Evaluating the impact of gypsum as a novel bedding material on broiler performance, foot pad health, and fear response

Flue Gas Desulfurization (FGD) gypsum is a byproduct of the coal-fired power plant process commonly used to remove sulfur dioxide emissions from the flue gas. FGD gypsum has numerous industrial, agricultural, and environmental applications. This study aimed to explore a novel approach involving the use of FGD gypsum combined with different litter treatments as bedding for broiler production. It focused on performance metrics, including adjusted feed conversion ratio (AFCR) and average body weight (BW), foot pad dermatitis (FPD), and fear response over 5 consecutive flocks. A total of 1,800 one-day-old Ross 708 chicks were randomly assigned to 24 pens (75 birds/pen), divided into 6 treatment groups (4 pens/treatment), with 5 replications and raised until 42 d old (d). Treatments were gypsum that was decaked (D), rotovated (E), and rotovated then windrowed (F) between flocks. Control treatments using pine shavings were decaked (A), rotovated (B), and windrowed postrotovating (C). AFCR, average BW, and mortality were used as a measure of production. Foot pad dermatitis scores were taken on d42 using a scale of 0 (absence), 1 (mild), and 2 (severe). Response to observer and human approach test were used to measure fear response. Data were analyzed as a 2-way ANOVA (Proc Glimmix) for the main effects of bedding type and litter treatment. Means were identified using Tukey's HSD. No effect of bedding type or litter treatment was found for AFCR, BW, or mortality. FPD scores 2 and 1, were higher with pine shavings than gypsum (P = 0.01 and P = 0.01, respectively). While FPD scores 0 were higher for gypsum than the pine shaving (P = 0.01). No difference in fear response was found among birds raised on any of the gypsum litter treatments and any of the pine shaving litter treatments. Overall, the use of gypsum as bedding results in equivalent production and fear response to pine shavings, while increasing FPD quality when compared to pine shaving.

Application of pressurized steam and forced hot air for cleaning broiler transport container flooring

In the United States, cleaning poultry transport containers prior to arrival at the broiler grow-out farm is not currently a widely adopted practice in the industry. However, previous studies have shown that transport containers have an important role in cross-contamination before the broilers arrive at the processing plant. The objective of this study was to evaluate the efficacy of pressurized steam followed by forced hot air to clean transport container flooring and compare it to conventional cleaning procedures. Fiberglass and plastic flooring were cut into even pieces and inoculated with chicken intestinal contents containing Salmonella Infantis or Campylobacter jejuni. The cleaning treatments were pressurized steam, forced hot air, pressurized steam followed by forced hot air, water pressure washing, water pressure washing before and after disinfectant, and no cleaning. Counts for Salmonella, Campylobacter, Escherichia coli, coliforms, and aerobic bacteria were assessed. All reductions were made in comparison to noncleaned samples. Forced hot air applied by itself was not efficient in reducing Campylobacter, coliforms, and E. coli; and limited reductions (less than 1 log10 CFU/cm2) were observed for Salmonella and aerobic bacteria. Then, for all bacteria types evaluated, pressurized steam by itself showed reductions of 2.4 to 3.5 log10 CFU/cm2. Samples that were cleaned with a single-pressure water wash showed reductions of 4.0 to 4.6 log10 CFU/cm2 for all bacteria types. For Salmonella, Campylobacter, and E. coli, the greatest reductions were observed when samples were cleaned with pressurized steam followed by forced hot air (4.3-6.1 log10 CFU/cm2) or water washed before and after disinfectant (4.5-6.2 log10 CFU/cm2), and these treatments did not differ from each other. Pressurized steam followed by forced hot air was shown to be an efficient cleaning procedure to reduce poultry-associated pathogens on transport cage flooring, with the benefit of using less water than conventional water cleaning. Processors may be able to adapt this process to reduce potential cross-contamination and lessen the level of pathogens entering the processing plant.

Quantification of Salmonella Infantis transfer from transport drawer flooring to broiler chickens during holding

Transportation is a potential point of cross-contamination before broiler chickens arrive at the processing plant for slaughter. Previous studies have associated the use of uncleaned transport containers with the introduction of pathogenic bacteria onto uncontaminated broilers. The objective of this study was to quantify the transfer of Salmonella from transport drawer perforated flooring to broiler chickens during different holding times. For traceability, the flooring of each drawer was inoculated with fecal content slurry containing a marker strain of Salmonella Infantis. Three drawers per treatment were used, and each drawer was subjected to one of the following treatments: pressure wash, disinfectant, and pressure wash (A), pressurized steam followed by forced hot air (B), or no cleaning (C). Drawers were classified as top, middle, or bottom based on their relative position with each other. After treatment, broilers were introduced to each drawer and held for 2, 4, or 6 h. At each timepoint, broilers were removed from drawers, euthanized, and carcasses rinsed to obtain Salmonella counts. Samples under the limit of direct plating detection were enriched, plated, and later confirmed positive or negative. Differences were observed per treatment, holding time, and drawer relative position (P < 0.0001). Broilers placed in transport containers that underwent a cleaning procedure (A or B) had lower levels of Salmonella when compared to broilers placed in noncleaned containers (C). However, most of the samples below the limit of detection were positive after enrichment, indicating that both procedures evaluated need improvement for efficient pathogen inactivation. A decrease in Salmonella transfer was observed after 6 h in rinsates obtained from broilers placed in noncleaned containers (C). Rinsates obtained from top drawers had less Salmonella than the middle or bottom drawers when broilers were placed in transport containers that underwent a cleaning procedure (A and B). The application of pressurized steam and forced hot air was comparable to the use of water washes and disinfectant indicating a potential role in cleaning poultry transport containers.

Vaccination Against Poultry Parasites

The complexity of parasites and their life cycles makes vaccination against parasitic diseases challenging. This review highlights this by discussing vaccination against four relevant parasites of poultry. Coccidia, i.e., Eimeria spp., are the most important parasites in poultry production, causing multiple billions of dollars of damage worldwide. Due to the trend of antibiotic-free broiler production, use of anticoccidia vaccines in broilers is becoming much more important. As of now, only live vaccines are on the market, almost all of which must be produced in birds. In addition, these live vaccines require extra care in the management of flocks to provide adequate protection and prevent the vaccines from causing damage. Considerable efforts to develop recombinant vaccines and related work to understand the immune response against coccidia have not yet resulted in an alternative. Leucozytozoon caulleryi is a blood parasite that is prevalent in East and South Asia. It is the only poultry parasite for which a recombinant vaccine has been developed and brought to market. Histomonas meleagridis causes typhlohepatitis in chickens and turkeys. The systemic immune response after intramuscular vaccination with inactivated parasites is not protective. The parasite can be grown and attenuated in vitro, but only together with bacteria. This and the necessary intracloacal application make the use of live vaccines difficult. So far, there have been no attempts to develop a recombinant vaccine against H. meleagridis. Inactivated vaccines inducing antibodies against the poultry red mite Dermanyssus gallinae have the potential to control infestations with this parasite. Potential antigens for recombinant vaccines have been identified, but the use of whole-mite extracts yields superior results. In conclusion, while every parasite is unique, development of vaccines against them shares common problems, namely the difficulties of propagating them in vitro and the identification of protective antigens that might be used in recombinant vaccines.

