Caprylic acid supplemented in feed reduces Campylobacter jejuni colonization in broiler chickens.

摘要

Campylobacter is one of the most commonly reported bacterial causes of human food-borne illness and epidemiological evidence indicates poultry and poultry products as significant sources of human Campylobacter infection. Reducing Campylobacter carriage in the intestinal tract of poultry would decrease contamination of meat and eggs. Caprylic acid is an 8-carbon fatty acid naturally found in milk and coconut oil. Caprylic acid is a food-grade chemical generally recognized as safe (GRAS) by the United States Food and Drug Administration (FDA), and has been shown to be bactericidal against several microbial pathogens, in vitro. However, it has not been tested in the control of Campylobacter in chickens. A series of studies were conducted to evaluate the ability of caprylic acid to reduce Campylobacter population in chickens. Caprylic acid was prophylactically supplemented for 10 consecutive days at 0.35%, 0.525%, 0.7%, 0.875%, 1.05%, 1.225% and 1.4% in four trials in the feed of 10 day old chickens, and therapeutically at 0.35%, 0.7%, 1.4% and 2.8% in the feed of 15 day old chickens (n= 10 chicks per treatment) in three trials. Chicks were orally challenged with at least 4 x 105 cfu/ml of a five-strain mixture of C. jejuni three days post hatch. When caprylic acid was prophylactically fed to birds for 10 consecutive days, the lower doses were more efficacious against C. jejuni than higher doses. When caprylic acid was therapeutically supplemented for three days prior to sacrifice, all doses were effective; however the 0.7% and 1.4% doses produced the greatest reduction in Campylobacter populations (3.5 to 4.8 log10 cfu) compared to control treatment (8.4 to 8.6 log10 cfu) across trials. When replicate studies were conducted in market age birds (42 days of age) with a similar experimental design, the 0.7% dose also significantly reduced enteric Campylobacter counts compared to control treatment. A follow up study with similar experimental design was carried out to evaluate if caprylic acid reduces C. jejuni by altering the composition of the bacterial population of the intestine. This study was conduced using the denaturing gradient gel electrophoresis (DGGE) technique. The bacterial population of caprylic acid treatments was similar to controls. Therefore, the efficacy of caprylic acid against C. jejuni was not the result of a change to the composition of the intestinal microflora. To our knowledge, few treatments have shown promise in reducing Campylobacter in chickens colonized with this food borne pathogen. The use of caprylic acid, a natural and safe feed additive shows to reduce this human pathogen in poultry.