Bacitracin agar vs. oleandomycin disk supplemented chocolate agar for the recovery of Haemophilus influenzae in diagnostic samples: A prospective comparison.

Haemophilus influenzae is an important pathogen able to cause various forms of respiratory and invasive disease. To provide high sensitivity for detection, culture media must inhibit growth of residential flora from the respiratory tract. This study aimed to identify and compare the diagnostic and economic advantages of using bacitracin containing selective agar (SEL) or oleandomycin disk supplemented chocolate agar (CHOC). Growth and semi-quantitative abundance of H. influenzae and growth suppression of residential flora was prospectively assessed in a 28-week period. H. influenzae was identified in 164 (5 %) of all included samples: CHOC and SEL, CHOC only, and SEL only were positive in 95, 24, and 45 cases. Diagnostic superiority of SEL was primarily attributable to the results of throat swabs. However, on average, € 200 had to be spent for the detection of each additional isolate that was recovered only because of additional incubation on SEL.

A mixture of organic acids and thymol protects primary chicken intestinal epithelial cells from Clostridium perfringens infection in vitro.

Necrotic enteritis causes economic losses estimated to be up to 6 billion US dollars per year. Clinical and subclinical infections in poultry are also both correlated with decreased growth and feed efficiency. Moreover, in a context of increased antibiotic resistance, feed additives with enhanced antimicrobial properties are a useful and increasingly needed strategy. In this study, the protective effects of a blend of thymol and organic acids against the effects of Clostridium perfringens type A (CP) on chicken intestinal epithelial cells were investigated and compared to bacitracin, a widely used antibiotic in poultry production. Primary chicken intestinal epithelial cells were challenged with CP for a total time of 3 h to assess the beneficial effect of 2 doses of citric acid, dodecanoic acid, and thymol-containing blend, and compare them with bacitracin. During the challenge, different parameters were recorded, such as transepithelial electrical resistance, cell viability, mRNA expression, and reactive oxygen species production. CP induced inflammation with cytokine production and loss of epithelial barrier integrity. It was also able to induce reactive oxygen species production and increase the caspase expression leading to cellular death. The high dose of the blend acted similarly to bacitracin, preventing the disruptive effects of CP and inducing also an increase in zonula occludens-1 mRNA expression. The low dose only partially prevented the disruptive effects of CP but successfully reduced the associated inflammation. This study shows that the usage of thymol combined with 2 organic acids can protect primary chicken intestinal epithelial cells from CP-induced damages creating a valid candidate to substitute or adjuvate the antibiotic treatment against necrotic enteritis.

Therapeutic effect of heat-killed Lactobacillus plantarum L-137 on the gut health and growth of broilers.

Although some studies on the effects of para-probiotics on the immune system and intestinal health have been conducted independently of research on antibiotics ass growth promoters. This study investigated the effects of heat-killed Lactobacillus plantarumL-137 (L-137) and antibiotics as preventive and/or therapeutic substances for broilers against subclinical necrotic enteritis caused by Clostridium perfringens (CP). In total, 300 1-day-old broilers (46.13 ± 1.38 g) were randomly stocked at 10 birds pen-1 in five replicates and divided into six groups, namely T1 and T2, positive and negative control of CP challenge; T3 and T4, prevention with basal diet plus 10 and 50 mg/kg L-137; T5 and T6, prevention and treatment with basal diet plus 50 mg/kg of L-137 and bacitracin at 50 ppm, respectively. Broilers administered L-137 in T4, T5 and bacitracin in T6 showed an improved (p < 0.05) villus height/crypt depth ratio than control groups, suggesting that it might significantly boost growth performance. In contrast to bacitracin, a high dosage of L-137 significantly increased (p < 0.05) the spleen index value and the cytokine levels, as well as the expression of intestinal ß-defensin genes on day 28. During the 42-day production period, broilers in T4 and T5 showed a significantly enhanced (p < 0.05) expression of cytokines, AvBD-1 and AvBD-7 on day 42 compared to the control and bacitracin groups. In particular, broilers given the L-137 diets demonstrated no cumulative mortality following CP exposure, compared to a 2% mortality in T6. Our findings provide insight into eco-friendly alternatives to antibiotics for maximizing growth performance, feed efficiency and long-term disease protection in chickens; however, this has to be proven in larger-scale commercial experiments.

