133 publications from this institution
This review highlights concerns with endophyte-infected tall fescue as a primary forage base in the southeastern United States and discusses specific physiological and ruminal effects caused by consumption of ergot alkaloids. Additionally, in an effort to promote various mitigation strategies to abate production limitations caused by fescue toxicosis, this review discusses the use of cool-season legumes, specifically red clover, with the already established forage base. Clovers are often mixed into pastures and help improve animal performance. Clovers contain phytoestrogenic compounds known as isoflavones that may be beneficial in reducing physiological limitations with consumption of endophyte-infected tall fescue.
Heifer development is crucial for the optimization of reproductive efficiency in beef production. Heifer development is largely influenced by nutrition. Nutritional status of these heifers can influence immunological responses that are crucial for reproduction. Commercial Angus heifers (n = 9) were utilized, in a pilot study, to elucidate the effects of sampling time (days 0, 7, 14, 21, 28, and 35), pregnancy status, and type of mating on individual cytokine concentrations and cytokine profiles in the vagina following breeding.
Animals with greater feed efficiency use fewer resources to produce skeletal muscle, the primary product in beef production. As muscle represents approximately 50% of BW in beef cattle, efficient utilization of feed is interconnected with growth. However, little is known about molecular pathways interconnecting these two components of production. The overall objective of the study was to determine relationships between feed efficiency and growth at the molecular level in skeletal muscle of beef cattle. The specific objective of this study was to identify genes and pathways that are associated with variation in ADG, as an index of growth. We hypothesize that increased expression of genes involved in energy utilization are associated with greater ADG. Angus steers (n = 100) were enrolled in 70-d feed efficiency trials using the Vytelle GrowSafe 8000 individual feed intake monitoring system. Muscle samples (~ 500 ug) were collected via needle biopsy from the wing of the ileum between the axis and transverse processes of the lumbar vertebrae during the last 30 d of the trial. Samples were snap-frozen in liquid nitrogen and stored at -80°C. Frozen tissue was pulverized and RNA extracted from ~ 50mg/sample using a commercial kit (zymoresearch.com). Quality was verified using Agilent 4200 Tapestation (agilent.com). Libraries were constructed using SMART Seq v4 3’ DE Kit. Libraries were assessed for quality and quantity, and subsequently pooled for sequencing using a Novaseq 6000 (illumina.com). STAR RNA-seq aligner was used to map the reads to the bovine genome (ARS-UCD_2.0). Animals were ranked according to ADG and grouped by 20th percentile; the first, third, and fifth groups were designated as “Very Low”, “Medium”, and “Very High”, respectively. Expression profiles between the groups were compared using DESeq2 in R (version 3.5). A total of 1,199 genes were identified as differentially expressed (fdr P-value < 0.05). Gene sets were functionally annotated using Database for Annotation, Visualization and Integrated Discovery (david.ncifcrf.gov). Genes expressed at greater levels in Very High ADG steers were significantly enriched (fdr P -value < 0.05) in Gene Ontology(GO) functions related to cellular metabolism (226 of 1199 genes). In addition, 92 genes in this set were associated with the KEGG pathway for VEGF/VEGFR-2 signaling, which regulates angiogenesis and has been associated with muscle growth. Genes expressed at greater levels in Very Low ADG steers were significantly enriched in GO terms related to proteasome degradation and mitophagy, both of which have been associated with muscle loss. In conclusion, these results support that variation in cellular metabolism contributes to variation in muscle growth, as reflected by ADG. They also highlight angiogenesis as a pathway that is worthy of further investigation for its role in beef cattle production.
Apart from the rumen, limited knowledge exists regarding the structure and function of bacterial communities within the gastrointestinal tract and their association with beef cattle feed efficiency. The objective of this study was to characterize the microbial communities of the cecum among steers differing in feed efficiency. Within 2 contemporary groups of steers, individual feed intake and BW gain were determined from animals fed the same diet. Within both of 2 contemporary groups, BW was regressed on feed intake and 4 steers within each Cartesian quadrant were sampled (n = 16/group). Bacterial 16S rRNA gene amplicons were sequenced from the cecal content using next-generation sequencing technology. No significant changes in diversity or richness were detected among quadrants, and UniFrac principal coordinate analysis did not show any differences among quadrants for microbial communities within the cecum. The relative abundances of microbial populations and operational taxonomic units revealed significant differences among feed efficiency groups (P < 0.05). Firmicutes was the dominant cecal phylum in all groups and accounted for up to 81% of the populations among samples. Populations were also dominated by families Ruminococcaceae, Lachnospiraceae, and Clostridiaceae, with significant shifts in the relative abundance of taxa among feed efficiency groups, including families Ruminococcaceae (P = 0.040), Lachnospiraceae (P = 0.020), Erysipelotrichaceae (P = 0.046), and Clostridiaceae (P = 0.043) and genera Coprobacillus (P = 0.049), Parabacteroides (P = 0.044), Blautia (P = 0.042), Ruminococcus (P = 0.040), Oscillospira (P = 0.042), and Prevotella (P = 0.042). The study identified cecal microbial associations with feed efficiency, ADG, and ADFI. This study suggests an association of the cecum microbial community with bovine feed efficiency at the 16S level.
