Anticoccidial efficacy of ‘Coxynil” a herbal feed additive was tested against Einieria tenella in broilers, vs. a vs. Salinomycin. Body weight of birds challenged with E. tenella in Coxynil treated groups was higher as compared to Coxynil untreated & Salinomycin treated groups.. Oocyst out put, lesion score, HI titres against New Castle disease virus and T Cells were significantly higher in Coxynil supplemented groups. Examination of ceaca of the birds, revealed that the Coxynil interfered with life cycle of coecidia. The typical second generation schizonts were absent in ceacal section of Coxynil treated groups. The results indicate that Coxynil is an effective herbal coccidiostat.
ABSTRACT
One hundred and sixty day old broiler chicks, procured from a recognized hatchery, were divided into eight groups, of 20 birds each as, CA- Normal feed, CB- Salinomycin @1 kg/ton of feed, CC-Coxynil @ 250 mg/kg of feed and CD- Coxynil @ 300 mg/kg of feed and respective infected groups as IA, IB, IC and ID. The birds were maintained on deep litter system and standard management practices were followed. Birds were weighed weekly and daily feed intake was recorded. This data was used to calculate the weekly FCR. Oocysts challenge with sporulated oocysts of E.tenella @20,000 oocysts/bird was carried out at the age of 21day. Birds were observed for clinical symptoms. Oocysts per gram (OPG) of droppings were calculated in infected groups on 4, 6, 8 and 10 day post infection (DPI). Three birds from each group were sacrificed on 3, 6 and 9 DPI. Gross changes in different organs, if any, and caecal lesion score was recorded. At the same time, tissue pieces from caeca, caecal tonsils, spleen and thymus were collected in 10% formaline for histopathological study; additionally pieces from caeca were collected in formal calcium to demonstrate T cells by ANAE method. Serum collected, at the time, was used for assessing the HI titer against NCDV.
Final body weights were significantly less in infected groups than the respective control groups. Weights were significantly higher in Coxynil groups than Salinomycin groups. Similar trend was observed for weekly weight gains. Total feed intake was less in infected groups than the respective control groups. Feed intake was higher in Coxynil groups than Salinomycin and control groups. After oocysts challenge, FCR in infected groups were higher than respective control groups. FCR in Coxynil groups was better than Salinomycin birds, while opposite was noted in infected groups.
Both the coccidiostats used in the study delayed the appearance of clinical symptoms as compared to infected control group (IA). Mortality was observed only in IA and IC. Average OPG was highest in IA followed by that in IC, ID and IB. Salinomycin was found to be better in reducing OPG as compared to Coxynil, and OPG, in Coxynil treated groups, was less than infected control (IA), over the period.
Haemorrhages, blood clots and distension of caeca, on 6 DPI and caecal core formation and thickening of caecal wall, on 9 DPI, were the prominent gross findings in IA. Salinomycin was found to be more effective than Coxynil in reducing the intensity of lesions. Caecal lesion score on 6 DPI was highest in the infected groups. Average score for the period did not differ significantly between the groups. Microscopically, catarrhal enteritis was evident in all the infected groups, on 3 DPI. Denuded epithelium, large number of schizonts and gametes, alongwith haemorrhages (in mucosa and submucosa), on 6 DPI and exfoliated epithelium alongwith oocysts in mucosa, on 9 DPI, were the prominent alterations in group IA. Salinomycin was found to be more effective than Coxynil, in reducing the changes.
ANAE cell counts, on 9 DPI, were significantly higher in infected groups than the respective control groups. Coxynil was found to be more beneficial over Salinomycin, as highest count, was observed in IC, amongst all the groups. Average HI titers, in the infected groups were low as compared to respective control groups and significantly lowest in IA, amongst all the groups. Coxynil groups revealed higher titers than Salinomycin treated birds.
MATERIALS AND METHODS
The present research work was conducted at the Department of Pathology, Bombay Veterinary College, Parel, Mumbai-12, India, to study the pathological and immunological changes following experimental coccidial infection and to evaluate the effects of Coxynil – a herbal coccidiostat on these changes and overall performance of broilers.
3.1 Experimental Chicks: One hundred and sixty, day old broiler chicks, obtained from a recognized hatchery, were maintained on deep litter system with optimum conditions of brooding and management.
3.2 Experimental Feed: Broiler starter and finisher feed, free of any coccidiostat was procured from recognized feed manufacturer.
3.2.1 Coccidiostats: Coxynil (Herbal coccidiostat) from M/S.‘GROWELL INDIA’, Pune, India was mixed in the feed as per the protocol. Salinomycin 6% (Coxistac premix) was purchased from market and mixed in the feed as per protocol.
