Isolation, characterization, and experimental infection of Streptococcus gallolyticus subspecies pasteurianus from commercial turkeys with acute septicemia: a pilot study

Streptococcus gallolyticus (SG) is a Gram-positive cocci found as commensal gut flora in animals and humans. SG has emerged as a cause of disease in young poults between 1 and 3 wk of age. SG is associated with septicemia resulting in acute mortality with no premonitory signs in turkeys. Three SG isolates were obtained from clinical field cases of acute septicemia of commercial turkeys and used in three independent experiments. In Experiment 1, embryos were inoculated 25 d of embryogenesis with varying concentrations of SG1, SG2, or SG3. In Experiment 2, day of hatch, poults were inoculated with varying concentrations using different routes of administration of SG1, SG2, or SG3. In Experiment 3, day of hatch, poults were inoculated with only isolate SG1 using different paths. Poults were randomly selected for necropsy on d 8 and d 15 and sampled to collect spleen, heart, and liver for SG on d 21, the remaining poults were necropsied and cultured. Samples were plated on Columbia nalidixic acid and colistin agar (CNA) (40°C, 18-24 h). Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) confirmed suspect colonies. Data were analyzed using the chi-square test of independence, testing all possible combinations to determine significance (P < 0.05). Weight data were subjected to ANOVA using JMP with significance (P < 0.05). No differences were found in BW or BWG on d 0, 8, 15, or 22. Splenomegaly, focal heart necrosis, and pericarditis were observed in all groups in experiments 1 through 3. In Experiment 3, only airsacculitis was observed in a negative control in separate isolation (P > 0.05). On d 21 of Experiment 3, increased (P < 0.05) recovery of SG from spleens were observed in co-housed negative controls, as well as poults challenged by oral gavage (P > 0.05 for d 7 and d 14). These results confirm numerous previous studies indicating that SG subsp. pasteurianus is a primary infectious microorganism that causes septicemia in young poults.

Evaluation of the impact of formaldehyde fumigation during the hatching phase on contamination in the hatch cabinet and early performance in broiler chickens

Commercial hatch cabinet environments promote replication of microorganisms. These pathogenic or apathogenic microorganisms may serve as pioneer colonizers of the gastrointestinal tract (GIT) of poultry. Some of these pioneer colonizers, such as Escherichia coli and Enterococcus spp., are opportunistic pathogens that lead to reduced performance in commercial poultry. Effective hatchery sanitation is imperative to limit contamination of naïve neonatal chicks and poults. Formaldehyde fumigation has been traditionally used to reduce the pathogen load in commercial hatch cabinets. To investigate potential alternatives to formaldehyde fumigation, models to mimic the microbial bloom in a laboratory setting must be utilized. The purpose of the present study was to evaluate the impact of a multispecies environmental challenge model (PM challenge) with and without formaldehyde fumigation during the hatching phase on early performance in broiler chicks. Three experiments were conducted to evaluate microbial contamination in the hatch cabinet environment (air samples, fluff samples), enteric colonization at day-of-hatch (DOH), and 7-day performance. In all experiments, significantly (P < 0.05) more gram-negative bacteria were recovered from the GIT at DOH in the PM challenge control group as compared to the nonchallenged control (NC) group and the formaldehyde-treated group (PM + F). There were no statistical differences in 7-day body weight gain or feed conversion ratio between the PM challenge control group, the NC group or the PM + F group. These data suggest this model could be utilized to evaluate alternatives to formaldehyde fumigation for controlling the microbial load during the hatching phase in a laboratory setting.

Dietary soy galactooligosaccharides affect the performance, intestinal function, and gut microbiota composition of growing chicks

