Maternal vaccination against subclinical necrotic enteritis in broilers

Abstract

The inclusion of antibacterial feed additives has until now been the major strategy for controlling Clostridium perfringens-associated necrotic enteritis in broilers. In the present study, the effect of maternal immunization against the disease was examined. Broiler breeder hens were injected intramuscularly with candidate vaccines based on C. perfringens type A and type C toxoids adjuvanted with aluminium hydroxide. Vaccination resulted in a strong serum immunoglobulin G response to C. perfringens alpha-toxin in parent hens, and specific antibodies were transferred to their progeny. Subclinical necrotic enteritis in broilers was induced under field conditions or in a disease model, and the occurrence of specific enteric and hepatic lesions was evaluated in randomly selected birds. In three experiments, estimates of odds ratio for developing such lesions were 0.23, 0.33 and 0.56 in maternally toxoid C-immunized broilers compared with non-immunized controls. In toxoid Aimmunized birds, odds ratios were estimated at 0.41, 0.61 and 0.63. From these results, immunoprophylaxis seems to be an interesting alternative for the control of necrotic enteritis in broilers.

Association between gizzard lesions and increased caecalClostridium perfringenscounts in broiler chickens

“…The main reason is that the C. perfringens counts of almost all birds with NE were very high, whether GEU was present or not. This association between NE and C. perfringens counts is in accordance with previous findings (Kaldhusdal & Hofshagen, 1992;Løvland et al ., 2004). Furthermore, our results show that NE may be found also in birds without GEU.…”

“…perfringens increased with age, reaching its maximum at 27 to 29 days of age, when it stabilized and even decreased. This development has been observed in other studies (Løvland et al ., 2004).…”

“…Pseudomembranes were spatially associated with ulcers, or appeared separately. Pseudomembranes (Kaldhusdal & Hofshagen, 1992) and ulcers (unpublished data; Løvland et al ., 2004) are associated with high counts of intestinal C. perfringens, and are considered specific for C. perfringens -associated NE. Both types of lesions have previously been used as indicators of NE in a vaccine study (Løvland et al ., 2004).…”

“…Pseudomembranes (Kaldhusdal & Hofshagen, 1992) and ulcers (unpublished data; Løvland et al ., 2004) are associated with high counts of intestinal C. perfringens, and are considered specific for C. perfringens -associated NE. Both types of lesions have previously been used as indicators of NE in a vaccine study (Løvland et al ., 2004). The distribution of NE lesions between intestinal regions was studied in a total of 267 birds from the six experiments, including birds that were not examined for C. perfringens (C. perfringens counts were available from 130 of these birds).…”

Non-soluble fibres and narasin reduce spontaneous gizzard erosion and ulceration in broiler chickens

“…Scoring for necrotic enteritis. In treatment group B2 (no oat hulls, access to litter, no narasin) and treatment group D2 (oat hulls, access to litter, no narasin), the mucosal surface of the small intestine of each chicken was inspected for ulcers (a distinct mucosal depression measuring at least 1 mm) and pseudomembranes (at least 1 mm), which are characteristic of C. perfringens-associated necrotic enteritis (Lovland et al, 2004). A lesion was recorded as focal if the maximum extension was at least 1 mm but less than the circumference of the small intestine.…”