Effects of cLFchimera peptide on intestinal morphology, integrity, microbiota, and immune cells in broiler chickens challenged with necrotic enteritis.

Three hundred and sixty 1-day-old male broiler chicks were randomly allocated to 4 treatments of 6 replicates to evaluate the effects of cLFchimera, a recombinant antimicrobial peptide (AMP), on gut health attributes of broiler chickens under necrotic enteritis (NE) challenge. Treatments were as follows: (T1) unchallenged group fed with corn-soybean meal (CSM) without NE challenge and additives (NC); (T2) group fed with CSM and challenged with NE without any additives (PC); (T3) PC group supplemented with 20 mg cLFchimera/kg diet (AMP); (T4) PC group supplemented with 45 mg antibiotic (bacitracin methylene disalicylate)/kg diet (antibiotic). Birds were sampled for villi morphology, ileal microbiota, and jejunal gene expression of cytokines, tight junctions proteins, and mucin. Results showed that AMP ameliorated NE-related intestinal lesions, reduced mortality, and rehabilitated jejunal villi morphology in NE challenged birds. While the antibiotic non-selectively reduced the count of bacteria, AMP restored microflora balance in the ileum of challenged birds. cLFchimera regulated the expression of cytokines, junctional proteins, and mucin transcripts in the jejunum of NE challenged birds. In conclusion, cLFchimera can be a reliable candidate to substitute growth promoter antibiotics, while more research is required to unveil the exact mode of action of this synthetic peptide.

Changes in cecum microbial community in response to total sulfur amino acid (TSAA: DL-methionine) in antibiotic-free and supplemented poultry birds.

The effect of essential total sulfur amino acids (TSAA) like methionine and cysteine on the cecal microbiome of broilers was investigated at 2 different time points (days 21 and 42) of broiler rearing. A total of 360-day-old Cobb male broiler chicks were randomly distributed to 6 dietary treatments in a 2 × 3 factorial arrangement, with 2 levels of antibiotic growth promoters (AGP: 0 and 0.05%) and 3 levels of TSAA (DL-methionine) either for starter (0.7, 0.8, and 0.9%) or finisher chicks (0.52, 0.62, and 0.72%), labeled as diets 1 to 6. Cecal digesta from each replicate (n = 10) were sampled on days 21 and 42. DNA was extracted for the amplification of the V4 region of bacterial 16S rRNA genes and subjected to Illumina sequencing. Bioinformatic analyses were performed using QIIME, Mothur, and ad hoc tools and functional profiles of the inferred metagenome were analyzed using PICRUST. Statistical difference was determined by 2-way ANOVA and PERMANOVA. Clustering of cecal communities using PCoA showed clear separation of microbial communities based on age (P < 0.05) of birds and between low and medium/ high levels of TSAA (DL-methionine). At day 21, bacterial richness and diversity were higher than at day 42 where Clostridium cluster XI and Lactobacillus were found most abundant. No variability in taxonomic richness at the genus level was observed with AGP and DL-methionine supplementation. Interbird variation for richness was greater at day 42 compared to day 21. The mean fold difference of richness was greater (1.5 mean fold) with diets 1 and 6, suggesting interactive effects of AGP and TSAA (DL-methionine) in the diet. KEGG function profiles calculated by PICRUST suggest that the cecal microbiome increased glycolysis and energy generation correlated with increased dietary TSAA (DL-methionine) supplementation levels during the late broiler growth period (day 42). This study increases our knowledge of microbial dynamics and functions that are relevant to host nutrition and performance that may help us tailoring alternative strategies for raising poultry birds under antibiotic-free conditions.

Effect of Bacillus subtilis DSM 32315 on the intestinal structural integrity and growth performance of broiler chickens under necrotic enteritis challenge.

