Necrotic enteritis in turkeys: Prophylactic measures, early detection and non-antibiotic treatments

In Norway, necrotic enteritis (NE) in turkeys is the main cause of usage of therapeutic antibiotics in poultry. New measures are needed in order to reduce the occurrence of NE, and thus reduce the use of antibiotics and improve animal welfare. We have collected data indicating that NE mostly occur in 4-7 weeks old slaugher turkeys. Our data also indicate that subclinical coccidiosis is an important predisposing factor in commercial Norwegian turkeys. This finding has made the turkey industry establish a surveillance program for coccidia in Norwegian slaughter turkeys. This program is used to assess the need for preventive measures on each farm. Furthermore, our findings indicate that a viral infection (haemorrhagic enteritis virus) can be of importance to NE occurrence in some farms. We are now in the process of summarizing data on the effect of drinking water supplementation with a probiotic product (Bacillus subtilis PB6 strain) as a preventive measure against high counts of faecal Clostridium perfringens. These are important findings with regard to future measures aimed at reducing the frequency of clinical NE and use of therapeutic antibiotics. The results suggest that this product reduces faecal Clostridium perfringens counts in turkey flocks free from coccidia. The effect in flocks infected with coccidia is more uncertain. These are important findings with regard to future measures intended to reduce the frequency of necrotic enteritis and coccidiosis, as well as reduced usage of therapeutic antibiotics and hence reduced risk of inducing resistance to antibiotics of importance to human and animal health. Whole genome sequencing of Clostridium perfringens isolates from NE outbreaks have produced results with relevance to understanding turkey NE pathogenesis. These results may also be helpful in the work with establishment of a consistent challenge model of turkey NE.

Necrotic enteritis is a leading cause of morbidity in Norwegian turkeys which necessitates antibiotic treatment of the flock. With growing needs to reduce antibiotic usage and improve animal welfare, new measures are needed to prevent or minimise the inci dence of necrotic enteritis in turkeys. However, almost nothing is reported in the literature on the disease in turkeys and assumptions that it is identical to NE in chickens need to be substantiated. In the absence of any understanding of the condition as assessed by histology and bacteriology, it is difficult to design rational measures with which to improve the welfare of the birds. We propose to characterise the disease in turkeys and develop an experimentally reproducible model in turkeys in order t o evaluate i) the role of predisposing factors such as coccidiosis and haemorrhagic enteritis virus infection, ii) the significance of the newly discovered NetB toxin of Clostridium perfringens and iii) the value of a Bacillus probiotic and zinc in reduci ng its incidence and/or severity.