Effects of a Bacillus-based direct-fed microbial on in vitro nutrient digestibility of forage and high-starch concentrate substrates

Alternatives to conventional antibiotics for the prevention and treatment of commonly occurring diseases in feedlot cattle

Antibiotic-resistant bacteria are a problem in human medicine. The development of antibiotic resistance in bacteria in feedlot cattle could have negative effects on their health and welfare and there is a theoretical possibility of transmission of antibiotic-resistant bacteria from food animals to humans. Alternatives to conventional antibiotics in feedlot health management could reduce the selective pressure for the development of antibiotic resistance. This review assesses the evidence supporting potential alternatives to conventional antibiotics in the prevention and treatment of diseases in feedlot cattle, including nitric oxide, plant extracts, supplemental yeast or yeast products, bacterial probiotics, organic acids, bacteriophages and non-specific immunostimulants. Further research is warranted with lactate utilising bacteria, the organic acid malate, bacteriophages and the non-specific immunostimulants β-1,3 glucan and those based on pox viruses. However, none of the alternatives to conventional antibiotics investigated in this review have sufficient supporting evidence to date to justify their use with feedlot cattle. Frequently, statistically weak results and studies without negative controls are cited as support for similar studies. The health and welfare of feedlot cattle are dependent on the use of products that have robust supporting data to ensure efficacy and to avoid adverse outcomes.

Bacillus paralicheniformis 809 and Bacillus subtilis 810 support in vitro intestinal integrity under hydrogen peroxide and deoxynivalenol challenges

We designed and conducted two in vitro experiments to evaluate the effects of two Bacillus spp. probiotics on gut barrier integrity using the transepithelial electrical resistance (TEER) assay under two different challenge models. In Exp. 1, intestinal epithelial cells received or not (CON) B. paralicheniformis 809 (BLI) or B. subtilis 810 (BSU) at a rate of 1 × 108 colony forming units (CFU)/transwell. Two hours after treatment application (CON, BLI, or BSU), 5 mM of the reactive oxygen species hydrogen peroxide, mimicking mucosal oxidative stress, was added alone (HYP) or with each of the Bacillus spp. (HYP + BLI or HYP + BSU). In Exp. 2, cells were assigned to the same treatments as in Exp. 1 (CON, BLI, and BSU), or mycotoxin deoxynivalenol (DON), which was added alone or in combination with BLI or BSU, resulting in another two treatments (DON + BLI and DON + BSU). Transepithelial electrical resistance was measured for 14 h postchallenge. In Exp. 1, a treatment × hour interaction was observed for TEER (P < 0.0001). Adding BLI and BSU resulted in greater TEER values vs. CON for most of the experimental period (P < 0.02), whereas HYP reduced mean TEER and area under the curve (AUC), while increasing the amount of sugar that translocated through the monolayer cells (P < 0.001). A treatment × hour interaction was also observed in Exp. 2 (P < 0.0001), as DON led to an immediate and acute drop in TEER that lasted until the end of the experimental period (P < 0.0001). Both BLI and BSU alleviated the DON-induced damaging effects on the integrity of intestinal epithelial cells, whereas both Bacillus spp. alleviated the damage caused by DON alone and the proportion of sugar that translocated through the monolayer cells was not different between CON and DON + BLI (P = 0.14) and DON + BLI and DON + BSU (P = 0.62). In summary, both Bacillus spp. strains (B. paralicheniformis 809 and B. subtilis 810) were able to counteract the damaging effects of the challenge agents, hydrogen peroxide and deoxynivalenol, on gut barrier integrity.

Influence of BOVAMINE DEFEND Plus on growth performance, carcass characteristics, estimated dry matter digestibility, rumen fermentation characteristics, and immune function in finishing beef steers

