Prevalence of Coccidia in Game-Farm Reared Pheasants in Iowa
Fisher, James Westbrook
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The problem. The present study was undertaken in order to obtain information concerning the kinds of coccidian species harbored by pheasants raised under game-farm conditions, and to determine the levels of infection of the coccidian species found. Procedure. Fecal samples collected from a mixed flock of 450 game-farm reared, adult ring-necked pheasants during a 20 week period beginning January 21, and ending June 3, 1973, were examined for coccidian oocysts. The number of oocysts per gm. of feces was determined for each week's sample by using a modified McMaster's helminth egg counting technique, and the proportion of the Eimeria species present in the block was determined by performing differential counts of the samples collected. One-hundred newly hatched pheasant chicks were also sampled for coccidian oocysts during a 5 week period beginning May 5, and ending June 3, 1973. The samples taken from the young birds were processed in a manner similar to that for the adult birds. Findings. Only four of the eight recognized species of Eimeria reported to infect the pheasant were found to be present in this study. They are Eimeria phasiani, E. pacifica, E. duodenalis, and E. tetartooimia. E. phasiani and E. pacifica were the most prevalent species in the adult birds each averaging 42.0 percent of the mean differential counts for the entire survey. E. tetartooimia and E. duodenalis were the next most prevalent species averaging 10.5 and 4.0 percent of the mean differential counts, respectively. E. phasiani, alone, dominated the differential counts of the samples taken from the young birds and occurred with 75.0 to 94.0 percent frequency. E. pacifica, E. tetartooimia, and E. duodenalis were the next most prevalent, respectively, all with percentages below 10. A small number of coccidian oocysts resembling those of Isospora lacazei were also found but these were considered to be contaminants from passeriform birds. Conclusions. As stated in the findings, four species of Eimeria and one of Isospora were found to be present in the ring-necked pheasants of this study. Oocyst production appeared to vary with the climatic conditions; if the climatic conditions were stable, the oocyst production was relatively stable, but if the climatic conditions were abruptly altered, the oocyst production appeared to increase. Immunity appeared to be well established in the young birds within 5 weeks after hatching and apparently a state of premunition existed within the hosts by this time. Recommendations. The epidemiological factors influencing coccidian infections are relatively unstudied. Investigations which attempt to analyze the influence of these factors on the etiology of coccidian infections should be of value not only from an academic point of view, but also from a practical point of view, namely, the control of the disease.