Effect of Anticoccidials and Antibiotics on the Control of Blackhead Disease in Broiler Breeder Pullets

Department of Poultry Science, University of Georgia, Атина, Georgia, United States
The Journal of Applied Poultry Research (Impact Factor: 0.59). 12/2002; 11(4):351-357. DOI: 10.1093/japr/11.4.351


Broiler chicks inoculated with both Histomonas and cecal coccidia developed moderately severe blackhead disease. Antibiotics tested at normal feed or water additive levels had little effect on Histomonas lesions or weight gains. Bacitracin at 100, 200, or 300 g/ton reduced liver lesion scores (P < 0.05) but had no other positive effects. Apramycin at 300 ppm in water reduced liver lesion scores (P < 0.05), but did not improve cecal lesions or weight gains. Penicillin (100 ppm), chlortetracycline (100 ppm), tylosin (110 ppm), and sarafloxacin (40 ppm) in water did not improve liver or cecal blackhead lesions. Weight gains were improved relative to infected controls by treating with penicillin, tylosin, or sarafloxacin (P < 0.05). Five anticoccidials (salinomycin, diclazuril, nicarbazin, roxarsone, and lasalocid) were tested at common use levels in two trials. Results were similar in both trials; liver lesion scores in the nicarbazin treatment were reduced (P < 0.05) compared with controls and other medicated groups, and the number of birds positive for liver lesions was lower (P < 0.05). Otherwise, anticoccidials had no effect on liver or cecal lesion scores or weight gains. Control of coccidiosis by the anticoccidials (as shown by oocyst counts) varied among products but was not correlated with severity of blackhead lesions. These results suggest that the effect of cecal coccidia on susceptibility of chickens to Histomonas meleagridis is not a simple function of mechanical damage to the cecal mucosa.

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    • "Previously used drugs have not yet been replaced resulting in an urgent need for new curative or prophylactic treatments. Several in vitro and in vivo experimental studies on chemotherapeutics have shown variable outcomes in finding a new and efficient therapy against H. meleagridis infections (Hu & McDougald, 2002; Hafez & Hauck, 2006; Bleyen et al., 2009; Hafez et al., 2010; Hauck et al., 2010b). Within recent years a trend towards non-chemotherapeutic alternative means has been set in the combat of histomonosis. "
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    ABSTRACT: Five different Artemisia annua-derived materials (i.e. dry leaves, pure artemisinin, and hexane, dichloromethane or methanol extracts of leaves) were screened for their in vitro activities against six clonal cultures of Histomonas meleagridis. Except for the methanol extract, all tested materials displayed in vitro activity against all tested protozoal clones. Neither the dry plant material, extracts nor artemisinin showed any antibacterial activity against the xenic bacteria accompanying the six H. meleagridis clones at concentration levels identical to the antihistomonal setting. The dichloromethane extract of dry leaves (Ext-DCM) (minimal lethal concentration=1.0 mg/ml) and artemisinin (half-maximal inhibitory concentration=1.295 mg/ml) had the most promising antihistomonal properties and were therefore subsequently tested in a standardized experimental infection model in both turkeys and chickens infected with clonal H. meleagridis. There were no differences between treatment groups, where all infected turkeys showed severe clinical histomonosis and demonstrated severe typhlohepatitis typical for histomonosis. Consistent with the infection model used, the infected chickens did not show any adverse clinical signs but contracted severe lesions in their caeca 7 and 10 days post infection (d.p.i.), liver lesions were absent to mild after 7 d.p.i. and progressed to severe lesions at 10 d.p.i.; thus no differences between treatment groups were observed. In conclusion, neither artemisinin nor Ext-DCM was able to prevent experimental histomonosis in turkeys and chickens at the given concentrations, which is contrary to the antihistomonal effect noticed in vitro even though the same clonal culture was used. The results of this study therefore clearly demonstrate the importance of defined in vivo experimentation in order to assess and verify in vitro results.
    Full-text · Article · Aug 2012 · Avian Pathology
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