The effect of dietary inclusion of Bacillus subtilis DSM 32315 on the intestinal health and growth performance of Cobb 500 male broilers subjected to a Clostridium perfringens-induced necrotic enteritis (NE) challenge was determined in 2 experiments. In experiment 1, chicks were randomly assigned to 4 treatments of 10 replicate/treatment. In experiment 2, chicks were randomly assigned to 4 treatments of 12 replicates/treatment. The experimental treatments were non-infected, non-supplemented control, infected, non-supplemented control (IC), infected + Bacillus subtilis DSM 32315 (B. subtilis DSM 32315), infected + bacitracin methylene disalicylate (BMD). In both experiments, NE was induced by oral inoculation of toxin producing C. perfringens on 3 consecutive days between 17 and 20 D of age, following exposure of birds to pre-disposing conditions. At day 28 (experiment 1), broilers fed diets with B. subtilis DSM 32315 exhibited a significantly higher body weight, lower mortality, and intestinal NE lesion score, compared to the IC treatment. At day 42 (experiment 2), B. subtilis DSM 32315 supplementation significantly improved BW, feed conversion ratio, production efficiency factor, NE lesion score, and mortality, compared to IC treatment. The effect of B. subtilis DSM 32315 on intestinal integrity of NE challenged chickens was evaluated with histomorphometry. A significantly shallower crypt depth and higher villus height to crypt depth ratio were observed in the mid-intestine of birds belonging to the B. subtilis DSM 32315 group, compared to the IC group. Furthermore, B. subtilis DSM 32315 supplementation significantly reduced the enteritis index associated with NE. In both experiments, the effect of B. subtilis DSM 32315 on the phenotypic measurements of NE and performance was comparable to the effect observed with BMD supplementation. In conclusion, supplementation of the direct fed microbial strain B. subtilis DSM 32315 can ameliorate the pathology and performance detriments associated with NE.

Evaluation of the carryover effect of antibiotic, bee pollen and propolis on growth performance, carcass traits and splenic and hepatic histology of growing rabbits.

Sixty-four nulliparous female rabbits were distributed among eight groups (eight animals/group). Group one was the unsupplemented control group; the other seven groups were supplemented with zinc bacitracin (ZnB) at 100 mg, or bee pollen (BP) and/or propolis (Pro) at 150 and 300 mg in a capsulated form, three times a week, day after day, continuously all over the experimental period. The experiment was run for eight parties; at each parity, 28 kids of each doe group (a total of 224 rabbits) were divided into two subgroups weaned, respectively, at 24 and 30 days of age. Thus, for each parity, there were 16 groups (eight does treatments × two weaning age, 14 rabbits per group). The growing rabbits fed the standard diets without supplements. The growth performance, the carcass traits, the liver and the spleen histology of rabbits were checked up to 90 days of age to find possible carryover effects of the supplements. The supplements had no significant effect on most of the growth performance at 90 days of age, but BP150 and BP+Pro300 increased the growth rate in comparison with ZnB group. The liver weight in the control, BP300 and Pro300 groups was higher than the ZnB one. The spleen weight was higher in the groups ZnB, BP150, Pro300 and BP+Pro300, followed by the control, BP300 and BP+Pro150 and thus Pro150. The heart % in the BP150 and Pro300 groups was higher than ZnB and BP+Pro150 groups. A lymphoid hyperplasia of splenic white pulp was observed in the BP+Pro groups, while propolis alone showed a mild activation of lymphobiosis. The Pro and BP groups showed the same picture of the control group exhibiting a hydropic degeneration of mostly hepatic cells, while the ZnB group exhibited adverse effect on the bile ducts featuring portal periductal inflammatory cells infiltration with epithelial hyperplasia reflecting chronic cholangitis.

Bee pollen and propolis as dietary supplements for rabbit: Effect on reproductive performance of does and on immunological response of does and their offspring.

To evaluate the effect of bee pollen (BP) and/or propolis (Pro) supplementation on rabbit does, 64 nulliparous NZW rabbits does were distributed among eight groups (eight animals/group). One unsupplemented group was the control; the other seven groups were supplemented, respectively, with zinc bacitracin (ZnB) at 100 mg, BP at 150 and 300 mg, Pro at 150 and 300 mg, BP+Pro at 150 and 300 mg of each three times/week, day after day continuously along eight parities. The BP300, Pro300 and BP+Pro150 groups had higher body weight of litter at birth and number of kids born alive. The BP supplementation at 150 mg increased plasma total protein and albumin than the control group. The BP or Pro at 150 mg decreased plasma T3 than the other groups except for BP+Pro150. The ZnB group had significantly greater T3 /T4 ratio compared to BP, Pro and BP+Pro at 150 mg. The BP+Pro150 group had less ALT than the control; BP300 and Pro 300 mg resulted in lower plasma AST than the groups Pro150 with or without BP and the control group. The plasma alkaline phosphatase of BP at 150 or 300 mg and BP+Pro150 was significantly greater than that of the Pro150 group. The BP+Pro300 group had higher WBCs than the other groups. In contrast, the lymphocytes were greater in the Pro and BP+Pro300 groups than in BP, Pro and BP+Pro at 150 mg. The groups supplemented with BP and BP+Pro at 150 and 300 mg had significantly greater SRBCs of doe rabbits and their offspring compared to the control and the ZnB group. The BP at 300 mg increased the serum albumin and α1 -globulin than the control group. The Pro300 group had greater serum α2 -globulin and ß-globulin than the control group. The total globulin was significantly greater for the 300 mg propolis-supplemented groups than the control.

