Effect Of Direct-fed Microbials Research Articles

Effects of direct-fed microbials on productive performance, qualitative traits of eggs, blood biochemicals and ileal microflora of laying hens fed wheat-soybean-based diet

In this study, effects of direct-fed microbial on qualitative traits of eggs and productive performance, ileal and cecal microflora and pH of hens fed wheat-based diets were investigated from 60 to 68 wk of age. The total number of 240 Hy-Line W-36 laying hens were randomly distributed between 40 cages, and the five experimental diets including (A) corn-soybean meal-based control diet, (B) wheat-based diet with no microbial additive, (C) wheat-based diet supplemented with Bacillus velezensis, (D) wheat-based diet supplemented with S. cerevisiae and (E) wheat-based diet supplemented with B. velezensis + S. cerevisiae were assigned to hens with 8 replicate cages per diet and 6 hens per each replicate. Increased egg weight and production (EP), feed intake (FI), improved feed conversion ratio (FCR) and decreased pH of ileum and caecum were observed in layers fed the diet included B. velezensis + S. cerevisiae (P<0.05). Improved intestinal morphology characteristics were observed in hens fed the microbe-added diets (P<0.05). Increased plasma protein, albumen and HDL in hens fed microbe-added diets (P<0.05). Adding B. velezensis + S. cerevisiae to diet, modulated the ileal and caecal microflora composition by decreasing the numbers of Salmonella and increasing the numbers of Lactobacilli. Based on the results of the current study, it can be concluded that adding B. velezensis + S. cerevisiae to the wheat-based diet improve performance and intestinal morphology characteristics of laying hens, decrease plasma levels of cholesterol, triglyceride, and LDL and the intestinal pH and number of Salmonella.

Impact of a live bacterial-based direct-fed microbial (DFM) postpartum and weaning system on performance, mortality, and health of Najdi lambs

Abstract Among the non-nutritive additives available for lamb nutrition, direct-fed microbial (DFM) stands out for altering rumen fermentation and increasing animal productivity. This study was conducted to evaluate the effects of DFM and weaning systems on performance, mortality, and health of newborn lambs. A total of 60 newborn lambs were divided into 4 equal groups and assigned to one of 4 treatments: Control (C) without DFM and late weaning; T1, DFM and early weaning; T2, DFM and mid weaning; and T3, DFM and late weaning. Each lamb in the treated group received 3 doses of DFM (5 mL/lamb). The mortality was reduced by 80% compared to the control group. Lambs in the T2 and T3 with DFM groups had significantly (P < 0.05) higher body weight (BW) and body weight gain (BWG) than lambs in the C group. Glucose, creatinine, and urea nitrogen levels of T3 lambs were significantly (P < 0.05) higher in late weaning compared with the remining treatments. DFM supplementation and weaning system significantly (P < 0.01) reduced serum Zn concentration. These results suggest that the addition of DFM to the diet of newborn lambs and weaning at 60 days improves the overall performance and immunity of the lambs and consequently reduces the mortality rate.

Effects of bacterial DFM and tannins on measures of immunity and growth performance of newly weaned beef calves

Weaning of beef calves has been previously shown to be a stressful event. A number of feed additives have been developed to attenuate the periods of stress in calves, such as direct-fed microbials (DFM) and tannins (TN). A two-year study was conducted to determine the effect of DFM plus tannins (DFM+TN) on newly weaned calf performance and indicators of innate and humoral immune response. Angus calves (n = 142 in year 1; 143 in year 2) were weaned at approximately 6 mo of age, immediately transferred to a feedlot, and fed one of two diets for 42 days: a receiving ration without added DFM+TN (CON), or the same ration with (DFM+TN; 2×108 CFU/hd/d Propionibacterium acidipropionici; 5×107 CFU/hd/d Lactobacillus animalis; 5×107 CFU/hd/d Bifidobacterium animalis and 15 g/hd/d tannins). Body weights were taken on two consecutive days and averaged at the beginning and ending of the study, while single day weights were taken on d 28. In year 2, blood samples from coccygeal vascular complex were collected on d 0, 14, and 28 to measure post-vaccination Bovine viral Diarrhea (BVDV) titers. Upon completion of the 42-d study (year 2 only), calves (n = 72) were transported to Laramie, WY (242 km for 3 h) and additional blood samples were taken on d 0, 2, 4, 7, and 9, relative to transportation, to measure plasma haptoglobin concentrations. There were no differences detected for year (P > 0.18), initial (P = 0.42) and final BW (P = 0.43) or DMI (P = 0.31) due to dietary treatment. However, DFM+TN calves had lower (P = 0.001) overall feed:gain (F:G) and a tendency for greater overall ADG (P = 0.06) compared to CON calves. DFM+TN calves tended to have greater (P = 0.11) total gain overall than CON calves. There were no differences (P ≥ 0.22) in growth performance of calves after transportation. The DFM+TN calves had lower (P < 0.001) haptoglobin concentrations at d 0 and d 4 compared to CON calves (treatment × day effect P = 0.09). Weaned calves fed DFM+TN tended to have greater growth performance, including an improved feed efficiency during the first 42 d post weaning and had a reduction in plasma haptoglobin (d 0 and d 4 post-transport) concentrations relative to CON calves.

