Prevalence of Arcobacter species on chicken carcasses during processing in Iran

The objective of this study was to determine the prevalence of Arcobacter spp. on chicken carcasses at different stages of broiler processing in a major commercial poultry processing plant in central Iran. Overall, 80 chicken carcasses were sampled from 5 sites along the processing line during a total of 10 visits. When the culture method was used, 185 of 400 (46.3%) carcasses were positive for Arcobacter. Arcobacter butzleri was more frequently isolated (82.7%) than Arcobacter cryaerophilus (12.4%) and Arcobacter skirrowii (4.9%). The frequency of Arcobacter spp. on carcasses was 36.3% before defeathering, 41.3% after defeathering, 48.8% after evisceration, 67.5% at 20 min postchilling, and 37.5% at 24 h postchilling. The frequency of Arcobacter spp.-positive carcasses was reduced in completely chilled chickens, but not during the slaughtering process. The PCR assay identified 57 Arcobacter-contaminated carcass samples that were negative when using the culture method. When the PCR method was used, the frequently of Arcobacter spp. on carcasses was 43.8% before defeathering, 45.0% after defeathering, 55.0% after evisceration, 88.8% at 20 min postchilling, and 85.7% at 24 h postchilling. Therefore, there was a high prevalence of Arcobacter spp., especially A. butzleri, in poultry carcasses. To our knowledge, the present study is the first report in which Arcobacter spp. were isolated from chicken carcasses in Iran.     

Impact of added sand on the recovery of Salmonella,Campylobacter, Escherichia coli,and coliforms from prechill and postchill commercial broiler carcass halves

Salmonella and Campylobacter are often associated with raw poultry products and continue to be leading causes of food-borne gastroenteritis in the United States. As a result, the presence of these organisms on broiler carcasses is monitored on a routine basis. Abrasive rinsing methods (e.g., adding glass beads) have been shown to increase the level of bacteria recovered from carcasses or carcass parts. The objective of this study was to evaluate the addition of sand to the rinse on bacterial enumeration and the prevalence of Salmonella and Campylobacter recovered from broiler carcasses. During each of 4 replications, 6 prechill and 6 postchill broiler carcasses were collected from a commercial processing plant. All carcasses were split along the dorso-ventral midline. Carcass halves were rinsed in buffered peptone water, whereas the companion half was rinsed in buffered peptone water with sterile sand added. All carcass halves were rinsed for 1 min and the rinsate was collected. Salmonella, coliforms, and Escherichia coli were enumerated and the prevalence of Salmonella and Campylobacter was determined. Salmonella and Campylobacter were isolated from 17 and 50% of the carcass halves, respectively. There was no significant (P > 0.05) difference in Salmonella or Campylobacter prevalence from carcass halves rinsed with or without sand. The addition of sand to the rinse had no effect on the number of Salmonella, coliforms, or E. coli recovered from prechill or postchill carcass halves. These results show that adding sand to the rinse liquid did not improve the recovery of bacteria present on the carcass in either moderate (2.6 log₁₀ cfu/mL rinsate) or low numbers (<3 cfu/mL of rinsate).     

Simulation model for Campylobacter cross-contamination during poultry processing at slaughterhouses

Broiler meat is regarded as the most common source of Campylobacter infection and risk management measures are required to reduce broiler meat contamination. Among the quantitative risk assessments for Campylobacter in broiler meat, evaluation of the poultry processing stage is particularly important for predicting the contamination level of broiler meat and the effects of control measures. In this study, we built a simulation model for cross‐contamination during poultry processing focusing on Campylobacter contamination at the individual carcass level. Using this model, we examined changes in the prevalence of contaminated carcasses and the number of Campylobacter per carcass after processing. As a result, it was found that the prevalence and number of Campylobacter after processing were largely influenced by the number of Campylobacter on the contaminated carcasses before processing. In the baseline model, where it was assumed that the mean number of Campylobacter on contaminated carcasses before processing was 4.7 log₁₀ cfu per carcass, the prevalence after processing was less than that before processing. Although the median value of Campylobacter on contaminated carcasses was reduced after processing, the distributions after processing became wider and the upper limit of the 95% credible interval of Campylobacter on contaminated carcasses remained elevated. The individual‐based simulation model can trace individual level changes considering discrete interactions, while models tracing mean values cannot handle these interactions in detail. The individual‐based approach is considered useful for modelling cross‐contamination among individual carcasses during poultry processing.     

