Author
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Allen, Patricia |
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Lydon, John |
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Danforth, Harry |
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Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 4/7/1997 Publication Date: N/A Citation: N/A Interpretive Summary: Dried leaves of Artemisia annua and several of its chemical constituents were tested as feed additives for possible anticoccidial activity. When fed for three wk at a level of 5%, a dried leaf supplement of A. annua provided signifcant protection against lesions due to E. tenella but not E. acervulina or E. maxima. When fed for five wk at a level of 1% to chicks undergoing immunization with a live vaccine, it provided significant protection in partially immunized chicks against E. acervulina and E. tenella lesions from a dual species challenge infection. It also afforded lower mean lesion scores in challenged chicks immunized over a period of 5 wk. The A. annua leaves contained 0.034% dry weight artemisinin, an antimalarial compound. A 5% leaf supplement thus afforded about 17 ppm artemesinin. Pure artemisinin fed at that level for a period of 3 wk protected weight gains and significantly reduced lesion scores attributable to E. tenella but not E. acervulina. Other components of A. annua, camphor and 1,8-cineole, at 119 ppm also protected weight gains, and reduced E. tenella lesion scores. Camphor reduced E. acervulina lesions. Artemesinin fed for four wk at levels of 2, 8.5, and 17 ppm significantly reduced oocyst output from separate E. acervulina and E. tenella infections and a dual species infection. Pure artemisinin thus appears to be effective against at least two coccidia species when used as a feed additive, and its activity may depend, in part, on the length of time it is administered before a challenge infection. Technical Abstract: Coccidiosis costs the American poultry industry approximately $350 million a year. Control has been primarily through the prophylactic use of anticoccidial drugs. However, many coccidia species have developed strains resistant to a large number of these drugs. Consequently new compounds are being investigated for their potential anticoccidial activity. One of these is artemisinin, an antimalarial compound found in leaves of artemisia annua (annual wormwood). A crop of A. annua was grown at this laboratory. In two experiments, using reduction in lesion scores as a criterion, dried leaves from this crop showed anticoccidial activity when added to starter feed and fed to chickens from one day of age. Pure artemisinin when fed for 3 wk at a level equivalent to 5% dried leaf supplement (17 ppm) also showed anticoccidial activity as did two other leaf constituents, camphor and 1,8-cineole when fed at levels approximating concentrations in a 5% leaf supplement (119 ppm). However, using a more sensitive criterion of reduction in oocyst output, pure artemesinin showed anticoccidial activity at a concentration as low as 2 ppm when fed for 4 wk. Thus, because of its apparent activity at low supplement levels, artemisinin shows a potential for use as a long term feed additive in the control of coccidiosis, and deserves further study. |
