Reducing the Colonization of Salmonella Enteritidis and Campylobacter Jejuni in Chickens with Caprylic Acid

NON-TECHNICAL SUMMARY: Salmonella Enteritidis and Campylobacter jejuni are important foodborne disease causing bacteria in the United States. Chickens harbor these harmful agents in their intestine resulting in the contamination of meat and eggs. Reducing S. Enteritidis and C. jejuni load in the live birds would reduce these bacteria on poultry meat and eggs. Caprylic acid is a natural chemical present in breast milk. Preliminary research by the Project Director indicated that caprylic acid kills S. Enteritidis in chicken's intestinal contents. Additionally, sodium caprylate (a form of caprylic acid) killed S. Enteritidis in water, suggesting its use as a bacterial killing agent in chicken drinking water. Finally, caprylic acid applied as a spray killed S. Enteritidis on shell eggs. These results indicated that caprylic acid could be new tool to reduce S. Enteritidis and C. jejuni in chickens, and the subsequent contamination of meat and eggs. The purpose of this study is to determine the effect of caprylic acid as a dietary supplement to reduce S. Enteritidis and C. jejuni load in broilers and S. Enteritidis in layers. We will also determine the effect of sodium caprylate for killing S. Enteritidis and C. jejuni in chicken drinking water, and if caprylic acid spray can be used for killing S. Enteritidis on eggs. We will also develop, implement and evaluate S. Enteritidis/C. jejuni prevention practices for poultry producers (broiler, layer, and egg) by extension programs, workshops, and educational materials.

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APPROACH: The effect of caprylic acid on S. Enteritidis and C. jejuni in chickens will be studied in day-old chicks. The birds will be provided feed containing 0, 0.7 or 1.4% caprylic acid and water ad libitum. On day 5, the birds will be infected orally ~ 10000000 CFU of a 5-strain mixture of nalidixic acid-resistant S. Enteritidis. In case of C. jejuni, the chicks will be infected with a 5-strain mixture (100000 CFU) at 2 weeks age. Fecal samples from all the birds will be collected on every third day for S. Enteritidis or C. jejuni counts and total bacterial load. Birds will be sacrificed on weeks 1, 2, 3, 4, 5, and 6. The ceca, liver and spleen from each bird will be collected for bacteriologic analysis. The pH, caprylic acid concentration, and counts of S. Enteritidis, C. jejuni and endogenous bacteria in the cecal contents will also be determined. The effect of caprylic acid on S. Enteritidis in layer chickens will be studied in pullets. The experimental set up is as described above. Following challenge with S. Enteritidis, eggs and fecal samples from all the birds will be collected on every third day for S. Enteritidis counts and total bacterial load. Birds from each group will be sacrificed on weeks 1, 3, 5, 7, 9, 11, 13. The ceca, liver, spleen, oviduct and ovaries from each bird will be collected for bacteriologic analysis. For determining the efficacy of sodium caprylate for killing S. Enteritidis and C. jejuni in water, water containing 0, 50, 75, 100 or 120 mM caprylate will be inoculated with S. Enteritidis or C. jejuni to obtain an inoculation level of 1000 CFU or 1000000 CFU/ml. The samples will be incubated at room temperature for 4 weeks. Water samples will be removed on days 0, 1, 3, 5, 7, and thereafter twice weekly over the 28-day period for enumerating the population of the pathogens. In addition, the pH of each sample will be determined on the specified days. To determine the effect of caprylic acid spray for killing S. Enteritidis on eggs, eggs will be inoculated with a five-strain mixture of S. Enteritidis (100000 CFU) and dried under a laminar flow hood at room temperature for 1 h before treatment. Immediately after drying, the surviving populations of S. Enteritidis on three eggs will be determined (baseline counts). The inoculated eggs will be sprayed with 10 ml of water (control), 10 ml of mineral oil containing 3% or 5% caprylic acid (treatment), or 10 ml of mineral oil (oil control). Following application of the treatments, the eggs will be dried under a laminar flow hood at room temperature for 1 h and sampled for surviving bacterial pathogens days 0, 1, 3, 5, 7 and weekly during a 4-week refrigerated storage. Our extension activities will develop, implement and evaluate S. Enteritidis/C. jejuni intervention practices for poultry producers by extension programs, workshops, and educational materials. Poultry extension specialists, educators, 4-H and FFA leaders, and Department of Agriculture personnel will be included in the outreach activities.