In vitro Effect of Photoactive Compounds Curcumin and Chlorophyllin Against Single Strains of Salmonella and Campylobacter

Salmonella and Campylobacter are two of the most common foodborne pathogens associated with poultry meat. Regulatory restrictions and consumer concerns have increased the interest for plant-derived antimicrobials and emerging novel technologies. The objective of this study was to determine the antimicrobial activity of photoactive compounds curcumin (CUR) and chlorophyllin (CH) followed by activating light exposure for the reduction of Salmonella and Campylobacter. Peroxyacetic acid (PAA) was also evaluated as a poultry industry standard antimicrobial processing aid. CUR and CH were evaluated in 96-well plates at concentrations of 100, 500, and 1,000 ppm, along with PAA at 100, 200, and 300 ppm, or distilled water (DW). Each well was inoculated with 105 CFU/mL of Salmonella Typhimurium or Campylobacter jejuni, and plates were exposed to activating light (430 nm) for 0 or 5 min. No detectable reductions were observed for Salmonella or Campylobacter when treated with CUR, CH, or 100 ppm PAA. However, when Salmonella was treated with 200 ppm PAA, counts were reduced from 4.57 to 2.52 log10 CFU/mL. When Salmonella was treated with 300 ppm PAA, counts were reduced to below detectable levels (5 CFU/mL). Campylobacter was reduced from 4.67 to 2.82 log10 CFU/mL when treated with 200 ppm PAA. However, no further reductions were observed when Campylobacter was treated with 300 ppm PAA (2.50 log10 CFU/mL). These results indicate that CUR and CH were not effective as antimicrobials under the evaluated conditions, particularly in comparison to the commonly used antimicrobial, PAA.

Buffering Capacity Comparison of Tris Phosphate Carbonate and Buffered Peptone Water Salmonella Pre-Enrichments for Manufactured Feed and Feed Ingredients

Various culture-based methods to detect Salmonella in animal feed have been developed due to the impact of this bacterium on public and animal health. For this project, tris phosphate carbonate (TPC) and buffered peptone water (BPW) buffering capacities were compared as pre-enrichment mediums for the detection of Salmonella in feed ingredients. A total of 269 samples were collected from 6 feed mills and mixed with the pre-enrichments; pH was measured before and after a 24 h incubation. Differences were observed when comparing pH values by sample type; DDGS and poultry by-product meal presented lower initial pH values for TPC and BPW compared to the other samples. For both TPC and BPW, meat and bone meal presented higher final pH values, while soybean meal and peanut meal had lower final pH values. Furthermore, for BPW, post cooling, pellet loadout, and wheat middlings reported lower final pH values. Additionally, most feed ingredients presented significant differences in pH change after 24 h of incubation, except DDGS. From meat and bone meal samples, four Salmonella isolates were recovered and identified: three using BPW and one using TPC. TPC provided greater buffer capacity towards neutral pH compared to BPW, but BPW was more effective at recovering Salmonella.

Mapping the poultry insectome in and around broiler breeder pullet farms identifies new potential Dipteran vectors of Histomonas meleagridis

BACKGROUND

Histomonas meleagridis can infect chickens and turkeys. It uses the eggs of the cecal worm Heterakis gallinarum as a vector and reservoir. Litter beetles (Alphitobius diaperinus) and other arthropod species have been implicated as potential vectors, but little information about other arthropod species as potential vectors is known.

METHODS

Four broiler breeder pullet farms were sampled every 4 months. On each farm, three types of traps were set inside and outside two houses. Trapped arthropod specimens were morphologically identified at order level and grouped into families/types when possible. Selected specimens from abundant types found both inside and outside barns were screened for H. meleagridis and H. gallinarum by qPCR.

RESULTS

A total of 4743 arthropod specimens were trapped. The three most frequently encountered orders were Diptera (38%), Coleoptera (17%), and Hymenoptera (7%). Three hundred seventeen discrete types were differentiated. More arthropods were trapped outside than inside. Alpha diversity was greater outside than inside but not significantly influenced by season. The composition of the arthropod populations, including the insectome, varied significantly between trap location and seasons. Up to 50% of litter beetles tested positive for H. meleagridis DNA 4 months after an observed histomonosis outbreak. Sporadically litter beetles were positive for H. gallinarum DNA. Thirteen further arthropod types were tested, and specimens of four Dipteran families tested positive for either one or both parasites.

CONCLUSIONS

This study describes the insectome in and around broiler breeder pullet farms and identifies new potential vectors of H. meleagridis through qPCR. The results show a limited but present potential of arthropods, especially flies, to transmit histomonosis between farms.

Multilocus Sequence Typing of Eimeria maxima in Commercial Broiler Flocks

About 35% of all broiler flocks in the United States receive an anticoccidial vaccine, but it is not possible to easily differentiate Eimeria vaccine strains from Eimeria field isolates. Being able to do that would allow using vaccines in a more targeted way. The objective of this study was to collect Eimeria maxima isolates from broiler flocks that received anticoccidial feed additives and flocks that had been vaccinated against coccidia and then test them with a multilocus sequencing typing (MLST) scheme developed for this study. Fecal samples were obtained from commercial broiler flocks in Alabama and Tennessee. Oocyst counts in samples tended to be lower in flocks receiving anticoccidial feed additives and higher in vaccinated flocks. Selected samples were screened for presence of E. maxima by quantitative PCR, and Eimeria spp. composition was investigated by next-generation amplicon sequencing (NGAS) in 37 E. maxima positive samples. Other detected Eimeria spp. besides E. maxima were Eimeria acervulina in 35 samples, Eimeria praecox in 23 samples, Eimeria mitis or Eimeria mivati in 17 samples, and Eimeria necatrix or Eimeria tenella in 10 samples. Six partial E. maxima genes (dnaJ domain containing protein, 70-kDa heat shock protein, prolyl endopeptidase, regulator of chromosome condensation domain containing protein, serine carboxypeptidase, and vacuolar proton-translocating ATPase subunit) of 46 samples were sequenced. The MLST scheme was able to differentiate two vaccines from each other. Three of 17 samples from vaccinated flocks differed from the vaccine used in the flock, while 16 of 29 samples from unvaccinated flocks differed from the vaccine. However, there was also a large number of low-quality, ambiguous chromatograms and negative PCRs for the selected genes. If and when more advanced, possibly next-generation sequencing-based methods will be developed, the genes should be considered as targets.