One hundred and eighty crossbred beef steers (406.0 ± 2.2 kg) were used to determine the impact of a novel direct-fed microbial (DFM) on growth performance, carcass characteristics, rumen fermentation characteristics, and immune response in finishing beef cattle. Steers were blocked by body weight (BW) and randomly assigned, within block, to 1 of 2 treatments (3 replicates/treatment: 30 steers/replicate). Treatments included: (1) no DFM (control) and (2) DFM supplementation at 50 mg ∙ animal-1 ∙ d-1 (BOVAMINE DEFEND Plus). All steers were fed a high-concentrate finishing diet and individual feed intake was recorded daily via the GrowSafe system. BWs were collected every 28 d. On day 55, 10 steers per pen were injected with ovalbumin (OVA). Jugular blood samples were collected from each steer on days 0, 7, 14, and 21 post injection. On day 112, the same steers were injected again with OVA and intramuscularly with a pig red blood cell solution. Jugular blood samples were collected from each steer on days 0, 7, 14, and 21 post injection. On day 124, rumen fluid was collected from 3 steers per treatment and used to estimate in vitro rumen fermentation characteristics. Equal numbers of steers per treatment were transported to a commercial abattoir on days 145, 167, and 185 of the experiment, harvested, and carcass data were collected. Initial BW was similar across treatments. On days 28 and 55, steers receiving DFM had heavier BW (P < 0.01) compared to controls. The average daily gain was greater in DFM-supplemented steers from days 0 to 28 (P < 0.01) and days 0 to 55 (P < 0.01) of the experiment compared to controls. Overall dry matter intake (DMI) was greater (P < 0.04) and overall feed efficiency was similar in DFM-supplemented steers compared to controls. Dressing percentage (P < 0.02) was greater in steers receiving DFM compared to controls. Antibody titers to injected antigens were similar across treatments. However, red blood cell superoxide dismutase activity was greater (P < 0.05) in DFM-supplemented steers compared to controls. In vitro molar proportions of isobutyric and butyric acid were greater (P < 0.01) and dry matter (DM) digestibility tended (P < 0.07) to be greater in rumen fluid obtained from steers supplemented with DFM. These data suggest that BOVAMINE DEFEND Plus supplementation improves growth performance during the initial period of the finishing phase, increases overall DMI and dressing percentage, and may impact antioxidant status in beef cattle.

An In Vitro Study on the Role of Cellulases and Xylanases of Bacillus subtilis in Dairy Cattle Nutrition

The administration of Bacilli to dairy cows exerts beneficial effects on dry matter intake, lactation performance, and milk composition, but the rationale behind their efficacy is still poorly understood. In this work, we sought to establish whether cellulases and xylanases, among the enzymes secreted by B. subtilis, are involved in the positive effect exerted by Bacilli on ruminal performance. We took advantage of two isogenic B. subtilis strains, only differing in the secretion levels of those two enzymes. A multi-factorial study was conducted in which eight feed ingredients were treated in vitro, using ruminal fluid from cannulated cows, with cultures of the two strains conveniently grown in a growth medium based on inexpensive waste. Feed degradability and gas production were assessed. Fiber degradability was 10% higher (p < 0.001) in feeds treated with the enzyme-overexpressing strain than in the untreated control, while the non-overexpressing strain provided a 5% increase. The benefit of the fibrolytic enzymes was maximal for maize silage, the most recalcitrant feed. Gas production also correlated with the amount of enzymes applied (p < 0.05). Our results revealed that B. subtilis cellulases and xylanases effectively contribute to improving forage quality, justifying the use of Bacilli as direct-fed microbials to increase animal productivity.

Effect of Replacing Corn Meal with Winged Bean Tuber (Psophocarpus tetragonolobus) Pellet on Gas Production, Ruminal Fermentation, and Degradability Using In Vitro Gas Technique

