Extension

Stocker cattle are exposed to several stress factors within a short period of time, including weaning, transport, exposure to novel diets and environments, and commingling with different animals.¹ These stressors impair their immunity and lead to bovine respiratory disease (BRD). With the increased regulations regarding the use of antimicrobials in cattle nutrition, novel dietary strategies to improve health and productivity of stocker cattle are warranted.² Research has shown that supplementing a Bacillus-based probiotic will enhance rumen function and immunocompetence in growing cattle.³

 

A recent Mississippi State University experiment evaluated the performance, health, and physiological responses of high-risk steers receiving a Bacillus-based probiotic during a 90-day grazing period.⁴ A total of 240 Angus-influenced steers were used in this experiment that was replicated over 2 years (2022 and 2023: 120 steers/year). Each year, steers were purchased from a commercial auction yard (Miller Cattle Company, Marion, MS) soon after weaning, transported 75 miles to the research facility (Starkville, MS), and assigned initial processing within a 48-hour period. The steers were allocated to 1 of 12 pastures with stockpiled native grass (10 acre pastures; 10 steers/pasture). Pastures were randomly assigned to receive daily supplementation with dried distillers’ grains at 1% of body weight containing either: 1) Bacillus subtilis + B. licheniformis probiotic (2 grams/steer daily of Bovacillus; Novonesis, Horsholm, Denmark) or 2) no feed additive. The steers received treatments from days 0 to 90 (8:00 AM) in portable feedbunks located in each pasture. In addition, the cattle had free-choice access to water and a commercial mineral + vitamin mix without an ionophore. The researchers noted that the supplements were promptly and entirely consumed within 2 hours after feeding. Steers were assessed for bovine respiratory disease (BRD) signs daily. Full body weight (BW) was recorded on days 0, 14, 28, 56, and 90. Shrunk BW was recorded on day 91 after 16 hours of feed and water,restriction, and a 4% pencil shrink was used to calculate the final BW. Average daily gain (ADG) was,calculated based on initial and final BW.,These authors reported that no treatment effects were detected for average daily gain (P = 0.80) and final BW (P = 0.73) during the experiment (Table 1). At the beginning of the experiment, the total liveweight per pasture did not differ between treatments (P = 0.77) as designed (Table 1). During the experiment, the total liveweight gain per pasture was greater (P = 0.04) in Bovacillus compared with Controls (1418 vs. 1107 lb). Therefore, pastures with CON steers had greater (P = 0.04) total liveweight at the end of the experiment compared with pastures housing Control steers (6630 vs. 6326 lb).

 

 

¹Steer BW was recorded at unloading on day -1 and at initial processing on day 0, and these values were averaged as initial BW. Shrunk BW was recorded on day 91 after 16 hours of feed and water restriction, and a 4% pencil shrink was used to calculate the final BW. ADG was calculated based on initial and final BW.

 

²Initial and final liveweight were calculated by summing the initial and final BW of steers within each pasture.

Adapted from Mackey et al., 2024.

 

 

The morbidity and mortality parameters of these high-risk stocker steers are reported in Table 2. No treatment effects were detected (P ≥ 0.97) for overall incidence of BRD signs nor the timing of BRD incidence during the experiment. Furthermore, no treatment effects were detected (P ≥ 0.15) for the proportion of steers diagnosed with BRD signs that required one, 2, or 3 antimicrobial treatments to eliminate BRD signs, nor the number of treatments required to eliminate BRD signs. However, the mortality rate tended to be less (P ≤ 0.08) in Bovacillus compared with Controls (0 vs. 2.52%), when comparing steers diagnosed with BRD signs or all steers enrolled in the experiment. The proportion of steers removed from the experiment for health reasons other than BRD also tended (P = 0.08) to be less in Bovacillus compared with Controls. Collectively, the proportion of steers excluded from the experiment (mortality + removals) was less (P = 0.01) in Bovacillus steers compared with Control steers

(0 vs. 5.04%).

 

 

These researchers concluded that “in general, supplementing steers with the Bacillus-based probiotic did not impact growth rates or BRD incidence. However, no steers that received the Bacillus-based probiotic died from BRD consequences nor were removed from the experiment due to health reasons, whereas 5% of un-supplemented steers did not complete the 90-day experiment”. As a result, pasturebased liveweight gain was increased by 28% due to Bacillus-based probiotic supplementation suggesting that supplementing a B. subtilis + B. licheniformis probiotic could be an alternative to improve the health and overall productivity of high-risk stocker cattle.

 

¹ Cooke, R. F. 2017. Invited paper: nutritional and management considerations for beef cattle experiencing stress induced inflammation. Prof. Anim. Sci. 33:1–11.

 

² Galyean, M. L., G. C. Duff, and J. D. Rivera. 2022. Galyean appreciation club review: revisiting nutrition and health of newly received cattle—what have we learned in the last 15 years? J. Anim. Sci. 100:17. . Available at: 10.1093/jas/skac067.

 

³ Cappellozza, B. I., J. N. Joergensen, G. Copani, K. A. Bryan, P. Fantinati, J. Bodin, M. M. Khahi, C. NinoDeGuzman, K. G. Arriola, L. O. Lima, et al. .2023. Evaluation of a Bacillus-based direct-fed microbial probiotic on in vitro rumen gas production and nutrient digestibility of different feedstuffs and total mixed rations. Trans. Anim. Sci. 7 Available at: 10.1093/tas/txad044.

 

⁴ Mackey, S. J., R. F. Cooke, A. T. Pickett, B. I. Cappellozza, K. M. Harvey, and B. B. Karisch. 2024. Supplementing a Bacillus-based probiotic to high-risk stocker cattle. J. Anim. Sci. 102. Available at: https://doi.org/10.1093/jas/skae209.