The objective of this experiment was to investigate the effects of the dietary soy galactooligosaccharides (GOS), raffinose and stachyose, on performance, gastrointestinal health, and systemic stress in young broilers. Birds were fed a GOS-devoid diet based on soy protein isolate (SPI) or the SPI diet with 0.9, 1.8, 2.7, or 3.6% added stachyose and raffinose in a ratio of 4:1 at the expense of corn starch. These 5 treatments were administered to 10 replicate cages of 8 birds. Performance was measured weekly and excreta moisture, N retention, apparent metabolizeable energy, and complete blood cell counts were determined at 14 and 21 d. At 21 d, 2 birds per cage were orally gavaged with fluorescein isothiocyanate-dextran (FITC-d) and serum samples were analyzed for FITC-d as a marker of gut leakage. Additionally, intestinal morphology, crop presumptive lactic acid bacteria (LAB) counts, crop and cecal pH, and cecal microbiota via16S rRNA microbial sequencing were evaluated at 21 d. From 0 to 21 d, feed intake increased linearly (P < 0.01) as dietary GOS increased, whereas BWG increased (P < 0.05) quadratically. Feed conversion ratio increased (P < 0.01) linearly as GOS increased. There were linear increases (P < 0.05) in excreta moisture as dietary GOS increased at 14 and 21 d, as well as dose-dependent responses (P < 0.05) in N retention, AME, and AME_n. There was a quadratic increase (P < 0.05) in crop LAB recovery and a linear decrease (P < 0.01) in ceca pH as GOS increased. At 14 d, a linear increase (P < 0.05) in blood heterophil to lymphocyte ratio was observed as dietary GOS increased. Serum concentrations of FITC-d increased quadratically (P < 0.01) to dietary GOS. Increasing levels of GOS influenced alpha and beta diversities and composition of gut microbiota, including the abundance of Ruminococcus and Bifidobacterium. Results from this trial indicate that soy-derived GOS exert dose-dependent effects on nutrient utilization and intestinal health in young broilers.

Development of an environmental contamination model to simulate the microbial bloom that occurs in commercial hatch cabinets

Microbial blooms that emerge in commercial hatch cabinets consist of apathogenic and pathogenic microorganisms, including Escherichia coli, Enterococcus faecalis, and Aspergillus fumigatus. Objectives of the present study included the development of a multipathogen contamination model to mimic commercial conditions and optimization of sampling methods to quantify bacterial or fungal presence within the hatch cabinet. The pathogen challenge mix (PM) was recreated from select bacterial or fungal isolates recovered from an egg homogenate (EH) derived from the contents of infertile eggs and late embryonic mortalities. Isolates selected for PM included Enterococcus faecalis (∼10⁸ CFU/egg), Staphylococcus aureus (∼10⁷ CFU/egg), Staphylococcus chromogenes (∼10⁷ CFU/egg), Aspergillus fumigatus (∼10⁶ spores/egg), and 2 Escherichia coli (∼10⁸ CFU/egg) isolates. Challenge (100 μL of PM or EH) was administered using a sterile loop to a 28 mm area on the blunt end of the eggshell at day 19 of embryogenesis (DOE). In 3 experiments, microbiological data were collected from environmental hatcher samples (open-agar plate method), fluff samples, postmortem whole-body chick rinse samples, and gastrointestinal tract (GIT) samples to evaluate select bacteria and fungi circulating within the hatch cabinet and colonization of GIT. Cumulative bacterial and fungal recovery from the PM hatching environment from DOE20 to hatch was higher than the nonchallenged group (NC) and EH group at ∼860 and ∼1,730 CFU, respectively. Bacterial recovery from GIT, fluff, and chick rinse samples were similar for the PM and EH group in Exp. 1. However, Aspergillus fumigatus recovery from fluff and chick rinse samples for the PM group was significantly (P < 0.001) higher than the NC and EH group. In Exp. 2 and 3, PM challenge significantly (P < 0.05) increased Gram-negative bacterial recovery from the GIT, fluff and chick rinse samples compared to both the NC and EH group. These data suggest this innovative multispecies environmental contamination model using PM could be utilized to evaluate strategies to mitigate microbial contamination in commercial hatch cabinets in a laboratory setting.

Evaluation of live-attenuated Histomonas meleagridis isolates as vaccine candidates against wild-type challenge