3.3 Experimental Procedure:
The chicks were divided into eight different dietary treatment groups as below,
3.4 Vaccination: Vaccination with Lasota F1 strains was carried out on 8th day of age by intraoccular route. Vaccination against IBD was done by intraoccular route on 11th day of age.
3.5 Isolation And Sporulation Of Eimeria tenella Oocysts For Infection: A field strain of E. tenella was isolated from the caeca collected from the local poultry slaughter house and the oocysts were identified on the basis of size, shape and location of lesions. Oocysts were separated by sedimentation method and were sporulated in 2.5% potassium dichromate solution at room temperature with intermittent bubbling. These sporulated oocyst of E. tenella were used for further experimental work (Chaudhari, 1993).
3.6 Oocyst Challenge: The oocysts challenge was carried out on 21st day by inoculating 20,000 sporulated oocysts per bird orally, as per the protocol.
3.7 Parameters Studied:
3.7.1 Body Weight And Feed Conversion Ratio: The birds were weighed at the end of every week and the daily feed consumption was recorded. Feed conversion ratio (FCR) was calculated as,
Average feed consumption per bird in the week (g)
FCR = ---------------------------------------------------------------------------------------------
Average weight gain per bird during the week (g)
3.7.2 Oocyst Production Per Gram Of Droppings: The numbers of oocysts per gram of droppings were estimated by Stoll’s method on 4, 6, 8 and 10th day post infection.
3.7.3 Pathology:Detailed post mortem of the birds died and sacrificed (3, 6 and 9 DPI) during the experiment was undertaken. Gross lesions in various organs, if any, were recorded. Tissue pieces from caeca, caecal tonsil, thymus and spleen were collected in 10% formaline for histopathological studies by Hematoxylin and Eosin staining method.
3.7.4 Lesion Scoring:Caeca were removed from the dead/sacrificed birds and lesion scored by 0 to + 4 scoring system as described by Johnson and Reid (1970). Wherein, 0 scores for no lesion and subsequent + 1 to + 4 scores allowed depending upon lesions noted in caeca from different groups.
3.7.5 Acid Alpha Naphthyl Acetate Esterase (ANAE) Staining : (Tissue section): Tissue pieces of caeca from the sacrificed birds were collected in formal calcium for demonstration of T cells. ANAE staining of tissue section: Identification of T cells in the tissue sections was carried out following combination of ANAE staining methods used by Yam et al. (1971) and Ranki et al. (1980) with slight modifications. from 20 oil immersion fields and for each group three different sections were taken.
3.7.6 HI Titer: Serum was collected at the time of sacrificing birds on 3, 6 and 9 day post infection. Serum was separated and stored at -200c for assessing the HI titer against NDV.
3.8 Preparation Of Soluble Oocyst Antigen Of E. tenella: A suspension of sporulated oocyst of E. tenella were thoroughly washed with normal saline and concentrated by sugar flotation method. Again, it was washed with normal saline. Then it was treated with 10% sodium hypochlorite solution at room temperature for 5 min. to remove any extraneous materials. The phosphate buffer saline was added to adjust the concentration of oocyst to 50,000 oocyst/ml. The suspension was then sonicated with Branson sonifier at 220 duty cycles. Three cycles of sonification of 20 min. each were used. The process was carried out on ice. After sonification, a drop of suspension was examined by light microscopy to confirm the disruption of the oocysts. Protein Estimation: Protein estimation of the antigen was carried out by the Lowery’ method. Antigen stored in refrigerator at - 200 C.
3.9 Statistical Analysis: Suitable statistical analysis was applied to the data obtained as suggested by Snedecor and Cochran (1994).
Observations and Results
The present study was carried out to understand the gross and microscopic changes and immunological status of birds having sub-clinical coccidiosis and to evaluate the effect of Coxynil – a herbal coccidiostat in broilers against it.
4.1 Average Weekly Body Weights: (gm) - Average weekly body weights, in grams, for different groups are presented in Table No.1
Table No. 1: Average weekly body weights (gm)
a) Before oocysts challenge.
* Significant at 5% level.
b) After oocysts challenge.
Mean with at least one common superscript do not differ significantly. ** Significant at 1% level.
Control group - CA : Control, CB : Salimomycin, CC : Coxynil @ 250gm/T, CD : Coxynil @ 300 gm/Ton
Infected group - IA : Control, IB : Salimomycin, IC : Coxynil @ 250gm/T, ID : Coxynil @ 300 gm/Ton
4.2 Average Weekly Weight Gains: (gm)
Average weekly gains in body weights, in grams, for all the groups are presented in Table No.2.
