Extension

Liver abscesses are the most common reason for liver condemnation in beef processors.¹ Liver abscesses in feedlot cattle are a cause of decreased performance and reduced carcass value. Loss in carcass value is due not only to the abscessed liver being condemned, but also due to trim loss associated with the condemned liver. Commercial abattoirs estimate this disease complex costs $400 million annually because of increased liver condemnations, carcass trimming, and decreased quality grade.²

 

The primary grain used in finishing diets is steam-flaked corn (SFC). Steam flaking is a process that increases the availability of starch in corn, thereby increasing the starch digestibility.³ Despite improvements in growth performance, increasing starch availability can increase the risk of rumenitis leading to an increased incident of liver abscesses.⁴ Finishing cattle diets generally include between 9% and 10% roughage on a dry matter (DM) basis and are not always balanced for roughage neutral; detergent fiber (NDF).⁵ Tylosin phosphate is an antibiotic that is commonly fed to feedlot cattle to decrease the incidence of liver abscesses. However, general concern that in-feed application of medically important antimicrobials increase antimicrobial resistant pathogen threats to human health remain, so alternative and efficacious means for reducing liver abscesses without antimicrobials are desired.

 

Identifying an optimal bulk density of steam-flaked corn and roughage NDF combination that optimizes growth performance and minimizes liver abscesses is a potential nutritional management strategy to decrease the prevalence of liver abscesses without feeding an antibiotic. Thus, Texas Tech University research evaluated the effects of dietary NDF concentration from alfalfa hay and bulk density of steamflaked corn on growth performance, carcass characteristics, and liver abscesses in finishing beef steers.⁶

 

In this study, 214 crossbred beef steers (60 pens; initial body weight [BW] = 919 lb) were blocked by BW and assigned randomly to treatments and fed an average of 112 days. The treatments were arranged as a 2 × 3 factorial with 10 pens per treatment and consisted of 3 NDF concentrations from alfalfa hay (3%, 4.5%, or 6%) and 24 lb/bu or 32 lb/bu SFC (69% or 33% starch availability, respectively). The steers were fed a common growing diet for approximately 42 days before being transitioned to the finishing diet over a 28-day period before the start of the study. During the diet transition, every 7 days a new diet was fed that contained increasing concentrations of SFC and decreasing concentrations of alfalfa hay and wet corn gluten feed until the steers were on a common finishing diet.

 

The roughage NDF concentrations were used because they represent a low, medium, and high inclusion of roughage in commercial feedlots diets (5.02, 7.46, and 10.07% of DM, respectively).^{5, 7} Roughage NDF inclusion was used instead of roughage inclusion because previous research suggested that dietary roughage concentration accounted for 69.9% of the variation in dry matter intake (DMI), with NDF from roughage accounting for 93% of the variation in DMI.⁸ The bulk densities of the SFC were selected to induce a large change in enzymatic starch availability. The roughage source was commercially purchased alfalfa hay.

 

DMI responded quadratically from day 0 to 35 as roughage NDF increased from 3% to 6% (19.38, 18.70, and 19.32 lb/day, respectively for 3, 4.5, and 6% roughage NDF; P < 0.05). In addition, DMI increased linearly as roughage NDF increased on day 70 to 105 (21.12, 21.72, and 22.60 lb/day, respectively for 3, 4.5, and 6% roughage NDF; P < 0.05) and day 0 to final (20.22, 20.33, and 20.84 growth performance were reported.

 

Marbling score responded quadratically to roughage level and was greater for steers fed 3% than for those fed 4.5% or 6% roughage NDF. Steers fed 24 lb/bu SFC tended to have a larger ribeye area than those fed 32 lb/bu SFC (14.55 vs. 14.29 in2; P = 0.10). The effects of roughage NDF concentration and bulk density of SFC on liver abscesses are shown in Table 1. The total percentage of abscessed livers at slaughter decreased linearly as roughage NDF was increased from 3% to 6% of DM (40.5, 22.6, and 17.2%, respectively for 3, 4.5, and 6% roughage NDF). The presence of A+ abscesses also decreased linearly with increasing roughage NDF (17.9, 6.7, and 3.8%, respectively for 3, 4.5, and 6% roughage NDF). In addition, total liver abscesses were 13.9 percentage points less in steers fed 24 versus 32 lb/bu SFC (34.8 vs 20.9%, P = 0.05).

