Mechanistic Studies on Selective Trimerization of Linear α-Olefins over a Supported Titanium Catalyst

The supported titanium catalyst s(FI)Ti, generated by adding (FI)TiCl3 to MAO-treated SiO2 (FI = (N-(5-methyl-3-(1-adamantyl)salicylidene)-2’-(2”-methoxyphenyl)anilinato)], effects the selective trimerization of the linear α-olefins (LAOs) propene, 1-pentene, 1-hexene, 1-decene, with >95% selectivity for trimers and ~85% selectivity to a single isomer thereof (2,3,5-trialkyl-1-hexene). Mechanistic interpretations are offered for the high regioselectivity as well as for some unusual kinetics behavior, including third-order dependence on LAO concentration and nearly identical initial rates at 0 and 25 °C

How Microbial Communities Differ in Ruminants on a Glycerin vs Common Diet

Can we reduce methane by using dietary interventions to reduce carbon footprint and increase feed efficiency? Ruminant livestock account for a significant amount of the anthropogenic methane produced in the U.S. All ruminant livestock produce 28% of the earth’s methane emissions. The methane within ruminants is produced by a microbial fermentation, especially by a group of bacteria known as the methanogens. However, the different species of methanogens and their pathways of methane production within ruminants are not fully understood. Cattle are considered one of the main producers of methane. They produce 20% of the U.S. methane emissions. Methane absorbs more heat than carbon dioxide. By reducing methane emissions, we are creating a more sustainable agriculture. Over the past few decades, the dairy industry has been able to increase feed efficiency while decreasing methane emissions. This project will evaluate the interaction between methane, dietary feed, and feed efficiency to reduce methane in cattle. This project will evaluate the microbial community shifts affected by different diets and how this correlates with changes in the microbial community and levels of methane released. To identify the microbial community structure, we will isolate microbial DNA from rumen contents and will amplify the 16S ribosomal gene using the polymerase chain reaction (PCR). The PCR products will be sequenced to identify microbial community structure and changes from dietary conditions. Volatile fatty acids will also be analyzed to help understand feed efficiency. The proposed study will help understand how dietary intervention can be used to change microbial community structure. In turn, this can reduce methane emission in cattle. By understanding the host-microbe relationship in this project, effective management decisions can be made to improve cattle production by manipulating the microbial ecosystem to increase animal feed efficiency and reduce methane emission

Impact of a Newly Developed Direct- Fed Microbial on Performance in Finishing Beef Steers

An individual feeding experiment (n = 60) was conducted to evaluate the effects of feeding a direct- fed microbial (DFM) or not on performance of finishing steers fed 0 or 40% modified distillers grains (MDGS) in a 2 × 2 factorial design. Gain and F:G were improved when cattle were fed MDGS compared to the corn diet. No significant differences (P ≥ 0.23) were observed between cattle fed DFM or not for DMI and ADG. However, numeric advantages were observed for F:G when cattle were fed a DFM, with a 5% improvement in feed efficiency for steers supplemented with DFM

Longitudinal assessment of the bovine ocular bacterial community dynamics in calves