Improvement in the Immunity- and Vitamin D3-Activity-Related Gene Expression of Coccidiosis-Challenged Ross 708 Broilers in Response to the In Ovo Injection of 25-Hydroxyvitamin D3

Effects of the in ovo administration of two vitamin D3 sources (vitamin D3 (D3) and 25-hydroxyvitamin D3 (25OHD3)) on the expression of D3 activity- and immunity-related genes in broilers subjected to a coccidiosis infection were investigated. At 18 d of incubation (doi), five in ovo injection treatments were administrated to live embryonated Ross 708 broiler hatching eggs: non-injected (1) and diluent-injected (2) controls, or diluent injection containing 2.4 μg of D3 (3) or 2.4 μg of 25OHD3 (4), or their combination (5). Birds in the in ovo-injected treatments were challenged at 14 d of age (doa) with a 20× dosage of a live coccidial vaccine. At 14 and 28 doa, the expression of eight immunity-related genes (IL-2, IL-6, IL-10, TLR-4, TLR-15, MyD88, TGF-β4, and IFN-γ) and four D3 activity-related genes (1α-hydroxylase, 25-hydroxylase, 24-hydroxylase, and VDR) in the jejunum of one bird in each treatment-replicate group were evaluated. No significant treatment effects were observed for any of the genes before challenge. However, at 2 weeks post-challenge, the expression of 1α-hydroxylase, TGF-β4, and IL-10 increased in birds that received 25OHD3 alone in comparison to all the other in ovo-injected treatment groups. Additionally, the expression of 24-hydroxylase and IL-6 decreased in birds that received 25OHD3 in comparison to those injected with diluent or D3 alone. It was concluded that the in ovo injection of 2.4 μg of 25OHD3 may improve the intestinal immunity as well as the activity of D3 in Ross 708 broilers subjected to a coccidiosis challenge.

Investigation of the potential of aerosolized Salmonella Enteritidis on colonization and persistence in broilers from day 3 to 21

The presence of Salmonella in air of poultry houses has been previously confirmed. Therefore, it is important to investigate the entry of Salmonella into broilers through air. The present study aimed to evaluate different levels of Salmonella Enteritidis aerosol inoculations in broiler chicks for colonization of ceca, trachea, and liver/spleen and persistence over time. In 3 independent trials, 112 one-day-old birds were randomly divided into 4 groups (n = 28/group). On d 1 of age, one group was exposed to an aerosol of sterile saline and the remaining three groups were exposed to an aerosol generated from one of 3 doses (10³, 10⁶, or 10⁹ CFU/mL) of S. Enteritidis inoculum. Aerosol exposure time was 30 min/group and was performed using a nebulizer. On d 3, 7, 14, and 21 of age, ceca, trachea, and liver/spleen were aseptically removed. Ceca were cultured for Salmonella counts (log₁₀ CFU/g) and all tissues were cultured for Salmonella prevalence. All tissues from the control group were Salmonella negative for all sampling days. On sampling d 3 and 7, ceca Salmonella counts were highest (5.14 and 5.11, respectively) when challenged with 10⁹Salmonella (P ≤ 0.0281). Ceca Salmonella counts increased from d 3 (2.43) to d 7 (4.43), then remained constant when challenged at 10³Salmonella, and counts decreased over time for all other groups. Tissue Salmonella prevalence increased with increasing challenge levels at all sampling timepoints (P ≤ 0.0213). Salmonella prevalence was low (0/18 to 4/18) and did not change over time following 10³Salmonella challenge (P ≥ 0.2394). Prevalence decreased over time in ceca and trachea following 10⁶ and 10⁹Salmonella challenge (P ≤ 0.0483). Liver/spleen Salmonella prevalence increased from d 3 (13/18) to d 14 (18/18) and then decreased at d 21 (10/18) in birds exposed to an aerosol of 10⁹Salmonella but remained constant over time for rest of the Salmonella inoculated groups. Overall, this study demonstrated the Salmonella colonization and persistence in different tissues in broilers following exposure to aerosolized Salmonella.

Heterakis gallinarum and Histomonas meleagridis DNA persists in chicken houses years after depopulation

The poultry pathogen Histomonas meleagridis is transmitted by chicken cecal worms (Heterakis gallinarum) and is potentially transmitted by second order insect vectors and paratenic hosts. Darkling beetles (Alphitobius diaperinus) are poultry farm pests that infest barns. An outstanding question is the degree to which darkling beetles transmit both Heterakis and Histomonas. In this study we monitored populations of darkling beetles and assessed their positivity for both Heterakis and Histomonas by PCR. Uniquely, this study was conducted during the scheduled deconstruction of Auburn University's Poultry Research Farm. Therefore, we were able to monitor beetle and litter infection status months and years after bird depopulation. The duration of our monitoring continued through three seasons. We show that environmental DNA from both Heterakis and Histomonas persist in the environment long after prior infections, even in the absence of living Heterakis and its hosts. Finally, in an intensive search for live Heterakis, we discovered reniform nematodes (plant parasitic nematodes) residing in the soil floor of poultry farms.

A Comparison of Colonizing Ability Between Salmonella Enteritidis and Salmonella Heidelberg in Broiler Chickens Challenged Through Feed Administration

With over 1 million estimated cases per year in the United States, foodborne salmonellosis is an important public health issue. Chicken products are frequent sources of foodborne Salmonella infection. These bacteria readily colonize the gastrointestinal tract of broiler chickens, and feed is a known vector. Past research has demonstrated that the survivability of Salmonella in feed is dependent on the serovar and strain. Therefore, the objective of this research was to compare colonization incidence of these two serovars in broiler chicken tissues by administration of feed contaminated with Salmonella enterica serovar Enteritidis (SE) or Salmonella enterica serovar Heidelberg (SH). A comparison was made with equal conditions so that there was no influence of other factors. Birds were inoculated by addition of Salmonella to the feed (1 × 10⁴ colony-forming unit [CFU]/g of feed) at 14 days of age, and the following tissue samples were collected from each bird after grow-out (days 34-41 depending on the trial): abdominal cavity swab, bone marrow swab, cloaca swab, lung swab, breast, bursa and thymus, ceca, crop, kidney, liver and spleen, skin, spinal cord, thigh, and trachea. A higher percentage of birds inoculated with SE were positive in at least one tissue compared with SH (68% and 9%, respectively), and the SE inoculated birds also showed a higher number of positive tissue samples than SH (13.1% and 0.7%, respectively). Recovery of SH was low for all tissue samples. However, recovery of SE was variable between samples, with ceca showing the highest percentage (50%). These results indicate that challenge at day 14 through feed administration results in greater colonization by SE compared with SH, suggesting that monitoring and control methods for Salmonella in feed should focus on SE to have the greatest positive effect.