Pulicaria gnaphalodes powder in broiler diets: consequences for performance, gut health, antioxidant enzyme activity, and fatty acid profile.

The search constantly continues to identify potential alternatives to the use of antimicrobial growth promoters (AGP) in broiler production. This trial was conducted with broiler chicks to investigate the effect of different levels of Pulicaria gnaphalodes powder (PGP) in comparison with AGP, and probiotic (PRO) on growth performance, gut microflora, intestinal morphology, antioxidant enzyme activity, and fatty acid profile of meat. Ross 308 male broiler chicks (n = 576) were randomly assigned into 6 dietary treatments with 8 replicate pens per treatment and 12 birds per pen. The dietary treatments consisted of a basal diet as control (CON, with no additive), CON + 0.1% PGP, CON + 0.2% PGP, CON + 0.3% PGP, CON + 0.1% probiotic mixture (PRO), and CON + 0.05% bacitracin methylene disalicylate (AGP). Higher body weight gain and lower feed conversion ratio were obtained in birds fed AGP and 0.3% PGP compared with those fed CON and 0.1% PGP during grower, finisher, and the entire study (P < 0.05). On day 42, birds on PRO, 0.2 and 0.3% PGP treatments had lower counts of Escherichia coli and higher lactobacillus spp. in ileum and cecal contents compared to the CON and 0.1% PGP (P < 0.05). Villus height and villus height to crypt depth ratio of the duodenum were increased (P < 0.05) in response to dietary AGP, PRO, and 0.3% PGP. The diets containing PRO and different levels of PGP increased superoxide dismutase and glutathione peroxidase activities and decreased malondialdehyde level in serum, liver, and thigh muscle (P < 0.05). Total polyunsaturated fatty acid and n-3 fatty acid of birds fed PRO and PGP diets were higher than birds in CON and AGP groups (P < 0.05). In summary, supplementation of PGP could be a potential alternative to AGP in broiler diets due to its combined positive impacts on performance, serum cholesterol, intestinal health, antioxidant activity, and fatty acid profile in meat. Such effects, however, need to be further verified under compromised health or a disease challenge condition.

Characterization of intestinal immune response to Clostridium perfringens infection in broiler chickens.

Necrotic enteritis toxin B (NetB)-producing Clostridium perfringens (CP) type A is the etiological agent of necrotic enteritis (NE) - an economically significant disease in broiler chickens. Understanding the immune response to CP infection in broiler chickens is becoming important to develop effective vaccines against NE. An experiment was conducted to determine the expression levels of selected cytokine genes in the intestine and cecal tonsil of CP-challenged broiler chickens. In a floor-pen housing, broiler chickens were randomly assigned to the following treatment groups: 1) bacitracin methylene disalicylate (BMD)-free control diet with no CP challenge (CX), 2) BMD-supplemented diet with no CP challenge (CM), 3) BMD-free control diet with CP challenge (PCX), or 4) BMD-supplemented diet with CP challenge (PCM). The establishment of CP infection was confirmed, with the treatment groups exposed to CP having a 1.5 to 2-fold higher CP levels (P < 0.05) compared to the non-exposed groups. On day 1 and 7 post-challenge, jejunal segments and cecal tonsils were collected from experimental chickens for quantitative real-time RT-PCR analysis to determine the expression levels of interleukin (IL)-1ß, interferon-γ (IFN-γ), IL-2, IL-13, IL-17, IL-10, and transforming growth factor (TGF)-ß genes. Levels of antibodies to CP recombinant proteins were also determined in the plasma of experimental chickens. Results indicated that on day 7 post-challenge, IL-1ß (proinflammatory cytokine), IL-13 (Th2 cytokine), and IL-17 (Th17 cytokine) were upregulated (P < 0.05) in CP-challenged PCX and PCM treatments, compared to the unchallenged (control) CX and CM treatments. A reverse trend was observed for TGF-ß (anti-inflammatory cytokine), while no change was observed in IFN-γ (Th1 cytokine). Levels of plasma antibodies (IgY) to CP recombinant proteins were higher in CP-challenged treatments (PCX and PCM; P < 0.05), compared to their corresponding controls (CX and CM). It was concluded that CP infection induced inflammatory response in the intestine of broiler chickens, and the mechanisms of inflammation are probably mediated via Th2 and Th17 cells.

