Submitted to: Avian Diseases
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/19/2006
Publication Date: 7/1/2006
Citation: Holt, P.S., Vaughn, L.E., Moore, R.W., Gast, R.K. 2006. Comparisons of s enterica serovar enteritidis levels in crops of fed or fasted infected hens. Avian Diseases.50(3):425-429. Interpretive Summary: Induced molting is an extremely important procedure for the table egg industry to achieve a second egg lay from aging layer flocks. It is estimated that over 160 million hens are molted via fasting in the U.S. annually. We had previously shown that significantly higher levels of Salmonella enteritidis (SE) and more inflamation was found in the lower intestinal tract of hens molted via fasting. The current study examined the effect of fasting on SE infection in the crop, an organ located in the esophagus just before the stomach. It was found that significantly higher numbers were observed in the crops of fasted hens compared with nonfasted hens at 1 and 2 weeks postinfection. Similar effects were observed in the lower intestinal tract. Antibody immunity of the crop was similar in both groups. However, heterophils, the phagocytic cell in chickens responsible for early defense against infection, were found to be lower in the crops of the fasted hens compared with nonfasted indicating that response by these cells was less effective in fasted birds. Much higher inflammation and damage was observed in fasted hens, even in the absence of SE infection, suggestng that fasting increases the susceptibility of the crop to problems besides SE. These results indicate that fasting can exert many effects along the GI tract.
Technical Abstract: Long term feed withdrawal has been shown to increase intestinal colonization of S. enterica serovar Enteritidis (SE) in challenged hens. Less information is available regarding effects of fasting on crop colonization. Two trials were conducted to compare effects of 14-day feed withdrawal vs full feed on crop colonization with SE. The levels of SE in the crop of fasted hens were significantly higher than in nonfasted hens on days 3 and 10 and days 3, 9 and 16 post-infection (PI) in trials 1 and 2, respectively. Fecal shedding of SE was significantly increased in the fasted hens on day 10 PI. Crop IgA anti-SE levels in crop lavage samples of hens revealed a humoral response post-infection in both treatment groups with no significant differences. Histologic evaluation of H & E crop sections from birds revealed mild to moderate heterophilic infiltration within the crop lamina propria ( LP) of nonfasted infected hens. In comparison, heterophils in crops of fasted infected hens at this time point were sparse, indicating a possible diminished heterophil response in the fasted birds. Multifocal areas of tissue inflammation were observed in crops from fasted hens at day 11 PI (14th day of feed withdrawal) but not in the fed groups. These results indicate that feed withdrawal can have a dramatic effect on the integrity of the crop and its ultimate response to infection.