Submitted to: Avian Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/10/2001
Publication Date: N/A
Citation: Interpretive Summary: Proventriculitis is a condition of broiler chickens in which the chicken's stomach becomes enlarged, swollen, and distended and can tear open when being processed, thus contaminating the carcass with feces. We have previously produced experimental proventriculitis by feeding a homogenate made from enlarged proventriculi to day-old broiler chickens. In the current study we looked at the ability of both viral and bacterial isolate from that homogenate to cause proventriculitis. One virus was purified from the homogenate by extraction with a specific monoclonal antibody to infectious bursal disease virus (IBDV) and will be called MAB-IBDV. Another virus preparation was made by passing the homogenate in cell culture and it will be called L&S Virus. A bacterial species was also isolated from swollen proventriculi which was not present in normal proventriculi. The MAB-IBDV virus caused some abnormalities in the proventriculus but did not cause enlargement. The L&S virus caused both abnormalities and enlargement at 3 weeks after infection. The bacteria caused abnormalities and enlargement at 3 and 4 weeks after infection. When the L&S virus and the bacteria were fed at the same time, the highest levels of abnormalities and enlargement were obtained. It is concluded that virus infections, as well as various dietary factors may make it easier for bacteria to invade the proventriculus.
Technical Abstract: Proventriculitis of broilers can be reproduced by oral inoculation of day- old chicks with a proventricular homogenate from affected 3-week-old broilers. The objective of the following studies was to determine the pathogenicity of viral and bacterial isolates present in this homogenate. Monoclonal antibody to infectious bursal disease virus (IBDV) was used to precipitate virus from the homogenate. A primary chicken digestive tract cell culture system was used to isolate virus and a bacterium was also isolated. In Trial 1, broiler chicks were challenged with either proventriculus homogenate, or with immunoprecipitated IBDV (MAB-IBDV). In Trial 2 birds were orally inoculated with either proventriculus homogenate, suspect virus isolated in cell-culture, or the bacterial isolate. In Trial 3, treatments were maintained in negative pressure isolation chambers and an additional treatment included virus + bacterial isolate. In Trial 1 proventriculus weights and lesion scores were increased by the homogenate. Bursa/spleen weight ratios were decreased at day 14, and feed conversion was increased at day 4 and 21. The MAB-IBDV treatment decreased proventriculus and gizzard relative weights at day 4 PI, increased proventriculus lesion scores and bursa/spleen weight ratios at day 14, and decreased heterophil/lymphocyte ratios at day 21. In Trial 2, all infected birds had higher proventriculus weights at 21 d PI and had higher 28 d proventriculus scores as compared to both control groups. In Trial 3, birds treated with homogenate and birds treated with both the virus and bacterial isolates had higher proventriculus lesion scores, higher organ weights and lower BW, compared to the saline control. These studies suggest that infectious proventriculitis may have a complex etiology.