PSXII-9 The effects of DFM plus tannins on measures of immunity and growth performance of weaned beef calves

Abstract A two-year study was conducted to determine the effects of direct-fed microbials plus tannins (DFM + TN) on weaned calf performance and indicators of innate immune response. Angus calves (n = 142 year 1; 143 year 2) were weaned at 6 months of age, transferred to a feedlot, and fed one of two diets for 42 days: a ration with added DFM + TN (2×108 Propionibacterium acidipropionici; 5×107 CFU/hd/day Lactobacillus animalis; 5×107 CFU/hd/day Bifidobacterium animalis; and tannins 15 g/hd/day) or a ration with no added DFM +TN (CON). Body weights were taken on consecutive days and averaged at the beginning and ending of the study, while single day weights were taken on d 14, and 28. Upon completion of the feeding study (year 2), calves (n = 72) were transported to Laramie, WY (204 km), where blood samples were taken on d 0, 2, 4, 7, and 9 relative to transportation to measure plasma haptoglobin. Data were compared among groups using a categorical response mixed model. The model included the fixed effect of treatment group and the data were measured repeatedly. DFM + TN calves had lower overall (P = 0.001) F:G and tended to have greater ADG (P = 0.15) and lower F:G (P = 0.12) during the first 28 days and greater overall ADG (P = 0.06) and greater (P = 0.11) total gain overall. There was a tendency (P = 0.09) for a treatment x day effect for DFM + TN calves to have lower plasma haptoglobin concentration on day 0 and 4 than CON calves. Weaned calves fed DFM + Tannins tended to have greater growth performance during the first 42 days post weaning and tended to have a reduction in plasma haptoglobin concentrations, suggesting a reduction in stress and a positive impact on calf growth.

PSVI-15 Effect of direct-fed microbials on fecal characteristics during an acidosis induction

Abstract The objective was to investigate the effects of two direct-fed microbial dosing strategies on fecal characteristics of beef cattle during an acidosis challenge. Ruminal acidosis is a metabolic disorder in beef cattle that may contribute to hindgut acidosis. Eighteen ruminally cannulated steers (BW = 328 ± 20 kg) were used in a completely randomized design with 6 steers in each period. Two steers in each period were randomly assigned to one of three treatments: blank media (NCON), a single strain of Megasphaera elsdenii at 108 CFU (DFM1), and a combination of Megasphaera elsdenii and proprietary microbial strains at 1010 CFU per dose (DFM2). On d 1, DFM1 was dosed once and DFM2 and NCON were dosed daily at 0700 on d 1-15. A basal diet (45% forage) was fed ad libitum on d 1-7. To induce acidosis, steers were fasted for 24 h on d 8 and were fed the challenge diet (10% forage) ad libitum on d 9-15. Fecal pH was measured throughout the challenge and total feces was collected on d 11-14 to determine washed fecal particle size and observe mucin casts. Fecal pH and mucin cast score was not affected (P ≥ 0.29) by treatment. Fecal particle size in DFM1-treated steers was greater (P = 0.01) than NCON and DFM2. Fecal particle size tended (P = 0.06) to increase over time. Fecal particle size was not correlated (P ≥ 0.56) to ruminal or fecal pH. Fecal mucin cast score was positively correlated to dry matter intake (P &amp;lt; 0.01) and mean ruminal pH (P = 0.06). Mucin cast score may help in monitoring ongoing bouts of ruminal acidosis. Overall, results indicate direct-fed microbial treatment affected fecal particle size but not fecal pH and mucin cast score during an acidosis challenge.

