Impact of a Natural Feed Additive or Tylosin on Finishing Beef Cattle Performance and Liver Abscess Rate

Receiving and finishing experiments were conducted utilizing 600 crossbred steers (initial BW = 261 kg; SD = 7.72 kg) to evaluate a non-antibiotic alternative for control of liver abscesses. Three treatments consisted of a negative control diet (-CON) without tylosin, a positive control diet (+CON) with tylosin (Tylan-40®; Elanco Animal Health) included at 90 mg/steer daily, and a diet containing Ramaekers Immune Primer (RAM; Ramaekers Nutrition) that contains a proprietary blend of vitamins, minerals, prebiotics, and probiotics. A total of 30 pens were used in the study with 20 steers per pen and 10 pens per treatment. During the receiving phase (d 1 – d 19), RAM steers received two boluses of RAM at arrival and two boluses on d 19. Steers also received 14 g/steer RAM daily through the supplement. All steers received the same receiving diet with 31.67% alfalfa hay, 31.66% dry-rolled corn (DRC), and 31.67% Sweet Bran along with 5% supplement (DM basis). During the finishing phase, RAM was fed once weekly, to target 14 g/steer daily. All steers were fed the same finishing diet of a 40:60 blend of DRC and high-moisture corn with 25% wet distillers grains plus solubles, 5% wheat straw, and 4% supplement. Monensin was included at 33.2 mg/kg DM in all diets during receiving and finishing. Carcass and performance data were analyzed using the MIXED procedure of SAS where pen was the experimental unit. Liver abscess incidence, morbidity, and mortality were analyzed as binomial using PROC GLIMMIX of SAS. During the receiving period, no differences were observed in ending BW, ADG, or G:F (P ≥ 0.48). However, DMI was significant (P ≥ 0.02) where +CON and RAM treatments had lesser DMI than the -CON. No differences (P ≥ 0.19) were observed for final BW, DMI, ADG, G:F, HCW, marbling, LM area, 12^th rib fat or calculated yield grade (P ≥ 0.25) over the entire feeding period (224 d). Morbidity and mortality percentages were not impacted by treatment (P ≥ 0.19). Liver abscess incidence was impacted by treatment (P < 0.01), with lesser percentage (P < 0.01) of total liver abscesses in the +CON (7.7 %) treatment compared to both RAM (20.3 %) and -CON (21.3 %), which were not different (P = 0.38). These data suggest there was no impact from treatment on overall performance. Compared to tylosin, RAM was not efficacious in reducing total liver abscesses.

Key Words: cattle, immunity, liver abscess