Performance and intestinal microbiota of chickens receiving probiotic in the feed and submitted to antibiotic therapy.

The purpose of this study was to verify the ability of a probiotic in the feed to maintain the stability of the gut microbiota in chickens after antibiotic therapy and its association with growth performance. One thousand six hundred twenty 1-day-old Cobb male were housed in floor pens (36 pens, 45 birds/pen) and were fed corn-/soya bean meal-based diets supplemented with or without probiotic (Bacillus subtilis) during the entire rearing phase. From 21 to 24 days of age (three consecutive days), the chickens were submitted to antibiotic therapy via drinking water (bacitracin and neomycin) in order to mimic a field treatment and induce dysbiosis. Growth performance was monitored until 42 days of age. At 2, 4 and 6 days after antibiotic therapy, three chickens from each pen were euthanized and the contents of the small intestine and caeca were collected and pooled. The trial was conducted with four treatments and nine replicates in a 2 × 2 factorial arrangement for performance characteristics (with and without probiotic × with and without antibiotic therapy); for the intestinal microbiota, it was in a 2 × 2 × 3 factorial arrangement (with and without probiotic × with and without antibiotic therapy × 2, 4 and 6 days after the antibiotic therapy) with three replicates per treatment. Terminal restriction length polymorphism (T-RFLP) analysis showed that the structure of gut bacterial community was shaped by the intestinal segment and by the time after the antibiotic therapy. The number of 16S rDNAs copies in caecum contents decreased with time after the therapeutic treatment. The antibiotic therapy and dietary probiotic supplementation decreased richness and diversity indexes in the caecal contents. The improved performance observed in birds supplemented with probiotic may be related to changes promoted by the feed additive in the structure of the intestinal bacterial communities and phylogenetic groups. Antibiotic therapy modified the bacterial structure, but did not cause loss of broiler performance.

Tannins and Bacitracin Differentially Modulate Gut Microbiota of Broiler Chickens.

Antibiotic growth promoters have been used for decades in poultry farming as a tool to maintain bird health and improve growth performance. Global concern about the recurrent emergence and spreading of antimicrobial resistance is challenging the livestock producers to search for alternatives to feed added antibiotics. The use of phytogenic compounds appears as a feasible option due to their ability to emulate the bioactive properties of antibiotics. However, detailed description about the effects of in-feed antibiotics and alternative natural products on chicken intestinal microbiota is lacking. High-throughput sequencing of 16S rRNA gene was used to study composition of cecal microbiota in broiler chickens supplemented with either bacitracin or a blend of chestnut and quebracho tannins over a 30-day grow-out period. Both tannins and bacitracin had a significant impact on diversity of cecal microbiota. Bacitracin consistently decreased Bifidobacterium while other bacterial groups were affected only at certain times. Tannins-fed chickens showed a drastic decrease in genus Bacteroides while certain members of order Clostridiales mainly belonging to the families Ruminococcaceae and Lachnospiraceae were increased. Different members of these groups have been associated with an improvement of intestinal health and feed efficiency in poultry, suggesting that these bacteria could be associated with productive performance of birds.

Antibiotic growth promoters virginiamycin and bacitracin methylene disalicylate alter the chicken intestinal metabolome.

