Developing an experimental necrotic enteritis model in turkeys - the impact of Clostridium perfringens, Eimeria meleagrimitis and host age on frequency of severe intestinal lesions

Abstract

Background: Necrotic enteritis is a significant problem to the poultry industry globally and, in Norway up to 30% of Norwegian turkey grow-outs can be affected. However, despite an awareness that differences exist between necrotic enteritis in chickens and turkeys, little information exists concerning the pathogenesis, immunity, microbiota or experimental reproduction of necrotic enteritis in turkeys. In particular, it is important to determine the appearance of the gross lesions, the age dependency of the disease and the role of netB toxin of Clostridium perfringens. To this end, we report our findings in developing an in vivo experimental model of necrotic enteritis in turkeys. Results: A four tier (0-3) scoring system with clearly defined degrees of severity of macroscopic intestinal lesions was developed, based on 2312 photographic images of opened intestines from 810 B.U.T. 10 or B.U.T. Premium turkeys examined in nine experiments. Loss of macroscopically recognizable villi in the anterior small intestine was established as the defining lesion qualifying for a score 3 (severe intestinal lesions). The developed scoring system was used to identify important factors in promoting high frequencies of turkeys with severe lesions: a combined Eimeria meleagrimitis and Clostridium perfringens challenge, challenge at five rather than 3 weeks of age, the use of an Eimeria meleagrimitis dose level of at least 5000 oocysts per bird and finally, examination of the intestines of 5-week-old turkeys at 125 to 145 h after Eimeria meleagrimitis inoculation. Numbers of oocysts excreted were not influenced by Clostridium perfringens inoculation or turkey age. Among three different lesion score outcomes tested, frequency of severe lesions proved superior in discriminating between impact of four combinations of Clostridium perfringens inoculation and turkey age at challenge. Conclusions: This study provides details for the successful establishment of an in vivo model of necrotic enteritis in turkeys.

The incidence of necrotic enteritis in turkeys is associated with farm, season and faecal Eimeria oocyst counts

“…housing, management, and feeding. Based on their field data, Droual et al [ 2 ] suggest that there may be a resistance to NE in young poults, a finding that agrees with published experimental data [ 7 , 10 ]. NE in commercial broilers is rarely found in birds younger than two weeks of age [ 11 ], and experimental NE in broilers is usually induced at about three weeks of age [ 5 ].…”

“…Climate is a possible element in this context, by influencing the environment in the turkey house, and consequently the conditions for the proliferation of pathogens. Moist litter [ 14 ] due to condensation caused by cold weather and restricted ventilation may promote Eimeria proliferation and subclinical coccidiosis, and thus predispose the turkeys to NE [ 2 , 6 , 7 ]. However, cold weather alone cannot explain the peak occurrence in March-April, because January and February usually are colder months at the locations of these farms (Table 6 ).…”

“…as a risk factor for NE in broilers [3][4][5], and a predisposing role of Eimeria spp. in turkey NE has been suggested based on field data [2,6] and experimental data [7].…”

The effect of different dietary ratios of lysine and arginine in diets with high or low methionine levels on oxidative and epigenetic DNA damage, the gene expression of tight junction proteins and selected metabolic parameters in Clostridium perfringens-challenged turkeys

“…In turkeys, necrotic enteritis (NE) is caused by Clostridium perfringens (C. perfringens) anaerobic bacteria and their toxins, and it causes considerable economic losses in poultry farming [1]. In a post-mortem analysis, the disease manifests by strong inflammation and necrosis of the intestinal mucosa, which impairs nutrient absorption, weakens immune and antioxidant systems and, consequently, compromises growth performance and increases bird mortality [2][3][4]. Pathological changes associated with NE are also observed in parenchymal organs such as the liver, which can disrupt many biochemical processes.…”

Antimicrobial peptides as an alternative to relieve antimicrobial growth promoters in poultry

“…Clinical signs are more likely to be present in young animals, although, sporadically, they can be seen in adult flocks. Such infections can trigger necrotic enteritis due to intestinal mucosa disruption (Sumners et al 2011;Wu et al 2014;Hardy et al 2020).…”