Effects of a blend of Saccharomyces cerevisiae-based direct-fed microbial and fermentation products on plasma carbonyl-metabolome and fecal bacterial community of beef steers

BackgroundPrevious studies have evaluated the metabolic status of animals fed direct-fed microbial (DFM) using enzyme-based assays which are time-consuming and limited to a few metabolites. In addition, little emphasis has been placed on investigating the effects of DFM on hindgut microbiota. We examined the effects of dietary supplementation of a blend of Saccharomyces cerevisiae-based DFM and fermentation products on the plasma concentrations of carbonyl-containing metabolites via a metabolomics approach, and fecal bacterial community, via 16S rRNA gene sequencing, of beef steers during a 42-day receiving period. Forty newly weaned steers were randomly assigned to receive a basal diet with no additive (CON; n = 20) or a basal diet supplemented with 19 g of Commence™ (PROB; n = 20) for a 42-day period. Commence™ (PMI, Arden Hills, MN) is a blend of 6.2 × 1011 cfu/g of S. cerevisiae, 3.5 × 1010 cfu/g of a mixture of Enterococcus lactis, Bacillus subtilis, Enterococcus faecium, and Lactobacillus casei, and the fermentation products of these aforementioned microorganisms and those of Aspergillus oryzae and Aspergillus niger. On d 0 and 40, rectal fecal samples were collected randomly from 10 steers from each treatment group. On d 42, blood was collected for plasma preparation.ResultsA total number of 812 plasma metabolites were detected. Up to 305 metabolites [fold change (FC) ≥ 1.5, FDR ≤ 0.01] including glucose, hippuric acid, and 5-hydroxykynurenamine were increased by PROB supplementation, whereas 199 metabolites (FC ≤ 0.63, FDR ≤ 0.01) including acetoacetate were reduced. Supplementation of PROB increased (P ≤ 0.05) the relative abundance of Prevotellaceae UCG-003, Megasphaera, Dorea, Acetitomaculum, and Blautia. In contrast, the relative abundance of Elusimicrobium, Moheibacter, Stenotrophomonas, Comamonas, and uncultured bacterium belonging to family p-2534-18B5 gut group (phylum Bacteroidetes) were reduced (P ≤ 0.05).ConclusionsThe results of this study demonstrated that supplementation of PROB altered both the plasma carbonyl metabolome towards increased glucose concentration suggesting an improved energy status, and fecal bacterial community, suggesting an increased hindgut fermentation of the beef steers.

Bacterial direct-fed microbials fail to reduce methane emissions in primiparous lactating dairy cows

Direct-fed microbials (DFM) are considered as a promising technique to improve animal productivity without affecting animal health or harming the environment. The potential of three bacterial DFM to reduce methane (CH4) emissions, modulate ruminal fermentation, milk production and composition of primiparous dairy cows was examined in this study. As previous reports have shown that DFM respond differently to different diets, two contrasting diets were used in this study. Eight lactating primiparous cows were randomly divided into two groups that were fed a corn silage-based, high-starch diet (HSD) or a grass silage-based, high-fiber diet (HFD). Cows in each dietary group were randomly assigned to four treatments in a 4 × 4 Latin square design. The bacterial DFM used were selected for their proven CH4-reducing effect in vitro. Treatments included control (without DFM) and 3 DFM treatments: Propionibacterium freudenreichii 53-W (2.9 × 1010 colony forming units (CFU)/cow per day), Lactobacillus pentosus D31 (3.6 × 1011 CFU/cow per day) and Lactobacillus bulgaricus D1 (4.6 × 1010 CFU/cow per day). Each experimental period included 4 weeks of treatment and 1 week of wash-out, with measures performed in the fourth week of the treatment period. Enteric CH4 emissions were measured during 3 consecutive days using respiration chambers. Rumen samples were collected for ruminal fermentation parameters and quantitative microbial analyses. Milk samples were collected for composition analysis. Body weight of cows were recorded at the end of each treatment period. Irrespective of diet, no mitigating effect of DFM was observed on CH4 emissions in dairy cows. In contrast, Propionibacterium increased CH4 intensity by 27% (g CH4/kg milk) in cows fed HSD. There was no effect of DFM on other fermentation parameters and on bacterial, archaeal and protozoal numbers. Similarly, the effect of DFM on milk fatty acid composition was negligible. Propionibacterium and L. pentosus DFM tended to increase body weight gain with HSD. We conclude that, contrary to the effect previously observed in vitro, bacterial DFM Propionibacterium freudenreichii 53-W, Lactobacillus pentosus D31 and Lactobacillus bulgaricus D1 did not alter ruminal fermentation and failed to reduce CH4 emissions in lactating primiparous cows fed high-starch or high-fiber diets.

