The effect of feeding a commercial essential oil product on Clostridium perfringens numbers in the intestine of broiler chickens measured by real-time PCR targeting the α-toxin-encoding gene (plc)

Proliferation of Clostridium perfringens type A in the broiler intestinal tract is related to poor growth and litter quality, and can under certain conditions lead to the development of necrotic enteritis (NE), a severe gastrointestinal disease in broilers. The aim of the present study was to investigate the influence of a commercial essential oil blend, CRINA® Poultry, on the intestinal C. perfringens population in broilers vaccinated against coccidiosis. The observed C. perfringens levels were relatively high in general and peaked at 27 days of bird age with numbers ranging from 7 to 8 log cells per g of ileal and caecal content; these numbers correspond to those typically found in birds suffering from NE. No C. perfringens-related pathological changes were observed, however, indicating low levels of virulent strains among the C. perfringens or lack of other predisposing factors. Dietary concentrations of 100 and 200 mg/kg feed of the essential oil blend did not reduce the intestinal numbers of C. perfringens compared to a non-supplemented control group (P>0.05). Further, the essential oil blend failed to improve (P>0.05) both the growth and feed conversion ratio of the broilers. For rapid quantification of C. perfringens type A in broilers, a real-time PCR assay, targeting the α-toxin-encoding plc gene, was developed for use in ileal and caecal samples and was shown to be a fast and reliable alternative to conventional plate counting.