The objective of this study is to evaluate the effects of replacing corn meal in ruminant diets with winged bean (Psophocarpus tetragonolobus) tubers (WBT) on ruminal fermentation, gas production parameters, and in vitro degradability. The study employed a completely random design (CRD) in its execution. The experimental design employed was a completely randomized design (CRD), featuring eleven levels of corn meal substitution with winged bean tubers pellet (WBTP) at 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 100%. The levels were grouped into four categories of replacement: control (0% in the diet), low levels (10%, 20%, and 30% in the diet), medium levels (40%, 50%, 60%, and 70% in the diet), and high levels (80%, 90%, and 100% in the diet). The experimental results indicated that substituting corn meal with WBTP at moderate and high levels in the diet could improve the performance of the fermentation process by increasing the gas production rate constant from the insoluble fraction (p < 0.01). The IVDMD exhibited a higher degree of in vitro degradation after 12 h (h), with the mean value being higher in the high group compared to the medium until the high group (p < 0.05). At the 4 h mark, the groups that substituted corn meal with WBTP exhibited a decrease in pH value (p < 0.05) in comparison to the control group. The substitution of corn meal with WBTP resulted in the lowest protozoal count after 8 h in the median group (p < 0.05). A significant difference in the effect of WBTP on total volatile fatty acid (TVFA) concentration was observed at 8 h after incubation (p < 0.05). The medium and high levels of WBTP replacement resulted in the lowest TVFA concentration at 8 h (p < 0.05). The mean proportion of acetic acid (C2) linearly declined and was lowest when a high level of WBTP replaced cornmeal (p < 0.05). The concentration of propionic acid (C3) at 8 h after incubation and average values were linearly significantly different when various levels of WBTP were utilized. Replacing corn meal with WBTP at a high level showed the highest concentration of C3. Moreover, substituting medium and high concentrations of WBTP for corn meal resulted in a significant reduction in both the C2:C3 ratio at 8 h and the mean value (p < 0.05). In conclusion, WBTP exhibits a nutritional composition that is advantageous and may be an energetic substitute for corn meal.

Maternal pre- and postpartum supplementation of a Bacillus-based DFM enhanced cow and calf performance

This study evaluated the effects of maternal supplementation of a Bacillus-based direct-fed microbial (DFM) on the physiology and growth performance of Bos indicus-influenced cow-calf pairs. On day 0 (~139 d before expected calving date), 72 fall-calving, Brangus crossbred beef heifers (20 to 22 mo of age) pregnant with first offspring were stratified by their initial body weight (BW; 431 ± 31 kg) and body condition score (BCS; 6.0 ± 0.36; scale 1 to 9), and randomly allocated into 1 of 12 bahiagrass pastures (1 ha and six heifers per pasture). Treatments were randomly assigned to pastures (six pastures per treatment) and consisted of heifers supplemented with 1 kg/d of soybean hulls (dry matter, DM) that was added (BAC) or not (CON) with DFM containing Bacillus subtilis and B. licheniformis (Bovacillus; Chr. Hansen A/S, Hørsholm, Denmark). Treatments were provided from days 0 to 242 (139 ± 4 d prepartum to 104 ± 4 d postpartum). Calves were weaned on day 242 (96 ± 30 d of age) and then allocated into 1 of 16 drylot pens and fed the same concentrate at 3.25% of BW (DM) until day 319. Maternal treatment effects were not detected (P ≥ 0.29) for herbage allowance and forage chemical composition. Heifer BCS on days 39 and 63 tended (P ≤ 0.09) to be greater for BAC vs. CON heifers, whereas heifer BCS on day 91 was greater (P = 0.01) for BAC vs. CON heifers. Heifer BCS did not differ (P ≥ 0.20) between treatments on days 179 and 242. Plasma glucose concentration did not differ from days 0 to 63 (P ≥ 0.14) but were greater (P < 0.01) on day 179 and tended (P = 0.09) to be greater on day 242 for BAC vs. CON heifers. Calf BW at birth, ADG from birth to weaning, and BW at weaning did not differ (P ≥ 0.19) between treatments, but calf BW at drylot exit (day 319) was greater (P = 0.05) for BAC vs. CON calves. Maternal treatment effects were not detected (P ≥ 0.42) for calf serum concentration of IgG at birth and postvaccination plasma concentrations of glucose, cortisol, and haptoglobin. Serum titers against bovine respiratory syncytial virus (BRSV) were greater (P = 0.04) for BAC vs. CON calves on day 287, whereas seroconversion against parainfluenza-3 virus (PI-3) was greater (P < 0.01) for BAC vs. CON calves on day 271. Thus, maternal supplementation of a Bacillus-based DFM increased prepartum BCS gain and postpartum plasma glucose concentration of heifers and led to positive carryover effects on postweaning BW gain and humoral immune response in their offspring.