Impact of poultry litter Salmonella levels and moisture on transfer of Salmonella through associated in vitro generated dust

Dust present in poultry houses can contain high concentrations of microorganisms and has the potential to include pathogens from the litter. The objective of this study was to examine in vitro the potential for litter to dust transfer of aerobic bacteria, Salmonella, E. coli, and coliforms, and the role of the litter moisture on this process. Poultry litter was inoculated with 10² to 10⁹ CFU/mL of Salmonella Typhimurium to evaluate litter to dust transfer of bacteria (Experiment 1). To evaluate the effect of litter moisture on litter to dust microbial transfer (Experiment 2), litter was inoculated with 10⁹S. Typhimurium with increasing amounts of sterilized water added for moisture adjustment. Dust was generated by blowing air in a direct stream onto inoculated litter while simultaneously collecting dust through impingement. Following litter and dust sample collection, microbial analyses for aerobic plate counts (APC),Salmonella, E. coli, and coliforms were conducted. Both experiments were repeated 5 times and their data analyzed by one-way ANOVA and simple logistic regression. In Experiment 1, APC of litter (log₁₀ CFU/g) and dust samples (log₁₀ CFU/L) were 10.55 and 4.92, respectively. Salmonella ranged from 1.70 to 6.16 log₁₀ CFU/g in litter and only one dust sample had 1.10 log₁₀ CFU/L of Salmonella. As Salmonella levels in litter increased, the probability of obtaining a dust Salmonella positive result also increased. In Experiment 2, attained moisture percentages were 13.0, 18.2, 23.0, 28.2, and 33.3%. Litter recovery for APC, Salmonella, E. coli, and coliforms counts did not differ (P > 0.05) with increasing moisture levels. Dust sample bacterial counts significantly decreased with increasing moisture levels (P < 0.0001). Results from this in vitro study indicate that there is potential for Salmonella to be present in generated dust and the higher levels of Salmonella in litter increase the likelihood of detecting Salmonella in dust. Additionally, with higher litter moisture percentage, prevalence of Salmonella in generated dust was decreased.

Influence of Eimeria spp. Infection on Chicken Jejunal Microbiota and the Efficacy of Two Alternative Products Against the Infection

Eimeria spp. are important intestinal pathogens of chickens (Gallus gallus domesticus). Anticoccidial feed additives, chemicals, and ionophores have traditionally been used to control Eimeria infections in broiler production. Thus, the trend toward antibiotic-free and organic production requires new approaches to coccidiosis prevention. Two not mutually exclusive methods are the use of plant extracts with antiparasitic activity and manipulation of the intestinal microbiota by pre- and probiotics. In the present study, birds were inoculated with a combination of Eimeria acervulina, Eimeria maxima, and Eimeria tenella. We profiled the jejunal microbiome at multiple time points postinfection to investigate the changes in jejunum microbiota and to identify the time point of the maximum difference between infected and noninfected birds. Additionally, we assessed the anticoccidial effects of two anecdotal treatment methods, green tea and apple cider vinegar, as well as amprolium. Green tea and apple cider vinegar had no effect on oocyst shedding, but green tea reduced the mild unspecific lesions in coccidia-infected birds; there was no influence on unspecific lesions in uninfected controls. Jejunal contents were collected on the day of the infection and 1, 2, 4, 6, 10, and 14 days postinfection (dpi) for investigation of the intestinal microbiota by 16S ribosomal (r)RNA gene sequencing. Comparison of the untreated-uninfected and the untreated-infected groups showed a maximum community dissimilarity of 10 dpi. From 4 days after infection, Clostridiales were significantly enriched at the expense of Lactobacillales in infected compared with uninfected birds. Interestingly, treatment with green tea prevented proliferation of Clostridiales induced by the coccidia and increased the relative abundance of Melainabacteria.

Evaluation of Next-Generation Amplicon Sequencing to Identify Eimeria spp. of Chickens

Identifying Eimeria spp. circulating in a poultry flock assists in designing vaccine preventive programs, as different species do not cross-protect. Because species differ in anticoccidial drug susceptibility, species identification can also be used to optimize anticoccidial medication. In the present study, we designed pan-Eimeria-specific primers for the 18S rDNA and the cytochrome oxidase I (COI) genes, and tested whether next-generation sequencing of their amplicons allowed reliable identification of Eimeria spp. in samples of isolated oocysts. For each gene, two sets of primers to be used in a nested PCR (nPCR) system were designed. In silico evaluation of the primers using published sequences showed that nucleotide sequence identities of the nested amplicons were less than 97% between most species, while only identities of 18S rDNA genes of Eimeria necatrix and Eimeria tenella and between the COI genes of Eimeria mitis and Eimeria mivati were higher than 97%. Three vaccines and five Eimeria samples from chickens in backyard flocks were investigated by nPCRs and by direct PCRs (dPCR) using the nested (inner) primers with genomic DNA as the template. Seventeen further Eimeria samples from chickens in backyard flocks and three Eimeria samples from commercial broiler flocks were investigated only by nPCR. Sequencing nPCR products tended to detect more species than sequencing dPCR products and sequencing 18S rDNA products tended to detect more species than sequencing COI products. Regarding the detected species, there was a clear difference between the commercial broiler flocks and the backyard flocks. Eimeria acervulina, Eimeria maxima, and E. tenella/E. necatrix were the only species detected in broiler flocks, while the population in the backyard flocks was more varied, with Eimeria brunetti and E. mitis/E. mivati and the previously described operational taxonomic unit Y being more prevalent. Several sequences having less than 97% identity with one of the sequences used for clustering were detected in samples from backyard flocks. In conclusion, next-generation amplicon sequencing can be a useful tool to determine which Eimeria spp. are circulating in chicken flocks.

