The mirn23a and mirn23b microrna clusters are necessary for proper hematopoietic progenitor cell production and differentiation

Mice deficient for microRNA (miRNA) cluster mirn23a exhibit increased B lymphopoiesis at the expense of myelopoiesis, whereas hematopoietic stem and progenitor cell (HSPC) populations are unchanged. Mammals possess a paralogous mirn23b gene that can give rise to three mature miRNAs (miR-23b, miR-24-1, and miR-27b) that have identical seed/mRNA-targeting sequences to their mirn23a counterparts. To assess whether compound deletion of mirn23a and mirn23b exacerbates the hematopoietic phenotype observed in mirn23a−/− mice, we generated a compound mirn23a−/−mirn23bfl/fl:Mx1-Cre conditional knockout mouse and assayed hematopoietic development after excision of mirn23b. Loss of both genes in adult bone marrow further skewed HSPC differentiation toward B cells at the expense of myeloid cells, demonstrating a dosage-dependent effect on regulating cell differentiation. Strikingly, double-knockout (DKO) mice had decreased bone marrow cellularity with significantly decreased hematopoietic stem cell and HSPC populations, a phenotype not observed in mice deficient for mirn23a alone. Competitive transplantation assays showed decreased contribution of mirn23a−/−mirn23b−/− HSPCs to hematopoietic lineages at 6 and 12 weeks after transplantation. Defects in the proliferation of mirn23a−/−b−/− HSPCs was not observed; however, DKO cells were more apoptotic compared with both wild-type and mirn23a−/− cells. Together, our data show that complete loss of mirn23a/mirn23b miRNAs results in decreased blood production and affects lineage output in a concentration-dependent manner

Influence of Corn Hybrid and Processing Method on Ruminal and Intestinal Digestion

Using the mobile bag technique, five commercially available corn hybrids harvested as either dry-rolled or high-moisture corn were evaluated for site and extent of DM and starch digestion. Total-tract DM digestibility was improved 7 to 16 percentage units, and total-tract starch digestibility was improved 9 to 18 percentage units among hybrids when processed as high-moisture corn compared to dry-rolled corn. The results of this trial suggest that hybrid and processing method interact and can influence DM and starch digestibility

Effect of CRINA RUMINANTS AF, a Mixture of Essential Oil Compounds, on Ruminal Fermentation and Digestibility

Eight ruminally fistulated steers were used in a metabolism experiment to determine effects of an essential oil feed additive in altering steer ruminal fermentation characteristics and nutrient digestibilities. Yearling steers were fed three treatments: 1) Control (CON) 2) CRINA RUMINANTS AF (CRINA) and 3) Rumensin® (RUM). There were no differences in DMI, OM intake, total tract DM and OM digestibilities, or pH among treatments. Steers receiving the CRINA treatment consumed 24.5% fewer meals than CON. Ruminal acetate was greatest and total VFA concentrations tended to be greatest for CRINA treatment. Acetate:propionate was 1.68, 1.49, and 1.43 for CON, CRINA, and RUM, respectively, suggesting addition of CRINA RUMINANTS AF favorably alters rumen fermentation end products without negatively affecting intake or rumen pH

Arid3b Is Critical for B Lymphocyte Development

Arid3a and Arid3b belong to a subfamily of ARID (AT-rich interaction domain) transcription factors. The Arid family is involved in regulating chromatin accessibility, proliferation, and differentiation. Arid3a and Arid3b are closely related and share a unique REKLES domain that mediates their homo- and hetero-multimerization. Arid3a was originally isolated as a B cell transcription factor binding to the AT rich matrix attachment regions (MARS) of the immunoglobulin heavy chain intronic enhancer. Deletion of Arid3a results in a highly penetrant embryonic lethality with severe defects in erythropoiesis and hematopoietic stem cells (HSCs). The few surviving Arid3a-/- (<1%) animals have decreased HSCs and early progenitors in the bone marrow, but all mature lineages are normally represented in the bone marrow and periphery except for B cells. Arid3b-/- animals die around E7.5 precluding examination of hematopoietic development. So it is unclear whether the phenotype of Arid3a loss on hematopoiesis is dependent or independent of Arid3b. In this study we circumvented this limitation by also examining hematopoiesis in mice with a conditional allele of Arid3b. Bone marrow lacking Arid3b shows decreased common lymphoid progenitors (CLPs) and downstream B cell populations while the T cell and myeloid lineages are unchanged, reminiscent of the adult hematopoietic defect in Arid3a mice. Unlike Arid3a-/- mice, HSC populations are unperturbed in Arid3b-/- mice. This study demonstrates that HSC development is independent of Arid3b, whereas B cell development requires both Arid3a and Arid3b transcription factors

Ruminal Sulfide Levels in Corn Byproduct Diets with Varying Roughage Levels

Ruminally fistulated steers with wireless pH probes were utilized to quantify ruminal pH plus hydrogen sulfide (H2S) levels produced at different times post feeding and to determine the effect of roughage level in high byproducts diets on hydrogen sulfide production. Because of variation in H2S levels, ruminal pH was not related to high H2S levels. When treatment means were used, pH and H2S levels were highly correlated. We observed lower H2S levels in diets with 7.5% or 15% grass hay compared with no roughage

Hydrogen Sulfide Gas Levels Post Feeding

Dietary sulfur level is associated with hydrogen sulfide gas (H2S) levels in the rumen. These studies quantified H2S levels at different times post feeding with or without added iron (Fe) or copper (Cu) to bind sulfur. In addition, the correlations of ruminal pH measurements to ruminal H2S gas levels were estimated. Correlations between ruminal pH and hydrogen sulfide levels were not large and Fe and Cu did not affect H2S levels

Effect of Dietary Cation-Anion Difference on Intake and Urinary pH in High Concentrate Diets

Seven experiments evaluated the effect of basal diet and dietary cation-anion difference (DCAD) on urinary and fecal pH, and DMI. Dry-matter intake(DMI) was reduced by DCAD level in dry-rolled corn basal diets but not in diets that included 20% wet distillers grains (WDGS). Urinary pH decreased with DCAD level in all experiments. Fecal pH was not influenced by either DCAD level or basal diet. Altering DCAD in concentrate diets with or without WDGS does impacturinary pH

Effects of Corn Processing and Wet Distillers Grains on Nutrient Metabolism

Seven ruminally cannulated steers were used in a metabolism experiment to determine the effects of distillers grains level (0% or 40% of diet DM) on diet digestibility and rumen metabolism in diets consisting of dry-rolled, high-moisture, or steam-flaked corn. Intakes were greater while digestibility was reduced for DM and organic matter in steers fed 40% compared to 0% distillers grains. Average and maximum pH were less for steers fed 40% distillers grains, but pH change and variance were also less for 40% compared to 0% WDGS. Feeding WDGS does not increase rumen pH, but does decrease variance. Starch intakes were equal whether 0 or 40% WDGS were fed because cattle fed 40% WDGS had greater DMI, which may influence rumen pH

Effect of Distillers Grains Fat Level on Digestibility

Four steers were used in a three-period switchback design to determine effects of dry distillers grains fat level on digestibility. Forage based diets were supplemented with distillers grains with differing fat levels (6.9% or 13.3 % dry matter). Intake and digestibility of DM and organic matter did not differ between treatments. Neutral detergent fiber intake was less and digestibility tended to be less in steers supplemented with high fat distillers grains. Differences in fiber type and intake as well as fat intake may be responsible for the small difference in neutral detergent fiber digestibility