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PROGRESS: 2007/09 TO 2008/09 <br>
OUTPUTS: The therapeutic efficacy of caprylic acid (CA) against cecal Campylobacter jejuni and Salmonella Enteritidis (SE) colonization was investigated. In three separate trials, day-of-hatch commercial broiler chicks (n = 60 per trial; mixed sex) were assigned to six treatment groups (n = 10 per group): negative controls (no Campylobacter; no caprylic acid); positive controls (Campylobacter; no caprylic acid); and four caprylic acid treatment groups (based on CA doses of 0.35%, 0.7%, 1.4%, and 2.8%). Caprylic acid was supplemented in starter feed for the last 72 h of each 15-day trial. At 3 days of age, chicks were inoculated with five wild-type strains of C. jejuni, and at 15 days of age, chicks were euthanized, and cecal contents were collected for Campylobacter enumeration. Birds were individually weighed on days 12 and 15 to determine body weight differences, feed consumption, and feed conversion during the treatment period. In separate experiments, 70 commercial, day-old chicks were randomly divided into 5 groups of 14 birds each: one control group (SE, no CA), and two groups each supplemented with 0.7 % or 1% CA. Water and feed were provided ad libitum and on day 1, two birds from each group were sacrificed to ensure that birds were initially Salmonella negative. On day 5, birds were inoculated with 6 log CFU/ml of SE by crop gavage and after 5 days post infection, 2 birds from each group were sacrificed to ensure SE colonization. Birds were fed with CA-supplemented feed from day 15 for 5 days followed by sacrifice for collecting tissue samples. Presented a poster at Poultry Science Association Annual meeting held during July 21-23, 2008 at Niagra Falls, Canada. At this meeting several hundred scientists, veterinarians and producers were introduced to our project results. The poster won the outstanding graduate student poster award for products and processing. We also presented a poster on Caprylic Acid and feed consumption at the combined meeting for the Pennsylvania Poultry Sales and Service Conference and the Northeast Conference on Avian Diseases held during September 16-17, 2008. At this meeting, producers, veterinarians and poultry service-people from all aspects of the industry had an opportunity to learn about this research in controlling Salmonella in chickens. The results of this project have also been reported at several smaller meetings of poultry producers, such as the Connecticut Poultry Association and the Pennsylvania Poultry Association. <br>
PARTICIPANTS: Kumar Venkitanarayanan (PI) Dan Donoghue (Co-PI) Mike Darre (Co-PI) Mazhar Khan (Co-PI) Annie Donoghue (Collaborator) Machael Hulet (Co-PI) Paul Patterson (Co-PI) Solis de los Santos (Graduate Student) Anoop Kollanoor (Graduate Student) Sangeetha Ananda Baskaran (Graduate Student) <br>
TARGET AUDIENCES: Poultry producers, Poultry Scientists, Poultry Extension Personnel. <br>
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IMPACT: 2007/09 TO 2008/09<br>
Caprylic acid, when fed for only 3 days, consistently reduced enteric Campylobacter populations in young chickens already colonized with the bacterium. In three separate trials, supplementation of a 0.7% and a 1.4% dose of caprylic acid reduced cecal Campylobacter counts by 3 to 4 logs compared with those in the positive controls. Supplementation of caprylic acid at 0.35% and 2.8% levels had an inconsistent effect on the reduction of C. jejuni populations in the cecal content. Supplementation of CA at 0.7 and 1% also consistently decreased SE populations recovered from the treated birds in comparison to those from positive control chicks. SE counts in the cecum, small intestine, cloaca, liver, spleen and crop of CA-treated chicks were substantially lesser (P < 0.05) than those of control birds. Feed intake and body weight did not differ between the CA and control groups. The results suggest that therapeutic supplementation of CA through feed can effectively reduce C. jejuni and SE colonization in chicks and may be a potential treatment for reducing the carriage of these major foodborne pathogens in poultry.