Effects of Bacillus subtilis PB6 and/or chromium propionate supplementation on serum chemistry, complete blood count, and fecal Salmonella spp. count in high-risk cattle during the feedlot receiving and finishing periods1,2

Abstract

The study objective was to determine the effects of Bacillus subtilis PB6 and/or chromium propionate supplementation on serum chemistry, complete blood count, and fecal Salmonella spp. count in high-risk beef cattle during a 56-d feedlot receiving period and the subsequent finishing period. Four truckload blocks of crossbred beef bulls (n=300) and steers (n=84; total n=384; average initial BW = 220 ± 16.2 kg) were sourced from regional auction markets and assigned randomly to treatments arranged in a 2 × 2 factorial. Blood samples were collected from two bulls nearest the median BW on arrival in each pen (n=96) and fecal samples were collected from cattle in block 3 (n=96). The generalized complete block design consisted of 12 pen replications per treatment with pen as the experimental unit. Treatments were: 1) negative control (CON); 2) 13 g/animal daily of prepared B. subtilis PB6 product (CST); 3) 450 ppb DM chromium propionate (CHR); and 4) 13 g/animal daily of prepared B. subtilis PB6 product and 450 ppb DM chromium propionate (CST+CHR). Treatments were top dressed in feed bunks daily using 0.45 kg/animal ground corn carrier immediately following feed delivery. Data were analyzed using mixed models with repeated measures. Day affected all serum chemistry variables (P ≤ 0.03) except total CO2 (P = 0.34) and all complete blood count variables during receiving (P ≤ 0.02) except percentage basophils (P ≥ 0.12). During the overall receiving period, serum calcium was decreased (P = 0.02) by CHR. Cattle fed CHR had greater total leukocyte count (P = 0.04) and neutrophil count (P = 0.02) during the overall receiving period. Fecal Salmonella spp. count was markedly reduced in cattle fed CST on day 28 (P = 0.01) and overall (P = 0.07). Overall, these data provide metabolic and hematologic insight into the unique challenges presented by lightweight, high-risk feeder cattle. Notably, CST was found to be effective in mitigating fecal enumeration and presumably replication of Salmonella spp. in the gastrointestinal tract.

Evaluation of Bacillus subtilis PB6 on feedlot phase growth performance, efficiency of dietary net energy utilization, and fecal and subiliac lymph node Salmonella prevalence in spring placement yearling beef steers fed in southeastern South Dakota1,2,3

“…On day 140 of the present study, there was numerically greater ( P = 0.34; 0.0 vs. 8.3%) fecal Salmonella prevalence for CLO compared to CON steers. Smock et al (2020b) noted an appreciable decrease in fecal Salmonella prevalence in high-stressed feeder steers supplemented with B. subtilis PB6 on day 28 of the feedlot-receiving period. However, no differences among treatments for fecal Salmonella incidence were noted on day 196 of the feeding period ( Smock et al, 2020b ).…”

“… Smock et al (2020b) noted an appreciable decrease in fecal Salmonella prevalence in high-stressed feeder steers supplemented with B. subtilis PB6 on day 28 of the feedlot-receiving period. However, no differences among treatments for fecal Salmonella incidence were noted on day 196 of the feeding period ( Smock et al, 2020b ). The lack of detectable Salmonella in these steers could be due to the fact that the steers used in the present experiment were not transitioned through a cattle auction facility.…”

“…Thus, there has been considerable attention focused on nonpharmaceutical alternatives to the use of these compounds in food production ( Sánchez-Mendoza et al, 2014 ). Bacillus subtilis PB6 (CLOSTAT500, Kemin Industries, Des Moines, IA) is a patented spore-forming bacterium that has been shown to impact clostridia and Salmonella in livestock species ( Broadway et al, 2020 ; Smock et al, 2020b ). Reducing subclinical illness in livestock that is associated with clostridia and Salmonella challenges can, in turn, improve immunological responses to more severe diseases associated with the respiratory tract in cattle.…”

Feeding a high-energy finishing diet upon arrival to high-risk feedlot calves: effects on health, performance, ruminal pH, rumination, serum metabolites, and carcass traits

“…Alanine transaminase is a marker of liver function, and an increased concentration can indicate liver damage (Pagana and Pagana, 2013 ). In high-risk cattle, Smock et al (2020) also observed a decline in ALT in the first 14 d after feedlot arrival. If liver function is reduced when high-risk cattle arrive at the feedlot, it is not surprising that blood glucose concentrations were also less on day 0 compared with day 14 ( P < 0.01).…”

The effects of chromium propionate supplementation to yearling steers in a commercial feedyard on growth performance, carcass characteristics, and health

“…During a lipopolysaccharide challenge, supplementing 0.20 mg/kg of dietary DM Cr propionate improved immune response parameters ( Burdick et al, 2011 ). Smock et al (2020a , 2020b ) reported a reduction in first-treat respiratory morbidity (43.9% vs. 35.8%, control or Cr, respectively), and improved immune function by supplementing 0.30 mg/kg dietary DM Cr propionate. In high-stress cattle populations, Cr supplementation with a high-Cr yeast product decreased serum cortisol, increased total immunoglobulin production ( Chang and Mowat, 1992 ), and decreased morbidity ( Moonsie-Shageer and Mowat, 1993 ).…”