Evaluating the effects of acidosis and bacterial inoculum concentrations on the development of liver abscess in beef x dairy steers

Authors: CHILDRESS, KALLIE - Texas Tech University; HALES, KRISTIN - Texas Tech University; NAGARAJA, T - Kansas State University; LAWRENCE, TY - West Texas A & M University; AMACHAWAADI, RAGHAVENDRA - Kansas State University; Sanchez, Nicole; THOMPSON, AUBREY - Texas Tech University; HANRATTY, ASHLEE - Texas Tech University; DORNBACH, COLTEN - Texas Tech University; ABBASI, MINA - Kansas State University; SHI, XIAORANG - Kansas State University; GALYEAN, MICHAEL - Texas Tech University; Broadway, Paul

Submitted to: Applied Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/19/2024
Publication Date: 4/1/2025
Citation: Childress, K.D., Hales, K.E., Nagaraja, T.G., Lawrence, T.E., Amachawaadi, R.G., Sanchez, N.C., Thompson, A.C., Hanratty, A.N., Dornbach, C.W., Abbasi, M., Shi, X., Galyean, M.N., Broadway, P.R. 2025. Evaluating the effects of acidosis and bacterial inoculum concentrations on the development of liver abscess in beef x dairy steers. Applied Animal Science. 41(2):93-103. https://doi.org/10.15232/aas.2024-02641.
DOI: https://doi.org/10.15232/aas.2024-02641

Interpretive Summary: Diet and management are thought to be play a large role in liver abscess formation in beef cattle. To understand the development of liver abscesses, a model to induce the disease was developed using diet changes and bacteria commonly found in abscesses. A study was designed by scientists with the USDA-ARS and university collaborators to further refine the model by testing different diets and doses of bacteria on liver abscess formation. Data from this study found that liver abscesses formed in the absence of a high starch diet. These results challenge the common theory of liver abscess formation. Also, using 3 low-doses of bacteria may be more like natural infection. This approach may be better for testing methods to reduce liver abscesses. These data will be of interest to scientists in the field of cattle physiology and immunology, and to cattle producers.

Technical Abstract: We evaluated the association of diet type, ruminal acidosis bout frequency, and intraruminal bacterial inoculum concentration on liver abscess (LA) development in steers. Beef x dairy steers (n = 40, initial BW = 107 +/- 11 kg) were assigned randomly to 1 of 5 treatments that included either a high-dose (HD; 1 x 10^9 and 1 x 10^9 CFU/mL) or a low-dose (LD; 1 x 10^6 and 1 x 10^6 CFU/mL) of Fusobacterium necrophorum subsp. necrophorum and Salmonella enterica serovar Lubbock, respectively. Treatments included: NCON = high-forage diet with no intraruminal inoculation; CON+HD = high-forage diet with a single HD inoculation; 2AD+HD = 2 acidotic diet cycles with a single HD inoculation; 4AD+3LD = 4 acidotic diet cycles with a series of 3 LD inoculations; and 4AD+HD = 4 acidotic diet cycles with a single HD inoculation. Individual animal was the experimental unit. Continuous data were analyzed using mixed models, and categorical data were analyzed as binomial proportions with treatment, time, and their interactions as the fixed effects. Hematology data were evaluated before harvest on d 21 to evaluate indications of systemic disease. Hematocrit differed among treatments (P < 0.01) in which, it was greater in NCON, 2AD+HD, and 4AD+HD, than CON+HD or 4AD+3 LD. Similarly, neutrophil:lymphocyte ratio differed among treatments (P = 0.03), with a greater ratio for CON+HD, and 2AD+HD than for NCON, 4AD+3LD, and 4AD+HD. Although no difference was observed in rumenitis among treatments (P = 0.79), steers with LA had 8 percentage points greater ruminitis frequency than steers without LA. Steers consuming the high-forage diet also presented with rumenitis. Prevalence of LA did not differ among treatments (P = 0.68), but varied considerably, with 0, 37.5, 37.5, 50, and 12.5% LA for NCON, CON+HD, 2AD+HD, 4AD+3LD, and 4AD+HD, respectively. A key finding of this study was that steers fed a high-forage diet presented with LA when given a high dose of F. necrophorum and S. enterica, even in the absence of the acidotic diet.