COMPREHENSIVE STUDY OF EIMERIAN COCCIDIA AND COCCIDIOSIS IN CHICKEN
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Date
2016-07
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Assam Agricultural University, Khanapara, Guwahati
Abstract
A field study cum laboratory investigation was conducted to assess the field situation in respect of coccidia and coccidiosis in broiler chickens of Assam. One year study beginning from June, 2015 to May, 2016 included a questionnaire based interview on the disease problem with farmers and veterinary consultants during the visits to 48 randomly selected integrated and non-integrated commercial small scale farms under deep litter system of management in the districts of undivided Kamrup, Morigaon and Darrang. Faecal and litter sample examination, on-farm necropsy, identification of species of coccidia prevalent and their pathogenecity study alone or in association with common bacterial pathogens Escherichia coli and Clostridium perfringens were the other parameters included in the study. The farmers adopting broiler farming on commercial basis were mostly non-matriculate and had no prior training on poultry farming. A small section of farmers (27.08%) were found aware of the disease coccidiosis which was popularly called “Cocci” that occurred in the caecum of birds. These farmers viewed the problem of coccidiosis in their farms as an occasional occurrence in the recent past.
Microscopic examination of faecal, litter samples, intestinal contents, on farm necropsy and lesion study revealed 83.33% farms as coccidia positive. Out of 62.39% birds positive to coccidia oocysts, coccidiosis was diagnosed in 29.36% birds from 44.44% of the farms studied. Highest farm positivity to coccidia infection was recorded in Morigaon district (100%) followed by Darrang district (85.71%) and lowest in farms of Kamrup district (79.41%). However highest mortality due to coccidiosis in birds was recorded in Kamrup (36.62%) followed by Darrang (16.67%) and Morigaon (14.29%). Incidence of coccidia infection was higher in integration farms (29.17%) than that in non-integration farms (12.50%). Age wise, mortality in birds was recorded at 2-5 weeks of age with highest observation in 4 weeks aged birds. Coccidiosis was recorded in both dry and wet seasons of the year, the incidence being higher in wet season (22.92%) than in dry season (18.75%).
Identification of oocysts by Morphometry, Coccimorph tool and molecular methods employing nested PCR and multiplex PCR revealed presence of E. tenella, E. acervulina, E. mitis and E. maxima in the birds of the study area. E. tenella (62.50%) was the most predominant in single or mixed infection followed by E. acervulina (23.43%), E. mitis (12.50%) and E. maxima (1.56%) in mixed infections. Morphometry could be a useful tool for identification of Eimeria species in field diagnosis, however it was not found as efficient as PCR.
E. tenella was recorded as most pathogenic causing 100% mortality in experimental birds when maintained on both commercial and non-commercial non- medicated feeds. Uniform mortality irrespective of feed type suggested acquisition of resistance by the Eimeria species to anticoccidial drugs incorporated as additive in the commercial feed.
Escherichia coli and Clostridium perfringens Type A were islolated from the coccidia positive enteritic intestines of broiler chickens from the study area. Indigenous chickens recorded infection with Ascaridia galli (34.65%), Raillietina species (34.65%), Heterakis gallinarum (19.80%), Strongyloides species (3.96%) and coccidia (1.98%). Presence of Trichuris eggs in faeces but without adult parasite in birds might indicate ingestion of Trichuris eggs during scavenging on domestic animal’s dung.
Experimental infection with Cl. perfringens and E. coli preceeded by coccidia infection resulted exhibition of clinical symptoms viz., depression, ruffled feather, huddling, droopiness, dozing, ceased feeding, bloody diarrhoea, frequent drinking and 66.67% mortality in Cl. perfringens infected birds against 16.67% mortality in E. coli infected birds. Body weight performance in these two groups were significantly affected at 2-4 weeks post infection in comparison to that observed in infected control groups and healthy control. It is suggested that coccidia infection might predispose the birds to colibacillosis and necrotic enteritis under field condition.
Histopathological alterations due to necrotic enteritis in birds primed with coccidia were degenerative changes like swelling, vacuolar degeneration, nuclear degeneration and necrosis of hepatocytes, congestion in sinusoids and blood vessels and infiltration with polymorphonuclear cells. Intestinal lesions observed due to coccidia infection alone or in concurrence with Cl. perfringens or E. coli infections were mostly coagulative necrosis, sloughing off villous epithelial cells, haemorrhage, cellular infiltrations and presence of developmental stages of coccidia.
Present findings suggest that coccidia is a common health problem in broiler chickens of Assam and the disease due to coccidia is influenced by lack of awareness, inadequate training on the part of farmers, managemental procedures applied and quality of commercial feed being used in the farms.
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