Effects of chlortetracycline alone or in combination with direct fed microbials on nursery pig growth performance and antimicrobial resistance of fecal Escherichia coli.

A total of 300 nursery pigs (initially 5.9 ± 0.05 kg BW) were used in a 42-d growth trial to evaluate the effects of feeding a therapeutic level of chlortetracycline (CTC) with or without direct fed microbials (DFM) on growth performance and antimicrobial resistance (AMR) of fecal Escherichia coli. CTC is a broad-spectrum in-feed antibiotic commonly used in the swine industry. Weaned pigs (~21 d of age) were allotted to pens based on initial BW and fed a common starter diet for 4 d. Pens were then blocked by BW and allotted to dietary treatments in a completely randomized block design. Dietary treatments were arranged in a 2 × 3 factorial consisting of combinations of CTC (none vs. 400 mg/kg from days 0 to 42) and DFM (0 vs. 0.05% DFM 1 vs. 0.05% DFM 2). Fecal samples were collected from three randomly selected pigs from each pen on days 0, 21, and 42 for E. coli isolation and AMR determination. Overall, pigs fed diets containing CTC had improved (P < 0.001) ADG, ADFI, and BW compared to those not fed CTC with no evidence for any effect of either DFM 1 or DFM 2. Regardless of CTC, inclusion of DFM 2 in diets improved (P < 0.05) ADFI from days 0 to 14 and on day 14 BW compared to diets that did not include DFM 2. The addition of CTC with or without DFMs to nursery pig diets increased (P < 0.05) the probability of AMR to tetracycline and ceftiofur of fecal E. coli isolates, but this resistance generally decreased (P < 0.05) over time. A decrease (P < 0.05) in AMR to ampicillin and tetracycline (TET) throughout the trial was observed, while resistance to ceftriaxone decreased (P < 0.020) from days 0 to 21 and increased from days 21 to 42 amongst dietary treatments regardless of CTC or DFM inclusion in the diet. A CTC × DFM × day interaction (P < 0.015) was observed for streptomycin, whereby from days 21 to 42 AMR increased in diets containing either CTC or DFM 1 alone, but the combination decreased resistance. There was no evidence for any effect of DFMs on AMR of fecal E. coli isolates to any other antibiotics evaluated. In conclusion, therapeutic levels of added CTC with or without DFM inclusion improved nursery pig performance, but increased AMR of fecal E. coli isolates to TET and ceftiofur. A moderate improvement in intake and day 14 BW was observed when DFM 2 was included in the diet with or without CTC, but, except for streptomycin, there was no evidence that added dietary DFMs affected resistance of fecal E. coli to antibiotics.

Effect of direct-fed microbials on culturable gut microbiotas in broiler chickens: a meta-analysis of controlled trials.

ObjectiveThis meta-analysis was conducted to evaluate the overall effect of direct-fed microbial (DFM) or probiotic supplementation on the log concentrations of culturable gut microbiota in broiler chickens.MethodsRelevant studies were collected from PubMed, SCOPUS, Poultry Science Journal, and Google Scholar. The studies included controlled trials using DFM supplementation in broiler chickens and reporting log concentrations of the culturable gut microbiota. The overall effect of DFM supplementation was determined using standardized mean difference (SMD) with a random-effects model. Subgroups were analyzed to identify pre-specified characteristics possibly associated with the heterogeneity of the results. Risk of bias and publication bias were assessed.ResultsEighteen taxa of the culturable gut microbiota were identified from 42 studies. The overall effect of DFM supplementation on the log concentrations of all 18 taxa did not differ significantly from the controls (SMD = −0.06, 95% confidence interval [−0.16, 0.04], p = 0.228, I2 = 85%, n = 699 comparisons), but the 18 taxa could be further classified into three categories by the direction of the effect size: taxa whose log concentrations did not differ significantly from the controls (category 1), taxa whose log concentrations increased significantly with DFM supplementation (category 2), and taxa whose log concentrations decreased significantly with DFM supplementation (category 3). Category 1 comprised nine taxa, including total bacterial counts. Category 2 comprised four taxa: Bacillus, Bifidobacterium, Clostridium butyricum, and Lactobacillus. Category 3 comprised five taxa: Clostridium perfringens, coliforms, Escherichia coli, Enterococcus, and Salmonella. Some characteristics identified by the subgroup analysis were associated with result heterogeneity. Most studies, however, were present with unclear risk of bias. Publication bias was also identified.ConclusionDFM supplementation increased the concentrations of some beneficial bacteria (e.g. Bifidobacterium and Lactobacillus) and decreased those of some detrimental bacteria (e.g. Clostridium perfringens and Salmonella) in the guts of broiler chickens.

