Location: Animal Parasitic Diseases LaboratoryTitle: Correlation between Clostridium perfringens alpha- and netB-toxin and chick mortality in commercial broiler farms during different anticoccidial control programs
Submitted to: Avian Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/28/2020
Publication Date: 9/1/2020
Citation: Jenkins, M.C., Parker, C.C., Obrien, C.N., Ritter, D. 2020. Correlation between Clostridium perfringens alpha- and netB-toxin and chick mortality in commercial broiler farms during different anticoccidial control programs. Avian Diseases. 64(3):401-406. https://doi.org/10.1637/aviandiseases-D-19-00118.
Interpretive Summary: Necrotic enteritis is a serious disease of poultry that is caused by the spore-forming bacterium Clostridium perfringens. In the spore stage, C. perfringens is highly refractory to extreme environmental temperatures and dessication, and can be found in high numbers in poultry litter. Necrotic enteritis occurs when there is damage to the intestine caused generally by coccidian parasites, namely Eimeria. Once a break occurs in intestinal lining, C. perfringens multiplies and releases toxins that enter the avian bloodstream causing weight depression, poor feed utilization, and, in high enough levels of infection, acute death. The purpose of this study was to determine if there was any correlation between the levels of Eimeria parasites or the presence of the two most important C. perfringens toxins- netB toxin and alpha-toxin and observed chick mortality during growth of broiler chickens during different types of anticoccidial controls (drugs vs. vaccines). Our data indicates that levels of netB- and alpha-toxin are strongly correlated with chick mortality, but that not all C. perfringens possess the genes for these toxins. The correlation was only observed during anticoccidial drug control program, and not during a vaccination program. The pattern of Eimeria oocyst and C. perfringens spore numbers over time of growout was different between drug and vaccine control programs, which may impact the effect on mortality. This information will be valuable to poultry producers is diagnosing causes for increased chick mortality during growth of broilers.
Technical Abstract: The purpose of the present study was to determine if there was a correlation between chick mortality and the presence of Clostridium perfringens alpha- and netB-toxins in C. perfringens recovered from litter in commercial broiler houses. Because coccidiosis predisposes chickens to necrotic enteritis, the concentration of Eimeria oocysts in these samples was measured and the numbers used in similar correlation analyses. Litter samples were collected at 0, 2, and 4 weeks growout from 6 broiler farms (18 houses total) during an anticoccidial drug (ACD) control program and from 9 broiler farms (23 houses total) during an Eimeria vaccine (VAC) control program. Of these, litter samples were collected from 5 farms during both ACD and VAC programs. The litter samples were processed for Eimeria oocyst and C. perfringens spore enumerations using standard parasitological and microbiological techniques. DNA was also extracted for C. perfringens DNA for PCR detection of genes coding for alpha- and netB-toxins. A general trend during the ACD programs was a transient decrease in both E. maxima and non-E. maxima (Eamipt) numbers at 2 wks growout. The pattern was slightly different during VAC with E. maxima and Eamipt levels increasing over time. Average concentrations of C. perfringens in litter were highest at 2 weeks (~ 105-6 spores/g) during ACD and at placement during VAC (~ 105-6 spores/g). During the ACD program a strong correlation was observed between 0-3 wk chick mortality and the presence at placement (0 wk) of netB-toxin (r = 0.42-0.48) or alpha-toxin (r = 0.55 - 0.67). A very strong correlation was observed between 0-5 wk chick mortality and the presence of netB-toxin at 4 wk growout (0.73 - 0.95). During a VAC program, a strong correlation was only observed between the presence of netB-toxin at placement and 0-1 wk chick mortality (r = 0.67).