Evidence of cross-contamination by Campylobacter spp. of broiler carcasses using genetic characterization of isolates

Campylobacter is recognized as one of the leading cause of gastroenteritis worldwide, and is frequently isolated from the small intestines and ceca microflora of chickens. Twenty-one out of 81 Campylobacter-positive poultry flocks were selected to evaluate the genetic diversity of Campylobacter isolates and to study the distribution of genotypes among flocks. Campylobacter isolates recovered from chicken carcasses and ceca were analyzed by pulsed-field gel electrophoresis (PFGE). Little diversity was found among Campylobacter strains isolated from a given carcass, with a maximum of 2 different genotypes being present. However, at flock level, as many as 4 different profiles were observed. Typing of strains showed that most strains isolated from ceca were similar to those isolated from corresponding broiler carcasses. A total of 39 different macrorestriction profiles were observed, with evidence of Campylobacter cross-contamination among broiler flocks in Quebec slaughterhouses. Surprisingly, some flocks shared related genotypes both with and without sharing similar rearing practices. Existence of such cross-contamination must be considered to in developing strategies to control Campylobacter in chickens, and to avoid bacteria contamination of noncolonized flocks. Further typing studies of Campylobacter found in hatcheries, farm environment, and crates or trucks in Quebec might be helpful in elucidating the kinetics of broiler chicken Campylobacter contamination.     

On-line brush and spray washers to lower numbers of Campylobacter and Escherichia coli and presence of Salmonella on broiler carcasses during processing

It is unclear how effective different types of broiler carcass wash steps are in lowering the presence or numbers of pathogenic bacteria. We tested for individual and combined effectiveness of 5 separate on-line wash steps applied between bleed-out and chilling in a commercial broiler processing plant. Carcasses were sampled directly before and after each wash step: pre-scald brush washer, post-feather pick (New York dressed) spray washer, inside/outside spray washer, postevisceration brush washer, and final prechill spray washer. Carcasses were examined for numbers of Campylobacter and Escherichia coli and presence of Salmonella using standard cultural methods. Overall, numbers of Campylobacter were lowered from log 2.58 to 1.15 cfu/mL of carcass rinse, but no single wash step caused a significant decrease. Overall, Salmonella prevalence was decreased from 80 to 24%; however, no wash step caused a significant decrease by itself. The 5 wash steps in series lowered E. coli numbers from log 4.60 to 2.69 cfu/mL; the New York-dressed spray wash and the postevisceration brush washer each had a significant effect on E. coli. When examined separately, the benefit of broiler carcass wash steps may not be evident. However, when combined with overall processing, wash steps can be effective to lessen bacterial contamination on carcasses and be useful for pathogen control. Additional studies are necessary to maximize the effectiveness of carcass washers.     

Presence and Numbers of Campylobacter,Escherichia coli,and Salmonella Determined in Broiler Carcass Rinses from United States Processing Plants in the Hazard Analysis and Critical Control Point-Based Inspection Models Project

In 1999, the USDA-Food Safety and Inspection Service introduced an inspection system called the Hazard Analysis and Critical Control Point-Based Inspection Models Project (HIMP). The HIMP varies from standard inspection in that the emphasis of Food Safety and Inspection Service inspection program personnel is shifted. Each carcass is still visually inspected according to the Poultry Products Inspection Act, but some responsibility for food safety and identification and removal of defects is shifted from the regulatory agency to the processor, freeing up inspectors to more effectively verify the process and food safety system of the establishment. This survey was conducted in 2 stages: first to examine carcasses collected in HIMP and non-HIMP plants and then to test carcasses from all 20 volunteer plants currently operating under HIMP inspection. Carcasses were collected at rehang and postchill being careful to follow the same flock through processing. Postchill carcasses from HIMP plants were found to have equal bacterial contamination (numbers of Campylobacter and Escherichia coli and presence of Salmonella) as carcasses from standard HACCP plants. Overall, HIMP inspection, which places additional responsibility on the plant for process control, does not affect the microbiological quality of fully processed broiler carcasses.     