Effect of Direct-fed Microbials, Bacillus subtilis, on Production Performance, Serotonin Concentrations and Behavioral Parameters in a Selected Dominant Strain of White Leghorn Hens

Effect of Direct-fed Microbials, Bacillus subtilis, on Production Performance, Serotonin Concentrations and Behavioral Parameters in a Selected Dominant Strain of White Leghorn Hens

Impact of Saccharomyces cerevisiae boulardii CNCMI-1079 and Lactobacillus acidophilus BT1386 on total lactobacilli population in the gastrointestinal tract and colon histomorphology of Holstein dairy calves

There is interest in the use of direct-fed microbials (DFM) as substitutes for antibiotic growth promoters in farm animal production. However, little information exists on their effects in dairy calves. The aims of this study were to: 1) determine the viability of supplemental DFM in feed and throughout the gastrointestinal tract (GIT) of calves; 2) evaluate the effect of DFM on total lactobacilli population in the digestive tract and in feces of calves; and 3) examine the influence of DFM on colon histomorphology and overall calf performance. Forty eight calves (2–7days old) were randomly allocated to four treatments as follows: 1) Control (CTRL) fed milk replacer (MR) followed by starter feed (SF); 2) CTRL supplemented with Saccharomyces cerevisiae boulardii CNCMI-1079 (SCB; 7.5×108 colony forming units (CFU)/L MR+3×109 CFU/kg SF); 3) CTRL supplemented with Lactobacillus acidophilus BT1386 (LA; 2.5×108 CFU/L MR+1×109 CFU/kg SF); and 4) CTRL supplemented with antibiotics (ATB) chlortetracycline and neomycin (528 and 357mg/L MR, respectively), and chlortetracycline (55mg/kg SF). Four calves per treatment were euthanized on day 33 (pre-weaning) and an additional four calves per treatment on day 96 (post-weaning) to sample different sections of the GIT. The effects of treatments were analyzed following a completely randomized design with repeated measures and Tukey adjustments for multiple comparisons. The DFM (SCB and LA) remained viable in the commercial product throughout the period of the experiment. Viable SCB was recovered throughout the GIT and in the feces pre- and post-weaning. There was no effect of DFM on total lactobacilli population in the GIT of calves. However, feces of SCB-treated calves showed a greater lactobacilli population compared with CTRL (P<0.01) around weaning. In the pre-weaning period, the distribution of lactobacilli population differed along the digestive tract (colon > ileum content > rumen > ileum mucosa; P<0.001). The lactobacilli population was significantly reduced in all compartments (P=0.02) post-weaning compared to pre-weaning, except in the rumen. Crypts depth and width of the colon decreased (P<0.01) whereas number of goblet cells containing neutral mucins tended to increase (P=0.058) while acidic mucins increased (P<0.05) in SCB- and ATB-treated calves compared with CTRL and LA-treated calves. Overall, growth performances were not affected by treatment. Feeding SCB stimulated total lactobacilli population around weaning and altered colon morphology with potential beneficial effects during the early period of growth in calves. Our findings suggest that SCB would deserve more attention as a modulator of the gastrointestinal health in young dairy calves.