Effects of pre-starter and starter diets varying in amino acid density given to broiler chickens that received coccidiosis vaccination at hatch1

An experiment was conducted to evaluate broilers vaccinated against coccidiosis fed combinations of pre-starter and starter diets varying in digestible amino acid (dAA) density from 1 to 19 d of age on subsequent growth performance and meat yield. A total of 1,800 Yield Plus Ross × Ross 708 male broilers were allocated to 60 floor pens and assigned to 1 of the 6 treatments. Four pre-starter diets varying in dAA density [1.15% dLys, 1.25% dLys, 1.35% dLys, and Positive Control (1.15% dLys + Diclazuril)] were fed until 9 d of age. Then, 3 starter diets varying in dAA density [1.15% dLys, 1.25% dLys, and PC (1.15% dLys + Diclazuril)] were given from 10 to 19 d of age. All diets were formulated to similar dAA ratios to dLys; hence, resulting in increasing amino acid (AA) density among the dietary treatments. Birds were given common grower and finisher diets for the remainder of the experiment. At 19, 27, and 40 d of age, broilers that received the 1.35% and 1.25% dLys density pre-starter and 1.25% dLys density starter diets had increased BW gain (P ≤ 0.006) compared with broilers fed the 1.15% dLys density diets. Broilers that received the 1.15% dLys density pre-starter diet had a lower cumulative BW gain (P = 0.007) than those fed the 1.35% and 1.25% dLys density pre-starter diets. Broilers that received the 1.35% and 1.25% dLys density pre-starter and 1.25% dLys density starter diets had the heaviest (P ≤ 0.008) total breast weights. Increasing the pre-starter dAA density enhanced (P ≤ 0.03) total breast weight by 28 g (1.25% dLys density) and 51 g (1.35% dLys density). Results from this study indicated that increasing dAA density from 1 to 19 d of age enabled a 1 to 19 d dAA intake increase of 4.8 g, which enhanced cumulative growth and meat yield of broilers vaccinated against coccidiosis.

Effects of dietary amino acid density and feed allocation during the starter period on 41 days of age growth performance and processing characteristics of broiler chickens given coccidiosis vaccination at hatch1

A study was conducted to determine if increasing digestible (dig) amino acid (AA) density or feed allocation of starter diets fed to broilers receiving coccidiosis vaccination can ameliorate poor cumulative growth performance and reduce meat yield. A total of 1,600 Yield Plus Ross × Ross 708 male broilers were assigned to a 2 × 3 factorial arrangement of dig AA density [moderate (1.15% dig Lys) and high (1.25% dig Lys)] and feed allotment (0.45, 0.73, and 1.00 kg/bird) with 2 positive control treatments during the starter period. Diets were formulated to essential AA ratios relative to dig Lys. Vaccinated birds received a 1x dosage of Coccivac- B52 prior to placement, whereas non-vaccinated birds in the positive control groups were fed diets containing diclazuril. Following consumption of the starter diets, birds were provided common grower and finisher diets. Broilers fed the high AA density diet during the starter period had higher cumulative BW gain and lower cumulative feed conversion ratios (P < 0.05) than those fed the moderate AA density diet. Broilers fed the high AA density diet had heavier (P ≤ 0.005) carcass and total breast weights than birds fed the moderate AA density diet. Broilers fed a starter allotment of 1.00 kg/bird produced heavier carcass weights (P ≤ 0.006) than did birds provided lower allotments. Additionally, broilers fed the high AA density diet had a greater percentage of 0 scores (P = 0.005) for the upper intestinal region during scoring. Results from this study indicated that feeding the high AA density diet at higher feed allotments during the starter period resulted in increased AA intake, which supported the bird through the vaccine challenge and enhanced the cumulative growth and meat yield.

Prevalence and antimicrobial resistance patterns of Salmonella isolated from poultry farms in southeastern United States

Salmonella spp. are among the most common foodborne pathogens, and increase in the occurrence of antimicrobial drug-resistant Salmonella poses a severe risk to public health. The main objective of this study was to determine changes in Salmonella prevalence and their antimicrobial resistance on poultry farms following recommendations to changes in biosecurity practices. Four poultry farms were sampled by collecting cloacal swabs, drag swabs, and litter samples prior to recommended biosecurity changes (March-April) and post recommendations (October-November). Prevalence of Salmonella was 3 to 4% during pre-recommendations, while the prevalence was higher (P > 0.05), ranging from 5 to 14% during post recommendations. Higher Salmonella prevalence was observed for pre- and post-recommendation phases by sample type in cloacal and drag samples -5% for farm 1, drag swab -6% on farm 2, cloacal swab -6% for farm 3, and drag swab -17% on farm 4. The PCR confirmed Salmonella were serotyped and tested for antimicrobial resistance. Six serotypes of Salmonella were identified with S. Enteritidis (52%) being the most prevalent, followed by S. Berta (38%), S. Mbandaka (7%), S. Typhimurium (2%), S. Kentucky (0.4%), and S. Tennessee (0.4%). A total of 7% isolates exhibited resistance to at least one of the 8 antimicrobials. Higher resistance was observed for tetracycline, streptomycin, and nalidixic acid. A single isolate of S. Mbandaka exhibited multidrug resistance to tetracycline, amoxicillin/clavulanic acid, and ampicillin. Based on these prevalence results, it can be inferred that, irrespective of implementation of improved biosecurity practices, seasonal variation can cause changes in the prevalence of Salmonella on the farms. Resistance to clinically important antimicrobials used to treat salmonellosis is a concern to public health.

Low Prevalence of netB and tpeL in Historical Clostridium perfringens Isolates from Broiler Farms in Alabama

The discovery of novel Clostridium perfringens toxins NetB and TpeL has initiated questions regarding their role in the pathogenesis of disease. However, data showing the prevalence of these genes in C. perfringens populations are limited to certain geographical areas. If netB and tpeL are important virulence factors for disease worldwide, one would expect to find these genes in isolates from other regions as well. To address this hypothesis, C. perfringens isolates collected from Alabama broiler farms over 15 yr ago were toxin genotyped using PCR. Each isolate was screened for netB and tpeL; the major lethal toxin genes cpa, cpb, etx, and ia; and the enterotoxin gene cpe. Results of the assay showed all isolates presumed to be C. perfringens were genotypically type A, cpe negative except for one broiler litter isolate, which was genotypically type C. Only two isolates were positive for netB. Similarly, only two isolates were positive for tpeL, one of which was also netB positive. The low incidence observed for netB and tpeL indicates that these genes are not significant virulence factors for the sampled population.

Detection and isolation of infectious laryngotracheitis virus on a broiler farm after a disease outbreak

A broiler farm in North Alabama suffered a mild infectious laryngotracheitis (ILT) outbreak, as determined by clinical disease and PCR. The poultry integrator sought help to control further outbreaks in subsequent flocks. Samples were collected from various areas of the poultry houses on the farm over an 8-wk period. The first sampling was conducted 8 days after the infected farm was depopulated; the second was conducted 2 days prior to subsequent flock placement; and the third was conducted when the new flock was 5 wk of age. Samples were examined for ILT virus (ILTV) DNA by real-time PCR and virus isolation in embryos. The infected houses were cleaned, disinfected, heated, litter composted, and curtains replaced after the first sampling and prior to placement of the next flock. Samples from all periods were positive for ILTV DNA. However, the number of positive samples and crossing point values indicated a decrease in the amount of viral DNA, while virus isolation in embryos was successful only on the first sampling. The subsequent flock was vaccinated against ILTV by in ovo route using a commercial recombinant vaccine. Cleaning and sanitation after the disease outbreak reduced the amount of ILTV on the farm and together with in ovo vaccination of the new flock may have prevented a recurrence of another ILT outbreak.