Effects of direct-fed microbial supplementation on performance and immune parameters of lactating dairy cows

We evaluated the effects of supplementing bacterial direct-fed microbial (DFM) on performance, apparent total-tract digestibility, rumen fermentation, and immune parameters of lactating dairy cows. One hundred fourteen multiparous Holstein cows (41 ± 7 DIM) were used in a randomized complete block design with an experiment comprising 14 d of a covariate (pre-experimental sample and data collection) and 91 d of an experimental period. Cows were blocked based on energy-corrected milk (ECM) yield during the covariate period and the following treatments were randomly assigned within each block: (1) control (CON), corn silage-based total mixed ration without DFM; (2) PRO-A, basal diet top-dressed with a mixture of Lactobacillus animalis and Propionibacterium freudenreichii at 3 × 109 cfu/d; and 3) PRO-B, basal diet top-dressed with a mixture of L. animalis, P. freudenreichii, Bacillus subtilis, and Bacillus licheniformis at 11.8 × 109 cfu/d. Milk yield, dry matter intake (DMI), and body weight were measured daily, while milk samples for component analysis were taken on 2 consecutive days of each week of data collection. Feces, urine, rumen, and blood samples were taken during the covariate period, wk 4, 7, 10, and 13 for estimation of digestibility, N-partitioning, rumen fermentation, plasma nutrient status and immune parameters. Treatments had no effect on DMI and milk yield. Fat-corrected milk (3.5% FCM) and milk fat yield were improved with PRO-B, while milk fat percent and feed efficiency (ECM/DMI) tended to increase with PRO-B compared with PRO-A and CON. Crude fat digestibility was greater with PRO-B compared with CON. Feeding CON and PRO-A resulted in higher total volatile fatty acid concentration relative to PRO-B. Percentage of neutrophils tended to be reduced with PRO-A compared with CON and PRO-B. The mean fluorescence intensity (MFI) of anti-CD44 antibody on granulocytes tended to be higher in PRO-B compared with CON. The MFI of anti-CD62L antibody on CD8+ T cells was lower in PRO-A than PRO-B, with PRO-A also showing a tendency to be lower than CON. This study indicates the potential of DFM to improve fat digestibility with consequential improvement in fat corrected milk yield, feed efficiency and milk fat yield by lactating dairy cows. The study findings also indicate that dietary supplementation with DFM may augment immune parameters or activation of immune cells, including granulocytes and T cells; however, the overall effects on immune parameters are inconclusive.

Stability of Bacillus and Enterococcus faecium 669 Probiotic Strains When Added to Different Feed Matrices Used in Dairy Production

Few data are available evaluating the stability of direct-fed microbials (DFM) following their inclusion in different feed matrices. Therefore, six Exp. evaluated the recovery of bacilli spores (BOVACILLUS^TM; Exp. 1 to 3) and an Enterococcus faecium DFM (LACTIFERM^®; Exp. 4 to 6) when included in different feed preparations. The Bacillus-based DFM was included into pelleted feed prepared in different temperatures (75 to 95 °C), whereas both DFM were assessed in premix and milk replacer preparations. Bacillus spores and E. faecium recovery was evaluated through standard methodologies and data were reported as log10 colony forming units/gram of feed. The recovery of Bacillus spores was within the expected range and was not impacted by the temperature of pellet preparation (Exp. 1). Bacilli recovery was also stable up to 12 months in the premix and was not impacted by the temperature of milk replacer preparation. Regarding the Exp. with E. faecium (Exp. 4 to 6), its recoveries in the mineral premix and milk powder did not differ from T0 and were not impacted by the conditions of milk replacer preparation. These data are novel and demonstrate the stability of a Bacillus-based and an E. faecium-based DFM when included in different feed matrices often used in dairy production.

The Effect of Direct-Fed Microbials on In-Vitro Rumen Fermentation of Grass or Maize Silage