Effect of Direct-fed Microbials on Intestinal Villus Height in Broiler Chickens: A Systematic Review and Meta-Analysis of Controlled Trials

Effect of Direct-fed Microbials on Intestinal Villus Height in Broiler Chickens: A Systematic Review and Meta-Analysis of Controlled Trials

Effects of a multi-strain spp. direct-fed microbial and a protease enzyme on growth performance, nutrient digestibility, blood characteristics, fecal microbiota, and noxious gas emissions of grower pigs fed corn-soybean-meal-based diets—A meta-analysis

Three studies involving 352 grower pigs were conducted to determine the effects of dietary supplementation with multistrain spp. direct-fed microbial (DFM) and protease, alone or in combination, on growth performance, nutrient digestibility, blood characteristics, fecal microbiota, and noxious gas emissions, and to use a meta-analysis to increase the reliability of the findings. Treatments ( = 4) were set up as a 2 × 2 factorial design with 2 levels of protease (0 and 5.000/6.000 units/kilogram of feed [U/KG]) and 2 levels of DFM (0 and 1.5 × 10 colony forming units/gram of feed [CFU/G]), plus a protease + DFM combination. Pigs were housed in groups of 3 or 4/pen with 8 replicate pens/treatment. Experimental diets were fed for 42 d and feed intake and BW were measured weekly. Fecal samples were collected at d 42 and analyzed to determine apparent total tract digestibility (ATTD). Fecal counts of and coliforms, and noxious gas emissions were measured. Blood samples were taken by anterior vena cava puncture to measure blood urea nitrogen (BUN) and creatinine. Data from the 3 studies were pooled and analyzed as a 2 × 2 factorial using the Fit Model platform of JMP 11 (SAS Inst. Inc., Cary, NC). Means separation was determined using Tukey's honest significant difference test. The main effect of protease and DFM increased: BW at 42 d, overall ADG, and overall G:F compared to the control ( < 0.04). There were no interactions between protease and DFM ( > 0.05); however, the protease + DFM combination was the only treatment to improve ADG and G:F in all phases compared to the control. The main effect of protease increased ATTD of DM, nitrogen (N), and ADF ( < 0.04). The main effect of DFM increased ATTD of DM, N, GE, DE, ADF, and fat ( < 0.02). There was a trend for an interaction between protease and DFM for ATTD of GE and DE ( < 0.08) because the protease + DFM combination increased energy digestibility more than the additive effects of the protease and DFM alone. The main effects of protease and DFM decreased fecal ammonia emissions ( < 0.01), but the protease + DFM combination was the only treatment to decrease ammonia emissions compared to the control. In conclusion, the main effects of protease and DFM improved growth performance and nutrient digestibility compared to the control, but there was a greater additive effect of the protease + DFM combination on energy and N digestibility.

Performance and carcass characteristics of commercial feedlot cattle from a study of vaccine and direct-fed microbial effects on Escherichia col O157:H7 fecal shedding.

The objective of this study was to quantify cattle performance and carcass characteristics associated with administration of a siderophore receptor and porin proteins-based vaccine (VAC) and a direct-fed microbial (DFM), which were originally evaluated for their impact on O157:H7 fecal shedding in a commercial feedlot population. Cattle (P = 17,148) were randomly allocated into 40 pens grouped by allocation dates into 10 complete blocks; pens within block were randomly allocated to control, VAC, DFM, or VAC + DFM treatment groups in a 2 × 2 factorial design. The DFM (Bovamine) was fed daily at the labeled dose of 10 cfu/animal of Lactobacillus acidophilus for the duration of the intervention period (mean = 86.6 d). The VAC cattle were vaccinated on Days 0 and 21 whereas unvaccinated cattle were not given a placebo or rehandled on Day 21. Data were analyzed using general and generalized linear mixed models that accounted for the study design. Main effects of DFM and VAC are reported as there were no significant treatment interactions for any of the outcomes evaluated. Vaccinated cattle had lower total weight gain (P < 0.01), ADG (P = 0.03), and cumulative DMI during the intervention period (P < 0.01) compared with unvaccinated cattle, whereas the DFM increased total weight gain (P = 0.03) and G:F (P = 0.05) during the intervention period. Daily DMI was decreased (P < 0.01) in vaccinated pens compared with unvaccinated pens during a 5-d period immediately following revaccination. After the intervention period was completed, cattle were sorted following the standard operating procedure for the feedlot and all cattle were fed the DFM from that point until harvest. Each steer was individually identified through harvest. At harvest, vaccinated cattle had more total days on feed (P < 0.01) with a larger HCW (P = 0.01) than nonvaccinated cattle, whereas cattle not fed the DFM during the intervention period had a significantly larger HCW (P < 0.01) than those fed the DFM during the intervention period. We conclude that the use of these DFM and vaccine products have differential and independent effects on cattle performance and carcass characteristics in a commercial feedlot setting. Although the magnitude of these effects may vary among production systems, a more comprehensive understanding of the potential production costs of preharvest food safety pathogen control programs is essential if such programs are to be fully adopted in the industry.