Table No. 2: Average weekly weight gains (gm).
a) Before oocysts challenge.
b) After oocysts challenge.
Mean with at least one common superscript do not differ significantly.
** Significant at 1% level
4.3 Average Weekly Feed Intake: (gm)
Average weekly feed intake, in grams, for all the groups are presented in Table No.3.
Table No. 3: Average weekly feed intake (gm).
a) Before oocysts challenge.
NS- Non Significant
b) After oocysts challenge.
Mean with at least one common superscript do not differ significantly.
** Significant at 1% level.
Control group - CA : Control, CB : Salimomycin, CC : Coxynil @ 250gm/T, CD : Coxynil @ 300 gm/Ton
Infected group - IA : Control, IB : Salimomycin, IC : Coxynil @ 250gm/T, ID : Coxynil @ 300 gm/Ton
4.4 Feed Conversion Ratio: (FCR)
Weekly feed conversion ratio, before and after oocysts challenge, for all the groups are presented in Table No.4.
Table No. 4: Weekly FCR.
a) Before oocysts challenge.
Mean with at least one common superscript do not differ significantly.
* Significant at 5% level.
Control group - CA : Control, CB : Salimomycin, CC : Coxynil @ 250gm/T, CD : Coxynil @ 300 gm/Ton
Infected group - IA : Control, IB : Salimomycin, IC : Coxynil @ 250gm/T, ID : Coxynil @ 300 gm/Ton
4.5 Clinical Symptoms:
The clinical symptoms observed and mortality during experimental period are presented in Table No. 5
Table No. 5: Clinical symptoms.
Mortality pattern in different groups:
Dullness and loose droppings, with slight mucus, were the first symptoms observed 3 days post infection (DPI) in infected group (IA). In Salinomycin treated (IB) and Coxynil groups (IC and ID), similar symptoms, were observed on 4 DPI. Appearance of blood in dropping was noted on 4 DPI in group IA and on 5 DPI in groups IB, IC and ID. The mortality was 15% in group IA and 5% in IC. Control groups CA, CB, CC and CD did not reveal any clinical symptoms or mortality. Clinical symptoms were first noticed in IA followed by those in treated groups. The symptoms observed in Salinomycin and Coxynil groups and those at two different dose levels were almost similar. Mortality was high in infected group (IA) as compared to treatment groups. Besides, birds in all the infected groups appeared lethargic and huddled together.
4.6 Oocyst Per Gram (OPG): (104)
The numbers of oocysts per gram of droppings were estimated by Stoll’s method on 4, 6, 8 and 10 days post infection and are depicted in Table No. 6.
Table No. 6: Average OPG count (104)
No coccidial oocysts could be observed in any of the control groups (CA, CB, CC and CD) during the period of experiment.
The average OPG count in infected group, IA, was highest followed by that in Coxynil groups IC and ID and it was lowest in Salinomycin treated group (IB). The differences in OPG count amongst infected groups were non-significant.
4.7 Gross Lesions:
The birds which died and those sacrificed on 3, 6 and 9 DPI during the experiment were autopsied to note the gross abnormalities.
NS- Non Significant
4.7.1 Dead Birds:
Three birds from group IA and one from Coxynil group (IC), died during the experiment. These birds revealed pale subcutaneous tissue and musculature. The gross lesions were found to be confined to caeca. Caecal pouches were distended with blood, blood clots and reddish brown contents. Extensive haemorrhages were observed in the caeca. Other organs did not reveal any gross abnormality.
4.7.2 Sacrificed Birds:
Three birds from each group were sacrificed on 3, 6 and 9 DPI. Control groups (CA, CB, CC and CD) did not reveal any gross abnormality during the experimental period. Except watery to stringy caecal contents, no prominent lesions could be noticed on 3 DPI in any of the infected groups (IA, IB, IC and ID). On 6 DPI, group IA revealed scattered petechiae, visible from serosal surface, distended caecae, which contained clotted and unclotted blood mixed with fibrin shreds. Caecal wall was thickened and congested with extensive haemorrhages. On comparison, lesions of petechial haemorrhages and distention of caeca appeared more pronounced in IC and ID than in IB. On 9 DPI, in group IA, caecal mucosa revealed few foci of petechiae and formation of caecal core, which appeared as detached from mucosa. It was dry and hard. Caecal wall was slightly thickened and edematous. Similar lesions were observed in rest of the infected groups, except absence of caecal core in groups IB and IC. Haemorrhagic foci were comparatively more in group IC. Thymus and Spleen did not reveal any gross abnormality in any of the groups.