Although dietary antibiotic growth promoters have long been used to increase growth performance in commercial food animal production, the biochemical details associated with these effects remain poorly defined. A metabolomics approach was used to characterize and identify the biochemical compounds present in the intestine of broiler chickens fed a standard, unsupplemented diet or a diet supplemented with the antibiotic growth promoters, virginiamycin or bacitracin methylene disalicylate. Compared with unsupplemented controls, the levels of 218 biochemicals were altered (156 increased, 62 decreased) in chickens given the virginiamycin-supplemented diet, while 119 were altered (96 increased, 23 decreased) with the bacitracin-supplemented diet. When compared between antibiotic-supplemented groups, 79 chemicals were altered (43 increased, 36 decreased) in virginiamycin- vs. bacitracin-supplemented chickens. The changes in the levels of intestinal biochemicals provided a distinctive biochemical signature unique to each antibiotic-supplemented group. These biochemical signatures were characterized by increases in the levels of metabolites of amino acids (e.g. 5-hydroxylysine, 2-aminoadipate, 5-hydroxyindoleaceate, 7-hydroxyindole sulfate), fatty acids (e.g. oleate/vaccenate, eicosapentaenoate, 16-hydroxypalmitate, stearate), nucleosides (e.g. inosine, N6-methyladenosine), and vitamins (e.g. nicotinamide). These results provide the framework for future studies to identify natural chemical compounds to improve poultry growth performance without the use of in-feed antibiotics.

Effects of bacitracin methylene disalicylate and diet change on gastrointestinal integrity and endotoxin permeability in the duodenum of broiler chicken.

OBJECTIVE: To determine the effect of bacitracin methylene disalicylate (BMD) and feed changes on gastrointestinal integrity, endotoxin permeability, and morphometric parameters in the duodenum of broilers. RESULTS: Birds were raised on a starter diet without growth promoting antibiotics for 31 days then switched to a grower diet. Four of the pens including 50 g/ton of BMD while 4 pens remained antibiotic free. Eight birds per treatment were sampled prior to the feed change and at 3 and 7 days following the feed change. Gastrointestinal integrity and endotoxin permeability in the duodenum were determined using a modified Ussing Chamber and an adjacent section fixed in 10% formalin for morphometric analysis. Data were analyzed using Proc Glimmix of SAS with the model fitting BMD treatment, time, and the interaction of BMD treatment and time as fixed effects. Intestinal integrity increased at d 3 and 7 compared to prior to the feed change and addition of BMD (P > 0.001) and villus height was decreased with BMD supplementation (P = 0.049). All other tested effects similar (P > 0.1). In conclusion, the practice of changing feed had a greater effect on intestinal health than addition of BMD. However, the factors driving these differences 42 are unclear.

The Effects of Direct-fed Microbial Supplementation, as an Alternative to Antibiotics, on Growth Performance, Intestinal Immune Status, and Epithelial Barrier Gene Expression in Broiler Chickens.

The objective of this study was to investigate the effects of Bacillus subtilis-based probiotic supplementation in broiler chicken diets on growth performance, feed efficiency, intestinal cytokine, and tight junction (TJ) protein mRNA expression. Zero-day-old broiler chicks (n = 140) were randomly assigned to one of five dietary treatments: basal diet (CON); basal diet supplemented with either antibiotic bacitracin methylene disalicylate (BMD); or probiotics, namely, B. subtilis strain 1781 (PB1), a combination of B. subtilis strain 1104 + strain 747 (PB2), or B. subtilis strain 1781 + strain 747 (PB3). Body weight and feed intake were measured at 14 days of age, and the feed conversion ratio (FCR) was calculated. At 14 days of age, ileal samples were collected and used for intestinal cytokine, TJ protein, and mucin gene expression analysis using qRT-PCR. The chickens supplemented with antibiotic (BMD) and B. subtilis strain 1781 alone (PB1) had significantly higher body weights compared to controls of the same age. Dietary supplementation with antibiotic (BMD) or probiotics (PB1, PB2, PB3) significantly improved the feed efficiency as evidenced by decreased FCR compared to controls. No differences were observed in the expression of IL1ß, IL17F, IFNγ, and MUC2 gene among the different treatment groups. However, elevated expression of IL6 (BMD, PB1, PB2), IL8 (PB2), and TNFSF15 (PB1, PB2, PB3) compared to controls was observed in the ileum. IL2 and IL10 expression was upregulated in chicks in the PB2 and PB3 groups, and IL4 was elevated in the PB1 group. IL13 was elevated in all probiotic-fed groups (PB1, PB2, PB3). Probiotic supplementation was also shown to significantly increase the expression of TJ proteins JAM2, ZO1 (PB2, PB3), and occludin (PB1, PB2). Taken together, B. subtilis supplementation altered intestinal immune activity and influenced gut barrier integrity through increased tight junction gene expression.

