Megasphaera elsdenii and Saccharomyces cerevisiae as direct fed microbials and their impact on ruminal microbiome during an acute acidosis challenge in continuous culture.

Our objective was to evaluate the effects of combinations of Saccharomyces cerevisiae and Megasphaera elsdenii as direct-fed microbials (DFM) on ruminal microbiome during an acute acidosis challenge in a continuous culture system. Treatments provided a DFM dose of 1 × 108 colony-forming unit (CFU)/mL, as follows: control (no DFM), YM1 (S. cerevisiae and M. elsdenii strain 1), YM2 (S. cerevisiae and M. elsdenii strain 2), and YMM (S. cerevisiae and half of the doses of M. elsdenii strains 1 and 2). We conducted four experimental periods of 11 d, which consisted of non-acidotic days (1 to 8) and acidotic challenge days (9 to 11) to establish acute ruminal acidosis conditions with a common basal diet containing 12% neutral detergent fiber and 58% starch. Treatments were applied from days 8 to 11, and samples of liquid and solid-associated bacteria were collected on days 9 to 11. Overall, 128 samples were analyzed by amplification of the V4 region of bacterial 16S rRNA, and data were analyzed with R and SAS for alpha and beta diversity, taxa relative abundance, and correlation of taxa abundance with propionate molar proportion. We observed a lower bacterial diversity (Shannon index, P = 0.02) when YM1 was added to the diet in comparison to the three other treatments. Moreover, compared to control, addition of YM1 to the diet increased relative abundance of phylum Proteobacteria (P = 0.05) and family Succinivibrioceae (P = 0.05) in the solid fraction and tended to increase abundance of family Succinivibrioceae (P = 0.10) and genus Succinivibrio (P = 0.09) in the liquid fraction. Correlation analysis indicated a positive association between propionate molar proportion and relative abundance of Proteobacteria (r = 0.36, P = 0.04) and Succinivibrioceae (r = 0.36, P = 0.05) in the solid fraction. The inclusion of YM1 in high-grain diets with a high starch content resulted in greater abundance of bacteria involved in succinate synthesis which may have provided the substrate for the greater propionate synthesis observed.

Induced endometrial inflammation compromises conceptus development in dairy cattle†.

Endometrial inflammation is associated with reduced pregnancy per artificial insemination (AI) and increased pregnancy loss in cows. It was hypothesized that induced endometritis alters histotroph composition and induces inflammatory signatures on conceptus that compromise development. In Experiment 1, lactating cows were assigned to control (CON; n = 23) or to an intrauterine infusion of Escherichia coli and Trueperella pyogenes (ENDO; n = 34) to induce endometritis. Cows received AI 26 days after treatment, and the uterine fluid and conceptuses were collected on day 16 after AI. In Experiment 2, Holstein heifers were assigned to CON (n = 14) or ENDO (n = 14). An embryo was transferred on day 7 of the estrous cycle, and uterine fluid and conceptuses were recovered on day 16. Composition of histotroph and trophoblast and embryonic disc gene expression were assessed. Bacterial-induced endometritis in lactating cows altered histotroph composition and pathways linked to phospholipid synthesis, cellular energy production, and the Warburg effect. Also, ENDO reduced conceptus length in cows and altered expression of genes involved in pathogen recognition, nutrient uptake, cell growth, choline metabolism, and conceptus signaling needed for maternal recognition of pregnancy. The impact of ENDO was lesser on conceptuses from heifers receiving embryo transfer; however, the affected genes and associated pathways involved restricted growth and increased immune response similar to the observed responses to ENDO in conceptuses from lactating cows. Bacterial-induced endometrial inflammation altered histotroph composition, reduced conceptus growth, and caused embryonic cells to activate survival rather than anabolic pathways that could compromise development.

Effects of partially replacing dietary corn with sugars in a dual-flow continuous culture system on the ruminal microbiome.

