Location: Livestock Issues ResearchTitle: Development of an experimental model to induce liver abscesses in calves using an acidotic diet and intraruminal bacterial inoculation
|MCDANIEL, ZACH - Texas Tech University|
|NAGARAJA, TIRUVOOR - Kansas State University|
|LAWRENCE, TY - Texas A&M University|
|AMACHAWADI, RAGHAVENDRA - Kansas State University|
|Carroll, Jeffery - Jeff Carroll|
|GALYEAN, MICHAEL - Texas Tech University|
|HALES, KRISTIN - Texas Tech University|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 12/12/2022
Publication Date: 1/24/2023
Citation: Mcdaniel, Z.S., Nagaraja, T.G., Lawrence, T.E., Amachawadi, R., Carroll, J.A., Sanchez, N.C., Galyean, M.L., Hales, K.E., Broadway, P.R. 2023. Development of an experimental model to induce liver abscesses in calves using an acidotic diet and intraruminal bacterial inoculation. Proceedings of the 103rd Conference of Research Workers in Animal Disease, January 20-24th, 2023, Chicago, Illinois. p. 218.
Technical Abstract: Weaned dairy steers (n = 40; initial BW = 84.9 ± 7.1 kg) were used to study the effects of diet and a bacterial inoculation on the development of liver abscesses. Steers were housed in a climate-controlled barn for 50 d and randomly assigned to 1 of 3 treatments: 1) control diet with no inoculation (CON), 2) acidotic diet with no inoculation (AD), 3) acidotic diet plus inoculation in which calves were intraruminally inoculated with Fusobacterium necrophorum spp. necrophorum, Salmonella enterica spp. Lubbock, and Trueperella pyogenes (1 x 109 CFU/mL in 100mL; ADF). Calves were fed the acidotic diet for 3 days then the control diet for 2 days for 4 cycles until inoculation then remained on the acidotic diet for the remainder of the study. Rumen pH boluses were randomly assigned to 20 steers to record ruminal pH. Daily health, fecal score, and feed intake were also recorded, and bodyweight, hematology, and rectal temperatures were measured on days -6, 0, 7, 15, 22, 30, 37, 43. At harvest, gross pathology was observed and scored on lung, livers, liver abscesses, liver scars, rumen, ileum, and colon. Data was analyzed as a completely randomized design with individual animal as the experimental unit, where an a of = 0.05 determined significance. Liver abscess prevalence was 50% in ADF vs. 0% in AD and CON treatments (P < 0.01). There was a treatment by time interaction for ruminal pH, where pH decreased in AD and ADF calves during each cycle of acidotic diet then returned to baseline (P < 0.01). There was no difference in any of the hematology variables (P = 0.15). Our challenge model successfully induced liver abscesses in weaned dairy calves and provides insight on possible mechanisms of liver abscess formation. These data suggest that acidosis in conjunction with intraruminal pathogen inoculation may prove to be a viable model to study liver abscess formation. Further research is needed to elucidate host pathogen interactions and determine the reliability and repeatability of this model.