Bacterial Populations of Broiler Carcasses Washed in Mixtures of Potassium Hydroxide and Lauric Acid

The bactericidal effect of mixtures of KOH and lauric acid (LA) on the microflora of broiler carcasses was examined. Carcasses were washed by shaking in KOH-LA for 1 min on a mechanical shaker. In one set of experiments, the population of bacteria recovered from carcasses following each of 3 successive washes in 1.0% KOH-2.0% LA or in distilled water (control) was enumerated. The number of total plate count bacteria, Campylobacter, and Escherichia coli in aliquots of whole-carcass-rinses of the washed carcasses was determined. Results indicated that fewer bacteria were generally recovered from carcasses after each successive wash in KOH-LA or distilled water, but significantly fewer bacteria were recovered from carcasses washed in KOH-LA than from carcasses washed in distilled water. Bacteria recovered from carcasses after the first and third wash in KOH-LA were identified using the MIDI Sherlock Microbial Identification System. Gram-positive and gram-negative bacteria were identified in the bacterial flora of carcasses washed once in KOH-LA; however, only gram-positive cocci were identified in the bacterial flora of carcasses washed 3 times in KOH-LA. Additional experiments were performed to compare the number of bacteria recovered from carcasses washed 2 times in 0.25% KOH-0.5% LA, 0.5% KOH-1.0% LA, or 1.0% KOH-2.0% LA or in distilled water (control). Results indicated that significantly fewer bacteria were recovered from carcasses washed in higher concentrations of KOH-LA than from carcasses washed in lower concentrations of KOH-LA. Findings from these experiments show that washing carcasses in KOH-LA can reduce carcass contamination by bacteria responsible for human foodborne diseases and spoilage of fresh poultry.     

Natural Occurrence of Campylobacter Species,Salmonella Serovars,and Other Bacteria in Unabsorbed Yolks of Market-Age Commercial Broilers

In the developing avian embryo, the main energy source is the yolk. Toward the end of the incubation period, the remaining yolk sac is internalized into the abdominal cavity. At hatch, the remaining yolk comprises 20% of the chick's BW and provides the nutrients needed for maintenance. Posthatch, chicks rapidly initiate the transition from yolk dependence to the utilization of exogenous feed. However, at present, it is not known what types of bacteria are found to be associated with unabsorbed yolk sacs from market-age broilers. For Experiment 1, one hundred 6-wk-old defeathered broiler carcasses were obtained from a commercial processing facility during each of 3 visits. In the second experiment, one hundred 8-wk-old defeathered broiler carcasses were obtained from a different commercial processing plant on 4 separate occasions. For both experiments, each carcass was aseptically opened and inspected for the presence of an unabsorbed yolk sac. Three to 5 carcasses containing a free-floating yolk sac (within the abdominal cavity) and the yolk stalk (without a yolk sac) and 3 to 5 carcasses containing an attached yolk and yolk stalk from each repetition were randomly selected and analyzed for levels and types of total aerobic bacteria (APC), Enterobacteriaceae (ENT), and for the presence of Campylobacter spp. and Salmonella serovars. The APC ranged from log 3.3 to >log 6.0, and the ENT ranged from log 2.8 to >log 6.0. Staphylococcus spp. and Streptococcus spp. were the predominant organisms in APC, whereas Escherichia coli and Hafnia alvei were found to comprise the ENT. Campylobacter spp. was found in 29% of the yolk stalks, 32% of the attached yolk sacs, and 13% of the free-floating yolk sacs. All Campylobacter isolates were determined to be Campylobacter jejuni, except for 1 attached yolk and yolk stalk, which was Campylobacter coli. Salmonella serovars were found in 26% of the yolk stalks, 48% of the attached yolk sacs, and 23% of the free-floating yolk sacs, and the majority of Salmonella isolates were Salmonella Typhimurium. The significance of these bacterial reservoirs and carcass contamination during processing is yet to be determined.     