The objective of this study was to evaluate the effects of feeding sugars as a replacement for starch on the ruminal microbiome using a dual-flow continuous culture system. Four periods of 10 days each were conducted with 8 fermenters in a 4 × 4 replicated Latin square design. Treatments included: 1) control with corn-CON, 2) molasses-MOL, 3) untreated condensed whey permeate-CWP, and 4) CWP treated with a caustic agent-TCWP as a partial substitute for corn. Sugars were defined as the water-soluble carbohydrates (WSC) concentration. Diets were formulated by replacing 4% of the diet DM in the form of starch from corn with the sugars in byproducts. Microbial samples for DNA analysis were collected from the solid and liquid effluent containers at 3, 6, and 9 h after feeding. Bacterial community composition was analyzed with sequencing the V4 region of the 16S rRNA gene using Illumina MiSeq platform. Data were analyzed with R 4.1.3 packages vegan, lmer, and ggplot to determine the effects of treatment on the relative abundance of taxa in the solid and liquid fractions, as well as the correlation of Acetate: Propionate ratio and pH to taxa relative abundance. Treatments did not affect alpha or beta diversity. At the phylum level the relative abundance of Proteobacteria was increased in CON compared to sugars in the solid fraction. In the liquid fraction, Firmicutes had greater relative abundance in sugar treatments while Bacteroidota and Spirochaetota were present in lower relative abundance in CWP. For solid and liquid samples, the family Lachnospiraceae had greater relative abundance in sugar treatments compared to CON. The decreased relative abundance of Christensenellaceae and Rikenellaceae paired with the greater relative abundance of Selenomonadaceae in CWP could help explain greater propionate molar proportion and decreased ruminal pH previously observed for this treatment. The genera Olsenella a lactic acid-producing bacterium, had the greatest relative abundance in MOL. Incorporating TCWP or MOL as a partial replacement for starch was more conservative of fibrolytic bacterial taxa compared to CWP. Additionally, TCWP did not increase bacterial taxa associated with synthesis of lactate as compared to MOL. Overall, replacing starch with sugars is mostly conservative of the ruminal microbiome; however, changes observed coincide with differences observed in acetate and propionate proportions and ruminal pH.

Effects of calcium-magnesium carbonate and calcium-magnesium hydroxide as supplemental sources of magnesium on ruminal microbiome.

Our objective was to evaluate the inclusion of calcium-magnesium carbonate [CaMg(CO3)2] and calcium-magnesium hydroxide [CaMg(OH)4] in corn silage-based diets and their impact on ruminal microbiome. Our previous work showed a lower pH and molar proportion of butyrate from diets supplemented with [CaMg(CO3)2] compared to [CaMg(OH)4]; therefore, we hypothesized that ruminal microbiome would be affected by Mg source. Four continuous culture fermenters were arranged in a 4 × 4 Latin square with the following treatments defined by the supplemental source of Mg: 1) Control (100% MgO, plus sodium sesquicarbonate as a buffer); 2) CO 3 [100% CaMg(CO3)2]; 3) OH [100% CaMg(OH)4]; and 4) CO 3 /OH [50% Mg from CaMg(CO3)2, 50% Mg from CaMg(OH)4]. Diet nutrient concentration was held constant across treatments (16% CP, 30% NDF, 1.66 MCal NEl/kg, 0.67% Ca, and 0.25% Mg). We conducted four fermentation periods of 10 d, with the last 3 d for collection of samples of solid and liquid digesta effluents for DNA extraction. Overall, 16 solid and 16 liquid samples were analyzed by amplification of the V4 variable region of bacterial 16S rRNA. Data were analyzed with R and SAS to determine treatment effects on taxa relative abundance of liquid and solid fractions. Correlation of butyrate molar proportion with taxa relative abundance was also analyzed. Treatments did not affect alpha and beta diversities or relative abundance of phylum, class and order in either liquid or solid fractions. At the family level, relative abundance of Lachnospiraceae in solid fraction was lower for CO3 and CO3/OH compared to OH and Control (P < 0.01). For genera, abundance of Butyrivibrio (P = 0.01) and Lachnospiraceae ND3007 (P < 0.01) (both from Lachnospiraceae family) was lower and unclassified Ruminococcaceae (P = 0.03) was greater in CO3 than Control and OH in solid fraction; while abundance of Pseudobutyrivibrio (P = 0.10) and Lachnospiraceae FD2005 (P = 0.09) (both from Lachnospiraceae family) and Ruminobacter (P = 0.09) tended to decrease in CO3 compared to Control in liquid fraction. Butyrate molar proportion was negatively correlated to Ruminococcaceae (r = -0.55) in solid fraction and positively correlated to Pseudobutyrivibrio (r = 0.61) and Lachnospiraceae FD2005 (r = 0.61) in liquid. Our results indicate that source of Mg has an impact on bacterial taxa associated with ruminal butyrate synthesis, which is important for epithelial health and fatty acid synthesis.

