Oocysts Output of Broilers Experimentally Infected with Eimeria tenella And Treated with N- Butanol Leaf Extract of Khaya senegalensis
A study to determine the anticoccidial efficacy of Khaya senegalensis in relation to oocyst shedding by broilers experimentally infected with Eimeria tenella was conducted. The development of drug- resistant field strains of Eimeria species has prompted the exploitation of alternative methods for controlling coccidiosis and there is an increasing use of medicinal plants as alternatives to orthodox medicine. Fresh leaves of Khaya senegalensis (KS) were collected dried under shade and the extract prepared using the maceration method in 70% methanol. The dried crude extract was partitioned into petroleum ether, chloroform, n-butanol and aqueous portions, dried with phytochemical analysis conducted on them. One hundred and twenty birds reared under standard management practice were divided into six groups (A, B, C, D, E and F). All the groups except group F (uninfected untreated group) were infected at four weeks old with sporulated Eimeria tenella oocysts (1.0 x 105 sporulated oocysts / ml / bird) obtained locally from the intestinal scrapings of experimentally infected broilers. Groups A, B and C were given calculated three dose levels of 11mg/kg, 33mg/kg, 99mg/kg respectively of the prepared n-butanol methanol extract twice daily for 5 days, group D was given Amprolium while E and F were each given 0.2ml water. Faecal samples were collected daily for 4 weeks into clean well labelled polythene bags and analysed in the laboratory for oocyst count using the McMaster counting chamber and were expressed as oocysts count per gramme of faeces. The birds were observed for pathological lesions grossly and histopathologically and the survival rates were determined. Data collected were analysed using analysis of variance and chi square. Results from the Phytochemical studies showed the presence of phenolic compounds in Khaya senegalensis. Post-infection faecal examination revealed oocyst load of +++ in all the infected pens (A-E) on the 6th day. Comparison of the groups with time showed statistical significance (P˂0.05). High mean oocyst production (A; 156060 ± 67020, B; 261590 ± 144310, C; 211620 ± 114280, D; 276930 ± 233650 and E; 159230 ± 100970) among the infected groups one week post infection as well as irregular oocyst production were observed in the course of this study. The higher mean oocysts count obtained in the infected untreated group (1748849 ± 40869) than the extract treated groups in the first week post treatment indicated that the extract had some inhibitory effects on oocyst production. This however, was dose dependent. Among the extract treated group, the 99mg/kg had lower mean oocyst production 2 weeks post treatment (9720 ± 3180) and this was comparable to the group treated with normal dose of the conventional drug Amprolium (8600 ± 40). This was therefore seen as the effective dose. Grossly, the extract had a beneficial effect in alleviating the damages to the caecal epithelium of the infected treated groups compared to the shrunken caeca of the infected untreated groups. The survival percentage was higher in the treated groups compared to the infected un treated group (55%) though Amprolium was more efficacious in the in vivo study with the highest survival rate of 90%. The histopathological lesions observed in the infected birds in this study were consistent with those associated with E tenella infection in which the parasite induced very severe lesions including severe villous atrophy and fusion. The anticoccidial efficacy of Khaya senegalensis promises greater areas for research as it relates to drug development and it is recommended that Khaya senegalensis should be exploited further for its anticoccidial properties using other parts of the plant.
Key words: Broiler chickens, Eimeria tenella, oocyst production, Khaya senegalensis, in vivo