The role of an attenuated anticoccidial vaccine on the intestinal ecosystem and on the pathogenesis of experimental necrotic enteritis in broiler chickens

Abstract

The objective of the present study was to investigate the effect of an attenuated anticoccidial vaccination on the intestinal ecosystem and on the pathogenesis of experimental necrotic enteritis (NE) in broiler chickens. Two hundred and forty 1-day-old Cobb 500 broiler chickens were randomly allocated to four treatment groups according to the following experimental design: control Group N; Group PN, where birds were vaccinated with anticoccidial vaccine; Group M, where birds were challenged with Clostridium perfringens and with Eimeria maxima; and Group PM, where birds were both vaccinated and challenged. From each bird, the intestine, gizzard and liver were scored for gross NE lesions. Intestinal digesta were collected for pH and viscosity determination. Samples from the gastrointestinal tract and liver were taken for microbiological analysis. Evaluation of the experimental data revealed that Group M had significantly higher overall mean NE intestinal lesions compared with Group PM. Viscosity values of jejunum digesta as well as pH values of the duodenum, jejunum and ileum digesta in Group M were significantly lower compared with Group PM. C. perfringens counts in the caeca of Group PM were significantly lower compared with Group M. The milder decrease of pH and viscosity values of intestinal content and the reduction of C. perfringens counts in the caeca in challenged and vaccinated birds may explain the lower score of NE gross intestinal lesions and may suggest a positive effect on intestinal ecosystem and a significant protective effect of attenuated anticoccidial vaccination against NE in a subclinical experimental model

Efficacy of an anticoccidial live vaccine in prevention of necrotic enteritis in chickens

“…Thus, vaccination prevented not only coccidia-specific lesions what is known from previous investigations (e.g., Shirley et al, 1995;Williams, 2003;Awad et al, 2013) but also NE lesions. This is consistent with the findings of Tsiouris et al (2013) who recently described the positive effect of anticoccidial vaccination on intestinal NE lesions as well as on C. perfringens counts in their complex subclinical NE model.…”

“…vaccine in prevention of clinical NE caused by mixed infections with E. tenella, E. brunetti and NetB positive C. perfringens. Up to now, most studies dealing with anticoccidial vaccines and NE aimed at induction of the disease employing vaccines (generally at overdoses) as predisposing factors to clostridial infections (Williams, 2003;McReynolds et al, 2004;Gholamiandehkordi et al, 2007) except of one study in a subclinical model describing the effect of vaccination against coccidiosis to prevent NE (Tsiouris et al, 2013). The trials described herein are based on a clinical model since most of the unvaccinated coinfected animals showed moderate to severe signs of clinical disease.…”

“…anticoccidial treatment (Lanckriet et al, 2010;Alnassan et al, 2013) or an experimental vaccination with a C. perfringens toxoid vaccine (Mot et al, 2013). Recently, Tsiouris et al (2013) showed the prophylactic efficacy of an anticoccidial live vaccine against experimentally induced subclinical NE due to infection with C. perfringens and Eimeria maxima. In the present study, we investigated the protective effect of an attenuated live vaccine on clinical NE which often occurs in the field and was in this trial induced by coinfections with C. perfringens, Eimeria tenella and Eimeria brunetti.…”

Temporary feed restriction partially protects broilers from necrotic enteritis

“…The gizzards were scored for gross lesions by the use of a 0 to 2 scale, described by Novoa-Garrido et al (2006). The livers were scored using a 0 to 2 scale, described by Tsiouris et al (2013), giving a score 0 when no gross lesions were observed, a score 1 when liver congestion and/or gall bladder distension and wall thickening and/or bile discoloration were observed, and a score 2 when necrotic lesions in liver were observed.…”

“…Although, netB-positive Clostridium perfringens type A strain is the causal agent of the disease, a number of cofactors are usually required to precipitate an outbreak of the disease, such as damage to the intestinal mucosa and increase of pH and viscosity of intestinal digesta (Kaldhusdal et al, 1999;McReynolds et al, 2007;Tsiouris et al, 2013). Various preventive and curative measures have been proposed to control necrotic enteritis Timbermont et al, 2010), including changes in feeding management (Mateos et al, 2002).…”