Application of chitosan microparticles for reduction of vibrio species in seawater and live oysters (Crassostrea virginica).

Human Vibrio infections associated with consumption of raw shellfish greatly impact the seafood industry. Vibrio cholerae-related disease is occasionally attributed to seafood, but V. vulnificus and V. parahaemolyticus are the primary targets of postharvest processing (PHP) efforts in the United States, as they pose the greatest threat to the industry. Most successful PHP treatments for Vibrio reduction also kill the molluscs and are not suitable for the lucrative half-shell market, while nonlethal practices are generally less effective. Therefore, novel intervention strategies for Vibrio reduction are needed for live oyster products. Chitosan is a bioactive derivative of chitin that is generally recognized as safe as a food additive by the FDA, and chitosan microparticles (CMs) were investigated in the present study as a potential PHP treatment for live oyster applications. Treatment of broth cultures with 0.5% (wt/vol) CMs resulted in growth cessation of V. cholerae, V. vulnificus, and V. parahaemolyticus, reducing culturable levels to nondetectable amounts after 3 h in three independent experiments. Furthermore, a similar treatment in artificial seawater at 4, 25, and 37°C reduced V. vulnificus levels by ca. 7 log CFU/ml after 24 h of exposure, but 48 h of exposure and elevated temperature were required to achieve similar results for V. parahaemolyticus and V. cholerae. Live oysters that either were artificially inoculated or contained natural populations of V. vulnificus and V. parahaemolyticus showed significant and consistent reductions following CM treatment (5%) compared to the amounts in the untreated controls. Thus, the results strongly support the promising potential for the application of CMs as a PHP treatment to reduce Vibrio spp. in intact live oysters.

Effects of dietary omega-3 polyunsaturated fatty acids on growth and immune response of weanling pigs.

The recognition that omega-3 polyunsaturated fatty acids (n-3 PUFA) possess potent anti-inflammatory properties in human models has prompted studies investigating their efficacy for animal growth and immunity. This study examined the effect of feeding an n-3 PUFA-enriched diet on growth and immune response of weanling piglets. Newly weaned pigs (averaging 27 ± 2 days of age and 8.1 ± 0.7 kg of body weight) were assigned randomly to receive a control (3% vegetable oil, n = 20) or n-3 PUFA-supplemented (3% marine n-3 PUFA, n = 20) diet for 28 day after weaning. Female pigs consuming the n-3 PUFA-enriched diet were lighter at week 4 post-weaning than those fed the vegetable oil supplement. Weanling pigs gained more weight, consumed more feed and had better growth to feed ratios between days 14 and 28 than between days 0 and 14 post-weaning. Plasma insulin-like growth factor I (IGF-I) decreased between days 0 (87.2 ± 17.0 ng/mL) and 14 (68.3 ± 21.1 ng/mL) after weaning and then increased again by day 28 (155.2 ± 20.9 ng/mL). In piglets consuming the vegetable oil-enriched diet, plasma tumor necrosis factor alpha (TNF-α) increased from 37.6 ± 14.5 to 102.9 ± 16.6 pg/mL between days 0 and 14 post-weaning and remained high through day 28 (99.0 ± 17.2 pg/mL). The TNF-α increase detected in the piglets fed vegetable oil was not observed in the piglets fed n-3 PUFA. Results indicate that weaning induces considerable immune stress in piglets and that this stress can be mitigated by dietary supplementation of n-3 PUFA.