Repeated serial in vitro passage of Histomonas meleagridis, the etiological agent of histomoniasis (blackhead) of turkeys, was demonstrated to markedly achieve attenuation and reduction of virulence as compared to the original wild-type isolate. Four experiments were performed to evaluate the route (oral vs. intracloacal) and age (day-of-hatch vs. d 14) for administration of attenuated H. meleagridis isolates as vaccine candidates against homologous or heterologous wild-type challenge. Attenuated H. meleagridis were developed from 2 different strains (Buford strain originating in Georgia; PHL2017 strain originating in Northwest Arkansas). Buford P80a (passage 80, assigned as isolate lineage “a” following repeated passage) was selected as the primary vaccine candidate and was evaluated in Experiments 1–3. Experiment 4 evaluated selected candidates of attenuated PHL2017 (P67, P129) and Buford (P80a, P200a, P138b, P198c) strains against Buford wild-type challenge. As has been demonstrated previously, wild-type H. meleagridis cultures administered orally after 1 day of age were not infective in the current studies, but infection with wild-type cultures could be induced orally at day-of-hatch. Infection was effectively achieved via the intracloacal route at day-of-hatch and in older turkeys (d 21, d 28–29, d 35). Intracloacal inoculation of turkeys with the attenuated passaged isolates as vaccine candidates at d 14 was shown to produce significant (P < 0.05) protection from mortality, reduction in body weight gain, as well as reduction in hepatic and cecal lesions in these experiments following challenge with either the homologous wild-type isolate or from a wild-type strain obtained years later from a geographically disparate area of the United States. Inoculation with the attenuated H. meleagridis isolates at day-of-hatch, either orally or cloacally, did not produce significant protection against subsequent wild-type challenge. While offering significant protection with minimal vaccine-related negative effects, the protection from cloacal vaccine administration was neither significantly robust nor encouraging for industry application using the methods evaluated in the present manuscript since mortalities and lesions were not completely reduced which could thereby potentially allow transmission from residual infection and shedding within a flock.

A comparison of formic acid or monoglycerides to formaldehyde on production efficiency, nutrient absorption, and meat yield and quality of Cobb 700 broilers

After being banned by the European Commission in 2018, the use of formaldehyde as a feed amendment in the United States has come into question. Therefore, this study was conducted to explore alternatives to formaldehyde, such as formic acid and monoglycerides, and their effects on poultry production. In total, 1,728 Cobb 700 broilers were randomly assigned to 96-floor pens on day of hatch (18 birds/pen). Using a randomized complete block design (4 blocks), treatments were assigned to pens with blocking based on location within the barn, with the eastern half of the barn designated for digestibility and the western half designated for production (per experiment: 8 control pens and 10 pens per treatment). All diets were based on a negative control (NC), basal diet. Dietary treatments consisted of: NC, NC + 0.25% formalin (F), NC + 0.25 and 0.50% Amasil NA (AML and AMH; 61% formic acid and 20.5% Na-formate), and NC + SILO Health 104L (SILO; mixture of monoglycerides; 0.5% from 0 to 14 d, 0.4% from 14 to 28 d, and 0.2% from 28 to 42 d). Water and feed were provided ad libitum. Performance data were collected during feed changes on d 0, 14, 28, and 42, with digestibility data collected at d 14 (2 per pen) and carcass quality (6 per pen) assessed at d 46 with a randomly selected group of broilers. A one-way ANOVA followed by Dunnett's multiple comparison, where treatments were evaluated against F were conducted using JMP 14.0 (P ≤ 0.05). Main effect of treatment was significant for performance, nutrient digestibility, and carcass quality. Differences in body weight and ADG were observed from d 14 to d 28, resulting in a trending improvement in lysine digestibility on d 14 and carcass quality on d 46 of birds fed AML and AMH in comparison to those fed F (P < 0.05). Whereas birds fed SILO had reduced digestibility of methionine on d 14 and a decrease in meat quality on d 46 in comparison to those fed F (P < 0.05). Therefore, Amasil NA at 0.25 or 0.50% may be an effective alternative to formaldehyde as a feed amendment for poultry production.

Development of a wild-type Escherichia coli environmental bloom model to evaluate alternatives to formaldehyde fumigation in broiler chicken hatch cabinets