Avi-Lution® supplemented at 1.0 or 2.0 g/kg in feed improves the growth performance of broiler chickens during challenge with bacitracin-resistant Clostridium perfringens.

Avi-Lution® is a defined, patented, synbiotic product containing Saccharomyces cerevisiae, Enterococcus faecium, and Bacillus spp. Broiler chickens (n = 1,250) were experimentally treated as uninoculated controls (uCon), inoculated controls (iCon) with Clostridium perfringens, or inoculated and treated with bacitracin methylene disalicylate (BMD) at 55 mg/kg as an infected/treated control or Avi-Lution® at 1.0 (AvL1) or 2.0 (AvL2) g/kg in feed for 42 d. Each treatment was applied to 10 replicate pens of 25 straight-run, newly hatched chicks. Pens treated with AvL1, AvL2, or BMD showed improved growth, feed efficiency, or mortality from necrotic enteritis compared with iCon pens at d 14, 28, and 42. No differences in these measurements, however, were observed between pens treated with AvL1 and AvL2, which suggests that Avi-Lution® was effective at 1.0 g/kg in feed. Despite improved performance, BMD, AvL1, and AvL2 treatments did not decrease the severity of intestinal lesion scores through 42 d of age compared with the infected control. These results demonstrate that Avi-Lution® improved growth performance and feed conversion rates in broilers challenged with Clostridium perfringens despite no difference in severity of intestinal lesion scores.

Effects of prebiotics, probiotics, and their combination on growth performance, small intestine morphology, and resident Lactobacillus of male broilers.

Effects of commercial antimicrobials and the individual and combinational use of commercial prebiotics and probiotics in feed from d zero to 41 on the growth performance, small intestine size, jejunal morphology, and ileal resident bacteria population of broiler chickens were determined. A total of 1,040 one-day-old male Ross × Ross 708 broilers were randomly distributed to 80 floor pens (5 treatments, 16 replications per treatment, 13 chicks per pen). Five dietary treatments were employed: 1) a corn soybean-meal basal diet (served as a negative control diet, NC); 2) a basal diet supplemented with a commercial prebiotic product (Pre); 3) a basal diet supplemented with a probiotic product containing Bacillus subtilis spores (Pro); 4) a basal diet supplemented with both prebiotic and probiotic products (Pre + Pro); and 5) a basal diet supplemented with commercial antimicrobials (served as a positive control diet, PC). At d 14, Pre diets improved the relative level of Lactobacillus in ileal mucosa as compared to NC, Pro, or PC diets (P = 0.045) without improving broiler BW. Broilers fed PC diets exhibited the highest BW gain from d 15 to 27, the lowest duodenum, jejunum, and ileum relative weights as percentage of BW at d 27, and the highest breast weight at d 42 (P = 0.026, 0.035, 0.002, 0.025, and 0.035, respectively). Broilers fed Pro or Pre + Pro diets exhibited higher BW gain from d 28 to 41 (P = 0.005) and higher overall BW gain from d zero to 41 (P = 0.039) than those fed other diets. Dietary treatments did not affect jejunal morphology or ileal resident Escherichia coli level at any age. From our results, including spores of Bacillus subtilis in feed may stimulate growth at a later age and may facilitate broilers in reaching their target weight sooner. Therefore, probiotics are recommended as potential alternatives to antimicrobials in chicken diets, especially in grower and finisher feed.

Novel adjuvant strategy to potentiate bacitracin against MDR MRSA.