Objectives Extensive efforts have been made to characterize the rumen microbiome under various conditions. However, few studies have addressed the long-term impacts of ruminal microbiome dysbiosis and the extent of host control over microbiome stability. These data can also inform host-microbial symbioses. The objective was to develop preliminary data to measure the changes that occur in the rumen bacterial communities following a rumen content exchange to understand the effects major perturbations may impart upon the rumen microbiome, which may be host-driven. Data description We report here an initial rumen content exchange between two SimAngus (Simmental/Angus) non-pregnant, non-lactating cows of ~ 6 years of age weighing 603.4 ± 37.5 kg. To measure bacterial community succession and acclimation following the exchange, rumen content was collected via rumen cannula at the beginning of the study immediately prior to and following the rumen content exchange, and weekly for 12 weeks. The V4 hypervariable region of the 16S rRNA gene was targeted for DNA sequencing and bacterial analysis. Over 12 weeks, numerous genera and diversity varied, before partial return to pre-exchange metrics. These preliminary data help support potential host control for the rumen microbiome, aiding in efforts to define bovine host-microbe relationships.
Within the past decade, the development and use of novel nutritional, genomic, and genetic improvement technologies has promoted and lead to great increases in the genetic propensity of beef cattle for a variety of traits including growth, carcass composition, and specifically feed efficiency. However, the optimization of feed efficiency has primarily focused on host genetics, management, and diet. The rumen and lower gastrointestinal tract (GIT) contain diverse microbial ecosystems that are essential for the host to digest plant material and regulate nutrient uptake and utilization, necessitating their examination to fully understand the microbial-associated interactions throughout the gut with production parameters. To assess the association of the microbial community with variation in feed efficiency, ADG, and average daily DMI (ADFI), we examined the microbial community of the GIT from steers differing in feed efficiency using deep 16S rRNA gene-based community profiling. Steers were selected from 2 contemporary groups and were ranked based on their standardized distance from the bivariate mean (ADG and ADFI), assuming a bivariate normal distribution with a calculated correlation between ADG and ADFI. Four steers with the greatest deviation within each Cartesian quadrant were sampled (n = 16/group; 2 groups). Bacterial 16S rRNA gene amplicons were sequenced from the GIT content using next-generation sequencing technology. Bacterial diversity and richness metrics revealed no differences among the quadrants. However, finer changes in the relative abundance of microbial populations and operational taxonomic units did reveal differences between feed efficiency groups (P < 0.05), including shifts in dominant phyla and functionally significant genera in several segments of the GIT such as Proteobacteria (P = 0.030) and Butyrivibrio (P = 0.019) in the jejunum. These studies suggest the GIT microbial community differs at the 16S level in cattle that vary in ADG, ADFI, and feed efficiency; however, it is not clear whether host factors are driving changes in the microbiome or changes in the microbiome are contributing to differences in feed efficiency.
The beef cattle industry represents a significant portion of the USA’s agricultural sect, with beef cattle accounting for the most red meat consumed
Bovine respiratory disease complex (BRDC) is caused by a variety of complex factors that involves host elements, environmental elements, inadequate management and housing, as well as viral and bacterial pathogens, such as Mannheimia haemolytica and Mycoplasma bovis. The objective of the study was to develop and evaluate a deep-nasopharyngeal bacterial community database to provide greater assignment of taxa within the bovine nasopharynx and as a site-specific tool for examining microbiome dysbioses involved in BRDC. A total of 180 cattle with an overall BW ranging from 164-269 kg were obtained from Athens, Tennessee (n = 60), Maryville, Missouri (n = 60), and Richmond, Kentucky (n = 60). Cattle were transported to a feeding facility in Kansas and housed in open air, dirt floor, group housing pens. At the first diagnosis of BRD, deep nasopharyngeal samples were collected. DNA library preparation of the bacterial 16S rRNA V1–V8 hypervariable regions was performed and sequenced on the Pacific Biosciences RSII instrument. Database construction and all sequencing data were curated using mothur (v1.39.5). For validation analyses using, a subset of cattle was sampled as described above, and three samples sequenced using the V1–V3 hypervariable 16SrRNA regions and the Illumina MiSeq. In the database, Mycoplasma accounted for over 57% of the reads and Mannheimia was present at 0.7%. When validating the database using short-reads, unassigned taxa in the Greengenes analysis was 4.22% contrasted to the 0.91% of the closed reference database analysis. The two taxonomic compositions were not correlated and the correlation was statistically significant (r = -0127; P = 0.001). All alpha diversity indices between the two analysis methods differed (P < 0.05). Development of this reference database provides researchers a tool with considerable improvements in performance for the analysis of bacterial communities in the nasopharynx relating to cattle diagnosed with BRDC.