Detection ofCampylobacter in 100 commercial flocks–Evaluation of plating media and filtration method

Campylobacter is a natural member of the gut microflora in many commercial broilers and as such can become a contaminant on edible surfaces during processing. Culturing gut contents or feces can be a means to determine flock status prior to live-haul. The wide variety of non-Campylobacter background bacteria in these complex samples contaminates growth media and can make it very difficult to isolateCampylobacter. Over the course of 17 months, we cultured cecal contents from 100 different broiler flocks. For the last 50 flocks, we tested 3 selective plating media with and without the additional selection of a 0.45-μm filter for detection ofCampylobacter from cecal contents. Furthermore, from the last 50 flocks we also collected and cultured carcass rinse samples. Growth media tested included: Campy–Cefex Agar, Campy–Line Agar, and RF-Campylobacter jejuni/coli agar. About half (52%) of the 100 tested flocks were positive forCampylobacter; positive flocks were detected during each month of the year. Overall, theCampylobacter status of cecal contents from one carcass was predictive of the status of a carcass rinse from the same flock. Placing a complex sample such as cecal contents onto a 0.45-μm filter laid on top of the plating medium improved the detection ofCampylobacter by eliminating non-Campylobacter background colonies. All media allowed for detection ofCampylobacter from less complex carcass rinse samples without filtering. However, Campy–Cefex agar had higher numbers of competing bacterial colonies than did Campy–Line agar or RF-Campylobacter jejuni/coli agar.     

Microbial Safety of Chickens Raised Without Antibiotics

The purpose of the current study was to verify whether there was any validity to the claim that consumers could reduce their exposure to antibiotic-resistant bacteria by purchasing poultry products that were produced without antibiotics. Rinse samples were taken from whole carcasses from chickens grown in small flocks and marketed as antibiotic-free. Salmonella bacteria were isolated from 18.7% of all the carcasses sampled. Campylobacter bacteria were found on 96.0% of the carcasses tested. More than two-thirds (69.4%) of the Salmonella isolates were resistant to at least 1 antibiotic. The antibiotic to which the Salmonella isolates were most commonly resistant was trimethoprim-sulfa, with almost two-thirds (62.9%) of the isolates being resistant to it. Almost three-fourths (73.4%) of the Campylobacter isolates were resistant to at least 1 antibiotic. The most common antibiotic to which Campylobacter isolates were resistant was tetracycline, with almost three-fourths (72.7%) of all Campylobacter isolates being resistant to it.     

Prevalence and risk factors of Campylobacter infection in broiler flocks from southern Spain

An extensive epidemiological study was performed to determine the prevalence and risk factors of Campylobacter infection in broiler farms in Andalusia (southern Spain). A total of 2221 cloacal swabs and 747 environmental swabs from 291 broiler flocks were screened between April 2010 and May 2012. The prevalence of Campylobacter in individual animals was 38.1%, and the flock prevalence was 62.9%. Flocks were predominantly infected by C. jejuni and C. coli but were also infected by untyped Campylobacter spp., and mixed-species infection could be found. Risk factors for Campylobacter infection were assessed from direct interview of the farmers. The number of positive samples by flock was modelled assuming a binomial distribution. Analysis indicated five factors associated with increased intra-flock prevalence: presence of dogs or cats on the farm, older age of the broiler flock, the application of thinning of flocks, the presence of windows with canvas blinds, and the presence of rodents in the poultry house. Two factors were associated with decreased intra-flock prevalence: the treatment of drinking water and having an entrance room for access into the poultry house. This is the first study performed on broilers farms from Spain reporting the risk factors of Campylobacter infection and is the largest study on the prevalence of Campylobacter infection.     

