Fowl Adenovirus Induced Gizzard Erosion in Broiler Chickens in Southern India

Abstract

Background: In Southern India, feed passage syndrome was on the rise in the late half of 2019 affecting broiler chicken flocks. The feed passage syndrome is an indication of poor gastrointestinal health in chickens, in which poorly digested coarse feed particles are observed to be more in the feces. This study investigated the causative factors for the feed passage syndrome in broiler flocks. Methods: Affected commercial broiler farms having incidences of feed passage syndrome, low body weight gain and poor feed conversion ratio, were visited in several regions of Karnataka and Andhra Pradesh. But there was no increase in mortality. Feed samples were collected from these regions for mycotoxin analysis. Intestinal health was examined in these flocks for lesions of coccidiosis and bacterial enteritis/dysbacteriosis. The common observation in all the birds examined was the presence of gizzard erosions. The gizzard in most of the birds was flaccid and moderate to severe erosions in the koilin layer of the gizzard were observed. In some birds, there were mild to moderate lesions caused by Eimeria maxima and Eimeria tenella. Tissue impressions on FTA cards were collected from gizzards having erosion on the koilin layer and submitted for identification of Fowl Adenovirus (FAdV) through the polymerase chain reaction (PCR) method. Result: All the samples were found positive for FAdV. Four samples were further processed for sequencing of the Hexone gene to identify the serotype of the virus. FAdV serotype 11 was detected in three samples and serotype 8a was detected in one. Among major mycotoxins, low levels of Aflatoxin B1 were the predominant finding in feed samples. Thus, it can be concluded that fowl adenovirus-induced gizzard erosions in commercial broiler birds along with mild coccidiosis could be leading to feed passage syndrome.