 

¹Roughage NDF was 3.0%, 4.5%, or 6.0%. Bulk density of SFC was 24 lb/bu or 32 lb/bu. No interaction of roughage NDF × bulk density of SFC was observed (P ≥ 0.24).

²Lin = linear effects of roughage NDF. *P < 0.05; NS = P > 0.10.

³Liver abscess scored as 0, A-, A, or A+ or abscessed. A score of 0 represents a normal liver with no abscesses, and A+ represents livers with multiple large abscesses.

Adapted from McDaniel et al.

 

In conclusion, in this study increasing roughage NDF in the diet resulted in increased DMI. In addition, increasing roughage NDF from 3% to either 4.5% or 6% also decreased liver abscesses, most notably in the severe A+ category. Steers fed the least roughage NDF had increased marbling score. Increasing the bulk density of SFC decreased the amount of liver abscesses but did not affect growth performance or carcass characteristics. Therefore, these results suggest that increasing roughage NDF concentration from alfalfa hay and the bulk density of SFC in diets without tylosin phosphate could be an effective dietary management strategy to decrease overall and severe liver abscesses in finishing beef cattle.

 

¹ Eastwood, L.C., C.A. Boykin, M.K. Harris, A.N. Arnold, D.S. Hale, C.R. Kerth, D.B. Griffin, J.W. Savell, K.E. Belk, D.R. Woerner, J.D. Hasty, R.J. Delmore Jr., J.N. Martin, T.E. Lawrence, T.J. McEvers, D.L. VanOverbeke, G.G. Mafi, M.M. Pfeiffer, T.B. Schmidt, R.J. Maddock, D.D. Johnson, C.C. Carr, J.M. Scheffler, T.D. Pringle, and A.M. Stelzleni. 2017. National Beef Quality Audit—2016: Transportation, mobility, and harvest-floor assessments of targeted characteristics that affect quality and value of cattle, carcasses, and by-products. Transl. Anim. Sci..1:229–238. Available at: https://doi.org/10.2527/tas2017.0029.

² Herrick, R. T., C. L. Rogers, T. J. McEvers, R. G. Amachawadi, T. G. Nagaraja, C. L. Maxwell, J. B. Reinbold, and T. E. Lawrence. 2022. Exploratory observational quantification of liver abscess incidence, specific to region and cattle type, and their associations to viscera value and bacterial flora. Appl. Anim. Sci. 38: 170-182. Available at: https://doi.org/10.15232/aas.2021-02228.

³ Zinn, R.A., 1990. Influence of flake density on the comparative feeding value of steam-flaked corn for feedlot cattle. J. Anim. Sci. 68:767-775. Available at: https://doi.org/10.2527/1990.683767x.

⁴ Nagaraja, T.G. and M. M. Chengappa. 1998. Liver abscesses in feedlot cattle: a review. J. Anim. Sci. 76:287-298. Available at: https://doi.org/10.2527/1998.761287x.

⁵ Samuelson, K. L., M. E. Hubbert, M. L. Galyean, and C. A. Löest. 2016. Nutritional recommendations of feedlot consulting nutritionists: The 2015 New Mexico State and Texas Tech University survey. J. Anim. Sci. 94: 2648-2663. Available at: https://doi.org/10.2527/jas.2016-0282.

⁶ McDaniel, Z. S., M. L. Galyean, P. R. Broadway, J. A. Carroll, N. C. B. Sanchez, A. N. Hanratty, C. W. Dornbach, D. J. Line, T. M. Smock, J. L. Manahan, and K. E. Hales. 2024. Effects of increasing the concentration of neutral detergent fiber in roughage and bulk density of steam-flaked corn on growth performance, carcass characteristics, and liver abscesses of finishing beef steers fed diets without tylosin phosphate. Appl. Anim. Sci. 40:269-278. Available at: https://doi.org/10.15232/aas.2023-02484.

⁷ Vasconcelos, J. T., and M. L. Galyean. 2007. Nutritional recommendations of feedlot consulting nutritionists: The 2007 Texas Tech University survey. J. Anim Sci. 85 2772-2781. Available at: https://doi.org/10.2527/jas.2007-0261.

⁸ Galyean, M. L., and P. J. Defoor. 2003. Effects of roughage source and level on intake by feedlot cattle. J. Anim. Sci. 81 (E. Suppl):E8-E16.