Incidence of Salmonella Contamination in Broiler Chickens in Saskatchewan

The incidence of Salmonella contamination in ten Saskatchewan broiler flocks varying in size from 6 200 to 14 000 was investigated from February, 1977 to April, 1979. Prior to the initial chick placement, brooding equipment, feed, water and fresh litter samples were found to be free of Salmonellae. Samples obtained from the clean and disinfected processing plant equipment before the commencement of daily operation were negative except the isolation for Salmonella anatum from the fingers of the defeathering machine in flock 4. There was no evidence of Salmonella contamination in flocks 5, 6, 8 and 10. The incidence of Salmonella was lower when cloacal swabs were taken from day old chicks fasted for 48 hours than for the same groups of chicks when carcasses were blended in nutrient broth (flocks 7 and 9). The blending of such chicks appears to be a more critical test. The serotypes isolated from eviscerated birds were the same as those isolated from used litter samples. Salmonella saintpaul was isolated from a water sample at 53 days in flock 1 and the same serotype was recovered from the intestinal contents and skin of eviscerated birds. Salmonella typhimurium was recovered from the eviscerated birds and neck samples in flock 3. In flock 4, S. saintpaul and S. anatum were isolated from 13% of the eviscerated birds sampled. Salmonella thompson, Salmonella agona and Salmonella heidelberg were recovered from 61%, 5% and 1%, respectively, of the processed carcasses sampled in flock 7.     

Effect of Immersion or Dry Air Chilling on Broiler Carcass Moisture Retention and Breast Fillet Functionality

A study was conducted to investigate the effect of chilling method on broiler carcass skin color, moisture retention, breast fillet quality, and functionality. One hundred fifty eviscerated broiler carcasses were removed from a commercial processing line before chilling, transported to the laboratory, weighed, and chilled by dry air or immersion in ice water. Postchill carcasses were weighed for moisture uptake or loss and held on ice at 4°C for 24 h. Carcass skin color was measured immediately after chilling and after storage. After storage, fillets were deboned, marinated, and cooked. Fillet color was measured on the medial surface before marination and after cooking. Cooked fillet shear values were determined using an Allo-Kramer multiple blade. After 150 min of air chilling, carcasses lost 2.5% of prechill weight, and weight loss ranged from 2.2 to 3.5%. Moisture uptake during immersion averaged 9.3% of the prechill weight but varied widely with a range of 3.4 to 14.7%. Immediately after chilling, breast skin for immersion-chilled carcasses was significantly lighter (higher L*), less red (lower a*), and less yellow (lower b*) than the breast skin color for air-chilled carcasses. Storage time improved appearance (lighter skin color) of air-chilled carcasses. Raw and cooked fillet color, fillet marination pickup, and cooked fillet tenderness were not affected by chilling method. Cook yield for fillets deboned from immersion-chilled carcasses was significantly lower than fillets from air-chilled carcasses.     

Positive Relationship of the Avian Leukosis-J Strain Virus to the Detection of Campylobacter in the Digestive Tract and Semen of Broiler Breeder Roosters

At 45 wk of age, 99 roosters housed in individual cages were tested for avian leukosis-J strain virus (ALV-J); 32 tested positive and 67 tested negative. These roosters were fed a restricted diet to maintain weight to primary breeder specifications. Individual semen and ceca samples were analyzed for presence and level of Campylobacter. Population levels of Campylobacter in semen and ceca of ALV-J individuals were 3.5 times higher than negative birds. Controlling viruses such as ALV-J may be an important part of limiting colonization of broiler breeders by organisms such as Campylobacter.     