4.8 Caecal Lesion Score:
Caecal lesions were scored from the three birds sacrificed on 3, 6 and 9 DPI and the results are presented in Table No. 7. Control groups (CA, CB, CC and CD) did not reveal any lesions during observation period.
Table No. 7: Average caecal lesion score.
NS- Non Significant
No lesions were observed on 3 DPI in any of the treatment groups.
Amongst all the infected groups, Salinomycin treated group (IB), revealed lowest caecal lesion score followed by that in Coxynil groups (IC and ID) while infected group (IA) revealed highest lesion score.
4.9 Microscopic Findings:
4.9.1 Dead Birds:
The birds died from groups IA and IC, revealed denuded caecal epithelium, increased thickness of the mucosa with developing schizonts and edematous changes in caecal wall. Thickened muscularis externa and narrowed submucosal space, as if compressed, were also observed. Large numbers of schizonts were observed in mucosal epithelium up to the muscularis and at some places muscularis mucosae revealed necrotic changes. Patchy areas of haemorrhages were observed in mucosa and submucosa. Infiltration of heterophils and mononuclear cells in all the three layers was observed.
4.9.2 Sacrificed Birds:
On 3 DPI, group IA revealed proliferation of caecal epithelium and exudate consisted of desquamated cells mixed with mucus. Vacuolation in glandular epithelium, suggestive of increased goblet cell activity and reduced submucosal space were also observed. Large numbers of merozoites were observed in the crypts and in caecal glands. Infiltration of lymphocytes and heterophils in the mucosa and around the glands was observed. Similar changes, with reduced intensity, were observed in Salinomycin (IB) and Coxynil groups (IC and ID).
On 6 DPI, group IA revealed wide spread damage to the caecal epithelium, which was necrotic and at most of the places it was totally exfoliated. Hyperemia of the mucosa and patchy areas of haemorrhages were observed in different depths of the thickness of the wall. Large numbers of second generation schizonts, micro and macro gametocytes were observed in mucosa and submucosa replacing the normal structures Microgametocytes were oval with multiple nuclei and of variable size. The macrogametocytes were oval with peripheral plastic granules in the cytoplasm. The nucleus of epithelial cells appeared displaced against cell wall due to gametocytes. Inflammatory cells, predominantly macrophages, lymphocytes and heterophils, along with few plasma cells, were found infiltrating mucosa, submucosa and in between muscle fibers of the intestinal wall.
Caecal lumen contained large number of erythrocytes along with exfoliated epithelium.
Salinomycin treated group (IB) revealed distorted epithelium, increased thickness of caecal mucosa, compressed submucosa, but the second generation schizonts and gametocytes were less in numbers. The patchy areas of haemorrhages in mucosa and submucosa were with low intensity than in IA.
Coxynil groups (IC and ID) revealed similar changes, but damage to the epithelium, intensity of the haemorrhages (in mucosa and submucosa), gametocytes and infiltration of inflammatory cells were more in IC than in ID. The lesions in these groups were with more intensity than IB.
On 9 DPI, group IA revealed desquamated superficial caecal mucosa. At some of the places it was totally exfoliated exposing mucosa and muscularis mucosae. In epithelial cells and many of the internal glands, gametogenous stages and oocysts were present. Musuclaris externa revealed increased thickness, thereby pushing the submucosa upwards. Infiltration of lymphocytes and heterophils was seen in the mucosa, submucosa and to some extent in between muscle layers of the caecal wall.
Similar changes were observed in Salinomycin treated group (IB), but the intensity of lesions was less and the regeneration of epithelial lining was evident. Thymus revealed mild depopulation of cells in cortex and medulla and degenerative changes in Hassall’s corpuscles.
In Coxynil groups (IC and ID) the severity of lesions was less than that of infected group (IA). The gametogenous stages and oocysts appeared in large numbers than in IB. At some places regeneration of the epithelium was noticed. No appreciable lesions were observed in thymus and spleen. In both the groups (IC and ID) the lesions were nearly similar and were comparable with IB.
4.10 T Cell Counts: (ANAE)
The ANAE activity, in lymphocytes, was characterized by the presence of small reddish brown dots or globules, either single or multiple in the cytoplasm. The monocytes revealed similar, brownish, but diffused reaction. ANAE negative lymphocytes did not reveal any reaction and had pale green cytoplasm. ANAE positive cells were counted from 20 oil immersion fields and for each group three different sections were taken. The mean cell count per 20 oil immersion fields are given in Table No. 8.
