Identification of isolated Eimeria species
Eimeria isolates were identified as
E.
bateri,
E.
uzura and
E.
tsunodai (Fig 1). The present study revealed that all collected fecal samples were
Eimeria positive and this agreed with
Gesek et al., (2014) who reported that coccidiosis is the most predominant parasitic disease in quails. Two
Eimeria species were isolated from intestine (
E.
uzura and
E.
bateri) and one from cecum (
E.
tsunodai). These results agreed with those of
Teixeira et al., (2004). The morphological characters of the isolated
Eimeria species in our study were similar to those previously described by
Berto et al., (2013).
Single oocyst isolation and propagation
Single oocyst isolation was successfully carried out for the three identified species. The group inoculated with
E.
bateri showed a mild decrease in the body weight with mucoid and watery diarrhea and this was similar to the findings of
Norton and Pierce (1971). Oocysts and lesions were found only in the intestine, represented by ballooning in the duodenum and jejunum with watery intestinal contents (Fig 2).
E.
uzura inoculated group showed a mild decrease in the body weight with mucoid and watery diarrhea and this agreed with the results of
Tsunoda and Muraki (1971) and
Ruff et al. (1984). Oocysts and lesions were found only in the intestine as ballooning with mucoid watery contents in the duodenum and jejunum, congested parts in jejunum and ballooning in ileum.
E.
tsunodai inoculated group showed a decrease in body weight, watery diarrhea on day 4 post-inoculation. Dropping was coffee-colored or tinged with blood on days 5 and 6 post-inoculation. These observations were similar to the findings of
Tsutsumi and Tsunoda (1972). Oocysts and lesions appeared in the cecum and to some extent in the rectum. Lesions ranged from ballooning in the 2 ceca with foamy watery cecal contents to hardened fibrous cecal contents tinged with blood and thickened cecal mucosa.
Experimental trial
Positive control groups of each
Eimeria species were severely affected and showed signs such as depression, ruffled feathers, huddle together, decrease in appetite and emaciated breast muscle. The fecal abnormalities ranged from soft to brownish foamy mucoid to watery diarrhea. Coffee-colored dropping, blood-tinged dropping and bloody diarrhea were seen in
E.
tsunodai positive control group. The immunized, challenged groups of each
Eimeria species showed lower clinical signs and fecal abnormalities compared to the non-immunized, challenged groups.
The groups challenged with
E.
bateri had no mortalities.
E.
uzura positive control group showed 6.67% mortality, while both 100 and 1000-
E.
uzura oocysts immunized groups had 3.33% mortality. A significant decrease (P<0.001) in mortality occurred in 100 and 1000-
E.
tsunodai oocysts immunized groups by 3.33% and 6.67%, respectively, compared to
E.
tsunodai positive control group which possessed the highest mortality percent (20%) (Table 1).
The immunized groups by
E.
bateri or
E.
uzura showed an insignificant decrease (P>0.05) in the lesion score compared to that of their positive controls. While, a significant decrease (P<0.05) in the lesion score was seen in
E.
tsunodai immunized groups compared to
E.
tsunodai positive control group where bloody cecal core and bloody diarrhea were present. Both 100 and 1000-oocysts immunized groups of each
Eimeria species showed the same lesion score (Table 1) (Fig 3-9). These observations were in agreement with those reported by
Gerhold et al., (2010) in Bobwhite quail immunized against
E.
lettyae.
Concerning oocyst output, the immunized groups of each
Eimeria species showed a dramatic highly significant decrease (P<0.001) in the oocyst output compared to their positive control groups. The 100-oocysts immunized groups had oocyst output insignificantly lower (P>0.05) than that of the 1000-oocysts immunized groups (Table 2). Similarly,
Gerhold et al., (2010) reported that the immunized Bobwhite quail by 100-oocysts of
E.
lettyae produced around 99.7% fewer oocysts compared to the non-immunized, challenged control.
Regarding feed consumption, the immunized groups of each
Eimeria species showed a significantly better feed consumption compared to their positive controls. The difference in feed consumption between the 100 and 1000-oocysts doses of different
Eimeria species was insignificant (Table 3).
The 100 and 1000-
E.
bateri oocysts immunized groups showed a significant increase (P<0.001) in the weight gain compared to the positive control group. The 100-
E.
bateri oocysts immunized group had a significantly higher (P<0.05) weight gain than that of the 1000-
E.
bateri oocysts immunized group. Both
E.
uzura and
E.
tsunodai immunized groups possessed a significantly higher (P<0.001) weight gain compared to their positive controls. The groups immunized by 100-oocysts of
E.
uzura or
E.
tsunodai showed an insignificant improvement in the weight gain compared to the 1000-oocysts immunized groups (Table 3).
Regarding FCR, both 100 and 1000-
E.
bateri oocysts immunized groups showed a significant improvement (P<0.001) in FCR compared to the positive control group. The 100-
E.
bateri oocysts immunized group had a significantly lower FCR than that of the 1000-
E.
bateri oocysts immunized group. Both
E.
uzura and
E.
tsunodai immunized groups showed a significant improvement (P<0.001) in FCR compared to their positive controls. The groups immunized by 100-oocysts of
E.
uzura or
E.
tsunodai showed an insignificant lower FCR than those of 1000-oocysts immunized groups (Table 3) (Fig 10).
The improvement in the performance parameters caused by immunization may be attributed to the produced immunity resulting in suppression of parasite development and so lowering the intestinal lesions and disorders.
Concerning the hematological parameters, PCV values were significantly higher in the immunized groups of each
Eimeria species compared to their positive controls except in case of the 1000-
E.
bateri oocysts immunized group where the increase was insignificant. There was an increase in Hb and WBCs values in the immunized groups compared to the positive controls. The positive control groups revealed a significant reduction in PCV and Hb values in comparison with the negative control group. MCHC value was significantly reduced in the
E.
uzura positive control group compared to the negative control group. RBCs, PCV, Hb and MCHC values were significantly reduced in
E.
tsunodai positive control group compared to the negative control group (Table 4) and this may be attributed to the hemorrhage and blood loose caused by this species. These negative impacts were reduced by immunization by
E.
tsunodai live oocysts, 100 and 1000-oocysts doses. In addition, the negative effects of coccidiosis on blood parameters may be due to the destructive effects caused by the endogenous developmental stages of
Eimeria resulting in disturbances in the absorption of the essential nutrients and traces required for erythropoiesis and Hb synthesis as supported by
Teixeira et al., (2004).
The differential leukocyte count revealed a significant increase in the number of lymphocytes in the immunized groups of each
Eimeria species compared to the negative and positive controls. Scattered immunocytes (reactive lymphocytes) were found in the blood films of the immunized, challenged groups of each
Eimeria species. Contrary, there was a significant increase in the number of heterophils in the positive controls compared to the immunized groups and the negative control group (Table 5). These observations can be explained by
Campbell (1994) who mentioned that scattered reactive lymphocytes may be noticed in the peripheral blood smear after antigenic stimulation by an immunization or a disease and that the infectious agents like bacteria, fungi, or parasites are associated with leukocytosis and heterophilia. The degree of heterophilia usually indicates the severity of the initial inflammatory process.