Horizontal transmission of opportunistic Escherichia coli during hatch can have detrimental effects on early performance, particularly as pioneer colonizers. Commercially, formaldehyde is often applied in the United States to combat the bacterial bloom that occurs inside of the hatching environment. The purpose of these experiments was to develop a replicable E. coli horizontal challenge model to evaluate alternatives to formaldehyde sanitation applied to the hatching environment. In experiment 1, two trials were conducted for 2 wild-type (WT) E. coli isolates (isolate 1 [I1] or isolate 2 [I2]) to determine the appropriate in ovo challenge dose and day of embryogenesis (DOE) for challenge administration. In experiment 1 trial 1, the most appropriate inoculation dose and time point were determined to be 10² cfu/embryo on DOE 19. Experiment 1 trial 2 evaluated whether placement of seeder (direct-challenged) embryos with contact (indirect-challenged) embryos during hatch affected contact hatchability. Trial 2 showed no differences in hatchability between groups. A 7-day experiment (experiment 1 trial 2) was conducted to evaluate the effects of I1 or I2 on horizontal transmission, gram-negative bacterial (GNB) recovery from the gastrointestinal tract (GIT), and impact on BW gain (BWG). Compared with the negative control, seeder, and contact chicks challenged with I1 or I2, we observed increased (P < 0.05) GNB recovered from GIT on the day of hatch. There was a marked (P < 0.05) reduction in 7-day BWG between the I1 indirect-challenged group and the negative control group. To further validate the model, 2 7-day trials (experiment 2, experiment 3) were conducted to evaluate the effects of formaldehyde fumigation on coliform recovery from the hatching environment and on early performance using I1 for the challenge. Isolate 1 positive control hatchers had increased levels of circulating coliforms compared with the negative control and formaldehyde-treated hatchers, although there was no significant impact on performance induced by challenge or formaldehyde treatment in experiment 2 or experiment 3. These data provide a potential model for investigations related to horizontal transmission of WT E. coli at a low dose on DOE 19 to promote simulated commercially relevant bacterial blooms under laboratory conditions.

Effect of Bacillus-direct-fed microbial on leaky gut, serum peptide YY concentration, bone mineralization, and ammonia excretion in neonatal female turkey poults fed with a rye-based diet

Rye is high in nonstarch polysaccharides (NSP), a complex carbohydrate which cannot be digested by poultry as they lack the endogenous enzymes to do so. Exogenous carbohydrases must therefore be supplemented to avoid the antinutritional effects associated with a high NSP diet. The objectives of the present study were to evaluate the effects of a rye-based diet with and without supplementation of a Bacillus direct-fed microbial (DFM) on body weight, bone mineralization, and leaky gut, as well as its role on influencing serum concentrations of peptide YY (PPY) and the ammonia concentration in turkey manure. Two independent trials were conducted. In each experiment, day-of-hatch female turkey poults were neck tagged and randomly assigned to either a control rye-based diet or a rye-based diet supplemented with the DFM (n = 25 birds/group). At 10 days-of-age, poults in both groups were administered with an appropriate dose of fluorescein isothiocyanate-dextran (FITC-d) by oral gavage. One hour later, all poults were euthanized. Blood was collected to evaluate serum FITC-d and PPY concentrations. Furthermore, in Trial 2 only, both tibias were removed for assessment of bone parameters, and turkey manure was collected to evaluate physicochemical analysis. In both trials, poults treated with the DFM showed a significant increase (P < 0.05) in body weight and body weight gain as compared with control nontreated poults. Poults that received the DFM also had a significant reduction in serum levels of PPY and FITC-d when compared with control nontreated poults. In Trial 2, turkeys treated with the DFM had a substantial increase in tibia strength, tibia diameter, total ash, calcium, and phosphorus when compared with control nontreated turkeys. Their manure was also shown to have a significant reduction in the concentration of ammonia. This is the first report of a commercial DFM reducing the concentration of this compound in turkey manure. In summary, the results of the present study confirm that turkeys fed with a rye-based diet have a significant increase in gut permeability, a reduced body weight, and decreased bone mineralization when compared with turkeys fed with the DFM. Turkeys that received the rye-based diet supplemented with the Bacillus-DFM also had a significant reduction in the serum concentration of PPY when compared with control turkeys. This finding suggests a possible prebiotic effect of rye, warranting future studies to test this effect. Further studies to evaluate the microbiota diversity, as well as the concentration of ceca short-chain fatty acids, are also necessary to confirm the reliability of PPY as a potential metabolomic biomarker in poultry.

