Accessing Dietary Effects on the Rumen Microbiome: Different Sequencing Methods Tell Different Stories

The current study employed both amplicon and shotgun sequencing to examine and compare the rumen microbiome in Angus bulls fed with either a backgrounding diet (BCK) or finishing diet (HG), to assess if both methods produce comparable results. Rumen digesta samples from 16 bulls were subjected for microbial profiling. Distinctive microbial profiles were revealed by the two methods, indicating that choice of sequencing approach may be a critical facet in studies of the rumen microbiome. Shotgun-sequencing identified the presence of 303 bacterial genera and 171 archaeal species, several of which exhibited differential abundance. Amplicon-sequencing identified 48 bacterial genera, 4 archaeal species, and 9 protozoal species. Among them, 20 bacterial genera and 5 protozoal species were differentially abundant between the two diets. Overall, amplicon-sequencing showed a more drastic diet-derived effect on the ruminal microbial profile compared to shotgun-sequencing. While both methods detected dietary differences at various taxonomic levels, few consistent patterns were evident. Opposite results were seen for the phyla Firmicutes and Bacteroidetes, and the genus Selenomonas. This study showcases the importance of sequencing platform choice and suggests a need for integrative methods that allow robust comparisons of microbial data drawn from various omic approaches, allowing for comprehensive comparisons across studies.

Dietary Sodium Restriction Results in Tissue-Specific Changes in DNA Methylation in Humans

Dietary sodium affects blood pressure (BP) and vascular function. Animal studies suggest epigenetic changes (eg, DNA methylation) are involved. We hypothesized that sodium restriction induces methylation changes in T cells and arterioles in humans. Fifty subjects (49% women) were placed on 1200-mg sodium/day diet for 2 weeks. BP and brachial artery flow-mediated dilation were evaluated. Methylation sequencing (pre- and post-diet) was performed on T-cell (n=50) and biopsied arteriolar (n=10) DNA. RNA sequencing was also performed on arterioles (n=11). Over 2 weeks, mean sodium consumption was 946 mg/day. Average BP reductions after low-sodium intake were −8±13/−4±9 mm Hg ( P <0.001). Flow-mediated dilation improved (5.8±2.9% to 6.8±3.4%; P =0.03). T-cell DNA was substantially more methylated than arterioles. The differentially methylated regions (false discovery rate, <0.05) identified in T cells and arterioles after sodium restriction were located in 117 and 71 genes, respectively. Four genes were identified in both T cells and arterioles ( P =0.009 for the overlap). The dietary effects on methylation in several DNA regions were associated with dietary effects on BP. Several differentially expressed genes in arterioles contained differentially methylated regions at the significance level of P <0.05. In addition, 46 genes contained differentially methylated regions in both human and SS/Mcw rat T cells ( P =0.03 for the overlap). Sodium restriction significantly affected DNA methylation in T cells and arterioles, some of which are associated with BP. Methylation patterns and sodium effects on methylation are largely tissue specific but also have overlaps between tissues and species. These findings may lead to better understanding of dietary sodium interactions with cellular processes and, therefore, novel therapeutic targets.

Dietary effects of Garcinia kola seed meal on growth performance, hematology and serum biochemical parameters of weaned rabbits

Background and Aim: Garcinia kola seed (GKS) is used to prevent and cure a number of gastric-related ailments. GKS contain a copious amount of polyphenols and can be utilized as a natural growth promoter in the nutrition of weaned rabbits. This study aimed to determine the dietary effects of GKS meal (GKSM) on the growth performance, hematology and serum biochemical parameters of weaned rabbits. Materials and Methods: GKS were dried and ground into powder. Thirty-two 8-week-old crossbred rabbits with an average weight of 614 g were randomly divided into four dietary groups. The diets were designated as follows: Control (corn-soybean based diet with 0% GKSM) and the GKSM-supplemented diets with 1.5% GKSM, 3% GKSM, and 4.5% GKSM. On the 56th day of the feeding trial, blood was collected from the marginal ear vein of all rabbits and transferred into two separate labeled tubes. The first set of blood was used to determine the hematological indices. The second set of blood was transferred into plain bottles and allowed to coagulate. The coagulated blood was subjected to standard methods of serum separation, and the sera were harvested and used to evaluate serum biochemical parameters. Results: Although the average final body weight was highest in rabbits fed with 1.5% GKSM; this value was similar to rabbits fed with 0% and 4.5% GKSM. The average daily weight gain was highest in rabbits fed with 1.5% GKSM, while the feed conversion ratio was improved in the 0% and 1.5% GKSM groups. The dietary treatments also had a significant effect on the red blood cell count (RBC) and hemoglobin (Hb) concentration, while other blood parameters did not differ significantly (p>0.05). Higher inclusion levels (3% and 4.5%) of GKSM led to a significant increase in RBC and Hb values (p<0.05). The total protein increased at all levels of GKSM inclusion (p<0.05). Bilirubin, sodium, and potassium levels significantly decreased at 4.5% GKSM inclusion (p<0.05). Urea levels were lowered at 1.5% and 4.5% GKSM inclusion, while cholesterol levels were decreased at 3% and 4.5% dietary levels. Conclusion: From the results of the present study, the supplementation of up to 4.5% GKSM revealed no harmful effect on the hematological and serum biochemical parameters of weaned rabbits, while their growth performance improved at a 1.5% inclusion level of GKSM.