Browsing by Author "Carroll, Jeff A."
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Item Ileal epithelial tissue transcript profiles of steers with experimentally induced liver abscesses*†(2024) Lindholm-Perry, Amanda K.; Keel, Brittney N.; Hales, Kristin E. (TTU); Wells, James E.; Kuehn, Larry A.; Keele, John W.; Crouse, Matthew S.; Nonneman, Dan J.; Nagaraja, T. G.; Lawrence, Ty E.; Amachawadi, Raghavendra G.; Carroll, Jeff A.; Burdick Sanchez, Nicole C.; Broadway, Paul R.Objective: Liver abscesses in cattle negatively affect production and cause economic losses across the beef cat- tle industry. Recently, a nutritional model has been devel- oped to induce liver abscesses that will provide a method to evaluate the underlying mechanisms driving their de- velopment. The objective of this study was to evaluate gene expression of ileal tissue from calves challenged using the new model. Materials and Methods: In the model, calves were fed a diet to induce ruminal acidosis and were then in- traruminally inoculated with bacteria typically associated with liver abscesses. On d 21, following inoculation, calves were euthanized. Seven of the 13 calves had liver abscess- es. Ileal tissues were collected and total RNA was isolated for RNA-sequencing. Results and Discussion: A total of 26 genes were dif- ferentially expressed in the calves with liver abscesses com- pared with those without. Two genes (COX2, COX3) are components of the cytochrome c oxidase enzyme in the electron chain transport pathway, and both were downreg- ulated among the animals with liver abscesses. Other genes involved in cellular restructuring, transport of compounds across cell membranes, protection of RNA, and protection of protein products were also identified. These functions il- lustrate that there are changes in the ileal epithelium that correspond to the development of liver abscesses. Implications and Applications: We identified sev- eral genes that were differentially expressed in the ileal tissue of calves that developed liver abscesses using the combination of an acidosis-inducing diet and intraruminal inoculation of bacteria. Our results suggest that the ileum has a role in liver abscess development, and future studies to validate the involvement of the mucosal barrier of the ileum are warranted.Item Metaphylactic antimicrobial effects on occurrences of antimicrobial resistance in Salmonella enterica, Escherichia coli and Enterococcus spp. measured longitudinally from feedlot arrival to harvest in high-risk beef cattle(2022) Long, Nathan S. (TTU); Wells, James E.; Berry, Elaine D.; Legako, Jerrad F. (TTU); Woerner, Dale R. (TTU); Loneragan, Guy H.; Broadway, Paul R.; Carroll, Jeff A.; Sanchez, Nicole C.Burdick; Fernando, Samodha C.; Bacon, Carley M. (TTU); Helmuth, Cory L. (TTU); Smock, Taylor M. (TTU); Manahan, Jeff L. (TTU); Hoffman, Ashley A. (TTU); Hales, Kristin E. (TTU)Aims: Our objective was to determine how injectable antimicrobials affected populations of Salmonella enterica, Escherichia coli and Enterococcus spp. in feedlot cattle. Methods and Results: Two arrival date blocks of high-risk crossbred beef cattle (n = 249; mean BW = 244 kg) were randomly assigned one of four antimicrobial treatments administered on day 0: sterile saline control (CON), tulathromycin (TUL), ceftiofur (CEF) or florfenicol (FLR). Faecal samples were collected on days 0, 28, 56, 112, 182 and study end (day 252 for block 1 and day 242 for block 2). Hide swabs and subiliac lymph nodes were collected the day before and the day of harvest. Samples were cultured for antimicrobial-resistant Salmonella, Escherichia coli and Enterococcus spp. The effect of treatment varied by day across all targeted bacterial populations (p ≤ 0.01) except total E. coli. Total E. coli counts were greatest on days 112, 182 and study end (p ≤ 0.01). Tulathromycin resulted in greater counts and prevalence of Salmonella from faeces than CON at study end (p ≤ 0.01). Tulathromycin and CEF yielded greater Salmonella hide prevalence and greater counts of 128ERYR E. coli at study end than CON (p ≤ 0.01). No faecal Salmonella resistant to tetracyclines or third-generation cephalosporins were detected. Ceftiofur was associated with greater counts of 8ERYR Enterococcus spp. at study end (p ≤ 0.03). By the day before harvest, antimicrobial use did not increase prevalence or counts for all other bacterial populations compared with CON (p ≥ 0.13). Conclusions: Antimicrobial resistance (AMR) in feedlot cattle is not caused solely by using a metaphylactic antimicrobial on arrival, but more likely a multitude of environmental and management factors.Item Validation of an experimental model to induce liver abscesses in Holstein steers using an acidotic diet challenge and intraruminal bacterial inoculation*†(2024) McDaniel, Zach S. (TTU); Hales, Kristin E. (TTU); Nagaraja, T. G.; Lawrence, Ty E.; Tennant, Travis C.; Amachawadi, Raghavendra G.; Carroll, Jeff A.; Burdick Sanchez, Nicole C.; Galyean, Michael L. (TTU); Davis, Emily (TTU); Kohl, Kesley (TTU); Line, Dalton J. (TTU); Dornbach, Colten W. (TTU); Abbasi, Mina; Deters, Alyssa; Shi, Xiaorong; Ballou, Michael A. (TTU); Machado, Vinicius S. (TTU); Smock, Taylor M. (TTU); Broadway, Paul R.Objective: Our objectives were to develop and evaluate a model to induce liver abscesses (LA) in cattle and assess roles of Fusobacterium and Salmonella on LA formation and severity. Materials and Methods: Holstein steers (n = 40; initial BW = 110 ± 12.0 kg) were assigned randomly to treatments (n = 10 per treatment): (1) control diet (CON); (2) acidotic diet (AD); (3) AD plus inoculation of Fusobacterium necrophorum ssp. necrophorum (8.81 × 1010 cfu/steer; ADFn); or (4) AD and intraruminal inoculation of F. necrophorum (8.81 × 1010 cfu/steer) and Salmonella enterica Lubbock (1.52 × 1011 cfu/steer; ADFS). On d 0, steers were subjected to 4 acidotic cycles where they were fed the acidotic diet for 3 d and then the control diet for 2 d. Intraruminal bacterial inoculation was on d 20. From d 21, AD, ADFn, and ADFS steers remained on the acidotic diet until d 38. Euthanasia occurred on d 38, and gross pathology of the lung, rumen, liver, and colon were recorded. Results and Discussion: Liver abscess prevalence was 40% in ADFn and 50% in ADFS versus 0% in CON and AD. No pathological differences were noted in lung nor colon among treatments; however, ruminal damage was more severe in ADFn and ADFS than in CON and AD steers. Implications and Applications: Acidotic diet alone caused mild ruminal acidosis but no LA. Acidotic diet with intraruminal bacterial inoculation increased rumenitis severity and resulted in LA, thus validating the nutritional model to induce LA. Therefore, acidotic diet with intraruminal bacterial inoculation is a viable model to study the formation of LA.