Table No. 8: Average ANAE cell count.
NS- Non Significant
Average ANAE cell counts of infected groups were higher than the respective control groups. Infected birds revealed significantly higher counts on 9 DPI. Within control groups highest count was noted in group CC. Amongst all the groups, lowest count was recorded in group CA and highest in group IC.
4.11 HI Titer: (log 2)
HI titer was calculated for each group from serum samples collected from the sacrificed birds. The titers were expressed in log2 values and are presented in Table No. 9.
Table No. 9: Average HI titer (log 2).
* Significant at 5% level.
The average titers of infected groups were lower than that of the respective control groups. Within control groups, higher titers were observed in Coxynil groups (CC and CD), but the differences were non-significant. Amongst infected groups, highest titer was observed in group IC. Significantly low titer, compared to control groups, was noted in IA. Titers in Coxynil groups, at two different dose levels did not show significant difference.
4.12 Oocysts Antigen: The protein percentage of oocysts antigen was 0.8 gm%.
SUMMARY AND CONCLUSIONS
Present study was conducted on 160 day old broilers chicks randomly divided into eight groups of 20 birds each, maintained on deep litter system for 42 days. Two different coccidiostats were used in the study and oocysts challenge was carried out by oral inoculation, on 21 day of age with 20,000 sporulated oocysts of E. tenella per bird. Three birds from each group were sacrificed on 3, 6 and 9 DPI and lesion score, gross and microscopic changes were studied.
Birds given oocysts and without treatment (Gr. IA) exhibited dullness, loose droppings on 3 DPI and blood in droppings appeared on 4 DPI. Both the coccidiostat used in the study delayed the appearance of clinical symptoms in treated groups as compared to IA. Mortality was observed in IA and IC and both the drugs were effective in reducing the mortality.
Body weights were significantly less in infected groups than their respective controls. Salinomycin group (IB) revealed higher body weight than IA and highest weights were observed in Coxynil birds. After oocysts challenge, weight gains were significantly less in infected groups than the respective control groups. Highest gains in weights were observed in CD and ID, amongst control and infected groups, respectively. After oocysts challenge, feed intake was significantly less in infected groups than the respective control groups, except for Coxynil birds, where the differences were non-significant. FCR for infected groups, were significantly higher than the respective control groups, after oocysts challenge. Amongst control groups, FCR was lowest in CD and amongst infected groups in IB and ID.
OPG count was high on 8 DPI in infected groups and it decreased later in the treated groups as compared to IA, where it was highest. Amongst treatment groups, Salinomycin was found to be more effective than Coxynil in reducing OPG.
Gross changes in sacrificed birds were confined to caecae. Haemorrhages, blood clots and distention were observed on 6 DPI; caecal core formation and thickening of caecal wall was seen on 9 DPI, in infected group (IA). Salinomycin was found to be more effective than Coxynil in reducing the intensity of lesions, over the period.
Lesion score on 6 DPI was highest in all the treatment groups. Average score, for the period, did not differ significantly between the groups. Highest score was noted in IA and lowest in IB. Coxynil was found to be more effective on late developmental stages of coccidia rather than early stages.
Microscopically, on 3 DPI, catarrhal enteritis was evident in all the infected groups. On 6 DPI, denuded epithelium, large number of second generation schizonts and gametes, alongwith haemorrhages (in mucosa and submucosa) and on 9 DPI, exfoliated epithelium, gametogenous stages and oocysts in mucosa, were the prominent findings, in IA. Salinomycin was found to be more effective than Coxynil in reducing the severity of lesions and later on, microscopic alterations were comparable within treated groups.
ANAE cell counts, on 9 DPI, were significantly higher in infected groups than the respective control groups. Coxynil was found to be more beneficial over Salinomycin, as highest count, was observed in IC, amongst all the groups.
Average HI titers, in all the infected groups were low as compared to respective control groups and significantly lowest titer was observed in IA, amongst all the groups. Coxynil groups revealed higher titers than Salinomycin treated birds.
Thus from the present study it could be concluded that:
1. Poor performance, as indicated by clinical symptoms, body weights, feed intake, FCR, OPG count, lesion score, ANAE cell count and HI titer, in coccidial infection indicated the adverse effects of disease, in absence of preventive medication.
2. Salinomycin was found to arrest early and late developmental stages of coccidia, while Coxynil was effective against late developmental stages. They both were effective in alleviating the adverse effects of coccidiosis.
3. Coxynil had beneficial effects on weight gain, feed intake, feed conversion ratio and reduced the severity of lesions. It was effective as a feed additive and coccidiostat.
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