Background: Infectious Bovine Keratoconjunctivitis (IBK), commonly known as pinkeye, is one of the most significant diseases of beef cattle. As such, IBK costs the US beef industry at least 150 million annually. However, strategies to prevent IBK are limited, with most cases resulting in treatment with antibiotics once the disease has developed. Longitudinal studies evaluating establishment of the ocular microbiota may identify critical risk periods for IBK outbreaks or changes in the microbiota that may predispose animals to IBK. Results: In an attempt to characterize the establishment and colonization patterns of the bovine ocular microbiota, we conducted a longitudinal study consisting of 227 calves and evaluated the microbiota composition over time using amplicon sequence variants (ASVs) based on 16S rRNA sequencing data and culture-based approaches. Beef calves on trial consisted of both male (intact) and females. Breeds were composed of purebred Angus and composites with varying percentages of Simmental, Angus, and Red Angus breeds. Average age at the start of the trial was 65 days ±15.02 and all calves remained nursing on their dam until weaning (day 139 of the study). The trial consisted of 139 days with four sampling time points on day 0, 21, 41, and 139. The experimental population received three different vaccination treatments (autogenous, commercial (both inactivated bacteria), and adjuvant placebo), to assess the effectiveness of different vaccines for IBK prevention. A significant change in bacterial community composition was observed across time periods sampled compared to the baseline (p \u3c 0.001). However, no treatment effect of vaccine was detected within the ocular bacterial community. The bacterial community composition with the greatest time span between sampling time periods (98d span) was most similar to the baseline sample collected, suggesting re-establishment of the ocular microbiota to baseline levels over time after perturbation. The effect of IgA levels on the microbial community was investigated in a subset of cattle within the study. However, no significant effect of IgA was observed. Significant changes in the ocular microbiota were identified when comparing communities pre- and post-clinical signs of IBK. Additionally, dynamic changes in opportunistic pathogens Moraxella spp. were observed and confirmed using culture based methods. Conclusions: Our results indicate that the bovine ocular microbiota is well represented by opportunistic pathogens such as Moraxella and Mycoplasma. Furthermore, this study characterizes the diversity of the ocular microbiota in calves and demonstrates the plasticity of the ocular microbiota to change. Additionally, we demonstrate the ocular microbiome in calves is similar between the eyes and the perturbation of one eye results in similar changes in the other eye. We also demonstrate the bovine ocular microbiota is slow to recover post perturbation and as a result provide opportunistic pathogens a chance to establish within the eye leading to IBK and other diseases. Characterizing the dynamic nature of the ocular microbiota provides novel opportunities to develop potential probiotic intervention to reduce IBK outbreaks in cattle

Differences in Fecal Bacterial Community Composition Between Beef Steers which are High-Shedders and Low-Shedders of Shiga Toxin-Producing \u3ci\u3eEscherichia coli\u3c/i\u3e (STEC)

The community composition of the fecal microbiota was compared between beef steers which were high-shedders and low-shedders of Shiga toxin-producing Escherichia coli. Based on Shannon and Chao 1 diversity indices, the high-shedders had a more diverse fecal bacterial community than the low-shedding steers. Members of the genus Prevotella were observed as being more abundant in the low-shedders compared to the high-shedders, while Succinivibrio were more abundant in the high-shedders. Isolation of specific bacteria which are significantly more abundant in low-shedders may pave the way to developing direct-fed microbials which are effective in reducing STEC shedding among high-shedding beef steers

Rumen bacterial composition in lambs is affected by β-adrenergic agonist supplementation and heat stress at the phylum level

The rumen has several important physiological functions, including absorption, transport, metabolic activity, and host protection (Roh et al., 2007). The rumen is extensively researched due to the importance of ruminants in agriculture and the major role played by rumen microbes in nutrient utilization and health of the ruminant animal. The microbial community of the rumen is altered by diet (McCann et al., 2014), age (Jami et al., 2013), and environment

The Effect of Commensal Microbial Communities on the Fecal Shedding of Shiga Toxin-Producing \u3ci\u3eE. coli\u3c/i\u3e (STEC) in Beef Cattle

This ongoing study compares the gut microbial community composition between shedding steers high in shiga toxin-producing E. coli (STEC) counts and low-shedding steers. Shedders were identified among 170 beef animals over three time periods using selective microbiological culture media. The isolated bacterial cultures were confirmed to be STEC using PCR, 16s rRNA sequencing and a shiga toxin immunoassay. The most abundant strains found in the cattle feces were those belonging to the serogroups O111 (40.3%) and O157:H7 (37.3%), with O103 (8.3%), O26 (6.0%), O83 (4.5%), and O55 (3.0%) being detected in much lower numbers . Out of the 52 animals which were identified as super-shedders of STECs which were selected for microbial community analysis, 61.54% shed STEC in at least two of the three sampling time points. Currently, work is being carried out to evaluate the microbial community composition of the identified STEC high-shedding and low-shedding cattle populations using 454-pyrosequencing