The effect of sodium bisulfate on Salmonella viability in broiler litter

Controlling Salmonella populations on commercial broiler grow out farms is a crucial step in reducing Salmonella contamination in processing plants. Broiler litter harbors many species of pathogenic bacteria including Salmonella. Sodium bisulfate has been shown to reduce concentration of bacteria in broiler litter. In experiments 1 and 2, sodium bisulfate was applied to broiler litter at rates that are comparable to what is commonly used by the poultry industry: 22.7, 45.4, and 68.0 kg/92.9 m(2). After application, sodium bisulfate was mixed into the litter. In experiments 3 and 4, sodium bisulfate was applied at 45.4 kg/92.9 m(2) to the surface of the litter. For all experiments, a cocktail of 5 Salmonella serovars was applied to the litter. Ammonia, pH, moisture, and water activity measurements were taken; additionally, total aerobic, anaerobic, enteric, and Salmonella concentrations were determined at 0, 24, and 96 h. In experiments 1 and 2, Salmonella concentrations were higher for treated litter than the control at 24 and 96 h (P < 0.001). In experiments 1 and 2, litter pH was lower for treated litter at 24 and 96 h; lowest pH was observed with the 68.0 kg/92.9 m(2), with a pH of 5.95 (P < 0.001). In experiments 3 and 4, litter pH was lowered for treated litter to 2.1 (P < 0.001). Even this lower pH did not reduce Salmonella concentrations compared with the control (P = 0.05). The decreased litter pH appeared to be responsible for increased viability of Salmonella. This research shows that the lowering of litter pH, which decreases litter ammonia production, could actually lead to an increased survivability of certain bacteria, such as Salmonella.

The association of various isolates of Escherichia coli from the United States with induced cellulitis and colibacillosis in young broiler chickens

An experiment was conducted to observe the effects of 10 different avian Escherichia coli isolates in 3-day post-hatch broiler chicks after subcutaneous administration. Isolates were originally obtained from various avian sources throughout the US. Chicks were injected subcutaneously on the ventral surface and necropsied at 7-day intervals for 3 weeks. Cellulitis was produced in all treatments receiving E. coli of cellulitis origin, with the highest incidence occurring 2 weeks post-infection in birds that received an isolate recovered in a previous challenge experiment. Cellulitis was also observed at week 1 post-infection in a small percentage of the birds in two of the treatments receiving E. coli of enteric origin, although lesions disappeared from the group after week 1 post-infection. Septicaemia was the most frequent sequel to challenge and occurred regardless of which isolate was injected. Chicks exposed to cellulitis origin isolates developed septicaemia more frequently than birds challenged with E. coli of non-cellulitis origin. The data implies that cellulitis is unlikely to occur early in the bird's life, since young birds exposed to E. coli frequently develop septicaemia.

Multilevel analysis of environmental Salmonella prevalences and management practices on 49 broiler breeder farms in four south-eastern States, USA

A two-part serial survey of 49 broiler breeder farms was conducted in four south-eastern states: Arkansas, Alabama, Georgia and North Carolina. Broiler breeder farms from three to five broiler company complexes in each state were visited on two separate occasions to document management practices and perform environmental sampling for Salmonella prevalence estimation. Salmonella was detected in 88% of the broiler breeder houses that were sampled and was identified on all 49 farms enrolled. Many management characteristics were consistent across the different states and companies. Multilevel analysis was used to evaluate management characteristics as risk factors for Salmonella prevalence and to estimate the proportion of variance residing at the different hierarchical sampling levels. Management characteristics associated with increased Salmonella prevalence included treatment of the flock for any disease, having dusty conditions in the house, having dry conditions under the slats and walking through the house more than one time per day to pick-up dead birds. After adjusting for state as a fixed effect, the percentages of variance in Salmonella prevalence occurring at the complex, farm, visit, house and individual sample levels were 5.2%, 6.8%, 11.8%, 2.8% and 73.4%, respectively. The intraclass correlations for samples collected from the same house; for samples from different houses during the same visit; for samples from different visits to the same farm; and for samples from different farms in the same complex were as follows: 0.27, 0.24, 0.12 and 0.05, respectively.

Comparison of a TaqMan real-time polymerase chain reaction assay with a loop-mediated isothermal amplification assay for detection of Gallid herpesvirus 1

A TaqMan real-time polymerase chain reaction (PCR) and loop-mediated isothermal amplification (LAMP) assay were developed to detect Gallid herpesvirus 1 (GaHV-1, formerly Infectious laryngotracheitis virus). The standard curve of real-time PCR was established, and the sensitivity reached 10 copies/μl. In the current study, the conversion between viral titer and GaHV-1 genomic copy number was constructed. Six primers for LAMP assay amplified target gene at 65°C within 45 min, and the detection limit was 60 copies/μl. The 6 primers were highly specific, sensitive, and reproducible for detection of GaHV-1. Although the sensitivity of LAMP was lower than that of real-time PCR, LAMP was faster, less expensive, and did not require a thermocycler. The LAMP assay would be a viable alternative assay in diagnostic laboratories that do not employ real-time PCR technology.

Effects of phytase supplementation in broiler diets on a natural Eimeria challenge in naive and vaccinated birds