OBJECTIVES: Bacitracin is an antimicrobial peptide that is frequently used as an active ingredient in antimicrobial ointments. However, bacitracin resistance is highly prevalent in community-associated MRSA (CA-MRSA) strains and significantly compromises the effectiveness of existing antimicrobial ointments. In this study, we aimed to develop novel adjuvants to enhance the antimicrobial activity of bacitracin by using alkyl gallates. METHODS: The growth of MRSA USA300, the predominant CA-MRSA strain in the USA, was determined in the presence of bacitracin and alkyl gallates at various concentrations. The viability of USA300 and MDR clinical isolates of MRSA was measured after exposure to various combinations of bacitracin and alkyl gallates. RESULTS: Whereas 100 U/mL bacitracin did not inhibit USA300, 1 U/mL bacitracin in combination with as low as 2 mg/L octyl gallate (OG) and 8 mg/L dodecyl gallate (DG), respectively, completely inhibited the growth of USA300. Among the tested alkyl gallates, OG most significantly enhanced the bactericidal activity of bacitracin. For example, 10(-3) U/mL bacitracin with 5 mg/L OG effectively killed USA300, which is an ∼200 000-fold decrease in the MBC of bacitracin for USA300. Furthermore, bacitracin/OG combinations demonstrated similar levels of antimicrobial activity against human clinical isolates of MRSA resistant to multiple antibiotics of clinical importance. CONCLUSIONS: Some alkyl gallates, particularly OG, significantly increased the antimicrobial activity of bacitracin against MDR MRSA.

Effect of Clostridium perfringens infection and antibiotic administration on microbiota in the small intestine of broiler chickens.

The etiological agent of necrotic enteritis (NE) is Clostridium perfringens (CP), which is an economically significant problem for broiler chicken producers worldwide. Traditional use of in-feed antibiotic growth promoters to control NE disease have resulted in the emergence of antibiotic resistance in CP strains. Identification of probiotic bacteria strains as an alternative to antibiotics for the control of intestinal CP colonization is crucial. Two experiments were conducted to determine changes in intestinal bacterial assemblages in response to CP infection and in-feed bacitracin methylene disalicylate (BMD) in broiler chickens. In each experiment conducted in battery-cage or floor-pen housing, chicks were randomly assigned to the following treatment groups: 1) BMD-supplemented diet with no CP challenge (CM), 2) BMD-free control diet with no CP challenge (CX), 3) BMD-supplemented diet with CP challenge (PCM), or 4) BMD-free control diet with CP challenge (PCX). The establishment of CP infection was confirmed, with the treatment groups exposed to CP having a 1.5- to 2-fold higher CP levels (P < 0.05) compared to the non-exposed groups. Next-generation sequencing of PCR amplified 16S rRNA genes, was used to perform intestinal bacterial diversity analyses pre-challenge, and at 1, 7, and 21 d post-challenge. The results indicated that the intestinal bacterial assemblage was dominated by members of the phylum Firmicutes in all treatments before and after CP challenge, especially the Lactobacillaceae and Clostridiales families. In addition, we observed post-challenge emergence of members of the Enterobacteriaceae and Streptococcaceae in the non-medicated PCX treatment, and emergence of the Enterococcaceae in the medicated PCM treatment. This study highlights the bacterial interactions that could be important in suppressing or eliminating CP infection within the chicken intestine. Future studies should explore the potential to use commensal strains of unknown Clostridiales, Lactobacillaceae, Enterobacteriaceae, Streptococcaceae, and Enterococcaceae in effective probiotic formulations for the control of CP and NE disease.

Effect of zinc bacitracin and phytase on growth performance, nutrient digestibility, carcass and meat traits of broilers.

A total of 336 one-day-old Hubbard broiler chickens were randomly distributed among 8 groups, each containing six replicates (7 chickens/replicate). From 1 to 40 days of age, the groups fed the same starter, grower and finisher diets. The control group was unsupplemented; zinc bacitracin (ZnB) group received the antibiotic at 0.5 g/kg; fungal phytase (FP) groups received 250, 500 and 1000 U/kg diet of Aspergillus niger phytase (FP_250, FP_500 and FP_1000 groups), respectively; bacterial phyatse (BP) groups received 250, 500 and 1000 U/kg diet of Escherichia coli phytase (BP_250EP, BP_500EP and BP_1000EP groups) respectively. Considering the whole experimental period, body weight gain was unaffected by ZnB and different concentrations of bacterial and fungal phytase; however, the feed conversion ratio of the group fed a diet supplemented with 500 U of BP was better (p < 0.01) than those fed with a diet supplemented with 500 U of FP. BP_250 group had a higher (p < 0.05) apparent digestibility of ether extract compared to FP_250 group. In conclusion, bacterial phytase at 500 U may enhance performance of broiler chickens fed during days 1-40 of age and yield similar growth performance and economic efficiency to those of eB-supplemented groups.