Histological sections of Fabricius bursa, liver and small intestines of chickens are shown in Fig 1 and Table 1.
Fig 1: Follicular necrosis with presence of neutrophils (soil control TS: 2nd slaughter, 49 days).
Table 1: Microscopic characteristics of gumboro disease.
Depending on the stage of the disease; lesions of hyperplasia, follicular atrophy and fibrosis were observed in control and experimental broilers. Follicular necrosis was especially dominant during the second sacrifice of broilers. During the experiment, the latter was also more intense in ground farming. Based on the diet and compared to the control lots, lymphoid follicle necrosis was moderate in the OAGS and GB group. Adding bentonite to the acorn diet nearly halved the intensity of follicular necrosis compared to the lesion appearance of CG or TB. The follicular scarring expressed by the extent of fibrosis was extensive on the bursae from the second sacrifice. Throughout the experiment and depending on the type of breeding, fibrosis was slightly more widespread on the purses from cage breeding. On the other hand, the diet based on acorn and bentonite (OAGBS and GBB) showed extensive follicular healing compared to the controls and the groups fed with the acorn (Fig 2 and 3).
Fig 2: Slight fibrosis (acorn+bentonite battery GBB: 2nd slaughter, 49 days).
Fig 3: Moderate necrosis of lymphoid follicles (GB battery gland: 2nd slaughter, 49 days).
Neither control diet nor accron or benotnite supplemented diets failed to prevent the development of microscopic hepatic lesions (Fig 4 and 5) which included the presence of heterogeneous perivascular infiltrates, cytogresomes, megalocytosis, hepatic steatosis, hepatitis, lysis and degeneration of hepatocytes. Depending on the type of farm, the lesions of steatosis and megalocytosis were more evident in cage culture. In contrast, the presence of cytogresomes in the cytoplasm of hepatocytes was more intense in the soil culture. Lysis and degeneration lesions were often observed on lots reared in soil compared to those in cages.
Fig 4: Heterogeneous perivascular hepatic infiltrates (Gland Battery GB: 1st slaughter).
Fig 5: Lysis and degeneration of hepatocytes (gland + bentonite battery GBB: 1st slaughter).
The majority of transverse intestinal sections exhibited tissue changes at different grades of inflammatory activity. In fact, the severity of the enteritis lesions ranged from mild, localized in the lamina propria, then from the strong infiltration of neutrophils in the crypts until diffuse ulceration with the presence of granulation tissue at the level of the cell. epithelium of the intestinal mucosa.
According to the type of breeding, in general, the enteritis lesions showed in the submucosa and the mucosa infiltration of the crypts by neutrophils and local epithelial erosions more or less important in the lots raised on soil compared to those on cages. Depending on the diet, the CG and TB exhibited less inflammatory activity compared to the other groups. On the other hand, the group fed with acorns (OAGS and GB) showed a more marked transmural inflammationthan that of the CG or TB where it was less intense compared to the batch fed with acorn and bentonite (Fig 6 and 7).
Fig 6: Enteritis with slight infiltration of neutrophils in the crypts (TB battery witness: 2nd slaughter).
Fig 7: Enteritis with strong neutrophil infiltration in the crypts (gland soil GS: 2nd slaughter).
The autopsy did not reveal any obvious macroscopic lesions on the different organs taken from the different groups of experimental animals, with the exception of those observed on the bursa of Fabricius which showed swelling associated with congestion and atrophy accompanied by grayish color. The involvement of these bursaries was accompanied by mild perihepatitis, congestion and intestinal petechiae, more marked in chickens fed the control and the acorn-based diet and less pronounced in the animals that consumed the diet supplemented with bentonite.Based on the diet consumed and compared to the control batch, histology revealed necrosis of the lymphoid follicles of the Fabricius bursa more moderate with the acornbased diet. Adding bentonite to the acorn diet al
most halved the intensity of follicular necrosis compared to the lesion appearance of control animals. In addition, depending on the diet consumed, hepatic infiltrates were much less in the acorn and bentonite diet, which even reduced the occurrence of hepatocyte lysis and degeneration compared to other experimental diets. Intestinal microscopy also revealed that the control batch exhibited less transmural inflammatory activity in comparison especially with the batch fed with acorns and bentonite.
De Vries et al., (2006)
reported that the laying hen reared in the open air consumed soil nearly 10% of the dry matter ingested.
Adding bentonite to broilers’ feed strengthens the animal’s immunity more and significantly reduces:
-The intensity of follicular necrosis of the bursa of Fabricius.
-Hepatic infiltrates, lysis and hepatocyte degeneration.
-Intestinal transmural inflammatory activity.
Throughout the experiment and depending on the type of farming, the fibrosis was slightly more widespread on the purses resulting from cage farming as opposed to farming carried out on the ground. Steatosis and megalocytosis lesions, as well as lysis and degeneration lesions were also more evident in hepatocytes from battery-reared animals. On the other hand, only appearance of cytogresomes in the cytoplasm of hepatic cells was noted in the culture carried out in the soil.
At the intestinal level, enteritis lesions in the submucosa and mucosa, infiltration of the crypts by neutrophils and more or less significant local epithelial erosions were observed in the birds of the batches raised on the ground than those raised in cages.
These responses are undoubtedly due to a difference in the breeding density of which the cage breeding was carried out more suffering by the animals because of the high density of 20 subjects per square meter compared to the ground breeding. having been established according to the required standard of 10 subjects per square meter.