Our study was conducted to determine the effects of dietary phytase on a natural Eimeria challenge in naive and vaccinated broilers. Prior to the experiment the litter was seeded with Eimeria by orally infecting 10-d-old chicks with a cocktail containing 100,000 and 5,000 sporulated Eimeria acervulina and Eimeria tenella oocysts, respectively. Straight-run broiler chicks were placed across 48 floor pens on fresh or seeded litter. Eight treatment combinations were created to include 2 dietary Ca-nonphytate P (npP) levels [0.9% Ca, 0.45% npP; 0.7% Ca, 0.35% npP, 500 phytase units of Optiphos phytase (JBS United, Sheridan, IN)], unchallenged versus challenged, and unvaccinated versus vaccinated groups of chicks. Body weights and feed consumption (FC) were recorded on d 10, 18, and 21. A total of 10 birds/treatment were killed on d 10 and 18 to obtain tissue samples from the duodena and ceca for lesion scoring and cytokine response measurement. At 21 d of age, the left tibia was removed from 18 birds/treatment to assess bone strength. Body weight, FC, and bone strength were unaffected (P > 0.05) by diet or vaccination. By d 21, birds exposed to coccidia had lower FC (P < 0.01), higher feed conversion (P < 0.001), and decreased bone strength (P < 0.01) compared with those not challenged. Regardless of treatment, gross and microscopic scoring of the intestines showed few differences (P > 0.05). Expression of interferon-γ did not differ (P > 0.05) in the duodena or ceca at either time point. The IL-17 gene expression was increased (P < 0.05) in phytase-supplemented, vaccinated, or challenged birds by 18 d of age, with significant interactions (P < 0.05) occurring between birds challenged and fed the marginal diet or vaccinated. Phytase supplementation was unable to provide additional benefits to performance or P utilization in birds vaccinated, subjected to a coccidiosis infection, or both. Based on cytokine production in the intestinal tract on d 10 and 18 postchallenge, the response to the Eimeria challenge was characterized by a T-helper type (Th) 17-like immune response and to a lesser extent a Th1-like immune response, whereas no Th2 cytokine was detected.

Evaluation of the efficacy of yeast extract in reducing intestinal Clostridium perfringens levels in broiler chickens

The etiological agent of necrotic enteritis is Clostridium perfringens. Traditionally, necrotic enteritis is controlled with in-feed antibiotics. However, increasing consumer demand for drug-free poultry has fostered the search for nonantibiotic alternatives. Yeast extract contain nucleotides that are immunomodulatory and also essential for cellular functions. An experiment was conducted to evaluate the efficacy of NuPro yeast extract (Alltech Inc., Nicholasville, KY) in reducing intestinal C. perfringens levels in broiler chickens. One hundred ninety-two 1-d-old male broiler chicks were obtained and randomly assigned to 6 treatments in a battery cage trial. Treatment 1 consisted of chicks fed a corn-soybean meal basal diet (BD) without added bacitracin methylene disalicylate or NuPro. Treatment 2 consisted of chicks fed BD into which bacitracin methylene disalicylate was added at 0.055 g/kg. Treatment 3 consisted of chicks fed BD supplemented with NuPro at a 2% level for the first 10 d of the experiment. Treatments 4 (PX), 5, and 6 (PN) consisted of chicks that were challenged with 3 mL of the C. perfringens inoculum (~10(7) cfu/mL) on d 14, 15, and 16 of the experiment and fed diets similar to treatments 1, 2, and 3, respectively. On d 1 and 7 postchallenge, intestinal C. perfringens levels, lesion scores, and alkaline phosphatase activity were assessed. On d 1 postchallenge, C. perfringens level in treatment 5 (2.09 log(10) cfu/g) was lower (P < 0.05) compared with the PX treatment (4.71 log(10) cfu/g) but similar to the PN treatment (2.98 log(10) cfu/g). A similar trend was observed on d 7 postchallenge. NuPro supplementation enhanced alkaline phosphatase activity (P < 0.05) in C. perfringens-challenged chicks and appeared to reduce intestinal lesion scores. Although dietary supplementation of NuPro in the PN treatment reduced C. perfringens levels by 1.73 and 0.68 log(10) cfu/g compared with the PX treatment on d 1 and 7 postchallenge, respectively, these reductions were not significant. Extending the period of NuPro supplementation beyond the first 10 d of life should be considered for achieving significant reduction in intestinal C. perfringensg levels.

Effect of the major histocompatibility complex on the inhibition of induced cellulitis development in a broiler chicken model

The chicken major histocompatibility complex (MHC) has been implicated in conferring resistance or susceptibility to several bacterial, parasitic, and viral diseases, the most notable of which is Marek's disease. In Marek's disease certain MHC haplotypes have been shown to confer relative resistance (B21), whereas other haplotypes are susceptible (B13). Relatively little work has been performed looking at the association of the MHC with bacterial diseases. One such disease is cellulitis, which is caused by several different bacteria but most notably by Escherichia coli. In this report, a commercial broiler chicken line known to contain standard B13 and B21, as well as the unique MHC types BA9 and BA12, was examined in a challenge model for cellulitis. The MHC-defined birds were challenged with a cellulitis-causing E. coli isolate and the frequency of lesion development and severity was quantified. In conclusion, B21 had the highest incidence of cellulitis development, B13 had the lowest incidence, and BA9 and BA12 had intermediate results. Results concerning the lesion severity showed that it was independent of the birds' MHC type.

A longitudinal study of Salmonella and Campylobacter jejuni isolates from day of hatch through processing by automated ribotyping

Comparisons of bacterial populations over long periods of time allow researchers to identify clonal populations, perhaps those responsible for contamination of farms or humans. Salmonella and Campylobacter can cause human illness, and our objective was to use a library typing system to track strains that persist in the poultry house and through the processing plant. Two farms, over four consecutive flocks, were studied. Multiple samples were taken of the poultry house environment, feed mill, transport crates, and carcasses in the processing plant. Sample collection on the farm took place on chick placement day, midgrowout, and the day of harvest. This study found that 80.3% of isolates belonged to a single strain of Salmonella Kentucky that persisted in several environmental samples for all flocks at both farms, from chick placement day to the final product at the plant. Surgical shoe covers produced most isolates (n = 26), and processing day yielded the highest recovery (n = 68). Additional serotypes were recovered, but the Salmonella Kentucky-positive eggshells and chick mortality appeared to be the source of the organism for both farms. All Campylobacter isolates recovered were identified as C. jejuni. Most Campylobacter isolates (90.1%) belonged to one of three core strains. C. jejuni was not recovered on chick placement day. Cecal droppings yielded all nine strains. Most isolates (98.2%) were from one farm. Cluster analysis grouped C. jejuni and Salmonella isolates into four and six distinct clusters, respectively, on the basis of a similarity level of 80%.

