Management strategies to decrease antimicrobial use and liver abscesses in growing and finishing beef cattle
Objective: Our objective was to evaluate the use of a novel direct-fed microbial as a viable alternative to antimicrobials to decrease liver abscesses in feedlot cattle. Materials and Methods: Angus beef steers (n = 240; initial BW = 263 ± 18.0 kg) were used in a randomized complete block design comprised of 3 BW blocks and 3 pen replications per treatment. Experimental treatments were randomly assigned to pen within BW block and consisted of: 1) negative control, dietary supplement contained no tylosin phosphate (Tylan-100; Elanco Animal Health, Greenfield, IN; NCON); 2) positive control, dietary supplement contained tylosin phosphate (PCON); 3) positive control with tylosin phosphate removed the last 65 d of the feeding period (PCONW); 4) novel direct-fed microbial fed at 1 g mixture/animal with 1 × 1011 CFU/g (DFM). Results and Discussion: By design, initial BW did not differ (P = 0.79) among treatments, and at the end of the 59-d receiving period, there were no differences in final live BW (P = 0.25). From d 0 to d 30, ADG, DMI, DMI as a percentage of BW, and G:F did not differ (P ≥ 0.21). Likewise, the ADG, DMI, DMI as a percentage of BW, and G:F, from d 31 to d 59, did not differ (P ≥ 0.30). In the overall receiving period from d 0 to d 59, there were no differences in ADG, DMI, DMI as a percentage of BW, or G:F (P ≥ 0.20). During the finishing period, live- and carcass-adjusted final BW did not differ (P ≥ 0.57) among treatments. For the overall finishing period, there were no differences in ADG, DMI, DMI as a percentage of BW, or G:F (P ≥ 0.17). Carcass-adjusted ADG, DMI as a percentage of BW, and G:F also did not differ (P ≥ 0.16). Across treatments, no differences in HCW were noted (P = 0.84). Dressing percentage, marbling score, longissimus dorsi (LM) area, 12th-rib fat thickness, and calculated yield grade (YG) were not different among dietary treatments (P ≥ 0.32). Liver abscess incidence and severity were not affected by dietary treatments (P ≥ 0.13). Implications and Applications: The inclusion of a novel direct-fed microbial in finishing cattle diets did not affect growth performance, carcass characteristics, or the development of liver abscesses. Given the limited existing literature in beef cattle, further research evaluating the supplementation of B. licheniformis as a direct-fed microbial to decrease liver abscesses is warranted.