Porcine circovirus type 2 (PCV2) and Campylobacter infection induce diarrhea in piglets: Microbial dysbiosis and intestinal disorder

Diarrhea is considered to be associated with microbial dysbiosis caused by infection of pathogens but poorly understood. We herein characterized the colonic microbiota of diarrheal early-weaning piglets infected with porcine circovirus type 2 (PCV2) and Campylobacter. Campylobacter infection significantly decreased species richness and Shannon diversity index of colonic microbiota together with a significant increase in the proportion of Campylobacter and Enterobacteriaceae, whereas no significant difference on the above indexes was observed in piglets infected with PCV2 compared with healthy piglets. PCV2 and Campylobacter infection could disturb the homeostasis of colonic microbiota through deterioration of ecological network within microbial community, and specially Campylobacter performed as a module hub in ecological networks. The microbial dysbiosis caused metabolic dysfunction and led to a remarkable reduction in production of short chain fatty acids, following by a higher pH level in colon cavity. Campylobacter infection disturbed the function of colonic tract barrier observed in terms of significant lower relative expression of claudin-1, occluding, and zonula occludens protein-1 genes, and PCV2 infection induced intestinal inflammation together with a higher permeability of colon. Generally, these results suggested that PCV2 and Campylobacter infection could induce microbial dysbiosis and metabolic dysfunction, and cause intestinal disorder, all of which finally were associated to contribute to the diarrhea of early-weaning piglets.     

Campylobacter spp. in Irish Feedlot Cattle: A Longitudinal Study Involving Pre‐harvest and Harvest Phases of the Food Chain

The aim of this study was to investigate faecal shedding and transmission of Campylobacter spp. in cohorts of cattle within a feedlot, to assess subsequent contamination of carcasses with this pathogen and to identify risk factors associated with faecal shedding of Campylobacter spp. A cohort of 133 heifers housed in four adjacent pens was examined over a five and a half month period, from entering the feedlot to slaughter. A parallel investigation of individual rectal faecal samples and pen environmental samples were taken at monthly intervals from November to February. The entire outer and inner surfaces of a carcass side of each animal were swabbed immediately following slaughter. Campylobacter spp. were isolated from 322 (54%) of the 600 rectal faecal samples. Campylobacter jejuni and C. coli accounted for 69 and 29.7% of the isolate recovered, respectively. A total of 159 environmental samples were examined, of these Campylobacter spp. was isolated from 46 samples (29%). Campylobacter jejuni and C. coli accounted for 35 and 59% of these isolates, respectively. Campylobacter spp. was not isolated from any of the dressed carcasses. Logistic regression indicated prevalence of Campylobacter spp. faecal shedding within pens was positively correlated to the pen, the month of sampling and the Campylobacter spp. contamination status of the pen dividing bars and the water trough surface. Campylobacter spp. should be considered as a pathogen shed in the faeces of a substantial proportion of feedlot cattle. However, with good hygienic practice during harvest, a very low level of this pathogen can be achieved on dressed carcasses.     

Multiple typing for the epidemiological study of contamination of broilers with thermotolerant Campylobacter

This study aims to investigate the genetic diversity of thermotolerant Campylobacter in commercial broiler flocks and in the environment of broiler farms in Belgium. Seven out of 18 investigated flocks became colonized during rearing. Fluorescent amplified fragment length polymorphism (FAFLP), pulsed field gel electrophoresis (PFGE), restriction fragment length polymorphism of the flagellin A gene (flaA-RFLP) and antimicrobial resistance profile (ARP) were used for typing of the isolates. By the combination of FAFLP and PFGE, 22 Campylobacter genotypes could be distinguished. Colonization was almost exclusively with Campylobacter jejuni and unique genotypes were found in each flock. Multiple genotypes were detected in the broilers of 3 flocks, either simultaneously or successively. In 5 flocks, strains that were resistant to at least one antibiotic (mostly tetracycline) were found. The presence of other broiler houses on the farm did not result in a higher probability of colonization. The nipple water was contaminated with the same genotype as the broilers, illustrating its importance for transmission of Campylobacter. The same genotype was detected in a water puddle and in the broiler flock during rearing in 3 flocks. Once, the same genotype was isolated from the ditch water shortly before it was detected in the broilers.     