Evaluation of in ovo Bacillus spp. based probiotic administration on horizontal transmission of virulent Escherichia coli in neonatal broiler chickens

This study evaluated the effect of in ovo Bacillus spp. base probiotic (BBP) administration on hatchability, Gram-negative bacteria (GNB) recovery, performance, and microbiota composition in 2 independent trials using a virulent E. coli seeder challenge model. In each trial, one hundred and eighty 18-day-old embryos were allocated into 1 of 2 groups: Control and treated group (inoculated with 107 BBP). On day 19 of embryogenesis, seeder embryos (n = 18) were inoculated with 4.5 × 104E. coli/mL+272 μg/mL tetracycline and segregated into mesh hatching bags. Twelve chicks per group were euthanized at hatch and at day 7 to evaluate the gastrointestinal composition of total GNB or total aerobic pasteurized bacteria. Also, in trial 2, ceca content from five chickens at day 7 were collected to evaluate microbiota composition. Embryos inoculated with BBP showed a significant (P < 0.05) reduction in the total number of GNB at day-of-hatch (DOH) and day 7. Probiotic treatment increased BW at DOH and day 7, and BW gain (days 0 to 7) when compared with Control chickens. Proteobacteria phylum was significantly reduced, while the Firmicutes was significantly increased by the BBP as compared to the Control (P < 0.05). At family level, Enterobacteriaceae was significantly decreased, while the Lachnospiraceae was significantly elevated in the BBP as compared to the Control group (P < 0.05). The genus Oscillospira was significantly enriched in the BBP group, whereas the unidentified genus of family Enterobacteriaceae in the Control group (P < 0.05). The BBP group increased the bacterial species richness, although there was no significant difference between treatments (P > 0.05). Interestingly, beta diversity showed a significant difference in bacterial community structure between Control and BBP groups (P < 0.05). The results of the present study suggest that in ovo administration of a BBP can reduce the severity of virulent E. coli horizontal transmission and infection of broiler chickens during hatch. The reduction in the severity of the transmission and infection by the BPP might be achieved through alterations of microbiota composition and its community structure.

Influential factors on the composition of the conventionally raised broiler gastrointestinal microbiomes

The microbiome has entered the vernacular of the consumer as well as broiler production and is, therefore, becoming increasingly important to poultry producers to understand. The microbiome is, by definition, compositional and relates to how the microbiological organisms within the gut inhabit that ecological niche. The gut is diverse, flexible, and data acquired requires a greater understanding of the host-microbiome axes, as well as advanced bioinformatics and ecology. There are numerous microbial populations that define the gut microbiome; however, there are even more effects that can influence its composition. As management practices vary between producers, documenting these influences is an essential component of beginning to understand the microbiome. This review targets broiler production and concatenates the currently understood compositional ecology of the broiler gastrointestinal tract microbiome as well as its influences.

A feed restriction milieu for Pekin meat ducks that may improve gait characteristics but also affects gut leakiness

In a previous study, we demonstrated that a 15% feed restriction (FR) during the first 2 wk after hatch could improve gait in Pekin meat ducks, but did result in reduced breast mass. We hypothesized that feed restriction after day 5 following muscle satellite cell development would allow the full growth of the breast meat. To accomplish this goal, 300 1-day-old ducklings (Maple Leaf Farms Inc.) were randomly allocated to 1 of the 3 groups (n = 4 pens, 25 ducks per pen): (1) Control group fed to ad libitum; (2) 85% daily feed intake from days 1 to 14 (FR 85% 1-14); 85% daily feed intake from days 5 to 14 (FR 85% 5-14). All ducks were vaccinated with inactivated Salmonella enteritidis on day 14 and boosted on day 26. The FR 85% 5-14 did show similar production standards to controls, and improved gait characteristics (P < 0.05). To determine if the partial feed restriction would have an impact on intestinal epithelial tight junction integrity, we treated ducks on days 7, 14, 21, 28, and 35 with 8.32 mg/kg FITC-d in water per os and blood samples were obtained via the tibial vein 1 h later. Serum samples were analyzed for presence and quantification of FITC-d. Feed restriction elicited a significant increase in FITC-d permeability at all points of evaluation. Anti-S. enteritidis specific IgY responses were assessed by ELISA from serum collected at 14 D, 28 D, and 35 D. Although all ducks showed an increase humoral immune response to the S. enteritidis, both feed restricted groups showed reduced IgY production compared to ad lib controls. Our data suggest that although the FR 5-14 feed restriction paradigm may reduce gait abnormalities without affecting production rates, some challenges exist due to increased gut leakiness or decreased acquired immune activity. Future studies will look at altering the feed restriction milieu to ameliorate these challenges.