Dataset Information

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

ABSTRACT:

Background

Specific studies on the epidemiology of necrotic enteritis in turkeys are absent in the literature. Necrotic enteritis is common in turkeys and a leading cause of use of therapeutic antibiotics. This study describes the incidence of necrotic enteritis in turkey farms, and the association between incidence and bird age, season, faecal oocyst counts, grow-out size and feed mill.

Results

Necrotic enteritis was diagnosed post mortem in 20.2 % of 545 grow-outs of commercial female and male B.U.T. 10 turkeys started during the years 2010-2016. 80 % of all cases occurred at four to seven weeks of age. Median (minimum-maximum) age at disease detection was 37 (18-115) days. Turkey age at detection was influenced by season, and varied from 33 days among grow-outs hatched in February to 42 days among those hatched in July-August. The incidence also varied with season, showing peak occurrence among grow-outs hatched during February-March and the lowest incidence in turkeys hatched in July-August. 59 % of all cases were detected in 25 % of the farms. The incidence per farm varied from below 4 to 59 %. A multilevel mixed-effects logistic regression model indicated clear impacts of farm and season on incidence, and border-line impacts of grow-out size and feed mill. Grow-outs diagnosed with necrotic enteritis had higher counts of faecal Eimeria oocysts than grow-outs without a diagnosis. This difference was particularly clear during the high-risk period at five to seven weeks of age. Necrotic enteritis was the cause of treatment with therapeutic antibiotics in 88.2 % of all cases of treatment.

Conclusions

Our data indicate that necrotic enteritis incidence in turkeys can be substantially influenced by risk factors at farm level. The incidence showed two seasonal peaks; a moderate peak in turkeys hatched in October/November and a marked peak in turkeys hatched during February/March. Mitigation measures at the farm may therefore be of particular importance during these months in farms located in the Northern temperate zone. Measures which effectively reduce counts of faecal Eimeria oocyst are likely to be among the more promising actions to take both at the farm and at population level.

SUBMITTER: Kaldhusdal M

PROVIDER: S-EPMC8418707 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description: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.

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