Effect of direct-fed microbials on utilization of degradable intake protein in receiving steers

Kenney, N. M., Vanzant, E. S., Harmon, D. L. and McLeod, K. R. 2015. Effect of direct-fed microbials on utilization of degradable intake protein in receiving steers. Can. J. Anim. Sci. 95: 93–102. One hundred ninety-two crossbred beef steers (280±25 kg) were assigned to a 5×2 factorial; degradable intake protein (DIP; 80, 90, 100, 110, 120% of requirement) with and without a direct-fed microbial (DFM) primarily containing Lactobacillus acidophilus and Enterococcus faecium (109CFU steer−1d−1). Dry matter intake, morbidity, and immune response were not affected (P≥0.11). The first 28 d, average daily gain (ADG) did not differ with DIP in control, but increased in a cubic fashion with DFM (DIP×DFM; P=0.05). No differences (P≥0.25) in ADG occurred from days 29 to 56; however, there was a tendency (P=0.08) for a cubic increase in ADG with increasing DIP with DFM over 56 d. The first 28 d, growth efficiency did not differ across DIP levels in control but increased linearly with DFM (DIP×DFM; P=0.05). No differences (P≥0.21) in efficiency were observed from days 29 to 56 or overall. Without DFM, fecal pH decreased between days 7 and 14; however, with DFM there was no change in pH (DFM×time; P&lt;0.05). Performance response to DFM is dependent on DIP; however, DFM does not impact morbidity or humoral immune response.

Use of a direct-fed microbial product as a supplement during the transition period in dairy cattle

Two studies were conducted. The objective of the first study was to assess the effects of a direct-fed microbial (DFM) product on dry matter intake, milk yield, milk components, disease incidence, and blood metabolites in dairy cattle. The objective of the second study was to assess the effects of DFM on apparent total-tract nutrient digestibility (ATTD). One hundred twenty primiparous and multiparous Holstein cows housed in a tiestall facility at the University of Guelph were used in study 1, and a subset (21) of the same cows participated in study 2. Cows were blocked by anticipated calving date (6 blocks) and then randomly assigned within parity to receive either a DFM supplement (Chr. Hansen Ltd., Milwaukee, WI) or placebo (control). The DFM supplement provided cows with 5.0 × 109 cfu/d of 3 strains of Enterococcus faecium and 2.0 × 109 cfu/d of Saccharomyces cerevisiae. The DFM supplement was mixed with 0.5kg of ground dry corn and top-dressed during the morning feeding. The placebo supplement contained the corn only. Individual feed intakes and milk yields were recorded daily. The experiment commenced 3wk before calving and ended 10wk postcalving. Milk samples for component analysis were collected on 3 d per week and pooled by week. Body weights and body condition scores were assessed 1 d before enrollment in the study (wk –3), postcalving (wk 1), and at the end of wk 3, 6, and 9. Blood samples were collected before calving (wk –3) and the end of wk 1 and 3. Study 1 showed that treatment had no effect on average dry matter intake or milk yield (kg/d) over the duration of the experiment. The changes in body weights and body condition scores and net energy balance over the duration of the experiment did not differ due to treatment. Treatment had no effect on plasma concentrations of β-hydroxybutyrate, nonesterified fatty acids, glucose, or haptoglobin. Study 2 investigated the effects of DFM on ATTD of starch and neutral detergent fiber (NDF) using insoluble NDF and lignin as internal markers. Study 2 used 21 cows (block 6) from the cows that participated in study 1 while the cows were between 60 and 70 d in milk. Cows receiving DFM had lower fecal starch content (0.88±0.10 vs. 1.39±0.25) and greater ATTD for starch (98.76%±0.28 vs. 97.87%±0.24) compared with those receiving placebo, and the AATD of NDF did not differ. Additionally, we detected no difference between internal markers for the measurement of ATTD. In conclusion, we were unable to detect a change in overall dry matter intake, milk yield, or milk and blood parameters with DFM supplementation. However, our results demonstrated that DFM can have a positive effect on total-tract starch digestibility. More studies are needed to investigate the effects of DFM and their modes of action under multiple management conditions.