Effect of different cleaning regimens on recovery of Clostridium perfringens on poultry live haul containers

Clostridium perfringens is important to both poultry producers and humans. The excretion rate of pathogenic foodborne bacteria increases after live haul; however, the majority of research into flock cross-contamination has been performed on Salmonella and Campylobacter. Research into the sources of C. perfringens in poultry operations have implied that dirty transport containers do harbor this organism and, therefore, can potentially contaminate subsequent flocks. The objectives of this study were to examine both small plastic crates and large dump coops to determine which cleaning regimens were most effective in reducing C. perfringens contamination. Additionally, 2 different holding periods for small crates were compared to determine whether holding time influences C. perfringens recovery before and after cleaning. Two experiments were performed. One involved small plastic crates; the other involved large dump coops. Four small crate cleaning and disinfection treatments consisted of pressure washing, pressure washing and sun-drying, pressure washing with a (5%, vol/vol) sodium hypochlorite dip, and pressure washing with a quaternary ammonium dip. The second experiment involved dump coops. The 5 dump coop cleaning and disinfection treatments consisted of pressure washing, pressure washing with a (5%, vol/vol) sodium hypochlorite spray, pressure washing with a quaternary ammonium spray, 48-h drying after the sodium hypochlorite spray, and 48-h drying after the quaternary ammonium spray. The recovery of C. perfringens from small and large dirty transport containers averaged 1.94 and 4.43 log10 cfu/mL, respectively. There was no significant difference in C. perfringens recovery based on holding time for small crates. With small crates, pressure washing provided a significant decrease in the amount of C. perfringens recovered. The greatest bacterial reduction in dump coops, 2 to 3 log10 cfu/mL, was observed after 48 h of drying. This information provides solutions to poultry operations to reduce the cross-contamination of this food safety pathogen via transport containers.

Evaluation of agar plates for direct enumeration of Campylobacter spp. from poultry carcass rinses

Campy-Cefex, a modification of Campy-Cefex, modified charcoal cefoperazone deoxycholate (mCCDA), Karmali, CAMPY, and Campy-Line agars were evaluated for their efficiency to isolate and enumerate Campylobacter spp. from poultry carcass rinses. Campy-Cefex and its modification produced the best results but were statistically similar to CAMPY, mCCDA, and Karmali.

Real-time quantitative PCR-based serum neutralization test for detection and titration of neutralizing antibodies to chicken anemia virus

Detection and titration of chicken anemia virus (CAV)-neutralizing antibodies has relied on tedious, time-consuming passaging of infected cells, or subjective recognition of cytopathic effect in individual cells, because CAV replicates in culture only in lymphoblastoid cell lines, and thus generates no plaques. This paper describes a rapid method, in which CAV genomes in infected cells are quantitated by qPCR 3-4 days postinfection (p.i.), without passaging cells. Three sera, weakly positive with a commercial CAV ELISA kit, from broiler chickens immunized with a commercial CAV vaccine, were used to develop the assay. Virus neutralization titers of these sera were determined using two different CAV-susceptible cell lines (MDCC-MSB1 and MDCC-CU147) by the conventional method of passaging cells infected with 10,000 TCID(50) CAV per well, and by qPCR-based methods using cells infected with 100 or 10,000 TCID(50) per well in 24-well or 96-well plates. The method was also adapted to conventional PCR. The positive sera exhibited virus neutralization activity at dilutions ranging from 1:10 to 1:320 by the various assays. Although virus neutralization titers differed somewhat depending on the assay conditions used, the relative order of the titers of the three positive sera was the same for all assays. The qPCR-based assays are as sensitive and more rapid for detection of neutralizing antibody than the conventional assay based on passaging infected cells, and more sensitive for detection of low-level CAV antibodies than a commercial blocking ELISA.

Major histocompatibility complex effect on cellulitis among different chicken lines

The chicken major histocompatibility complex (MHC) has been implicated in conferring resistance/susceptibility to several bacterial, parasitic, and viral diseases. Investigators have shown that the chicken MHC plays a major role in determining the outcome of a Marek's disease infection, in that standard B(13) is susceptible to the virus while B(21) confers resistance to the virus. Previous work with a broiler line has shown that B(21) is susceptible to an Escherichia coli-induced cellulitis infection and that B(13) conferred resistance to the infection. For this experiment, a broiler and a Leghorn chicken line shown to contain standard B(13) and B(21) were examined in a challenge model for cellulitis. The birds were challenged with a cellulitis-causing E. coli isolate. Homozygous B(21) had the highest incidence of cellulitis development compared with either homozygous B(13) or the heterozygous B(13)/B(21) for both the broiler and Leghorn lines. Additionally, cellulitis lesion severity was measured in both lines and shown to be independent of MHC type.

Differences in the pathogenicity of various bacterial isolates used in an induction model for gangrenous dermatitis in broiler chickens

A gangrenous dermatitis model was developed in broiler chickens, in which birds previously vaccinated at 14 days of age with a bursal disease virus vaccine were challenged at 4 wk of age with various bacterial combinations with the combination of subcutaneous and intramuscular injection. Gangrenous dermatitis lesions were not produced in birds injected with one of the Staphylococcus aureus isolates, either alone or in combination with various Clostridium septicum isolates. Other S. aureus isolates produced significant levels of gangrenous dermatitis either alone or in combination with the same C. septicum isolates. These same C. septicum isolates when given alone did not produce gangrenous lesions. Data from this experiment show the highest level of mortality occurred in birds challenged with a mixture of C. septicum and S. aureus isolates, whereas lower or no mortality was associated with the same isolates given separately. The data clearly demonstrate that the pathogenicity of isolates responsible for gangrenous dermatitis varies widely, indicating that the frequency and severity of lesion production, as well as the occurrence of mortality, are largely dependent upon the specific isolate or isolates with which the birds are challenged.

The effect of vitamin E on cellulitis in broiler chickens experiencing scratches in a challenge model

Two experiments are described; each experiment contained five treatments with each treatment consisting of a specific diet and vitamin E at 8.82 mg, 41.89 mg, 74.96 mg, 108.03 mg, or 141.10 mg vitamin E per kilogram of feed. Birds were raised with continuous feed containing the various levels of vitamin E available throughout the experiment. At 4 wk of age, the birds were scratched on the breast and placed onto avian cellulitis Escherichia coli-seeded litter. One week later, the birds were euthanatized and lesion presence was noted. There appeared to be a positive correlation between vitamin E and the inhibition of cellulitis formation when the birds were fed a diet containing 74.96 mg vitamin E/kg feed. Conflicting results were seen in the two experiments when the birds were fed 41.89 and 108.03 mg vitamin E/kg feed. Both experiments had a high incidence of cellulitis in birds whose diets consisted of 141.10 mg vitamin E/kg feed.

Evaluation of scratches as an essential element in the development of avian cellulitis in broiler chickens

Currently, the published cellulitis models do not adequately address the actual pathogenesis as seen in the commercial broiler industry. In this model, small dermal scratches were made on the skin of broiler chickens, which were then placed on litter seeded with avian cellulitis-associated Escherichia coli. The research confirms scratches are required for the induction of avian cellulitis. The research also confirms that "type I" cellulitis lesions or those previously thought to be due to hatchery-borne infections can be induced with scratches. The described methods provide a realistic model for cellulitis development that will improve the reliability of prophylactic and therapeutic-regimen efficacy testing data, thereby providing information more directly useful to the commercial broiler industry.