Direct-fed microbial products (DFM) are probiotics that can be used advantageously in ruminant production. The in vitro gas production technique (IVGPT) is a method to simulate rumen fermentation and can be used to measure degradation, gas production, and products of fermentation of such additives. However, inter-laboratory differences have been reported. Therefore, tests using the same material were used to validate laboratory reproducibility. The objective of this study was to assess the effect of adding two DFM formulations on fermentation kinetics, methane (CH4) production, and feed degradation in two different basal feeds while validating a newly established IVGPT laboratory. Six treatments, with three replicates each, were tested simultaneously at the established IVGPT lab at the University of Copenhagen, and the new IVGPT lab at Chr. Hansen Laboratories. Maize silage (MS) and grass silage (GS) were fermented with and without the following DFM: P1: Ligilactobacillus animalis and Propionibacterium freudenreichii (total 1.5 × 107 CFU/mL), P2: P1 with added Bacillus subtilis and B. licheniformis (total 5.9 × 107 CFU/mL). The DFM were anaerobically incubated in rumen fluid and buffer with freeze-dried silage samples for 48 h. Total gas production (TGP: mL at Standard Temperature and Pressure/gram of organic matter), pH, organic matter degradability (dOM), CH4concentration (MC) and yield (MY), and volatile fatty acid (VFA) production and profiles were measured after fermentation. No significant differences between the laboratories were detected for any response variables. The dOM of MS (78.3%) was significantly less than GS (81.4%), regardless of the DFM added (P1 and P2). There were no significant differences between the effects of the DFM within the feed type. MS produced significantly more gas than GS after 48 h, but GS with DFM produced significantly more gas at 3 and 9 h and a similar gas volume at 12 h. Both DFM increased TGP significantly in GS at 48 h. There was no difference in total VFA production. However, GS with and without probiotics produced significantly more propionic acid and less butyric acid than MS with and without probiotics. Adding P2 numerically reduced the total methane yield by 4–6% in both MS and GS. The fermentation duration of 48 h, used to determine maximum potential dOM, may give misleading results. This study showed that it is possible to standardize the methodology to achieve reproducibility of IVGPT results. Furthermore, the results suggest that the P2 DFM may have the potential to reduce CH4 production without affecting organic matter degradation.

Effects of Bacillus licheniformis and Combination of Probiotics and Enzymes as Supplements on Growth Performance and Serum Parameters in Early-Weaned Grazing Yak Calves

Early weaning is an effective strategy to improve cow feed utilization and shorten postpartum intervals in cows; however, this may lead to poor performance of the weaned calves. This study was conducted to test the effects of supplementing milk replacer with Bacillus licheniformis and a complex of probiotics and enzyme preparations on body weight (BW), size, and serum biochemical parameters and hormones in early-weaned grazing yak calves. Thirty two-month-old male grazing yaks (38.89 ± 1.45 kg body weight) were fed milk replacer at 3% of their BW and were randomly assigned to three treatments (n = 10, each): T1 (supplementation with 0.15 g/kg Bacillus licheniformis), T2 (supplementation with a 2.4 g/kg combination of probiotics and enzymes), and a control (without supplementation). Compared to the controls, the average daily gain (ADG) from 0 to 60 d was significantly higher in calves administered the T1 and T2 treatments, and that from 30 to 60 d was significantly higher in calves administered the T2 treatment. The ADG from 0 to 60 d was significantly higher in the T2- than in the T1-treated yaks. The concentration of serum growth hormone, insulin growth factor-1, and epidermal growth factor was significantly higher in the T2-treated calves than in the controls. The concentration of serum cortisol was significantly lower in the T1 treatment than in the controls. We concluded that supplementation with probiotics alone or a combination of probiotics and enzymes can improve the ADG of early-weaned grazing yak calves. Supplementation with the combination of probiotics and enzymes had a stronger positive effect on growth and serum hormone levels, compared to the single-probiotic treatment with Bacillus licheniformis, providing a basis for the application of a combination of probiotics and enzymes.