Effects of direct-fed microbials and their combinations with yeast culture on &lt;i&gt;in vitro&lt;/i&gt; rumen fermentation characteristics

1. Influence of Yeast Fermented Cassava Chip Protein (YEFECAP) and Roughage to Concentrate Ratio on Ruminal Fermentation and Microorganisms Using <italic>In vitro</italic> Gas Production Technique S. Polyorach, M. Wanapat, A. Cherdthong Asian-Australasian Journal of Animal Sciences CrossRef

Direct-fed Microbials for Ruminant Animals

Direct-fed microbials (DFM) are dietary supplements that inhibit gastrointestinal infection and provide optimally regulated microbial environments in the digestive tract. As the use of antibiotics in ruminant feeds has been banned, DFM have been emphasized as antimicrobial replacements. Microorganisms that are used in DFM for ruminants may be classified as lactic acid producing bacteria (LAB), lactic acid utilizing bacteria (LUB), or other microorganisms including species of Lactobacillus, Bifidobacterium, Enterococcus, Streptococcus, Bacillus and Propionibacterium, strains of Megasphaera elsdenii and Prevotella bryantii and yeast products containing Saccharomyces and Aspergillus. LAB may have beneficial effects in the intestinal tract and rumen. Both LAB and LUB potentially moderate rumen conditions and improve feed efficiency. Yeast DFM may reduce harmful oxygen, prevent excess lactate production, increase feed digestibility, and improve fermentation in the rumen. DFM may also compete with and inhibit the growth of pathogens, stimulate immune function, and modulate microbial balance in the gastrointestinal tract. LAB may regulate the incidence of diarrhea, and improve weight gain and feed efficiency. LUB improved weight gain in calves. DFM has been reported to improve dry matter intake, milk yield, fat corrected milk yield and milk fat content in mature animals. However, contradictory reports about the effects of DFM, dosages, feeding times and frequencies, strains of DFM, and effects on different animal conditions are available. Cultivation and preparation of ready-to-use strict anaerobes as DFM may be cost-prohibitive, and dosing methods, such as drenching, that are required for anaerobic DFM are unlikely to be acceptable as general on-farm practice. Aero-tolerant rumen microorganisms are limited to only few species, although the potential isolation and utilization of aero-tolerant ruminal strains as DFM has been reported. Spore forming bacteria are characterized by convenience of preparation and effectiveness of DFM delivery to target organs and therefore have been proposed as DFM strains. Recent studies have supported the positive effects of DFM on ruminant performance.

Effects of direct-fed microbials on growth performance, gut morphometry, and immune characteristics in broiler chickens

This study was conducted to compare growth performance, gut morphometry, and parameters of local and systemic immunity in broiler chickens fed for 22 consecutive days with a diet supplemented with Bacillus spp. as direct-fed microbials (DFM), a commercial product incorporating 3 DFM, or a nonsupplemented diet. Direct-fed microbials did not significantly modify BW gain and most failed to affect serum antibody levels in response to immunization with a recombinant Eimeria protein. However, altered intestinal morphometric measurements were readily apparent in DFM-fed chickens as revealed by increased villus height and crypt depth compared with non-DFM-fed controls. In addition, serum levels of alpha-1-acid glycoprotein as an inflammatory marker were reduced in DFM-fed birds, whereas splenic lymphocyte proliferation, intestine intraepithelial lymphocyte subpopulations, and cytokine mRNA levels in intraepithelial lymphocytes were increased, decreased, or unchanged compared with controls depending on the DFM used. These results provide a rational scientific basis for future studies to investigate DFM as immunomodulating agents to enhance host protective immunity against enteric pathogens in broiler chickens.

Direct-Fed Microbials and Their Impact on the Intestinal Microflora and Immune System of Chickens

Direct-fed microbials (DFMs) are live microorganisms which confer a health benefit to the host. The mode of action of DFMs involves multiple mechanisms, including direct inhibition of enteric pathogens and indirectly through competitive exclusion of pathogens by the normal gut microbiota. Additionally, recent basic research efforts have focused on the effects of DFMs on promoting host immunity and on the complex interactions between the gut microflora and immune system development. This review will summarize the latest developments in DFM studies with particular emphasis on the underlying mechanisms of immune enhancement.