies(n=56).Fecal samples were taken at prebreeding(n=32)and during the first trimester(n=32),including bred and open individuals.Next generation sequencing of the V4 region of the 16 S rRNA gene via the Illumina Mi Seq platform was applied to all samples.Shannon indices and the number of observed bacterial features were the same in fecal samples.However,significant differences in vaginal microbiome diversity between gestation stages were observed.No differences in beta-diversity were detected in vaginal or fecal samples regarding pregnancy status,but such differences were seen with fecal microbiome over time.Random Forest was developed to identify predictors of pregnancy status in vaginal(e.g.,Histophilus,Clostridiaceae,Campylobacter)and fecal(e.g.,Bacteroidales,Dorea)samples.Conclusions:Our study shows that bovine vaginal and fecal microbiome could be used as biomarkers of bovine reproduction.Further experiments are needed to validate these biomarkers and to examine their roles in a female’s ability to establish pregnancy.

Transcriptomic and metabolomic insights into the roles of exogenous β-hydroxybutyrate acid for the development of rumen epithelium in young goats

Beta-hydroxybutyric acid(BHBA),as one of the main metabolic ketones in the rumen epithelium,plays critical roles in cellular growth and metabolism.The ketogenic capacity is associated with the maturation of rumen in young ruminants,and the exogenous BHBA in diet may promote the rumen development.However,the effects of exogenous BHBA on rumen remain unknown.This is the first study to investigate the mechanisms of BHBA on gene expression and metabolism of rumen epithelium using young goats as a model through multi-omics techniques.Thirty-two young goats were divided into control,low dose,middle dose,and high dose groups by supplementation of BHBA in starter(0,3,6,and 9 g/day,respectively).Results demonstrated the dietary of BHBA promoted the growth performance of young goats and increased width and length of the rumen papilla(P<0.05).Hub genes in host transcriptome that were positively related to rumen characteristics and BHBA concentration were identified.Several upregulated hub genes including NDUFC1,NDUFB4,NDUFB10,NDUFA11 and NDUFA1 were enriched in the gene ontology(GO)pathway of nicotinamide adenine dinucleotide(NADH)dehydrogenase(ubiquinone)activity,while ATP5ME,ATP5PO and ATP5PF were associated with ATP synthesis.RT-PCR revealed the expression of genes(HMGCS2,BDH1,SLC16A3,etc.)associated with lipolysis increased significantly by BHBA supplementation(P<0.05).Metabolomics indicated that some metabolites such as glucose,palmitic acid,cortisol and capric acid were also increased(P<0.05).This study revealed that BHBA promoted rumen development through altering NADH balance and accelerating lipid metabolism,which provides a theoretical guidance for the strategies of gastrointestinal health and development of young ruminants.

Effects of weaning age on growth, nutrient digestibility and metabolism,and serum parameters in Hu lambs

This study was conducted to investigate the effect of weaning age on growth performance, nutrient digestion and metabolism, and serological indicators, and to obtain an optimal weaning age in Hu lambs.Forty-eight newborn Hu lambs(birth weight, 2.53 ± 0.14 kg) were randomly divided into 4 groups. The lambs in control group(ER) suckled their dams. The lambs in other three experimental groups were weaned on milk replacer at 10.20, and 30 days of age(EW10, EW20, and EW30 groups),respectively. The results were as follows: 1) lambs in EW10 and EW30 groups had a lower(P < 0.05) ADG than those in ER group within 10 days post-weaning; the weaned lambs began to show a higher(P < 0.05) ADG than those in ER group after 20 days post-weaning. 2) EW10 and EW20 groups had a higher(P < 0.05) creep feed intake than EW30 and ER groups from 15 to 60 days of age. 3) The apparent digestibility of dry matter, organic matter, gross energy, nitrogen, ether extract and phosphorus, and the deposition of nitrogen and phosphorus did not differ(P > 0.05) among groups; however, the apparent digestibility and deposition of calcium in early weaned lambs were lower(P < 0.05) than those in ewe-reared lambs. 4)The albumin content in EW30 group was lower(P < 0.05) than that in ER group; the globulin content in EW30 group was higher(P < 0.05) than that in other groups; the content of serum insulin-like growth factor-1 in weaned lambs tended to increase compared with lambs in ER group. Finally, the growth rate of lambs decreased within 10 days post-weaning, but early weaning boosted creep feed intake, leading to better growth and health later in life. The Hu lambs can be weaned on milk replacer and creep feed at 10 days of age.