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

We evaluated the effects of a Bacillus-based direct-fed microbial (DFM) on total in vitro gas production, dry matter (DM), neutral detergent fiber (NDF), and starch disappearance of different feedstuffs and total mixed rations (TMR) in three different experiments. In experiment 1, six single fiber-based feedstuffs were evaluated: alfalfa hay, buffalo grass, beet pulp, eragrostis hay, oat hay, and smutsvinger grass. Experimental treatments were control (with no probiotic inoculation; CON) or incubation of a probiotic mixture containing Bacillus licheniformis and B. subtilis (3.2 × 10⁹ CFU/g; DFM). The calculation of DFM dose under in vitro conditions was based on the assumption of a rumen capacity of 70 liter and the dose of 3 g of the DFM mixture/head/d (9.6 × 10⁹ CFU). Total in vitro gas production, DM, and NDF disappearance were evaluated at 24- and 48 h posttreatment incubation. Mean treatment effects were observed at 24- and 48 h gas production (P < 0.0001), as DFM incubation increased in vitro gas production by 5.0% and 6.5%, respectively. For nutrient digestibility, mean DM digestibility was increased at 48 h (P = 0.05), whereas mean NDF digestibility increased at both timepoints by incubating DFM in vitro (P ≤ 0.02). In experiment 2, nine commercial dairy TMR were collected and evaluated for the same variables and treatments described in experiment 1, with the additional analysis of starch digestibility at 7 h post in vitro incubation. The only difference was the concentration of the DFM included, being representative for a dosage of 8.8 × 10⁹ CFU/head/d. In vitro gas production was increased only at 48 h due to DFM incubation (P = 0.05), whereas DM and NDF digestibility were improved at 24 and 48 h (P ≤ 0.02). No treatment effects were observed on in vitro starch digestibility (P = 0.31). In experiment 3, a combined analysis of DM and NDF digestibility was performed by using quality values (NDF and crude protein or CP) of 16 substrates. Regardless of CP and NDF levels of the substrates, DFM improved in vitro 24 and 48 h DM and NDF digestibility (P ≤ 0.03). In summary, incubating a Bacillus-based DFM (B. licheniformis and B. subtilis; BOVACILLUS) improved mean in vitro gas production, DM, and NDF digestibility of single feedstuffs and commercial dairy TMR, highlighting the potential of this combination of Bacillus spp. to improve nutrient utilization, mainly fiber.

Effects of feeding different probiotic types on metabolic, performance, and carcass responses of Bos indicus feedlot cattle offered a high-concentrate diet

Two experiments were designed to evaluate the effects of different probiotic combinations on rumen fermentation characteristics, performance, and carcass characteristics of feedlot Bos indicus beef bulls offered a high-concentrate diet. In experiment 1, 30 rumen-fistulated Nellore steers were blocked by initial body weight (BW = 350 ± 35.0 kg) and within blocks (n = 10), animals were randomly assigned to receive: 1) high-concentrate diet without probiotic supplementation (n = 10; CONT), 2) CONT plus 1 g per head of a probiotic mixture containing three strains of Enterococcus faecium and one strain of Saccharomyces cerevisiae (3.5 × 109 CFU/g; n = 10; EFSC), and 3) CONT plus 2 g per head of a probiotic mixture containing Bacillus licheniformis and Bacillus subtilis (3.2 × 109 CFU/g; n = 10; BLBS). The experimental period lasted 35 d, being 28 d of adaptation and 7 d of sampling. From day 34 to day 35 of the experimental period, ruminal fluid and fecal samples were collected every 3 h, starting immediately before feeding (0 h) for rumen fermentation characteristics and apparent nutrient digestibility analysis, respectively. In experiment 2, 240 Nellore bulls were ranked by initial shrunk BW (375 ± 35.1 kg), assigned to pens (n = 4 bulls per pen), and pens randomly assigned to receive the same treatments as in experiment 1 (n = 20 pens per treatment). Regardless of treatment, all bulls received the same step-up and finishing diets throughout the experimental period, which lasted 115 d. In both experiments, data were analyzed as orthogonal contrasts to partition-specific treatment effects: 1) probiotic effect: CONT vs. PROB and 2) probiotic type: EFSC vs. BLBS (SAS Software Inc.). In experiment 1, no contrast effects were observed on nutrient intake, overall nutrient digestibility, and rumen fermentation analyses (P ≥ 0.13). Nonetheless, supplementation of probiotics, regardless of type (P = 0.59), reduced mean acetate:propionate ratio and rumen ammonia-N concentration vs. CONT (P ≤ 0.05). In experiment 2, no significant effects were observed for final BW and dry matter intake (P ≥ 0.12), but average daily gain and feed efficiency tended to improve (P ≤ 0.10) when probiotics were offered to the animals. Probiotic supplementation or type of probiotic did not affect carcass traits (P ≥ 0.22). In summary, supplementation of probiotics containing a mixture of E. faecium and S. cerevisiae or a mixture of B. licheniformis and B. subtilis reduced rumen acetate:propionate ratio and rumen ammonia-N levels and tended to improve the performance of feedlot cattle offered a high-concentrate diet.