Prevalence and antimicrobial susceptibility of Campylobacter in broiler flocks in Japan

Campylobacter was isolated from 67 (47.2%) of 142 broiler flocks between September 2009 and February 2010. The prevalence of Campylobacter in broiler flocks was significantly lower during January and February than it was from September to December. Campylobacter colonization was more common in flocks that were not provided with a disinfected water supply, which was consistent with the findings of a previous study. The prevalence of antimicrobial drug‐resistant Campylobacter spp. was investigated, and the minimum inhibitory concentrations of eight antimicrobial agents were determined for 122 Campylobacter jejuni isolates and 46 Campylobacter coli isolates from broiler flocks between 2007 and 2010. In this study, 29.5% (36/122) of C. jejuni isolates and 41.3% (19/46) of C. coli isolates were resistant to enrofloxacin (ERFX), whereas all isolates were susceptible to erythromycin. Furthermore, the ERFX‐resistant isolates were tested for susceptibility to other classes of antimicrobial agents, and 55.6% (20/36) of ERFX‐resistant C. jejuni isolates and 47.4% (9/19) of ERFX‐resistant C. coli isolates were resistant to at least one of aminobenzyl penicillin, dihydrostreptomycin and oxytetracycline. To avoid an impact of antimicrobial drug‐resistant Campylobacter spp. on the efficacy of antimicrobial treatment for human campylobacteriosis, prudent use of antimicrobial agents is a requisite. The use of antimicrobial agents should be accompanied by various approaches such as prevention of Campylobacter colonization in broiler flocks with the aim of lowering the occurrence of Campylobacter infection in humans.     

Use of Digestible Amino Acids and the Concept of Ideal Protein in Feed Formulation for Broilers

The objective of this study was to evaluate diet formulation based on digestible amino acids (DAA), the formulation of low protein diets supplemented with synthetic amino acids, and L-Thr supplementation to increase the Thr:Lys ratio from 67:100 to 70:100. Two experiments were carried out with Hubbard male broilers from 3 to 6 wk of age. In experiment 1, corn-soybean meal diets containing 20% CP were used. In experiment 2, 20% CP diets were formulated with corn, soybean meal, wheat bran, feather meal, and meat meal. In both experiments, body weight gain and economic evaluations were better for broilers fed diets formulated on DAA. Carcass yields and carcass composition were not significantly affected by formulation procedures. In experiment 2, birds fed diets based on DAA had improved feed efficiency compared with those fed total amino acids (TAA). In experiment 1, a reduction of CP from 20 to 18.2% did not affect broiler performance. It did, however, result in fatter carcasses, lower percentages of breast meat, and lower economic evaluation. In both experiments, performance and economic evaluation were not affected by the Thr:Lys ratio. In experiment 1, however, abdominal fat and carcass fatness were reduced, and, in both experiments, carcass protein level was higher with a Thr:Lys ratio of 70:100 than with 67:100 ratio (P < 0.05).     

Microbial cross-contamination by airborne dispersion and contagion during defeathering of poultry

1. A readily identifiable strain of Escherichia coli K12 was used as a 'marker' organism to determine the sources, routes and patterns of microbial cross-contamination during mechanical defeathering of broiler chicken carcases. 2. Inoculation of scald water with the marker organism led to a relatively even pattern of carcase contamination during subsequent defeathering. Microbial cross-contamination was greater by this route of inoculation than by either surface inoculation of a 'seeder' carcase or oral inoculation of a live bird one day before slaughter. 3. Dispersal of the marker organism was strongly influenced by the mechanical action of the defeathering machines. Forward transmission of the marker occurred by aerosol or large airborne droplets and particulates such as feathers. Moving carcases through the defeathering machines when these were non-operational clearly reduced backward transmission of the marker. 4. Although microbial dispersal was unaffected by increasing the spacing between individual carcases or installing a water curtain at the entry and exit of the defeathering machines, shielding of carcases with aluminium baffles reduced counts of the marker organism from contaminated carcases by > 90%. 5. The results imply that microbial cross-contamination of broiler chicken carcases during defeathering occurs mainly via the airborne route, which could be contained by physical means.